Mixed Signal ISP Flash MCU Family
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Preliminary Rev. 1.4 12/05 Copyright © 2005 by Silicon Laboratories C8051F12x C8051F1 3x
Analog Peripherals
-10 or 12-bit SAR ADC
•± 1 LSB INL
•Programmable throughput up to 100 ksps
•Up to 8 external inputs; programmable as single-
ended or differential
•Programmable amplifier gain: 16, 8, 4, 2, 1, 0.5
•Data-dependent windowed interrupt generator
•Built-in temperature sensor
-8-bit SAR ADC (‘F12x Only)
•Programmable throughput up to 500 ksps
•8 external inputs (single-ended or differential)
•Programmable amplifier gain: 4, 2, 1, 0.5
-Two 12-bit DACs (‘F 12x Only)
•Can synchronize outputs to timers for jitter-free wave-
form generation
-Two Analog Comparators
-Voltage Referenc e
-VDD Monitor/Brown-Out Detector
On-Chip JTAG Debug & Boundary Scan
-On-chip debug circuitry facilitates full-speed, non-
intrusive in-circuit/in-system debugging
-Provides breakpoints, single-stepping, watchpoints,
stack monitor; inspect/modify memory and registers
-Superior performance to emulation systems using
ICE-chips, target pods, and sockets
-IEEE1149.1 compliant boundary scan
-Complete development kit
100-Pin TQFP or 64-Pin TQFP Packaging
-Temperature Range: –40 to +85 °C
-RoHS Available
High Speed 8051 µC Core
-Pipelined instruction architecture; executes 70% of
instruction set in 1 or 2 system clocks
-100 MIPS or 50 MIPS throughput with on-chip PLL
-2-cycle 16 x 16 MAC engine (C8051F120/1/2/3 and
C8051F130/1/2/3 only)
Memory
-8448 bytes internal data RAM (8 k + 256)
-128 or 64 kB Banked Flash; in -system programma-
ble in 1024-byte sectors
-External 64 kB data memory interface (programma-
ble multiplexed or non-multiplexed modes)
Digital Peripherals
-8 byte-wide port I/O (100TQFP); 5 V tolerant
-4 Byte-wide port I/O (64TQFP); 5 V tolerant
-Hardware SMBus™ (I2C™ Compatible), SPI™, and
two UART serial ports available concurrently
-Programmable 16-bit counter/timer array with
6 capture/compare modules
-5 general purpose 16-bit counter/timers
-Dedicated watchdog timer; bi-directional reset pin
Clock Sources
-Internal precision oscillator: 24.5 MH z
-Flexible PLL technology
-External Oscillator: Crystal, RC, C, or clock
Voltage Supples
-Range: 2.7–3.6 V (50 MIPS) 3.0–3.6 V (100 MIPS)
-Power saving sleep and shutdown modes
JTAG
128/64 kB
ISP FLASH 8448 B
SRAM 16 x 16 MAC
('F120/1/2/3, 'F13x)
+
-
10/12-bit
100ksps
ADC
CLOCK / PLL
CIRCUIT
PGA
VREF
12-Bit
DAC
TEMP
SENSOR
VOLTAGE
COMPARATORS
ANALOG PERIPHERALS
Port 0
Port 1
Port 2
Port 3
CROSSBAR
DIGITAL I/O
HIGH-SPEED CONTROLLER CORE
DEBUG
CIRCUITRY
20
INTERRUPTS
8051 CPU
(50 or 100MIPS)
12-Bit
DAC
+
-
8-bit
500ksps
ADC
Port 4
Port 5
Port 6
Port 7
Extern al Memory In terface
100 pin64 pin
PGA
UART0
SMBus
SPI Bus
PCA
Timer 0
Timer 1
Timer 2
Timer 3
Timer 4
UART1
AMUX
AMUX
C8051F12x Only
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
2 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 3
Table of Contents
1. System Overview.................................................................................................... 19
1.1. CIP-51™ Microcontroller Core.......................................................................... 27
1.1.1. Fully 8051 Compatible.............................................................................. 27
1.1.2. Improved Throughput............................................................................... 27
1.1.3. Additional Features .................................................................................. 28
1.2. On-Chip Memory............................................................................................... 29
1.3. JTAG Debug and Boundary Scan..................................................................... 30
1.4. 16 x 16 MAC (Multiply and Accumulate) Engine ............................................... 31
1.5. Programmable Digital I/O and Crossbar........................................................... 32
1.6. Programmable Counter Array........................................................................... 33
1.7. Serial Ports ....................................................................................................... 33
1.8. 12 or 10-Bit Analog to Digital Converter ........................................................... 34
1.9. 8-Bit Analog to Digital Converter....................................................................... 35
1.10.12-bit Digital to Analog Converters................................................................... 36
1.11.Analog Comparators......................................................................................... 37
2. Absolute Maximum Ratings .................................................................................. 38
3. Global DC Electrical Characteristics.................................................................... 39
4. Pinout and Package Definitions............................................................................ 41
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)........................................................... 55
5.1. Analog Multiplexer and PGA............................................................................. 55
5.2. ADC Modes of Operation.................................................................................. 57
5.2.1. Starting a Conversion............................................................................... 57
5.2.2. Tracking Modes........................................................................................ 58
5.2.3. Settling Time Requirements..................................................................... 59
5.3. ADC0 Programmable Window Detector ........................................................... 66
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)................................ 73
6.1. Analog Multiplexer and PGA............................................................................. 73
6.2. ADC Modes of Operation.................................................................................. 75
6.2.1. Starting a Conversion............................................................................... 75
6.2.2. Tracking Modes........................................................................................ 76
6.2.3. Settling Time Requirements..................................................................... 77
6.3. ADC0 Programmable Window Detector ........................................................... 84
7. ADC2 (8-Bit ADC, C8051F12x Only)...................................................................... 91
7.1. Analog Multiplexer and PGA............................................................................. 91
7.2. ADC2 Modes of Operation................................................................................ 92
7.2.1. Starting a Conversion............................................................................... 92
7.2.2. Tracking Modes........................................................................................ 92
7.2.3. Settling Time Requirements..................................................................... 94
7.3. ADC2 Programmable Window Detector ......................................................... 100
7.3.1. Window Detector In Single-Ended Mode ............................................... 100
7.3.2. Window Detector In Differential Mode.................................................... 101
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
4 Rev. 1.4
8. DACs, 12-Bit Voltage Mode (C8051F12x Only).................................................. 105
8.1. DAC Output Scheduling.................................................................................. 105
8.1.1. Update Output On-Demand ................................................................... 106
8.1.2. Update Output Based on Timer Overflow .............................................. 106
8.2. DAC Output Scaling/Justification.................................................................... 106
9. Voltage Reference................................................................................................ 113
9.1. Reference Configuration on the C8051F120/2/4/6......................................... 113
9.2. Reference Configuration on the C8051F121/3/5/7......................................... 115
9.3. Reference Configuration on the C8051F130/1/2/3......................................... 117
10.Comparators......................................................................................................... 119
11.CIP-51 Microcontroller......................................................................................... 127
11.1.Instruction Set................................................................................................. 129
11.1.1.Instruction and CPU Timing................................................................... 129
11.1.2.MOVX Instruction and Program Memory............................................... 129
11.2.Memory Organization..................................................................................... 133
11.2.1.Program Memory ................................................................................... 133
11.2.2.Data Memory.......................................................................................... 135
11.2.3.General Purpose Registers.................................................................... 135
11.2.4.Bit Addressable Locations...................................................................... 135
11.2.5.Stack ..................................................................................................... 135
11.2.6.Special Function Registers .................................................................... 136
11.2.7.Register Descriptions............................................................................. 151
11.3.Interrupt Handler............................................................................................. 154
11.3.1.MCU Interrupt Sources and Vectors...................................................... 154
11.3.2.External Interrupts.................................................................................. 155
11.3.3.Interrupt Priorities................................................................................... 156
11.3.4.Interrupt Latency.................................................................................... 156
11.3.5.Interrupt Register Descriptions............................................................... 157
11.4.Power Management Modes............................................................................ 163
11.4.1.Idle Mode ............................................................................................... 163
11.4.2.Stop Mode.............................................................................................. 164
12.Multiply And Accumulate (MAC0)....................................................................... 165
12.1.Special Function Registers............................................................................. 165
12.2.Integer and Fractional Math............................................................................ 166
12.3.Operating in Multiply and Accumulate Mode.................................................. 167
12.4.Operating in Multiply Only Mode .................................................................... 167
12.5.Accumulator Shift Operations......................................................................... 167
12.6.Rounding and Saturation................................................................................ 168
12.7.Usage Examples ............................................................................................ 168
12.7.1.Multiply and Accumulate Example......................................................... 168
12.7.2.Multiply Only Example............................................................................ 169
12.7.3.MAC0 Accumulator Shift Example......................................................... 169
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 5
13.Reset Sources....................................................................................................... 177
13.1.Power-on Reset.............................................................................................. 178
13.2.Power-fail Reset............................................................................................. 178
13.3.External Reset................................................................................................ 179
13.4.Missing Clock Detector Reset ........................................................................ 179
13.5.Comparator0 Reset........................................................................................ 179
13.6.External CNVSTR0 Pin Reset........................................................................ 179
13.7.Watchdog Timer Reset................................................................................... 179
13.7.1.Enable/Reset WDT ................................................................................ 180
13.7.2.Disable WDT.......................................................................................... 180
13.7.3.Disable WDT Lockout ............................................................................ 180
13.7.4.Setting WDT Interval.............................................................................. 180
14.Oscillators............................................................................................................. 185
14.1.Internal Calibrated Oscillator.......................................................................... 185
14.2.External Oscillator Drive Circuit...................................................................... 187
14.3.System Clock Selection.................................................................................. 187
14.4.External Crystal Example............................................................................... 190
14.5.External RC Example..................................................................................... 190
14.6.External Capacitor Example........................................................................... 190
14.7.Phase-Locked Loop (PLL).............................................................................. 191
14.7.1.PLL Input Clock and Pre-divider ............................................................ 191
14.7.2.PLL Multiplication and Output Clock...................................................... 191
14.7.3.Powering on and Initializing the PLL...................................................... 192
15.Flash Memory ....................................................................................................... 199
15.1.Programming the Flash Memory.................................................................... 199
15.1.1.Non-volatile Data Storage...................................................................... 200
15.1.2.Erasing Flash Pages From Software ..................................................... 201
15.1.3.Writing Flash Memory From Software.................................................... 202
15.2.Security Options............................................................................................. 203
15.2.1.Summary of Flash Security Options....................................................... 207
16.Branch Target Cache ........................................................................................... 211
16.1.Cache and Prefetch Operation....................................................................... 211
16.2.Cache and Prefetch Optimization................................................................... 212
17.External Data Memory Interface and On-Chip XRAM ........................................ 219
17.1.Accessing XRAM............................................................................................ 219
17.1.1.16-Bit MOVX Example........................................................................... 219
17.1.2.8-Bit MOVX Example............................................................................. 219
17.2.Configuring the External Memory Interface.................................................... 219
17.3.Port Selection and Configuration.................................................................... 220
17.4.Multiplexed and Non-multiplexed Selection.................................................... 222
17.4.1.Multiplexed Configuration....................................................................... 222
17.4.2.Non-multiplexed Configuration............................................................... 223
17.5.Memory Mode Selection................................................................................. 224
17.5.1.Internal XRAM Only ............................................................................... 224
17.5.2.Split Mode without Bank Select.............................................................. 224
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
6 Rev. 1.4
17.5.3.Split Mode with Bank Select................................................................... 225
17.5.4.External Only.......................................................................................... 225
17.6.EMIF Timing................................................................................................... 225
17.6.1.Non-multiplexed Mode........................................................................... 227
17.6.2.Multiplexed Mode................................................................................... 230
18.Port Input/Output.................................................................................................. 235
18.1.Ports 0 through 3 and the Priority Crossbar Decoder..................................... 238
18.1.1.Crossbar Pin Assignment and Allocation............................................... 238
18.1.2.Configuring the Output Modes of the Port Pins...................................... 239
18.1.3.Configuring Port Pins as Digital Inputs................................................... 240
18.1.4.Weak Pullups......................................................................................... 240
18.1.5.Configuring Port 1 Pins as Analog Inputs .............................................. 240
18.1.6.External Memory Interface Pin Assignments......................................... 241
18.1.7.Crossbar Pin Assignment Example........................................................ 243
18.2.Ports 4 through 7 (100-pin TQFP devices only)............................................. 252
18.2.1.Configuring Ports which are not Pinned Out.......................................... 252
18.2.2.Configuring the Output Modes of the Port Pins...................................... 252
18.2.3.Configuring Port Pins as Digital Inputs................................................... 253
18.2.4.Weak Pullups......................................................................................... 253
18.2.5.External Memory Interface..................................................................... 253
19.System Management Bus / I2C Bus (SMBus0).................................................. 259
19.1.Supporting Documents................................................................................... 260
19.2.SMBus Protocol.............................................................................................. 260
19.2.1.Arbitration............................................................................................... 261
19.2.2.Clock Low Extension.............................................................................. 261
19.2.3.SCL Low Timeout................................................................................... 261
19.2.4.SCL High (SMBus Free) Timeout .......................................................... 261
19.3.SMBus Transfer Modes.................................................................................. 262
19.3.1.Master Transmitter Mode....................................................................... 262
19.3.2.Master Receiver Mode........................................................................... 262
19.3.3.Slave Transmitter Mode......................................................................... 263
19.3.4.Slave Receiver Mode............................................................................. 263
19.4.SMBus Special Function Registers................................................................ 264
19.4.1.Control Register..................................................................................... 264
19.4.2.Clock Rate Register............................................................................... 267
19.4.3.Data Register......................................................................................... 268
19.4.4.Address Register.................................................................................... 268
19.4.5.Status Register....................................................................................... 269
20.Enhanced Serial Peripheral Interface (SPI0)...................................................... 273
20.1.Signal Descriptions......................................................................................... 274
20.1.1.Master Out, Slave In (MOSI).................................................................. 274
20.1.2.Master In, Slave Out (MISO).................................................................. 274
20.1.3.Serial Clock (SCK)................................................................................. 274
20.1.4.Slave Select (NSS) ................................................................................ 274
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 7
20.2.SPI0 Master Mode Operation......................................................................... 275
20.3.SPI0 Slave Mode Operation........................................................................... 277
20.4.SPI0 Interrupt Sources................................................................................... 277
20.5.Serial Clock Timing......................................................................................... 278
20.6.SPI Special Function Registers...................................................................... 280
21.UART0.................................................................................................................... 287
21.1.UART0 Operational Modes ............................................................................ 288
21.1.1.Mode 0: Synchronous Mode.................................................................. 288
21.1.2.Mode 1: 8-Bit UART, Variable Baud Rate.............................................. 289
21.1.3.Mode 2: 9-Bit UART, Fixed Baud Rate.................................................. 291
21.1.4.Mode 3: 9-Bit UART, Variable Baud Rate.............................................. 292
21.2.Multiprocessor Communications .................................................................... 293
21.2.1.Configuration of a Masked Address....................................................... 293
21.2.2.Broadcast Addressing............................................................................ 293
21.3.Frame and Transmission Error Detection....................................................... 294
22.UART1.................................................................................................................... 299
22.1.Enhanced Baud Rate Generation................................................................... 300
22.2.Operational Modes......................................................................................... 301
22.2.1.8-Bit UART............................................................................................. 301
22.2.2.9-Bit UART............................................................................................. 302
22.3.Multiprocessor Communications .................................................................... 303
23.Timers.................................................................................................................... 309
23.1.Timer 0 and Timer 1....................................................................................... 309
23.1.1.Mode 0: 13-bit Counter/Timer................................................................ 309
23.1.2.Mode 1: 16-bit Counter/Timer................................................................ 311
23.1.3.Mode 2: 8-bit Counter/Timer with Auto-Reload...................................... 311
23.1.4.Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)................................. 312
23.2.Timer 2, Timer 3, and Timer 4........................................................................ 317
23.2.1.Configuring Timer 2, 3, and 4 to Count Down........................................ 317
23.2.2.Capture Mode ........................................................................................ 318
23.2.3.Auto-Reload Mode................................................................................. 319
23.2.4.Toggle Output Mode (Timer 2 and Timer 4 Only).................................. 320
24.Programmable Counter Array............................................................................. 325
24.1.PCA Counter/Timer........................................................................................ 326
24.2.Capture/Compare Modules ............................................................................ 328
24.2.1.Edge-triggered Capture Mode................................................................ 329
24.2.2.Software Timer (Compare) Mode........................................................... 330
24.2.3.High Speed Output Mode....................................................................... 331
24.2.4.Frequency Output Mode ........................................................................ 332
24.2.5.8-Bit Pulse Width Modulator Mode......................................................... 333
24.2.6.16-Bit Pulse Width Modulator Mode....................................................... 334
24.3.Register Descriptions for PCA0...................................................................... 335
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
8 Rev. 1.4
25.JTAG (IEEE 1149.1) .............................................................................................. 341
25.1.Boundary Scan............................................................................................... 342
25.1.1.EXTEST Instruction................................................................................ 343
25.1.2.SAMPLE Instruction............................................................................... 343
25.1.3.BYPASS Instruction............................................................................... 343
25.1.4.IDCODE Instruction................................................................................ 343
25.2.Flash Programming Commands..................................................................... 344
25.3.Debug Support ............................................................................................... 347
Document Change List............................................................................................. 349
Contact Information.................................................................................................. 350
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 9
List of Figures
1. System Overview
Figure 1.1. C8051F120/124 Block Diagram............................................................. 21
Figure 1.2. C8051F121/125 Block Diagram............................................................. 22
Figure 1.3. C8051F122/126 Block Diagram............................................................. 23
Figure 1.4. C8051F123/127 Block Diagram............................................................. 24
Figure 1.5. C8051F130/132 Block Diagram............................................................. 25
Figure 1.6. C8051F131/133 Block Diagram............................................................. 26
Figure 1.7. On-Board Clock and Reset.................................................................... 28
Figure 1.8. On-Chip Memory Map............................................................................ 29
Figure 1.9. Development/In-System Debug Diagram............................................... 30
Figure 1.10. MAC0 Block Diagram........................................................................... 31
Figure 1.11. Digital Crossbar Diagram..................................................................... 32
Figure 1.12. PCA Block Diagram.............................................................................. 33
Figure 1.13. 12-Bit ADC Block Diagram................................................................... 34
Figure 1.14. 8-Bit ADC Diagram............................................................................... 35
Figure 1.15. DAC System Block Diagram ................................................................ 36
Figure 1.16. Comparator Block Diagram.................................................................. 37
2. Absolute Maximum Ratings
3. Global DC Electrical Characteristics
4. Pinout and Package Definitions
Figure 4.1. C8051F120/2/4/6 Pinout Diagram (TQFP-100) ..................................... 49
Figure 4.2. C8051F130/2 Pinout Diagram (TQFP-100) ........................................... 50
Figure 4.3. TQFP-100 Package Drawing................................................................. 51
Figure 4.4. C8051F121/3/5/7 Pinout Diagram (TQFP-64) ....................................... 52
Figure 4.5. C8051F131/3 Pinout Diagram (TQFP-64) ............................................. 53
Figure 4.6. TQFP-64 Package Drawing................................................................... 54
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)
Figure 5.1. 12-Bit ADC0 Functional Block Diagram................................................. 55
Figure 5.2. Typical Temperature Sensor Transfer Function..................................... 56
Figure 5.3. ADC0 Track and Conversion Example Timing....................................... 58
Figure 5.4. ADC0 Equivalent Input Circuits.............................................................. 59
Figure 5.5. ADC0 Data Word Example .................................................................... 65
Figure 5.6. 12-Bit ADC0 Window Interrupt Example:
Right Justified Single-Ended Data......................................................... 68
Figure 5.7. 12-Bit ADC0 Window Interrupt Example:
Right Justified Differential Data ............................................................. 69
Figure 5.8. 12-Bit ADC0 Window Interrupt Example:
Left Justified Single-Ended Data ........................................................... 70
Figure 5.9. 12-Bit ADC0 Window Interrupt Example:
Left Justified Differential Data................................................................ 71
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
10 Rev. 1.4
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)
Figure 6.1. 10-Bit ADC0 Functional Block Diagram................................................. 73
Figure 6.2. Typical Temperature Sensor Transfer Function..................................... 74
Figure 6.3. ADC0 Track and Conversion Example Timing....................................... 76
Figure 6.4. ADC0 Equivalent Input Circuits.............................................................. 77
Figure 6.5. ADC0 Data Word Example .................................................................... 83
Figure 6.6. 10-Bit ADC0 Window Interrupt Example:
Right Justified Single-Ended Data......................................................... 86
Figure 6.7. 10-Bit ADC0 Window Interrupt Example:
Right Justified Differential Data ............................................................. 87
Figure 6.8. 10-Bit ADC0 Window Interrupt Example:
Left Justified Single-Ended Data ........................................................... 88
Figure 6.9. 10-Bit ADC0 Window Interrupt Example:
Left Justified Differential Data................................................................ 89
7. ADC2 (8-Bit ADC, C8051F12x Only)
Figure 7.1. ADC2 Functional Block Diagram............................................................ 91
Figure 7.2. ADC2 Track and Conversion Example Timing....................................... 93
Figure 7.3. ADC2 Equivalent Input Circuit................................................................ 94
Figure 7.4. ADC2 Data Word Example .................................................................... 99
Figure 7.5. ADC2 Window Compare Examples, Single-Ended Mode.................... 100
Figure 7.6. ADC2 Window Compare Examples, Differential Mode........................ 101
8. DACs, 12-Bit Voltage Mode (C8051F12x Only)
Figure 8.1. DAC Functional Block Diagram............................................................ 105
9. Voltage Reference
Figure 9.1. Voltage Reference Functional Block Diagram (C8051F120/2/4/6)...... 114
Figure 9.2. Voltage Reference Functional Block Diagram (C8051F121/3/5/7)...... 115
Figure 9.3. Voltage Reference Functional Block Diagram (C8051F130/1/2/3)...... 117
10.Comparators
Figure 10.1. Comparator Functional Block Diagram .............................................. 119
Figure 10.2. Comparator Hysteresis Plot ............................................................... 121
11.CIP-51 Microcontroller
Figure 11.1. CIP-51 Block Diagram....................................................................... 128
Figure 11.2. Memory Map ...................................................................................... 133
Figure 11.3. Address Memory Map for Instruction Fetches (128 kB Flash Only)... 134
Figure 11.4. SFR Page Stack................................................................................. 137
Figure 11.5. SFR Page Stack While Using SFR Page 0x0F To Access Port 5...... 138
Figure 11.6. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs. 139
Figure 11.7. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR140
Figure 11.8. SFR Page Stack Upon Return From PCA Interrupt........................... 140
Figure 11.9. SFR Page Stack Upon Return From ADC2 Window Interrupt........... 141
12.Multiply And Accumulate (MAC0)
Figure 12.1. MAC0 Block Diagram......................................................................... 165
Figure 12.2. Integer Mode Data Representation.................................................... 166
Figure 12.3. Fractional Mode Data Representation................................................ 166
Figure 12.4. MAC0 Pipeline.................................................................................... 167
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 11
13.Reset Sources
Figure 13.1. Reset Sources.................................................................................... 177
Figure 13.2. Reset Timing...................................................................................... 178
14.Oscillators
Figure 14.1. Oscillator Diagram.............................................................................. 185
Figure 14.2. PLL Block Diagram............................................................................. 191
15.Flash Memory
Figure 15.1. Flash Memory Map for MOVC Read and MOVX Write Operations ... 201
Figure 15.2. 128 kB Flash Memory Map and Security Bytes ................................. 204
Figure 15.3. 64 kB Flash Memory Map and Security Bytes ................................... 205
16.Branch Target Cache
Figure 16.1. Branch Target Cache Data Flow........................................................ 211
Figure 16.2. Branch Target Cache Organiztion...................................................... 212
Figure 16.3. Cache Lock Operation........................................................................ 214
17.External Data Memory Interface and On-Chip XRAM
Figure 17.1. Multiplexed Configuration Example.................................................... 222
Figure 17.2. Non-multiplexed Configuration Example............................................ 223
Figure 17.3. EMIF Operating Modes...................................................................... 224
Figure 17.4. Non-multiplexed 16-bit MOVX Timing................................................ 227
Figure 17.5. Non-multiplexed 8-bit MOVX without Bank Select Timing ................. 228
Figure 17.6. Non-multiplexed 8-bit MOVX with Bank Select Timing ...................... 229
Figure 17.7. Multiplexed 16-bit MOVX Timing........................................................ 230
Figure 17.8. Multiplexed 8-bit MOVX without Bank Select Timing......................... 231
Figure 17.9. Multiplexed 8-bit MOVX with Bank Select Timing.............................. 232
18.Port Input/Output
Figure 18.1. Port I/O Cell Block Diagram ............................................................... 235
Figure 18.2. Port I/O Functional Block Diagram..................................................... 237
Figure 18.3. Priority Crossbar Decode Table (EMIFLE = 0; P1MDIN = 0xFF)....... 238
Figure 18.4. Priority Crossbar Decode Table
(EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xFF)................ 241
Figure 18.5. Priority Crossbar Decode Table
(EMIFLE = 1; EMIF in Non-Multiplexed Mode; P1MD IN = 0xFF)........ 242
Figure 18.6. Crossbar Example.............................................................................. 244
19.System Management Bus / I2C Bus (SMBus0)
Figure 19.1. SMBus0 Block Diagram ..................................................................... 259
Figure 19.2. Typical SMBus Configuration............................................................. 260
Figure 19.3. SMBus Transaction............................................................................ 261
Figure 19.4. Typical Master Transmitter Sequence................................................ 262
Figure 19.5. Typical Master Receiver Sequence.................................................... 262
Figure 19.6. Typical Slave Transmitter Sequence.................................................. 263
Figure 19.7. Typical Slave Receiver Sequence...................................................... 263
20.Enhanced Serial Peripheral Interface (SPI0)
Figure 20.1. SPI Block Diagram............................................................................. 273
Figure 20.2. Multiple-Master Mode Connection Diagram....................................... 276
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram............. 276
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
12 Rev. 1.4
Figure 20.4. 4-Wire Single Master and Slave Mode Connection Diagram............. 276
Figure 20.5. Master Mode Data/Clock Timing........................................................ 278
Figure 20.6. Slave Mode Data/Clock Timing (CKPHA = 0).................................... 279
Figure 20.7. Slave Mode Data/Clock Timing (CKPHA = 1).................................... 279
Figure 20.8. SPI Master Timing (CKPHA = 0)........................................................ 283
Figure 20.9. SPI Master Timing (CKPHA = 1)........................................................ 283
Figure 20.10. SPI Slave Timing (CKPHA = 0)........................................................ 284
Figure 20.11. SPI Slave Timing (CKPHA = 1)........................................................ 284
21.UART0
Figure 21.1. UART0 Block Diagram....................................................................... 287
Figure 21.2. UART0 Mode 0 Timing Diagram........................................................ 288
Figure 21.3. UART0 Mode 0 Interconnect.............................................................. 288
Figure 21.4. UART0 Mode 1 Timing Diagram....................................................... 289
Figure 21.5. UART0 Modes 2 and 3 Timing Diagram ............................................ 291
Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram .............................. 292
Figure 21.7. UART Multi-Processor Mode Interconnect Diagram.......................... 294
22.UART1
Figure 22.1. UART1 Block Diagram....................................................................... 299
Figure 22.2. UART1 Baud Rate Logic.................................................................... 300
Figure 22.3. UART Interconnect Diagram.............................................................. 301
Figure 22.4. 8-Bit UART Timing Diagram.............................................................. 301
Figure 22.5. 9-Bit UART Timing Diagram............................................................... 302
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram.......................... 303
23.Timers
Figure 23.1. T0 Mode 0 Block Diagram.................................................................. 310
Figure 23.2. T0 Mode 2 Block Diagram.................................................................. 311
Figure 23.3. T0 Mode 3 Block Diagram.................................................................. 312
Figure 23.4. T2, 3, and 4 Capture Mode Block Diagram........................................ 318
Figure 23.5. Tn Auto-reload (T2,3,4) and Toggle Mode (T2,4) Block Diagram..... 319
24.Programmable Counter Array
Figure 24.1. PCA Block Diagram............................................................................ 325
Figure 24.2. PCA Counter/Timer Block Diagram.................................................... 326
Figure 24.3. PCA Interrupt Block Diagram............................................................. 328
Figure 24.4. PCA Capture Mode Diagram.............................................................. 329
Figure 24.5. PCA Software Timer Mode Diagram.................................................. 330
Figure 24.6. PCA High Speed Output Mode Diagram............................................ 331
Figure 24.7. PCA Frequency Output Mode............................................................ 332
Figure 24.8. PCA 8-Bit PWM Mode Diagram......................................................... 333
Figure 24.9. PCA 16-Bit PWM Mode...................................................................... 334
25.JTAG (IEEE 1149.1)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 13
List Of Tables
1. System Overview
Table 1.1. Product Selection Guide ......................................................................... 20
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings .................................................................... 38
3. Global DC Electrical Characteristics
Table 3.1. G lobal DC Electrical Characteristics
(C8051F120/1/2/3 and C8051F130/1/2/3) ............................................. 39
Table 3.2. Global DC Electrical Characteristics (C8051F124/5/6/7) ....................... 40
4. Pinout and Package Definitions
Table 4.1. Pin Definitions ......................................................................................... 41
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)
Table 5.1. 12-Bit ADC0 Electrical Characteristics (C8051F120/1/4/5) .................... 72
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)
Table 6.1. 10-Bit ADC0 Ele c trical Characteristics
(C8051F122/3/6/7 and C8051F13x) ...................................................... 90
7. ADC2 (8-Bit ADC, C8051F12x Only)
Table 7.1. ADC2 Electrical Characteristics ............................................................ 103
8. DACs, 12-Bit Voltage Mode (C8051F12x Only)
Table 8.1. DAC Electrical Characteristics .............................................................. 111
9. Voltage Reference
Table 9.1. Voltage Reference Electrical Characteristics ....................................... 118
10.Comparators
Table 10.1. Comparator Electrical Characteristics ................................................ 126
11.CIP-51 Microcontroller
Table 11.1. CIP-51 Instruction Set Summary ........................................................ 129
Table 11.2. Special Function Register (SFR) Memory Map .................................. 144
Table 11.3. Special Function Registers ................................................................. 146
Table 11.4. Interrupt Summary .............................................................................. 155
12.Multiply And Accumulate (MAC0)
Table 12.1. MAC0 Rounding (MAC0SAT = 0) ....................................................... 168
13.Reset Sources
Table 13.1. Reset Electrical Characteristics .......................................................... 183
14.Oscillators
Table 14.1. Oscillator Electrical Characteristics .................................................... 185
Table 14.2. PLL Frequency Characteri stics .......................................................... 195
Table 14.3. PLL Lock Timing Characteristics ........................................................ 196
15.Flash Memory
Table 15.1. F lash Electrical Characteristics .......................................................... 200
16.Branch Target Cache
17.External Data Memory Interface and On-Chip XRAM
Table 17.1. AC Parameters for External Memory Interface ................................... 233
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
14 Rev. 1.4
18.Port Input/Output
Table 18.1. Port I/O DC Electrical Characteristics ................................................. 236
19.System Management Bus / I2C Bus (SMBus0)
Table 19.1. SMB0STA Status Codes and States .................................................. 270
20.Enhanced Serial Peripheral Interface (SPI0)
Table 20.1. SPI Slave Timing Parameters ............................................................ 285
21.UART0
Table 21.1. UART0 Modes .................................................................................... 288
Table 21.2. Oscillator Frequencies for Standard Baud Rates ............................... 295
22.UART1
Table 22.1. T imer Settings for Standard Baud Rates
Using The Internal 24.5 MHz Oscillator ............................................... 305
Table 22.2. T imer Settings for Standard Baud Rates
Using an External 25.0 MHz Oscillator ................................................ 306
Table 22.3. T imer Settings for Standard Baud Rates
Using an External 22.1184 MHz Oscillator .......................................... 306
Table 22.4. Timer Settings for Standard Baud Rates Using the PLL .................... 307
Table 22.5. Timer Settings for Standard Baud Rates Using the PLL .................... 307
23.Timers
24.Programmable Counter Array
Table 24.1. PCA Timebase Input Options ............................................................. 326
Table 24.2. PCA0CPM Register Settings for PCA Capture/Compare Modules .... 329
25.JTAG (IEEE 1149.1)
Table 25.1. Boundary Data Register Bit Definitions .............................................. 342
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 15
List of Registers
SFR Definition 5.1. AMX0CF: AMUX0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 60
SFR Definition 5.2. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . 61
SFR Definition 5.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
SFR Definition 5.4. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
SFR Definition 5.5. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 64
SFR Definition 5.6. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 66
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 66
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 67
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . 67
SFR Definition 6.1. AMX0CF: AMUX0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 78
SFR Definition 6.2. AMX0SL: AMUX0 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . . 79
SFR Definition 6.3. ADC0CF: ADC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
SFR Definition 6.4. ADC0CN: ADC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
SFR Definition 6.5. ADC0H: ADC0 Data Word MSB . . . . . . . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 6.6. ADC0L: ADC0 Data Word LSB . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
SFR Definition 6.7. ADC0GTH: ADC0 Greater-Than Data High Byte . . . . . . . . . . . . . 84
SFR Definition 6.8. ADC0GTL: ADC0 Greater-Than Data Low Byte . . . . . . . . . . . . . . 84
SFR Definition 6.9. ADC0LTH: ADC0 Less-Than Data High Byte . . . . . . . . . . . . . . . . 85
SFR Definition 6.10. ADC0LTL: ADC0 Less-Than Data Low Byte . . . . . . . . . . . . . . . 85
SFR Definition 7.1. AMX2CF: AMUX2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 95
SFR Definition 7.2. AMX2SL: AMUX2 Channel Select . . . . . . . . . . . . . . . . . . . . . . . . 96
SFR Definition 7.3. ADC2CF: ADC2 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
SFR Definition 7.4. ADC2CN: ADC2 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
SFR Definition 7.5. ADC2: ADC2 Data Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
SFR Definition 7.6. ADC2GT: ADC2 Greater-Than Data Byte . . . . . . . . . . . . . . . . . . 102
SFR Definition 7.7. ADC2LT: ADC2 Less-Than Data Byte . . . . . . . . . . . . . . . . . . . . 102
SFR Definition 8.1. DAC0H: DAC0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 8.2. DAC0L: DAC0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
SFR Definition 8.3. DAC0CN: DAC0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
SFR Definition 8.4. DAC1H: DAC1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SFR Definition 8.5. DAC1L: DAC1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
SFR Definition 8.6. DAC1CN: DAC1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
SFR Definition 9.1. REF0CN: Reference Control (C8051F120/2/4/6) . . . . . . . . . . . . 114
SFR Definition 9.2. REF0CN: Reference Control (C8051F121/3/5/7) . . . . . . . . . . . . 116
SFR Definition 9.3. REF0CN: Reference Control (C8051F130/1/2/3) . . . . . . . . . . . . 117
SFR Definition 10.1. CPT0CN: Comparator0 Control . . . . . . . . . . . . . . . . . . . . . . . . . 122
SFR Definition 10.2. CPT0MD: Comparator0 Mode Selection . . . . . . . . . . . . . . . . . 123
SFR Definition 10.3. CPT1CN: Comparator1 Control . . . . . . . . . . . . . . . . . . . . . . . . . 124
SFR Definition 10.4. CPT1MD: Comparator1 Mode Selection . . . . . . . . . . . . . . . . . 125
SFR Definition 11.1. PSBANK: Program Space Bank Select . . . . . . . . . . . . . . . . . . 134
SFR Definition 11.2. SFRPGCN: SFR Page Control . . . . . . . . . . . . . . . . . . . . . . . . . 142
SFR Definition 11.3. SFRPAGE: SFR Page . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
16 Rev. 1.4
SFR Definition 11.4. SFRNEXT: SFR Next Register . . . . . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 11.5. SFRLAST: SFR Last Register . . . . . . . . . . . . . . . . . . . . . . . . . 143
SFR Definition 11.6. SP: Stack Pointer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 11.7. DPL: Data Pointer Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 11.8. DPH: Data Pointer High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 151
SFR Definition 11.9. PSW: Program Status Word . . . . . . . . . . . . . . . . . . . . . . . . . . . 152
SFR Definition 11.10. ACC: Accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 11.11. B: B Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
SFR Definition 11.12. IE: Interrupt Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157
SFR Definition 11.13. IP: Interrupt Priority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
SFR Definition 11.14. EIE1: Extended Interrupt Enable 1 . . . . . . . . . . . . . . . . . . . . . 159
SFR Definition 11.15. EIE2: Extended Interrupt Enable 2 . . . . . . . . . . . . . . . . . . . . . 160
SFR Definition 11.16. EIP1: Extended Interrupt Priority 1 . . . . . . . . . . . . . . . . . . . . . 161
SFR Definition 11.17. EIP2: Extended Interrupt Priority 2 . . . . . . . . . . . . . . . . . . . . . 162
SFR Definition 11.18. PCON: Power Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
SFR Definition 12.1. MAC0CF: MAC0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . 170
SFR Definition 12.2. MAC0STA: MAC0 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171
SFR Definition 12.3. MAC0AH: MAC0 A High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 171
SFR Definition 12.4. MAC0AL: MAC0 A Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SFR Definition 12.5. MAC0BH: MAC0 B High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SFR Definition 12.6. MAC0BL: MAC0 B Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . 172
SFR Definition 12.7. MAC0ACC3: MAC0 Accumulator Byte 3 . . . . . . . . . . . . . . . . . . 173
SFR Definition 12.8. MAC0ACC2: MAC0 Accumulator Byte 2 . . . . . . . . . . . . . . . . . 173
SFR Definition 12.9. MAC0ACC1: MAC0 Accumulator Byte 1 . . . . . . . . . . . . . . . . . 173
SFR Definition 12.10. MAC0ACC0: MAC0 Accumulator Byte 0 . . . . . . . . . . . . . . . . . 174
SFR Definition 12.11. MAC0OVR: MAC0 Accumulator Overflow . . . . . . . . . . . . . . . . 174
SFR Definition 12.12. MAC0RNDH: MAC0 Rounding Register High Byte . . . . . . . . . 174
SFR Definition 12.13. MAC0RNDL: MAC0 Rounding Register Low Byte . . . . . . . . . 175
SFR Definition 13.1. WDTCN: Watchdog Timer Control . . . . . . . . . . . . . . . . . . . . . . 181
SFR Definition 13.2. RSTSRC: Reset Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182
SFR Definition 14.1. OSCICL: Internal Oscillator Calibration. . . . . . . . . . . . . . . . . . . 186
SFR Definition 14.2. OSCICN: Internal Oscillator Control . . . . . . . . . . . . . . . . . . . . . 186
SFR Definition 14.3. CLKSEL: System Clock Selection . . . . . . . . . . . . . . . . . . . . . . . 188
SFR Definition 14.4. OSCXCN: External Oscillator Control . . . . . . . . . . . . . . . . . . . . 189
SFR Definition 14.5. PLL0CN: PLL Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
SFR Definition 14.6. PLL0DIV: PLL Pre-divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 14.7. PLL0MUL: PLL Clock Scaler . . . . . . . . . . . . . . . . . . . . . . . . . . . 194
SFR Definition 14.8. PLL0FLT: PLL Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
SFR Definition 15.1. FLACL: Flash Access Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
SFR Definition 15.2. FLSCL: Flash Memory Control . . . . . . . . . . . . . . . . . . . . . . . . . 208
SFR Definition 15.3. PSCTL: Program Store Read/Write Control . . . . . . . . . . . . . . . 209
SFR Definition 16.1. CCH0CN: Cache Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
SFR Definition 16.2. CCH0TN: Cache Tuning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 216
SFR Definition 16.3. CCH0LC: Cache Lock Control . . . . . . . . . . . . . . . . . . . . . . . . . 216
SFR Definition 16.4. CCH0MA: Cache Miss Accumulator . . . . . . . . . . . . . . . . . . . . . 217
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 17
SFR Definition 16.5. FLSTAT: Flash Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217
SFR Definition 17.1. EMI0CN: External Memory Interface Control . . . . . . . . . . . . . . 220
SFR Definition 17.2. EMI0CF: External Memory Configuration . . . . . . . . . . . . . . . . . 221
SFR Definition 17.3. EMI0TC: External Memory Timing Control . . . . . . . . . . . . . . . . 226
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0 . . . . . . . . . . . . . . . . . . . . . 245
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1 . . . . . . . . . . . . . . . . . . . . . 246
SFR Definition 18.3. XBR2: Port I/O Crossbar Register 2 . . . . . . . . . . . . . . . . . . . . . 247
SFR Definition 18.4. P0: Port0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 18.5. P0MDOUT: Port0 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 248
SFR Definition 18.6. P1: Port1 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
SFR Definition 18.7. P1MDIN: Port1 Input Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249
SFR Definition 18.8. P1MDOUT: Port1 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . . 250
SFR Definition 18.9. P2: Port2 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
SFR Definition 18.10. P2MDOUT: Port2 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 251
SFR Definition 18.11. P3: Port3 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251
SFR Definition 18.12. P3MDOUT: Port3 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 252
SFR Definition 18.13. P4: Port4 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 18.14. P4MDOUT: Port4 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 254
SFR Definition 18.15. P5: Port5 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
SFR Definition 18.16. P5MDOUT: Port5 Output Mod e . . . . . . . . . . . . . . . . . . . . . . . 255
SFR Definition 18.17. P6: Port6 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 256
SFR Definition 18.18. P6MDOUT: Port6 Output Mode . . . . . . . . . . . . . . . . . . . . . . . . 256
SFR Definition 18.19. P7: Port7 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257
SFR Definition 18.20. P7MDOUT: Port7 Output Mode . . . . . . . . . . . . . . . . . . . . . . . 257
SFR Definition 19.1. SMB0CN: SMBus0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 266
SFR Definition 19.2. SMB0CR: SMBus0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . 267
SFR Definition 19.3. SMB0DAT: SMBus0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 268
SFR Definition 19.4. SMB0ADR: SMBus0 Address . . . . . . . . . . . . . . . . . . . . . . . . . . 269
SFR Definition 19.5. SMB0STA: SMBus0 Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269
SFR Definition 20.1. SPI0CFG: SPI0 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . 280
SFR Definition 20.2. SPI0CN: SPI0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 281
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
SFR Definition 20.4. SPI0DAT: SPI0 Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282
SFR Definition 21.1. SCON0: UART0 Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296
SFR Definition 21.2. SSTA0: UART0 Status and Clock Selection . . . . . . . . . . . . . . . 297
SFR Definition 21.3. SBUF0: UART0 Data Buffer . . . . . . . . . . . . . . . . . . . . . . . . . . . 298
SFR Definition 21.4. SADDR0: UART0 Slave Address . . . . . . . . . . . . . . . . . . . . . . . 298
SFR Definition 21.5. SADEN0: UART0 Slave Address Enable . . . . . . . . . . . . . . . . . 298
SFR Definition 22.1. SCON1: Serial Port 1 Control . . . . . . . . . . . . . . . . . . . . . . . . . . 304
SFR Definition 22.2. SBUF1: Serial (UART1) Port Data Buffer . . . . . . . . . . . . . . . . . 305
SFR Definition 23.1. TCON: Timer Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 313
SFR Definition 23.2. TMOD: Timer Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314
SFR Definition 23.3. CKCON: Clock Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
SFR Definition 23.4. TL0: Timer 0 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315
SFR Definition 23.5. TL1: Timer 1 Low Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
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18 Rev. 1.4
SFR Definition 23.6. TH0: Timer 0 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
SFR Definition 23.7. TH1: Timer 1 High Byte . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316
SFR Definition 23.8. TMRnCN: Timer 2, 3, and 4 Control . . . . . . . . . . . . . . . . . . . . . 321
SFR Definition 23.9. TMRnCF: Timer 2, 3, and 4 Configuration . . . . . . . . . . . . . . . . 322
SFR Definition 23.10. RCAPnL: Timer 2, 3, and 4 Capture Register Low Byte . . . . . 323
SFR Definition 23.11. RCAPnH: Timer 2, 3, and 4 Capture Register High Byte . . . . 323
SFR Definition 23.12. TMRnL: Timer 2, 3, and 4 Low Byte . . . . . . . . . . . . . . . . . . . . 323
SFR Definition 23.13. TMRnH Timer 2, 3, and 4 High Byte . . . . . . . . . . . . . . . . . . . 324
SFR Definition 24.1. PCA0CN: PCA Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 335
SFR Definition 24.2. PCA0MD: PCA0 Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 336
SFR Definition 24.3. PCA0CPMn: PCA0 Capture/Compare Mode . . . . . . . . . . . . . . 337
SFR Definition 24.4. PCA0L: PCA0 Counter/Timer Low Byte . . . . . . . . . . . . . . . . . . 338
SFR Definition 24.5. PCA0H: PCA0 Counter/Timer High Byte . . . . . . . . . . . . . . . . . . 338
SFR Definition 24.6. PCA0CPLn: PCA0 Capture Module Low Byte . . . . . . . . . . . . . . 338
SFR Definition 24.7. PCA0CPHn: PCA0 Capture Module High Byte . . . . . . . . . . . . 339
JTAG Register Definition 25.1. IR: JTAG Instruction Register . . . . . . . . . . . . . . . . . . 341
JTAG Register Definition 25.2. DEVICEID: JTAG Device ID . . . . . . . . . . . . . . . . . . . 343
JTAG Register Definition 25.3. FLASHCON: JTAG Flash Control . . . . . . . . . . . . . . . 345
JTAG Register Definition 25.4. FLASHDAT: JTAG Flash Data . . . . . . . . . . . . . . . . . 346
JTAG Register Definition 25.5. FLASHADR: JTAG Flash Address . . . . . . . . . . . . . . 346
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 19
1. System Overview
The C8051F12x and C8051F13x device families are fully integrated mixed-signal System-on-a-Chip
MCUs with 64 digital I/O pins (100-pin TQFP) or 32 digital I/O pins (64-pin TQFP).
Highlighted featu re s ar e liste d be low. Refer to Table 1.1 for specific product feature selection.
• High-Speed pipelined 8051-compatible CIP-51 microcontroller core (100 MIPS or 50 MIPS)
• In-system, full-speed, non-intrusive debug interface (on-chip)
• True 12 or 10-bit 100 ksps ADC with PGA and 8-channel analog multiplexer
• True 8-bit 500 ksps ADC with PGA and 8-channel analog multiplexer (C8051F12x Family)
• Two 12-bit DACs with programmable update sch eduling (C8051F12x Family)
• 2-cycle 16 by 16 Multiply and Accumulate Engine (C8051F120/1/2/3 and C8051F130/1/2/3)
• 128 or 64 kB of in-system programmable Flash memory
• 8448 (8 k + 256) bytes of on-chip RAM
• External Data Memory Interface with 64 kB address space
• SPI, SMBus/I2C, and (2) UART serial interfaces implemented in hardware
• Five general purpose 16-bit Timers
• Programmable Counter/T imer Array with 6 capture/compare modules
• On-chip Watchdog Timer, VDD Monitor, and Temperature Sensor
With on-chip VDD monitor, Watchdog Timer, and clock oscillator, the C8051F12x and C8051F13x devices
are truly stand-alone System-on-a-Chip solutions. All analog and digital peripherals are enabled/disabled
and configured by user firmware. The Flash memory can be reprogrammed even in-circuit, providing non-
volatile data storage, and also allowing field upgrades of the 8051 firmware.
On-board JTAG debug circuitry allows non-intrusive (uses no on-chip resources), full speed, in-circuit
debugging using the produ ctio n MCU inst a lled in the fina l app lication. This debug system supports inspec-
tion and modification of memory and registers, setting breakpoints, watchpoints, single stepping, run and
halt commands. All analog and digital peripher a ls are fully functional while debugging using JTAG.
Each MCU is specified for operation over the industrial temperature range (–45 to +85 °C). The Port I/O,
RST, and JTAG pins are tolerant for input signals up to 5 V. The devices are available in 100-pin TQFP or
64-pin TQFP packaging. Table 1.1 lists the specific device features and package offerings for each part
number. Figure 1.1 through Figure 1.6 show functional block diagrams for each device.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
20 Rev. 1.4
Table 1.1. Product Selection Guide
Ordering Part Number
MIPS (Peak)
Flash Memory
RAM
2-cycle 16 by 16 MAC
External Memory Interface
SMBus/I2C
SPI
UARTS
Timers (16-bit)
Programmable Counter Array
Digital Port I/O’s
12-bit 100ksps ADC Inputs
10-bit 100ksps ADC Inputs
8-bit 500ksps ADC Inputs
Voltage Reference
Tem p er at ure Sensor
DAC Resolution (bits)
DAC Outputs
Analog Comparators
Lead-Free (RoHS Compliant)
Package
C8051F120 100 128 k 8448
25
64 8 - 8
12 2 2 - 100TQFP
C8051F120-GQ 100 128 k 8448
25
64 8 - 8
12 2 2
100TQFP
C8051F121 100 128 k 8448
25
32 8 - 8
12 2 2 - 64TQFP
C8051F121-GQ 100 128 k 8448
25
32 8 - 8
12 2 2
64TQFP
C8051F122 100 128 k 8448
25
64 - 8 8
12 2 2 - 100TQFP
C8051F122-GQ 100 128 k 8448
25
64 - 8 8
12 2 2
100TQFP
C8051F123 100 128 k 8448
25
32 - 8 8
12 2 2 - 64TQFP
C8051F123-GQ 100 128 k 8448
25
32 - 8 8
12 2 2
64TQFP
C8051F124 50 128 k 8448 -
25
64 8 - 8
12 2 2 - 100TQFP
C8051F124-GQ 50 128 k 8448 -
25
64 8 - 8
12 2 2
100TQFP
C8051F125 50 128 k 8448 -
25
32 8 - 8
12 2 2 - 64TQFP
C8051F125-GQ 50 128 k 8448 -
25
32 8 - 8
12 2 2
64TQFP
C8051F126 50 128 k 8448 -
25
64 - 8 8
12 2 2 - 100TQFP
C8051F126-GQ 50 128 k 8448 -
25
64 - 8 8
12 2 2
100TQFP
C8051F127 50 128 k 8448 -
25
32 - 8 8
12 2 2 - 64TQFP
C8051F127-GQ 50 128 k 8448 -
25
32 - 8 8
12 2 2
64TQFP
C8051F130 100 128 k 8448
25
64 - 8 -
- - 2 - 100TQFP
C8051F130-GQ 100 128 k 8448
25
64 - 8 -
--2
100TQFP
C8051F131 100 128 k 8448
25
32 - 8 -
- - 2 - 64TQFP
C8051F131-GQ 100 128 k 8448
25
32 - 8 -
--2
64TQFP
C8051F132 100 64 k 8448
25
64 - 8 -
- - 2 - 100TQFP
C8051F132-GQ 100 64 k 8448
25
64 - 8 -
--2
100TQFP
C8051F133 100 64 k 8448
25
32 - 8 -
- - 2 - 64TQFP
C8051F133-GQ 100 64 k 8448
25
32 - 8 -
--2
64TQFP
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 21
Figure 1.1. C8051F120/124 Block Diagram
P0, P1,
P2, P3
Latches
JTAG
Logic
TCK
TMS
TDI
TDO
UART1
SMBus
SPI Bus
PCA
128 kB
FLASH
256 byte
RAM
VDD
Monitor
SFR Bus
8
0
5
1
C
o
r
e
Timers 0,
1, 2, 4
Timer 3/
RTC
P0
Drv
C
R
O
S
S
B
A
R
Po rt I/O
Config.
Crossbar
Config.
AV+
AV+
VDD
VDD
VDD
DGND
DGND
DGND
AGND
AGND
Reset
RST
XTAL1
XTAL2 External Oscillator
Circuit
System
Clock
Calibrated Internal
Oscillator
Digital Power
Analog Power
Debug HW
Boundary Scan
8 kB
XRAM
P2.0
P2.7
P1.0/AIN2.0
P1.7/AIN2.7
P0.0
P0.7
P1
Drv
P2
Drv
Data Bus
Address Bus
Bus Control
DAC1 DAC1
(12-Bit)
VREF
DAC0
(12-Bit)
ADC
100 ksps
(12-Bit)
A
M
U
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
DAC0
CP0+
CP0-
CP1+
CP1-
VREF
TEMP
SENSOR
UART0
P3.0
P3.7
P3
Drv
8:1
MONEN WDT
VREFD
VREF0
Prog
Gain
CP0
CP1
C
T
L
P4 Latch
D
a
t
a
P7 Latch
A
d
d
r
P5 Latch
P6 Latch
P7.0/D0
P7.7/D7
P7
DRV
P5.0/A8
P5.7/A15
P5
DRV
P6.0/A0
P6.7/A7
P6
DRV
P4
DRV P4.5/ALE
P4.6/RD
P4.7/WR
P4.0
P4.4
Prog
Gain
ADC
500 ksps
(8-Bit)
A
M
U
X
VREF2
PLL
Circuitry
Ex ter n a l D a ta
Memory Bus
64x4 byte
cache
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
22 Rev. 1.4
Figure 1.2. C8051F121/125 Block Diagram
P0, P 1,
P2, P3
Latches
JTAG
Logic
TCK
TMS
TDI
TDO
UART1
SMBus
SPI Bus
PCA
VDD
Monitor
Timers 0,
1, 2, 4
Timer 3/
RTC
P0
Drv
C
R
O
S
S
B
A
R
Port I/O
Config.
Crossbar
Config.
AV+
VDD
VDD
VDD
DGND
DGND
DGND
AGND
Reset
RST
Digital Power
Analog Power
Debug HW
Boundary Scan
P2.0
P2.7
P1.0/AIN2.0
P1.7/AIN2.7
P0.0
P0.7
P1
Drv
P2
Drv
Data B us
Address Bus
Bus Control
DAC1 DAC1
(12-Bit)
VREF
DAC0
(12-Bit)
ADC
100 ksps
(12-Bit)
A
M
U
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
DAC0
CP0+
CP0-
CP1+
CP1-
VREF
TEMP
SENSOR
UART0
P3.0
P3.7
P3
Drv
8:1
MONEN WDT
VREFA
Prog
Gain
CP0
CP1
C
T
L
P4 Latch
D
a
t
a
P7 Latch
A
d
d
r
P5 Latch
P6 Latch
P7
DRV
P5
DRV
P6
DRV
P4
DRV
Prog
Gain
ADC
500 ksps
(8-Bit)
A
M
U
X
VREFA
AV+
XTAL1
XTAL2 External Oscillator
Circuit
System
Clock
Calibrated Internal
Oscillator
PLL
Circuitry 128 kB
FLASH
256 byte
RAM
SFR Bus
8
0
5
1
C
o
r
e
8 kB
XRAM
Extern a l D a ta
Memory Bus
64x4 byte
cache
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 23
Figure 1.3. C8051F122/126 Block Diagram
P0, P1,
P2, P3
Latches
JTAG
Logic
TCK
TMS
TDI
TDO
UART1
SMBus
SPI Bus
PCA
VDD
Monitor
Timers 0,
1, 2, 4
Timer 3/
RTC
P0
Drv
C
R
O
S
S
B
A
R
Po rt I/O
Config.
Crossbar
Config.
AV+
AV+
VDD
VDD
VDD
DGND
DGND
DGND
AGND
AGND
Reset
RST
Digital Power
Analog Power
Debug HW
Boundary Scan
P2.0
P2.7
P1.0/AIN2.0
P1.7/AIN2.7
P0.0
P0.7
P1
Drv
P2
Drv
Data Bus
Address Bus
Bus Control
DAC1 DAC1
(12-Bit)
VREF
DAC0
(12-Bit)
ADC
100 ksps
(10-Bit)
A
M
U
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
DAC0
CP0+
CP0-
CP1+
CP1-
VREF
TEMP
SENSOR
UART0
P3.0
P3.7
P3
Drv
8:1
MONEN WDT
VREFD
VREF0
Prog
Gain
CP0
CP1
C
T
L
P4 Latch
D
a
t
a
P7 Latch
A
d
d
r
P5 Latch
P6 Latch
P7.0/D0
P7.7/D7
P7
DRV
P5.0/A8
P5.7/A15
P5
DRV
P6.0/A0
P6.7/A7
P6
DRV
P4
DRV P4.5/ALE
P4.6/RD
P4.7/WR
P4.0
P4.4
Prog
Gain
ADC
500 ksps
(8-Bit)
A
M
U
X
VREF2
XTAL1
XTAL2 Ext ern al Oscilla tor
Circuit
System
Clock
Calibrated Internal
Oscillator
PLL
Circuitry 128 kB
FLASH
256 byte
RAM
SFR Bus
8
0
5
1
C
o
r
e
8 kB
XRAM
Ex ter n a l D a ta
Memory Bus
64x4 byte
cache
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
24 Rev. 1.4
Figure 1.4. C8051F123/127 Block Diagram
P0, P 1,
P2, P3
Latches
JTAG
Logic
TCK
TMS
TDI
TDO
UART1
SMBus
SPI Bus
PCA
VDD
Monitor
Timers 0,
1, 2, 4
Timer 3/
RTC
P0
Drv
C
R
O
S
S
B
A
R
Port I/O
Config.
Crossbar
Config.
AV+
VDD
VDD
VDD
DGND
DGND
DGND
AGND
Reset
RST
Digital Power
Analog Power
Debug HW
Boundary Scan
P2.0
P2.7
P1.0/AIN2.0
P1.7/AIN2.7
P0.0
P0.7
P1
Drv
P2
Drv
Data B us
Address Bus
Bus Control
DAC1 DAC1
(12-Bit)
VREF
DAC0
(12-Bit)
ADC
100 ksps
(10-Bit)
A
M
U
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
DAC0
CP0+
CP0-
CP1+
CP1-
VREF
TEMP
SENSOR
UART0
P3.0
P3.7
P3
Drv
8:1
MONEN WDT
VREFA
Prog
Gain
CP0
CP1
C
T
L
P4 Latch
D
a
t
a
P7 Latch
A
d
d
r
P5 Latch
P6 Latch
P7
DRV
P5
DRV
P6
DRV
P4
DRV
Prog
Gain
ADC
500 ksps
(8-Bit)
A
M
U
X
VREFA
AV+
XTAL1
XTAL2 External Oscillator
Circuit
System
Clock
Calibrated Internal
Oscillator
PLL
Circuitry 128 kb
FLASH
256 byte
RAM
SFR Bus
8
0
5
1
C
o
r
e
8 kb
XRAM
Extern a l D a ta
Memory Bus
64x4 byte
cache
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 25
Figure 1.5. C8051F130/132 Block Diagram
P0, P1,
P2, P3
Latches
JTAG
Logic
TCK
TMS
TDI
TDO
UART1
SMBus
SPI Bus
PCA
VDD
Monitor
Time rs 0 ,
1, 2, 4
Timer 3/
RTC
P0
Drv
C
R
O
S
S
B
A
R
Po rt I/O
Config.
Crossbar
Config.
AV+
AV+
VDD
VDD
VDD
DGND
DGND
DGND
AGND
AGND
Reset
RST
Digital Power
Analog Power
Debug HW
Bounda ry S can
P2.0
P2.7
P1.0/AIN2.0
P1.7/AIN2.7
P0.0
P0.7
P1
Drv
P2
Drv
Data Bus
Address Bus
Bus Control
VREF
ADC
100ksps
(10-Bit)
A
M
U
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
CP0+
CP0-
CP1+
CP1-
VREF
TEMP
SENSOR
UART0
P3.0
P3.7
P3
Drv
MONEN WDT
VREF0
Prog
Gain
CP0
CP1
C
T
L
P4 Latch
D
a
t
a
P7 Latch
A
d
d
r
P5 Latch
P6 Latch
P7.0/D0
P7.7/D7
P7
DRV
P5.0/A8
P5.7/A15
P5
DRV
P6.0/A0
P6.7/A7
P6
DRV
P4
DRV P4.5/ALE
P4.6/RD
P4.7/WR
P4.0
P4.4
XTAL1
XTAL2 External Oscillator
Circuit
System
Clock
Ca librate d Inte rn a l
Oscillator
PLL
Circuitry FLASH
128kbyte
(‘F130)
64kbyte
(‘F132)
256 byte
RAM
SFR Bus
8
0
5
1
C
o
r
e
8kbyte
XRAM
Ex te rn al Data
Memory Bus
64x4 byte
cache
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
26 Rev. 1.4
Figure 1.6. C8051F131/133 Block Diagram
P0, P1,
P2, P3
Latches
JTAG
Logic
TCK
TMS
TDI
TDO
UART1
SMBus
SPI Bus
PCA
VDD
Monitor
Time rs 0 ,
1, 2, 4
Timer 3/
RTC
P0
Drv
C
R
O
S
S
B
A
R
Po rt I/O
Config.
Crossbar
Config.
AV+
VDD
VDD
VDD
DGND
DGND
DGND
AGND
Reset
RST
Digital Power
Analog Power
Debug HW
Boundary Scan
P2.0
P2.7
P1.0/AIN2.0
P1.7/AIN2.7
P0.0
P0.7
P1
Drv
P2
Drv
Data Bus
Address Bus
Bus Control
VREF
ADC
100ksps
(10-Bit)
A
M
U
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
CP0+
CP0-
CP1+
CP1-
VREF
TEMP
SENSOR
UART0
P3.0
P3.7
P3
Drv
MONEN WDT
VREF0
Prog
Gain
CP0
CP1
C
T
L
P4 Latch
D
a
t
a
P7 Latch
A
d
d
r
P5 Latch
P6 Latch
P7
DRV
P5
DRV
P6
DRV
P4
DRV
XTAL1
XTAL2 External Oscillator
Circuit
System
Clock
Ca librate d Inte rn a l
Oscillator
PLL
Circuitry
256 byte
RAM
SFR Bus
8
0
5
1
C
o
r
e
8kbyte
XRAM
Ex te rn al Data
Memory Bus
FLASH
128kbyte
(‘F131)
64kbyte
(‘F133)
64x4 byte
cache
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 27
1.1. CIP-51™ Microcontroller Core
1.1.1. Fully 8051 Compatible
The C8051F12x and C8051F13x utilize Silicon Labs’ proprietary CIP-51 mic rocontroller core. The CIP-51
is fully compatible with the MCS-51™ instruction set; standard 803x/805x assemblers and compilers can
be used to develop software. The core has all the peri phera ls inclu de d with a standard 8052, includi ng five
16-bit counter/timers, two full-duplex UARTs, 256 bytes of internal RAM, 128 by te Special Function Regis-
ter (SFR) address space, and 8/4 byte-wide I/O Ports.
1.1.2. Improved Throughput
The CIP-51 employ s a p ipelined architectu re that grea tly increases it s instr uction throughpu t over the st an-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute with a maximum system clock of 12-to-24 MHz. By contrast, the CIP-51 core exe-
cutes 70% of its instructions in one or two syste m cloc k cycles, with only four instructions taking more than
four system clock cycles.
The CIP-51 has a total of 109 instructions. The table below shows the total number of instructions that
require each execution time.
With the CIP-51's maximum system clock at 100 MHz, the C8051F120/1/2/3 and C8051F130/1/2/3 have a
peak throughput of 100 MIPS (the C8051F124/5/6/7 have a peak throughput of 50 MIPS).
Clocks to Execute 1 22/333/444/55 8
Number of Instructions 26 50 5 14 7 3 1 2 1
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
28 Rev. 1.4
1.1.3. Additional Features
Several key enhancements are implemented in the CIP-51 core and peripherals to improve overall perfor-
mance and ease of use in end applications.
The extended interrup t handler provides 20 interrupt sources into th e CIP-51 (as opposed to 7 for the st an-
dard 8051), allowing the numerous analog and digital peripherals to interrupt the controller. An interrupt
driven system requires less intervention by the MCU, giving it more effective throughput. The extra inter-
rupt sources are very useful when building multi-tasking, real-time systems.
There are up to seven reset sources for the MCU: an on-board VDD monitor, a Watchdog Timer, a missing
clock detector, a voltage level detection from Comparator0, a forced software reset, the CNVSTR0 input
pin, and the RST pin . The RST pin is bi-directiona l, accommodating an external re set, or allowing the inter-
nally generated POR to be output on the RST pin. Each reset source except for the VDD monitor and Reset
Input pin may be disabled by the user in software; the VDD monitor is enabled/disabled via the MONEN
pin. The Watchdog Timer may be permanently enabled in software after a power-on reset during MCU ini-
tialization.
The MCU has an internal, stand alone clock generator which is used by default as the system clock after
any reset. If desired, the clock source may be switched on the fly to the external oscillator, which can use a
crystal, ceramic resonator, capacitor, RC, or external clock source to generate the system clock. This can
be extremely useful in low power applications, allowing the MCU to run from a slow (power saving) exter-
nal crystal source, while periodically switching to the 24.5 MHz intern al oscillator as needed. A dditionally,
an on-chip PLL is provided to achieve higher system clock speeds for increased thro ughput.
Figure 1.7. On-Board Clock and Reset
WDT
XTAL1
XTAL2 OSC
Internal
Clock
Generator
System
Clock CIP-51
Microcontroller
Core
Missing
Clock
Detector
(one-
shot)
WDT
Strobe
Software Reset
Extended Interrupt
Handler
Clock Select
RST
+
-
VDD
Supply
Reset
Timeout (wired-OR)
System Reset
Supply
Monitor
PRE
Reset
Funnel
+
-
CP0+ Comparator0
CP0-
(Port I/O) Crossbar CNVSTR
(CNVSTR
reset
enable)
(CP0
reset
enable)
EN
WDT
Enable
EN
MCD
Enable
PLL
Circuitry
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 29
1.2. On-Chip Memory
The CIP-51 has a standard 8051 program and data address configuration. It includes 256 bytes of data
RAM, with the upper 128 bytes dual-ma pped. Indirect addressing accesses the upper 128 bytes of general
purpose RAM, and direct addressing accesses the 128 byte SFR address space. The lower 128 bytes of
RAM are accessible via direct and indirect addressing. The first 32 bytes are addressable as four banks of
general purpose registers, and the next 16 bytes can be byte addressable or bit addressable.
The devices include an on- chip 8k byte RAM b lock an d a n extern al memory in terf ace (EM IF) for acce ssing
off-chip data memory. The on-chip 8k byte block can be addressed over the entire 64k external data mem-
ory address range (overlapping 8k boundaries). External data memory address space can be mapped to
on-chip memory only, off- chip memory only, or a combination of the two (addresses up to 8k directed to on-
chip, above 8k directed to EMIF). The EMIF is also configurable for multiplexed or non-multiplexed
address/data lines.
On the C8051F12x and C8051F130/1, the MCU’s program memory consists of 128 k bytes of banked
Flash memory. The 1024 bytes from addresses 0x1FC00 to 0x1FFFF are reserved. On the C8051F132/3,
the MCU’s program m em o ry co ns ists of 64 k bytes of Flash memory. This memory may be reprogrammed
in-system in 1024 byte sectors, and requires no special off-chip programming voltage.
On all devices, there are also two 128 byte sectors at addresses 0x20000 to 0x200FF, which may be used
by software for data storage. See Figure 1.8 for the MCU system me mory map.
Figure 1.8. On-Chip Memory Map
PROGRAM/DATA MEMORY
(FLASH)
FLASH
(In-System
Programmable in 1024
Byte Sectors)
0x00000
0x1FFFF RESERVED
0x1FC00
0x1FBFF
Scrachpad Memory
(DATA only)
0x200FF
0x20000
(Direct and Indirect
Addressing)
Upper 128 RAM
(Indirect Addressing
Only)
Special Function
Registers
(Direct Addressing Only)
DATA MEMORY (RAM)
General Purpose
Registers
Bit Addressable Lower 128 RAM
(Direct and Indirect
Addressing)
INTERNAL DATA ADDRESS SPACE
EXTERNAL DATA ADDRESS SPACE
XRAM - 8192 Bytes
(accessable using MOVX
instruction)
0x0000
0x1FFF
Off-chip XRAM space
0x2000
0xFFFF
Up To
256 SFR Pages
13
02
C8051F120/1/2/3/4/5/6/7
C8051F130/1
FLASH
(In-System
Programmable in 1024
Byte Sectors)
0x00000
0x0FFFF
Scrachpad Memory
(DATA only)
0x200FF
0x20000
C8051F132/3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
30 Rev. 1.4
1.3. JTAG Debug and Boundary Scan
JTAG boundary scan and debug circuitry is included which provides non-intrusive, full speed, in-circuit
debugging using the production part installed in the end application, via the four-pin JTAG interface. The
JTAG port is fully compliant to IEEE 1149.1, providing full boundary scan for test and manufacturing pur-
poses.
Silicon Labs' debugging system supports inspection and modification of memory and registers, break-
points, watchpoints, a stack monitor, and single stepping. No additional t arget RAM, pr og ram memor y, tim-
ers, or communications channels are required. All the digital and analog peripherals are functional and
work correctly while debugging. All the peripherals (except for the ADC and SMBus) are stalled when the
MCU is halted, during single stepping, or at a breakpoint in order to keep them synchronized.
The C8051F120DK development kit provides all the hardware and software necessary to develop applica-
tion code and perform in-circuit debugging with the C8051F12x or C8051F13x MCUs.
The kit includes a Windows (95 or later) development environ ment, a serial adapter for connecting to the
JTAG port, and a target application board with a C8051F120 MCU installed. All of the necessary commu-
nication cables and a wall-mount power supply are also supplied with the development kit. Silicon Labs’
debug environment is a vastly superior config uration for develop ing and debugg ing embedded applica tions
compared to standard MCU em ulat ors, which use on-bo ard "ICE Chips" and target cables and require the
MCU in the application board to be socketed. Silicon Labs' debug environment both increases ease of use
and preserves the performance of the precision, on-chip analog peripherals.
Figure 1.9. Development/In-System Debug Diagram
TARGET PCB
Serial
Adapter
JT A G (x4 ), V D D, GND
WINDO W S 95 O R LATER
Silicon Labs Integrated
Development Environment
C8051
F12x/13x
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 31
1.4. 16 x 16 MAC (Multiply and Accumulate) Engine
The C8051F120/1/2/3 and C8051F130/1/2/3 devices include a multiply and accumulate engine which can
be used to speed up many mathematical operations. MAC0 contains a 16-by-16 bit multiplier and a 40-bit
adder, which can perform integer or fractional multiply-accumulate and multiply operations on signed input
values in two SYSCLK cycles. A rounding engine provides a rounded 16-bit fractional result after an addi-
tional (third) SYSCLK cycle. MAC0 also contains a 1-bit arithmetic shifter that will left or right-shift the con-
tents of the 40-bit accumulator in a single SYSCLK cycle.
Figure 1.10. MAC0 Block Diagram
MAC0CF
MAC0MS
MAC0FM
MAC0SAT
MAC0CA
MAC0SD
MAC0SC
MAC0STA
MAC0N
MAC0SO
MAC0Z
MAC0HO
16 x 1 6 M u ltip ly
MAC0RNDH MAC0RNDL
MAC0 Rounding Register
MAC0OVR MAC0ACC3 MAC0ACC2 MAC0ACC1 MAC0ACC0
MAC0 Accumulator
40 bit Add
MAC0MS
1
0
0
Rounding Engine1 bit S hift
MAC0FM
Flag Logic
MAC0BH MAC0BL
MAC0 B Register
MAC0AH MAC0AL
MAC0 A Register
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
32 Rev. 1.4
1.5. Programmable Digital I/O and Crossbar
The standard 8051 8-bit Ports (0, 1, 2, and 3) are available on the MCUs. The devices in the larger (100-
pin TQFP) packag ing ha ve 4 additional po rts (4, 5, 6, and 7) for a total of 64 general- pur pose por t I/O. The
Port I/O behave like the standard 8051 with a few enhancements.
Each Port I/O pin can be configured as either a push-pull or open-drain output. Also, the "weak pullups"
which are normally fixed on an 8051 can be globally disabled, provid ing additional power saving capabili-
ties for low-power applications.
Perhaps the most uniq ue enhancement is the Digit al Crossba r. This is a large digital switching network that
allows mapping of internal digital system resources to Port I/O pins on P0, P1, P2, and P3. (See
Figure 1.11) Unlike microcontrollers with standard multiplexed digital I/O, all combinations of functions are
supported.
The on-chip counter/timers, serial buses, HW interrupts, ADC Start of Conversion inputs, comparator out-
puts, and othe r digi tal signals in the controller can be configured to appear on the Port I/O pins specified in
the Crossbar Control registers. Th is allows the user to select the exact mix of ge neral purpose Port I/O an d
digital resources needed for the particular application.
Figure 1.11. Digital Crossbar Diagram
External
Pins
Digital
Crossbar
Priority
Decoder
SMBus
2
SPI 4
UART0
2
PCA
2
T0, T1,
T2, T2EX,
T4,T4EX
/INT0,
/INT1
P1.0
P1.7
P2.0
P2.7
P0.0
P0.7
Highest
Priority
Lowest
Priority
8
8
Comptr.
Outputs
(Internal Digital Signals)
Highest
Priority
Lowest
Priority
UART1
/SYSCLK divided by 1,2,4, or 8
CNVSTR0/2
7
2
P3.0
P3.7
8
8
P0MDOUT, P1MDOUT,
P2MDO UT , P3MDOU T
Registers
XBR0, XBR1,
XBR2, P1MDIN
Registers
P1
I/O
Cells
P3
I/O
Cells
P0
I/O
Cells
P2
I/O
Cells
8
Port
Latches
P0
P1
P2
8
8
8
P3
8
(P2.0-P2.7)
(P1.0-P1.7)
(P0.0-P0.7)
(P3.0-P3.7)
To ADC 2 Input
(‘F12 x O nly)
To E xte rn a l
Memory
Interface
(EMIF)
2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 33
1.6. Programmable Counter Array
An on-board Programmable Counter/Timer Array (PCA) is included in addition to the five 16-bit general
purpose counter/timers. The PCA consists of a dedicated 16-bit counter/timer time base with 6 program-
mable capture/compare modules. The timebase is clocked from one of six sources: the system clock
divided by 1 2, the system clock divid ed by 4, Timer 0 overflow, an Exter nal Cloc k Input (ECI pin ), the sys-
tem clock, or the external oscillator source divided by 8.
Each capture/compare module can be configured to operate in one of six modes: Edge-T riggered Capture,
Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Wid th Modulato r, or 16-Bit Pulse Width
Modulator. The PCA Capt ure/ Compare M odule I /O an d Exte rnal Clo ck Inpu t are route d to the MCU Po rt I/
O via the Digital Crossbar.
Figure 1.12. PCA Block Diagram
1.7. Serial Ports
Serial peripherals included on the devices are two Enhanced Full-Duplex UARTs, SPI Bus, and SMBus/
I2C. Each of the serial buses is fully implemented in hardware and makes extensive use of the CIP-51's
interrupts, thus requiring very little intervention by the CPU. The serial buses do not "share" resources
such as timers, interrupt s, or Port I/O, so any or all of the seria l buses may be used together with any other.
Capture/Compare
Module 1
Capture/Compare
Module 0 Capture/Compare
Module 2 Capture/Compare
Module 3
CEX1
ECI
Crossbar
CEX2
CEX3
CEX0
Port I/O
16-Bit Counter/Timer
PCA
CLOCK
MUX
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
Capture/Compare
Module 4
CEX4
Capture/Compare
Module 5
CEX5
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
34 Rev. 1.4
1.8. 12 or 10-Bit Analog to Digital Converter
All devices include either a 12 or 10-bit SAR ADC (ADC0) with a 9-channel input multiplexer and program-
mable gain amplifier. With a maximum throughput of 100 ksp s, the 12 and 10 -bi t ADCs offer true 12-bit lin-
earity with an INL o f ±1LSB. The ADC0 voltage reference can be selected from an external VREF pin, or
(on the C8051F12x device s) the DAC0 outpu t. On the 100-pin TQFP device s, ADC0 has it s own dedicated
Voltage Reference input pin; on the 64-pin TQFP devices, the ADC0 shares a Voltage Reference input pin
with the 8-bit ADC2. The on-chip voltage reference may generate the voltage reference for other system
components or the on-chip ADCs via the VREF output pin.
The ADC is under full control of the CIP-51 microcontroller via its associated Special Function Registers.
One input channel is tied to an internal temperature sensor, while the other eight channels are available
externally. Each pair of the eight external input channels can be configured as either two single-ended
inputs or a single differential input. The system controller can also put the ADC into shutdown mode to
save power.
A programmable gain amplifier follows the analog multiplexer. The gain can be set in software from 0.5 to
16 in powers of 2. The gain stage can be especially useful when different ADC input channels have widely
varied input voltage signals, or when it is necessary to "zoom in" on a signal with a large DC offset (in dif-
ferential mode, a DAC could be used to provide the DC offset).
Conversions can be started in four ways; a software command, an overflow of Timer 2, an overflow of
Timer 3, or an external signal input. This flexibility allows the start of conversion to be triggered by sof tware
events, external HW signals, or a periodic timer overflow signal. Conversion completions are indicated by a
status bit and an interrupt (if enabled). The resulting 10 or 12-bit data word is latched into two SFRs upon
completion of a conversion. The data can be right or left justified in these registers under software control.
Window Compare registers for the ADC data can be configured to interrupt the controller when ADC data
is within or outside of a specified range. The ADC can monitor a key voltage continuously in back ground
mode, but not interrupt the controller unless the converted data is within the specified window.
Figure 1.13. 12-Bit ADC Block Diagram
12 -Bit
S A R
ADC 12
+
-
TEMP
SENSOR
+
-
+
-
+
-
9-to-1
AMUX
(SE o r
DIFF)
+
-
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
AV+
Pro grammab le Gain
Amplifier
Analog Multiple xer Window Com pare
Logic
ADC Data
Registers
Window
Compare
Interrupt
Conversion
Complete
Interrupt
Configuration, Control, and Data
Registers
Start
Conversion Timer 3 Overflow
Timer 2 Overflow
Write to AD0BUS Y
CNVSTR0
External VREF
Pin
DAC0 Output
VREF
AGND
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 35
1.9. 8-Bit Analog to Digital Converter
The C8051F12x devices have an on-board 8-bit SAR ADC (ADC2) with an 8 -channel input multip lexer and
programmable gain amplifier. This ADC features a 500 ksps maximum throughput and true 8-bit linearity
with an INL of ±1LSB. Eight input pins are available for measurement. The ADC is under full control of the
CIP-51 microcontroller via the Special Function Registers. The ADC2 voltage reference is selected
between the analog power supp ly (AV+) and an external VREF pin. On the 100-pin TQFP devices, ADC2
has its own dedicated Voltage Reference input pin; on the 64-pin TQFP devices, ADC2 shares a Voltage
Reference input pin with ADC0. User software may put ADC2 into shutdown mode to save power.
A programmable gain amplifier follows the analog multiplexer. The gain stage can be especially useful
when different ADC input channels have widely varied input voltage signals, or when it is necessary to
"zoom in" on a sign al with a large DC offset (in differential mode, a DAC could be used to provide the DC
offset). The PGA gain can be set in software to 0.5, 1, 2, or 4.
A flexible conversion scheduling system allows ADC2 conv ersions to be initiated by software command s,
timer overflows, o r an extern al input signal . ADC2 conv ersions may also be synchro nized with ADC0 soft-
ware-commanded conversions. Conversion completions are indicated by a status bit and an interrupt (if
enabled), and the resulting 8-bit data word is latched into an SFR upon completion.
Figure 1.14. 8-Bit ADC Diagram
+
-
AV+ 8
8-to-1
AMUX X
AIN2.0
AIN2.1
AIN2.2
AIN2.3
AIN2.4
AIN2.5
AIN2.6
AIN2.7
Configuration, Control, and Data Registers
Programmable Gain
Amplifier
Ana lo g Mu ltip le x er
8-Bit
SAR
ADC
Start Conversion Timer 3 Overflow
Timer 2 Overflow
Write to AD2BU S Y
CNVSTR2 Input
Write to AD0BU S Y
(synchronized with
ADC0)
ADC Data
Register
Conversion
Complete
Interrupt
External VREF
Pin
AV+
VREF
Window
Compare
Logic
Window
Compare
Interrupt
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
36 Rev. 1.4
1.10. 12-bit Digital to Analog Converters
The C8051F12x devices have two integrated 12-bit Digital to Analog Converters (DACs). The MCU data
and control interface to each DAC is via the Special Function Registers. The MCU can place either or both
of the DACs in a low power shutdown mode.
The DACs are voltage output mode and include a flexible output scheduling mechanism. This scheduling
mechanism allows DAC output updates to be for ced by a sof t ware write or scheduled on a Timer 2, 3, or 4
overflow. The DAC voltage refer ence is supplied from the dedicate d VREFD input pin on the 100-p in TQFP
devices or via the internal Voltage reference on the 64-pin TQFP devices. The DACs are especially useful
as references for the comparators or offsets for the differential inputs of the ADCs.
Figure 1.15. DAC System Block Diagram
DAC0
AV+
12
AGND
8
8
REF
DAC0
DAC0CN
DAC0EN
DAC0MD1
DAC0MD0
DAC0DF2
DAC0DF1
DAC0DF0
DAC0HDAC0L
Dig. MUX
Latch Latch
8
8
DAC1
AV+
12
AGND
8
8
REF
DAC1
DAC1CN
DAC1EN
DAC1MD1
DAC1MD0
DAC1DF2
DAC1DF1
DAC1DF0
DAC1HDAC1L
Dig. MUX
Latch Latch
8
8
DAC0H
Timer 3
Timer 4
Timer 2
DAC1H
Timer 3
Timer 4
Timer 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 37
1.11. Analog Comparators
Two analog comparators with dedicated input pins are included on-chip. The comparators have software
programmable hysteresis a nd response time. Each comparator can genera te an in terr upt on a rising edge,
falling edge, or both. The interrupts are capable of waking up the MCU from sleep mode, and Comparator
0 can be used as a rese t source. T he output st ate o f the comp ar ators can be polled in sof tware or r outed to
Port I/O pins via the Crossbar. The comparators can b e pr ogrammed to a lo w powe r shut do wn mo de whe n
not in use.
Figure 1.16. Comparator Block Diagram
+
-
CPn+
CPn-
CIP-51
and
Interr u pt
Handler
CPn
CPn Output
(P o rt I/O)
SFR's
(Data
and
Control)
CROSSBAR
2 Com parators
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
38 Rev. 1.4
2. Absolute Maximum Ratings
Table 2.1. Absolute Maximum Ratings*
Parameter Conditions Min Typ Max Units
Ambient temperature under bias –55 — 125 °C
Storage Temperature –65 — 150 °C
Voltage on any Pin (except VDD and Port I/O) with
Respect to DGND –0.3 — VDD +
0.3 V
Voltage on any Port I/O Pin or RST with Respect to
DGND –0.3 — 5.8 V
Voltage on VDD with Respect to DGND –0.3 — 4.2 V
Maximum Total Current through VDD, AV+, DGND,
and AGND ——800mA
Maximum Output Current Sunk by any Port pin ——100mA
Maximum Output Current Sunk by any other I/O pin —— 50mA
Maximum Output Current Sourced by an y Port pin ——100mA
Maximum Output Current Sourced by any other I/O
Pin —— 50mA
*Note: S tresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device.
This is a stress rating only and functional operation of the devices at those or any other conditions above those
indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for
extended periods may affect device reliability.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 39
3. Global DC Electrical Characteristics
Table 3.1. Global DC Electrical Characteristics
(C8051F120/1/2/3 and C8051F130/1/2/3)
–40 to +85 °C, 100 MHz System Clock unless otherwise specified.
Parameter Conditions Min Typ Max Units
Analog Supply Voltage1SYSCLK = 0 to 50 MHz
SYSCLK > 50 MHz 2.7
3.0 3.0
3.3 3.6
3.6 V
V
Analog Supply Current Internal REF, ADCs, DACs, Com-
parato rs all active —1.7—mA
Analog Supply Current with
analog sub-systems inactive Internal REF, ADCs, DACs, Com-
parators all disabled, oscillator
disabled
—0.2—µA
Analog-to-Digital Supply
Delta (|VDD –AV+|) ——0.5V
Digital Supply Voltage SYSCLK = 0 to 50 MHz
SYSCLK > 50 MHz 2.7
3.0 3.0
3.3 3.6
3.6 V
V
Digital Supply Current with
CPU active VDD = 3.0 V, Clock = 100 MHz
VDD = 3.0 V, Clock = 50 MHz
VDD = 3.0 V, Clock = 1 MHz
VDD = 3.0 V, Clock = 32 kHz
—65
35
1
33
—mA
mA
mA
µA
Digital Supply Current with
CPU inactive (not accessing
Flash)
VDD = 3.0 V, Clock = 100 MHz
VDD = 3.0 V, Clock = 50 MHz
VDD = 3.0 V, Clock = 1 MHz
VDD = 3.0 V, Clock = 32 kHz
—40
20
0.4
15
—mA
mA
mA
µA
Digital Supply Current (shut-
down) Oscillator not running —0.4—µA
Digital Supply RAM Dat a
Retention Voltage —1.5— V
SYSCLK (System Clock)2,3 VDD, AV+ = 2.7 to 3.6 V
VDD, AV+ = 3.0 to 3.6 V 0
0—50
100 MHz
MHz
Sp ec ifie d Operating Temper-
ature Range –40 — +85 °C
Notes:
1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
2. SYSCLK is the internal device clock. For operational speeds in excess of 30 MHz, SYSCLK must be derived
from the Phase-Locked Loop (PLL).
3. SYSCLK must be at least 32 kHz to enable debuggi ng.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
40 Rev. 1.4
Table 3.2. Global DC Electrical Characteristics (C8051F124/5/6/7)
–40 to +85 °C, 50 MHz System Clock unless otherwise specifi ed.
Parameter Conditions Min Typ Max Units
Analog Supply Voltage12.7 3.0 3.6 V
Analog Supply Current Internal REF, ADC, DAC, Com-
parators all active —1.7—mA
Analog Supply Curren t with
analog sub-systems inactive Internal REF, ADC, DAC, Com-
parators all disabled, oscillator
disabled
—0.2—µA
Analog-to-Digital Supply
Delta (|VDD –AV+|) ——0.5V
Digital Supply Voltage 2.7 3.0 3.6 V
Digital Supply Current with
CPU active VDD =3.0V, Clock=50MHz
VDD = 3.0 V, Clock = 1 MHz
VDD =3.0V, Clock=32kHz
—35
1
33
—mA
mA
µA
Digital Supply Current with
CPU inactive (not accessing
Flash)
VDD =3.0V, Clock=50MHz
VDD = 3.0 V, Clock = 1 MHz
VDD =3.0V, Clock=32kHz
—27
0.4
15
—mA
mA
µA
Digital Supply Current (shut-
down) Oscillator not running —0.4—µA
Digital Supply RAM Data
Retention Voltage —1.5— V
SYSCLK (System Clock)2,3 0—50MHz
Specified Operating
Temperature Range –40 — +85 °C
Notes:
1. Analog Supply AV+ must be greater than 1 V for VDD monitor to operate.
2. SYSCLK is the internal device clock. For operational speeds in excess of 30 MHz, SYSCLK must be derived
from the phase-locked loop (PLL).
3. SYSCLK must be at least 32 kHz to enable debugging.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 41
4. Pinout and Package Definitions
Table 4.1. Pin Definitions
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
VDD 37,
64, 90 24,
41, 57 37,
64, 90 24,
41, 57 Digital Supply Voltage. Must be tied to +2.7 to
+3.6 V.
DGND 38,
63, 89 25,
40, 56 38,
63, 89 25,
40, 56 Digital Ground. Must be tied to Ground.
AV+ 11, 14 6 11, 14 6 Analog Supply Voltage. Must be tied to +2.7 to
+3.6 V.
AGND 10, 13 5 10, 13 5 Analog Ground. Must be tied to Ground.
TMS 1 58 1 58 D In JTAG Te st Mode Select with internal pullup.
TCK 2 59 2 59 D In JTAG Test Cloc k with int ernal pullup.
TDI 3 60 3 60 D In JTAG Test Data Input with internal pullup. TDI is
latched on the rising edge of TCK.
TDO 4 61 4 61 D Out JT AG Test Data Output with internal pullup. Dat a
is shifted out on TDO on the falling edge of TCK.
TDO output is a tri-state driver.
RST 5 62 5 62 D I/O Device Reset. Open-drain output of internal VDD
monitor. Is driven low when VDD is < VRST and
MONEN is high. An external source can initiate
a system reset by driving this pin low.
XTAL1 26 17 26 17 A In Crystal Input. This pin is the return for the inter-
nal oscillator circuit for a crystal or ceramic reso-
nator. For a precision internal clock, connect a
crystal or ceramic resonator from XTAL1 to
XTAL2. If overdriven by an external CMOS
clock, this becomes the syst em clock.
XTAL2 27 18 27 18 A Out Crystal Output. This pin is the excitation drive r
for a crystal or ceramic resonator.
MONEN 28192819D InV
DD Monitor Enable. When tied high, this pin
enables the internal V DD monitor , which forces a
system reset when VDD is < VRST. When tied
low, the internal VDD monitor is disabled.
This pin must be tied high or low.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
42 Rev. 1.4
VREF 12 7 12 7 A I/O Bandgap Vo ltage Refere nc e Ou tp ut
(all devices).
DAC Voltage Reference In put
(C8051F121/3/5/7 only).
VREFA 8 A In ADC0 and ADC2 Voltage Reference Input.
VREF0 16 16 8 A In ADC0 Voltage Reference Input.
VREF2 17 17 A In ADC2 Voltage Reference Input.
VREFD 15 15 A In DAC Voltage Reference Input.
AIN0.0 18 9 18 9 A In ADC0 Input Chan nel 0 ( See ADC0 Specification
for complete description).
AIN0.1 19 10 19 10 A In ADC0 Input Channel 1 (S ee ADC0 Specification
for complete description).
AIN0.2 20 11 20 11 A In ADC0 Input Channel 2 (S ee ADC0 Specification
for complete description).
AIN0.3 21 12 21 12 A In ADC0 Input Channel 3 (S ee ADC0 Specification
for complete description).
AIN0.4 22 13 22 13 A In ADC0 Input Channel 4 (S ee ADC0 Specification
for complete description).
AIN0.5 23 14 23 14 A In ADC0 Input Channel 5 (S ee ADC0 Specification
for complete description).
AIN0.6 24 15 24 15 A In ADC0 Input Channel 6 (S ee ADC0 Specification
for complete description).
AIN0.7 25 16 25 16 A In ADC0 Input Channel 7 (S ee ADC0 Specification
for complete description).
CP0+ 9 4 9 4 A In Comparator 0 Non-Inverting Input.
CP0- 8 3 8 3 A In Comparator 0 Inverting Input.
CP1+ 7 2 7 2 A In Comparator 1 Non-Inverting Input.
CP1– 6 1 6 1 A In Comparator 1 Inverting Input.
DAC0 100 64 A Out Digital to Analog Converter 0 Voltage Output.
(See DAC Specification for complete descrip-
tion).
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 43
DAC1 99 63 A Out Digital to Analog Converter 1 Voltage Output.
(See DAC Specification for complete descrip-
tion).
P0.0 62 55 62 5 5 D I/O Port 0.0. See Port Input/Output sectio n fo r com -
plete description.
P0.1 61 54 61 5 4 D I/O Port 0.1. See Port Input/Output sectio n fo r com -
plete description.
P0.2 60 53 60 5 3 D I/O Port 0.2. See Port Input/Output sectio n fo r com -
plete description.
P0.3 59 52 59 5 2 D I/O Port 0.3. See Port Input/Output sectio n fo r com -
plete description.
P0.4 58 51 58 5 1 D I/O Port 0.4. See Port Input/Output sectio n fo r com -
plete description.
ALE/P0.5 57 50 57 50 D I/O ALE Strobe for External Memory Address bus
(multiplexed mode)
Port 0.5
See Port Input/Out pu t sectio n fo r com p let e
description.
RD/P0.6 56 49 56 49 D I/O /RD Strobe for External Memory Address bus
Port 0.6
See Port Input/Out pu t sectio n fo r com p let e
description.
WR/P0.7 55485548D I/O/WR Strobe for External Memory Address bus
Port 0.7
See Port Input/Out pu t sectio n fo r com p let e
description.
AIN2.0/A8/P1.0 36 29 36 29 A In
D I/O ADC2 Input Channel 0 (See ADC2 Specification
for complete description).
Bit 8 External Memory Addr es s bus (Non -m u lti-
plexed mode)
Port 1.0
See Port Input/Out pu t sectio n fo r com p let e
description.
AIN2.1/A9/P1.1 35 28 35 28 A In
D I/O Port 1.1. See Port Inpu t/Output sectio n fo r com -
plete description.
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
44 Rev. 1.4
AIN2.2/A10/P1.234273427A In
D I/O Port 1.2. See Port Inpu t/Output sectio n fo r com -
plete description.
AIN2.3/A11/P1.3 33 26 33 26 A In
D I/O Port 1.3. See Port Inpu t/Output sectio n fo r com -
plete description.
AIN2.4/A12/P1.432233223A In
D I/O Port 1.4. See Port Inpu t/Output sectio n fo r com -
plete description.
AIN2.5/A13/P1.531223122A In
D I/O Port 1.5. See Port Inpu t/Output sectio n fo r com -
plete description.
AIN2.6/A14/P1.630213021A In
D I/O Port 1.6. See Port Inpu t/Output sectio n fo r com -
plete description.
AIN2.7/A15/P1.729202920A In
D I/O Port 1.7. See Port Inpu t/Output sectio n fo r com -
plete description.
A8m/A0/P2.0 46 37 46 37 D I/O Bit 8 External Memory Addres s bus (Multiplexed
mode)
Bit 0 External Memory Addr es s bus (Non -m u lti-
plexed mode)
Port 2.0
See Port Input/Out pu t sectio n fo r com p let e
description.
A9m/A1/P2.145364536D I/OPort 2.1. See Port Input/O ut pu t se ctio n fo r c om-
plete description.
A10m/A2/P2.2 44 35 44 35 D I/O Port 2.2. See Port Input/Out pu t se ctio n fo r com -
plete description.
A11m/A3/P2.3 43 34 43 34 D I/O Port 2.3. See Port Input/Out pu t se ctio n fo r com -
plete description.
A12m/A4/P2.4 42 33 42 33 D I/O Port 2.4. See Port Input/Out pu t se ctio n fo r com -
plete description.
A13m/A5/P2.5 41 32 41 32 D I/O Port 2.5. See Port Input/Out pu t se ctio n fo r com -
plete description.
A14m/A6/P2.6 40 31 40 31 D I/O Port 2.6. See Port Input/Out pu t se ctio n fo r com -
plete description.
A15m/A7/P2.7 39 30 39 30 D I/O Port 2.7. See Port Input/Out pu t se ctio n fo r com -
plete description.
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 45
AD0/D0/P3.0 54 47 54 47 D I/O Bit 0 External Memory Address/Data bus (Multi-
plexed mode)
Bit 0 External Memory Data bus (Non-mult i -
plexed mode)
Port 3.0
See Port Input/Out pu t sectio n fo r com p let e
description.
AD1/D1/P3.153465346D I/OPort 3.1. See Port Input/Output section for c om-
plete description.
AD2/D2/P3.252455245D I/OPort 3.2. See Port Input/Output section for c om-
plete description.
AD3/D3/P3.351445144D I/OPort 3.3. See Port Input/Output section for c om-
plete description.
AD4/D4/P3.450435043D I/OPort 3.4. See Port Input/Output section for c om-
plete description.
AD5/D5/P3.549424942D I/OPort 3.5. See Port Input/Output section for c om-
plete description.
AD6/D6/P3.648394839D I/OPort 3.6. See Port Input/Output section for c om-
plete description.
AD7/D7/P3.747384738D I/OPort 3.7. See Port Input/Output section for c om-
plete description.
P4.0 98 98 D I/O Port 4.0. See Port Inp u t/O ut pu t se ctio n for com-
plete description.
P4.1 97 97 D I/O Port 4.1. See Port Inp u t/O ut pu t se ctio n for com-
plete description.
P4.2 96 96 D I/O Port 4.2. See Port Inp u t/O ut pu t se ctio n for com-
plete description.
P4.3 95 95 D I/O Port 4.3. See Port Inp u t/O ut pu t se ctio n for com-
plete description.
P4.4 94 94 D I/O Port 4.4. See Port Inp u t/O ut pu t se ctio n for com-
plete description.
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
46 Rev. 1.4
ALE/P4.5 93 93 D I/O ALE Strobe for External Memory Address bus
(multiplexed mode)
Port 4.5
See Port Input/Out pu t sectio n fo r com p let e
description.
RD/P4.6 92 92 D I/O /RD Strobe for External Mem ory Address bus
Port 4.6
See Port Input/Out pu t sectio n fo r com p let e
description.
WR/P4.7 91 91 D I/O /WR Strobe for External Memory Address bus
Port 4.7
See Port Input/Out pu t sectio n fo r com p let e
description.
A8/P5.0 88 88 D I/O Bit 8 External Memory Address bus (Non-multi-
plexed mode)
Port 5.0
See Port Input/Out pu t sectio n fo r com p let e
description.
A9/P5.1 87 87 D I/O Port 5.1. See Port Input/Output section fo r com -
plete description.
A10/P5.2 86 86 D I/O Port 5.2. See Port Input/Output section for com-
plete description.
A11/P5.3 85 8 5 D I/O Port 5.3. See Port Input/O ut put section for com-
plete description.
A12/P5.4 84 84 D I/O Port 5.4. See Port Input/Output section for com-
plete description.
A13/P5.5 83 83 D I/O Port 5.5. See Port Input/Output section for com-
plete description.
A14/P5.6 82 82 D I/O Port 5.6. See Port Input/Output section for com-
plete description.
A15/P5.7 81 81 D I/O Port 5.7. See Port Input/Output section for com-
plete description.
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 47
A8m/A0/P6.0 80 80 D I/O Bit 8 External Memo ry Address bus (Multiplexed
mode)
Bit 0 External Memory Addr es s bus (Non -m u lti-
plexed mode)
Port 6.0
See Port Input/Out pu t sectio n fo r com p let e
description.
A9m/A1/P6.1 79 79 D I/O Port 6.1. See Port Input/Output section for com-
plete description.
A10m/A2/P6.2 78 78 D I/O Port 6.2. See Port Input/Output section for com-
plete description.
A11m/A3/P6.3 77 77 D I/O Port 6.3. See Port Input/Output section for com-
plete description.
A12m/A4/P6.4 76 76 D I/O Port 6.4. See Port Input/Output section for com-
plete description.
A13m/A5/P6.5 75 75 D I/O Port 6.5. See Port Input/Output section for com-
plete description.
A14m/A6/P6.6 74 74 D I/O Port 6.6. See Port Input/Output section for com-
plete description.
A15m/A7/P6.7 73 73 D I/O Port 6.7. See Port Input/Output section for com-
plete description.
AD0/D0/P7.0 72 72 D I/O Bit 0 External Memory Address/Data bus (Multi-
plexed mode)
Bit 0 External Memory Data bus (Non-mult i -
plexed mode)
Port 7.0
See Port Input/Out pu t sectio n fo r com p let e
description.
AD1/D1/P7.1 71 71 D I/O Port 7.1. See Port Input/Output section for com-
plete description.
AD2/D2/P7.2 70 70 D I/O Port 7.2. See Port Input/Output section for com-
plete description.
AD3/D3/P7.3 69 69 D I/O Port 7.3. See Port Input/Output section for com-
plete description.
AD4/D4/P7.4 68 68 D I/O Port 7.4. See Port Input/Output section for com-
plete description.
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
48 Rev. 1.4
AD5/D5/P7.5 67 67 D I/O Port 7.5. See Port Input/Output section for com-
plete description.
AD6/D6/P7.6 66 66 D I/O Port 7.6. See Port Input/Output section for com-
plete description.
AD7/D7/P7.7 65 65 D I/O Port 7.7. See Port Input/Output section for com-
plete description.
NC 15,
17,
99,
100
63, 64 No Connection.
Table 4.1. Pin Definitions (Continued)
Name
Pin Numbers
Type Description
‘F120
‘F122
‘F124
‘F126
‘F121
‘F123
‘F125
‘F127
‘F130
‘F132 ‘F131
‘F133
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 49
Figure 4.1. C8051F120/2/4/6 Pinout Diagram (TQFP-100)
C8051F120
C8051F122
C8051F124
C8051F126
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
42
43
44
45
46
47
48
49
50
1
2
3
4
5
6
7
8
9
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
75
74
73
72
71
70
69
68
67 AD6/D6/P7.6
AD7/D7/P7.7
VDD
DGND
P0.0
P0.1
P0.2
P0.3
P0.4
ALE/P0.5
/RD/P0.6
/WR/P0.7
AD0/D0/P3.0
AD1/D1/P3.1
AD2/D2/P3.2
AD3/D3/P3.3
A13m/A5/P6.5
A14m/A6/P6.6
A15m/A7/P6.7
AD0/D0/P7.0
AD1/D1/P7.1
AD2/D2/P7.2
AD3/D3/P7.3
AD4/D4/P7.4
AD5/D5/P7.5
DAC0
DAC1
P4.0
P4.1
P4.2
P4.3
P4.4
ALE/P4.5
/RD/P4.6
/WR/P4.7
VDD
DGND
A8/P5.0
A9/P5.1
A10/P5.2
A11/P5.3
A12/P5.4
A13/P5.5
A14/P5.6
A15/P5.7
A8m/A0/P6.0
A9m/A1/P6.1
A10m/A2/P6.2
A11m/A3/P6.3
A12m/A4/P6.4
AGND
AV+
VREF
AGND
AV+
VREFD
VREF0
VREF2
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
TMS
TCK
TDI
TDO
/RST
CP1-
CP1+
CP0-
CP0+
XTAL1
XTAL2
MONEN
AIN2.7/A15/P1.7
AIN2.6/A14/P1.6
AIN2.5/A13/P1.5
AIN2.4/A12/P1.4
VDD
DGND
AIN2.3/A11/P1.3
AIN2.2/A10/P1.2
AIN2.1/A9/P1.1
AIN2.0/A8/P1.0
A15m/A7/P2.7
A14m/A6/P2.6
A13m/A5/P2.5
A12m/A4/P2.4
A11m/A3/P2.3
A10m/A2/P2.2
A9m/A1/P2.1
A8m/A0/P2.0
AD7/D7/P3.7
AD6/D6/P3.6
AD5/D5/P3.5
AD4/D4/P3.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
50 Rev. 1.4
Figure 4.2. C8051F130/2 Pinout Diagram (TQFP-100)
C8051F130
C8051F132
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
42
43
44
45
46
47
48
49
50
1
2
3
4
5
6
7
8
9
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
75
74
73
72
71
70
69
68
67 AD6/D6/P7.6
AD7/D7/P7.7
VDD
DGND
P0.0
P0.1
P0.2
P0.3
P0.4
ALE/P0.5
/RD/P0.6
/WR/P0.7
AD0/D0/P3.0
AD1/D1/P3.1
AD2/D2/P3.2
AD3/D3/P3.3
A13m/A5/P6.5
A14m/A6/P6.6
A15m/A7/P6.7
AD0/D0/P7.0
AD1/D1/P7.1
AD2/D2/P7.2
AD3/D3/P7.3
AD4/D4/P7.4
AD5/D5/P7.5
NC
NC
P4.0
P4.1
P4.2
P4.3
P4.4
ALE/P4.5
/RD/P4.6
/WR/P4.7
VDD
DGND
A8/P5.0
A9/P5.1
A10/P5.2
A11/P5.3
A12/P5.4
A13/P5.5
A14/P5.6
A15/P5.7
A8m/A0/P6.0
A9m/A1/P6.1
A10m/A2/P6.2
A11m/A3/P6.3
A12m/A4/P6.4
AGND
AV+
VREF
AGND
AV+
NC
VREF0
NC
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
TMS
TCK
TDI
TDO
/RST
CP1-
CP1+
CP0-
CP0+
XTAL1
XTAL2
MONEN
AIN2.7/A15/P1.7
AIN2.6/A14/P1.6
AIN2.5/A13/P1.5
AIN2.4/A12/P1.4
VDD
DGND
AIN2.3/A11/P1.3
AIN2.2/A10/P1.2
AIN2.1/A9/P1.1
AIN2.0/A8/P1.0
A15m/A7/P2.7
A14m/A6/P2.6
A13m/A5/P2.5
A12m/A4/P2.4
A11m/A3/P2.3
A10m/A2/P2.2
A9m/A1/P2.1
A8m/A0/P2.0
AD7/D7/P3.7
AD6/D6/P3.6
AD5/D5/P3.5
AD4/D4/P3.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 51
Figure 4.3. TQFP-100 Package Drawing
A
A1
A2
b
D
D1
e
E
E1
L
-
0.05
0.95
0.17
-
-
-
-
-
0.45
-
-
1.00
0.22
16.00
14.00
0.50
16.00
14.00
0.60
1.20
0.15
1.05
0.27
-
-
-
-
-
0.75
MIN
(mm) NOM
(mm) MAX
(mm)
100
e
A1
b
A2
A
PIN 1
DESIGNATOR 1
E1 E
D1
D
L
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
52 Rev. 1.4
Figure 4.4. C8051F121/3/5/7 Pinout Diagram (TQFP-64)
C8051F121
C8051F123
C8051F125
C8051F127
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
DAC0
DAC1
/RST
TDO
TDI
TCK
TMS
VDD
DGND
P0.0
P0.1
P0.2
P0.3
P0.4
ALE/P0.5
/RD/P0.6
/WR/P0.7
AD0/D0/P3.0
AD1/D1/P3.1
AD2/D2/P3.2
AD3/D3/P3.3
AD4/D4/P3.4
AD5/D5/P3.5
VDD
DGND
AD6/D6/P3.6
AD7/D7/P3.7
A8m/A0/P2.0
A9m/A1/P2.1
A10m/A2/P2.2
A11m/A3/P2.3
A12m/A4/P2.4
CP1-
CP1+
CP0-
CP0+
AGND
AV+
VREF
VREFA
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
XTAL1
XTAL2
MONEN
AIN2.7/A15/P1.7
AIN2.6/A14/P1.6
AIN2.5/A13/P1.5
AIN2.4/A12/P1.4
VDD
DGND
AIN2.3/A11/P1.3
AIN2.2/A10/P1.2
AIN2.1/A9/P1.1
AIN2.0/A8/P1.0
A15m/A7/P2.7
A14m/A6/P2.6
A13m/A5/P2.5
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 53
Figure 4.5. C8051F131/3 Pinout Diagram (TQFP-64)
C8051F131
C8051F133
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
NC
NC
/RST
TDO
TDI
TCK
TMS
VDD
DGND
P0.0
P0.1
P0.2
P0.3
P0.4
ALE/P0.5
/RD/P0.6
/WR/P0.7
AD0/D0/P3.0
AD1/D1/P3.1
AD2/D2/P3.2
AD3/D3/P3.3
AD4/D4/P3.4
AD5/D5/P3.5
VDD
DGND
AD6/D6/P3.6
AD7/D7/P3.7
A8m/A0/P2.0
A9m/A1/P2.1
A10m/A2/P2.2
A11m/A3/P2.3
A12m/A4/P2.4
CP1-
CP1+
CP0-
CP0+
AGND
AV+
VREF
VREF0
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
XTAL1
XTAL2
MONEN
AIN2.7/A15/P1.7
AIN2.6/A14/P1.6
AIN2.5/A13/P1.5
AIN2.4/A12/P1.4
VDD
DGND
AIN2.3/A11/P1.3
AIN2.2/A10/P1.2
AIN2.1/A9/P1.1
AIN2.0/A8/P1.0
A15m/A7/P2.7
A14m/A6/P2.6
A13m/A5/P2.5
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
54 Rev. 1.4
Figure 4.6. TQFP-64 Package Drawing
A
A1
A2
b
D
D1
e
E
E1
L
-
0.05
0.95
0.17
-
-
-
-
-
0.45
-
-
1.00
0.22
12.00
10.00
0.50
12.00
10.00
0.60
1.20
0.15
1.05
0.27
-
-
-
-
-
0.75
MIN
(mm) NOM
(mm) MAX
(mm)
1
64
E
E1
e
A1
b
D
D1
PIN 1
DESIGNATOR
A2
A
L
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 55
5. ADC0 (12-Bit ADC, C8051F120/1/4/5 Only)
The ADC0 subsystem for the C8051F120/1/4/5 consists of a 9-channel, configurable analog multiplexer
(AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 12-bit successive-approximation-regis-
ter ADC with integrated track-and-hold and Programmable Window Detector (see block diagram in
Figure 5.1). The AMUX0, PGA0 , Dat a Conversion Modes, a nd Window Detector are all configur able under
software control via the Special Function Registers shown in Figure 5.1. The voltage reference used by
ADC0 is selected as described in Section “9. Voltage Reference” on page 113. The ADC0 subsystem
(ADC0, track-and-hold and PGA0) is enabled only when the AD0EN bit in the ADC0 Control register
(ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shutdown when this bit is logic 0.
Figure 5.1. 12-Bit ADC0 Functional Block Diagram
5.1. Analog Multiplexer and PGA
Eight of the AMUX channels are available for external measurements while the ninth channel is internally
connected to an on-chip temperature sensor (temperature transfer function is shown in Figure 5.2). AMUX
input pairs can be programmed to operate in either differential or single-ended mode. This allows the user
to select the best measurement technique for each input channel, and even accommodates mode
changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are two registers
associated with the AMUX: the Cha nnel Selection register AMX0SL (SFR Definition 5.2), and the Configu-
ration register AMX0CF (SFR Definition 5.1). The table in SFR Definition 5.2 shows AMUX functionality by
channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount deter-
mined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (SFR Definition
5.3). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.
12-Bit
SAR
ADC
REF
+
-
AV+
TEMP
SENSOR
12
+
-
+
-
+
-
9-to-1
AMUX
(SE or
DIFF)
AV+
24
12
AD0EN
SYSCLK
+
-
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
Start Conversion
AGND
AGND
ADC0L ADC0H
ADC0LTLADC0LTHADC0GTLADC0GTH
AD0CM
Timer 3 Overflow
Timer 2 Overflow
00
01
10
11
AD0BUSY (W)
CNVSTR0
AD0WINT
Comb.
Logic
AMX0CF AMX0SL
AMX0AD0
AMX0AD1
AMX0AD2
AMX0AD3
AIN01IC
AIN23IC
AIN45IC
AIN67IC
ADC0CF
AMP0GN0
AMP0GN1
AMP0GN2
AD0SC0
AD0SC1
AD0SC2
AD0SC3
AD0SC4
ADC0CN
AD0LJST
AD0WINT
AD0CM0
AD0CM1
AD0BUSY
AD0INT
AD0TM
AD0EN
AD0CM
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
56 Rev. 1.4
The Temperature Sensor transfer function is shown in Figure 5.2. The output voltage (VTEMP) is the PGA
input when the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will
be amplified by the PGA ac cording to the user-p rogrammed PGA se ttings. Typical values fo r the Slope and
Offset parameters can be found in Table 5.1.
Figure 5.2. Typical Temperature Sensor Transfer Function
0-50 50 100
Temperature (Celsius)
Voltage
VTEMP = (Slope x TempC) + Offset
Offset (V at 0 Celsius)
Slope (V / deg C)
TempC = (VTEMP - Offset) / Slope
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 57
5.2. ADC Modes of Operation
ADC0 has a maximum conversion speed of 100 ksp s. T he ADC0 con version clock is der ived from the sys-
tem clock divided by the value held in the ADCSC bits of register ADC0CF.
5.2.1. Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by:
1. Writing a ‘1’ to th e AD0BUSY bit of ADC0CN;
2. A Timer 3 overflow (i.e. timed continuous conversions);
3. A rising edge detected on the external ADC convert start signal, CNVSTR0;
4. A Timer 2 overflow (i.e. timed continuous conversions).
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete.
The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag
(ADC0CN.5). Converted dat a is available in the ADC0 dat a word MSB and LSB r egisters, ADC0H, ADC0L.
Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in
Figure 5.5) depending on the programmed state of the AD0LJST bit in the ADC0CN register.
When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine
when a conversion has completed (ADC0 interrupts may also be used). The recomm ended polling proce-
dure is shown below.
Step 1. Write a ‘0’ to AD0INT;
Step 2. Wr ite a ‘1’ to AD0BUSY;
Step 3. Poll AD0INT for ‘1’;
Step 4. Process ADC0 data.
When CNVSTR0 is used as a co nversion start source, it must be enabled in the crossba r, and the corre-
sponding pin must be set to open-drain, high-impedance mode (see Section “18. Port Input/Output” on
page 235 for more details on Port I/O configuration).
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
58 Rev. 1.4
5.2.2. Tracking Modes
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0
input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0
operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking
period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR0 signal is used to initiate
conversions in low-po wer tracking mode , ADC0 tracks only when CNVSTR0 is low; conversion begins on
the rising edge of CNVSTR0 (see Figure 5.3). Tracking can also be disabled (shutdown) when the entire
chip is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX
or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section
“5.2.3. Settling Time Requirements” on page 59).
Figure 5.3. ADC0 Track and Conversion Example Timing
12345678910111213141516
CNVSTR0
(AD0CM[1:0]=10)
ADC0TM=1
ADC0TM=0
Timer 2, Timer 3 Overflow;
Write '1' to AD0BUSY
(AD0CM[1:0]=00, 01, 11)
ADC0TM=1
ADC0TM=0
A. ADC Timing for External Trigger Source
B. ADC Timing for Internal Trigger Sources
SAR Clocks
SAR Clocks
1234567891011121314151617 18 19
12345678910111213141516
SAR Clocks
Track Convert Low Powe r M ode
Low Power
or Convert
Track Or Convert Convert Track
Track Convert Low Power Mode
Low Power
or Convert
Track or
Convert Convert Track
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 59
5.2.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This trackin g time is
determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 5.4 shows the equivalent ADC0 input circuits
for both Differential and Single-ended modes. Notice that the equivalent time constant for both input cir-
cuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by
Equation 5.1. When measuring the Temperature Sensor output, RTOTAL reduces to RMUX. An absolute
minimum settling time of 1.5 µs is required after any MUX or PGA selection. Note that in low-power track-
ing mode, three SAR clocks are used for tracking at the start of every conversion. For most applica tions,
these three SAR clocks will meet the tracking requirements.
Equation 5.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the ADC0 MUX resistance and any external source resist ance.
n is the ADC resolution in bits (12).
Figure 5.4. ADC0 Equivalent Input Circuits
t2n
SA
-------
RTOTALCSAMPLE
ln=
R
MUX
= 5k
RC
Input
= R
MUX
* C
SAMPLE
R
MUX
= 5k
C
SAMPLE
= 10pF
C
SAMPLE
= 10pF
MUX Select
MUX Select
Differe ntial Mode
AIN0.x
AIN0.y
R
MUX
= 5k
C
SAMPLE
= 10pF
RC
Input
= R
MUX
* C
SAMPLE
MUX Select
Single -Ended Mode
AIN0.x
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
60 Rev. 1.4
SFR Definition 5.1. AMX0CF: AMUX0 Configuration
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3: AIN67IC: AIN0.6, AIN0.7 Input Pair Configuration Bit.
0: AIN0.6 and AIN0.7 are independent single-ended input s.
1: AIN0.6, AIN0.7 are (respectively) +, – dif ferential input pair.
Bit2: AIN45IC: AIN0.4, AIN0.5 Input Pair Configuration Bit.
0: AIN0.4 and AIN0.5 are independent single-ended input s.
1: AIN0.4, AIN0.5 are (respectively) +, – dif ferential input pair.
Bit1: AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit.
0: AIN0.2 and AIN0.3 are independent single-ended input s.
1: AIN0.2, AIN0.3 are (respectively) +, – dif ferential input pair.
Bit0: AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit.
0: AIN0.0 and AIN0.1 are independent single-ended input s.
1: AIN0.0, AIN0.1 are (respectively) +, – dif ferential input pair.
Note: The ADC0 Data Word is in 2’s complement format for channels configured as differenti al.
SFR Page:
SFR Address: 0
0xBA
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - AIN67IC AIN45IC AIN23IC AIN01IC 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 61
SFR Definition 5.2. AMX0SL: AMUX0 Channel Select
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bits3–0: AMX0AD3–0: AMX0 Address Bits.
0000-1111b: ADC Input s selected per chart below.
SFR Page:
SFR Address: 0
0xBB
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
AMX0AD3–0
0000 0001 0010 0011 0100 0101 0110 0111 1xxx
AMX0CF Bits 3–0
0000 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0001 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0010 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0011 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0100 AIN0.0 AIN0.1 AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
0101 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
0110 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
0111 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
1000 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1001 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1010 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1011 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1100 AIN0.0 AIN0.1 AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1101 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1110 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1111 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
62 Rev. 1.4
SFR Definition 5.3. ADC0CF: ADC0 Configuration
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
The SAR Conversion clock is derived from system clock by the following equation, where
AD0SC refers to the 5-b it value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0
SAR clock (Note: the ADC0 SAR Conversion Clock should be less than or equal to
2.5 MHz).
When the AD0SC bits are equal to 00000b, the SAR Conversion clock is equal to SYSCLK
to facilitate faster ADC conversions at slower SYSCLK speeds.
Bits2–0: AMP0GN2–0: ADC0 Internal Amplifier Gain (PGA).
000: Gain = 1
001: Gain = 2
010: Gain = 4
011: Gain = 8
10x: Gain = 16
11x: Gain = 0.5
SFR Page:
SFR Address: 0
0xBC
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
AD0SC SYSCLK
2CLKSAR0
--------------------------------1–=
AD0SC 00000b
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 63
SFR Definition 5.4. ADC0CN: ADC0 Control
Bit7: AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and ready for data conversions.
Bit6: AD0TM: ADC Tr ack Mode Bit.
0: When the ADC is enabled, tracking is continuous unless a conversion is in process.
1: Tracking Defined by ADCM1-0 bits.
Bit5: AD0INT: ADC0 Conversion Complete Interrupt Flag.
This flag must be cleared by software.
0: ADC0 has not completed a data conversion since the last time this flag was cleared.
1: ADC0 has completed a da ta conversion.
Bit4: AD0BUSY: ADC0 Busy Bit.
Read:
0: ADC0 Conversion is complete or a conversion is not currently in progress. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 Conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM1-0 = 00b.
Bits3–2: AD0CM1–0: ADC0 Start of Conversion Mode Select.
If AD0TM = 0:
00: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
01: ADC0 conversion initiated on overflow of Timer 3.
10: ADC0 conversion initiated on rising edge of external CNVSTR0.
11: ADC0 conversion initiated on overflow of Timer 2.
If AD0TM = 1:
00: Tracking starts with the write of ‘1’ to AD0BUSY and lasts for 3 SAR clocks, followed by
conversion.
01: Tracking started by the overflow of Timer 3 and lasts for 3 SAR clocks, followed by con-
version.
10: ADC0 tracks only when CNVSTR0 input is logic low; conversion starts on rising
CNVSTR0 edge.
11: Tracking started by the overflow of Timer 2 and lasts for 3 SAR clocks, followed by con-
version.
Bit1: AD0WINT: ADC0 Window Compare Inte rr upt Flag.
This bit must be cleared by software.
0: ADC0 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC0 Window Comparison Data match has occurred.
Bit0: AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-justified.
1: Data in ADC0H:ADC0L registers are left-justified.
SFR Page:
SFR Address: 0
0xE8 (bit addressable)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0EN AD0TM AD0INT AD0BUSY AD0CM1 AD0CM0 AD0WINT AD0LJST 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
64 Rev. 1.4
SFR Definition 5.5. ADC0H: ADC0 Data Word MSB
SFR Definition 5.6. ADC0L: ADC0 Dat a Word LSB
Bits7–0: ADC0 Da ta Word High-Order Bits.
For AD0LJST = 0: Bit s 7–4 are the sign exte nsion of Bit3. Bits 3–0 are the upper 4 bits of the
12-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-s ignificant bits of the 12-bit ADC0 Data Word.
SFR Page:
SFR Address: 0
0xBF
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: ADC0 Da ta Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 12-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–4 are the lower 4 bits of the 12-bit ADC0 Data Word. Bits 3–0 will
always read ‘0’.
SFR Page:
SFR Address: 0
0xBE
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 65
Figure 5.5. ADC0 Data Word Example
12-bit ADC0 Data Word appears in the ADC0 Dat a Word Registers as follows:
ADC0H[3:0]:ADC0L[7:0], if AD0LJST = 0
(ADC0H[7:4] will be sign-extension of ADC0H.3 for a differential reading, otherwise
=0000b).
ADC0H[7:0]:ADC0L[7:4], if AD0LJST = 1
(ADC0L[3:0] = 0000b).
Example: ADC0 Data Word Conversion Map , AIN0.0 Input in Single-Ended Mode
(AMX0CF = 0x00, AMX0SL = 0x00)
Example: ADC0 Data Word Conversion Map, AIN0.0-AIN0.1 Differential Input Pair
(AMX0CF = 0x01, AMX0SL = 0x00)
For AD0LJST = 0:
; ‘n’ = 12 for Single-Ended; ‘n’=11 for Differential.
AIN0.0–AGND
(Volts) ADC0H:ADC0L
(AD0LJST = 0) ADC0H:ADC0L
(AD0LJST = 1)
VREF x (4095/4096) 0x0FFF 0xFFF0
VREF / 2 0x0800 0x8000
VREF x (2047/4096) 0x07FF 0x7FF0
0 0x0000 0x0000
AIN0.0–AIN0.1
(Volts) ADC0H:ADC0L
(AD0LJST = 0) ADC0H:ADC0L
(AD0LJST = 1)
VREF x (2047/2048) 0x07FF 0x7FF0
VREF / 2 0x0400 0x4000
VREF x (1/2048) 0x0001 0x0010
0 0x0000 0x0000
–VREF x (1/2048) 0xFFFF (–1d) 0xFFF0
–VREF / 2 0xFC00 (–1024d) 0xC000
–VREF 0xF800 (–2048d) 0x8000
Code Vin Gain
VREF
---------------
2n
=
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
66 Rev. 1.4
5.3. ADC0 Programmable Window Detector
The ADC0 Programmable Win do w Detector continuou sly compares the ADC0 output to user-prog ramme d
limits, a nd no tifies th e system whe n a n out- of-boun d co ndition is detected. This is especially effective in an
interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response
times. The window detector interrupt flag (AD0WINT in ADC0CN) can also be used in polled mode. The
high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than
registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting
on page 68. Notice that the windo w detecto r flag can be asser ted when the measur ed da t a is inside or out-
side the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx regis-
ters.
SFR Definition 5.7. ADC0GTH: ADC0 Greater-Than Data High Byte
SFR Definition 5.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
Bits7–0: High byte of ADC0 Greater-Than Data Word.
SFR Page:
SFR Address: 0
0xC5
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: Low byte of ADC0 Gr ea ter-Than Data Word.
SFR Page:
SFR Address: 0
0xC4
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 67
SFR Definition 5.9. ADC0LTH: ADC0 Less-Than Data High Byte
SFR Definition 5.10. ADC0LTL: ADC0 Less-Than Data Low Byte
Bits7–0: High byte of ADC0 Less-Than Data Word.
SFR Page:
SFR Address: 0
0xC7
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: Low byte of ADC0 Le ss- T ha n Data Word.
SFR Page:
SFR Address: 0
0xC6
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
68 Rev. 1.4
Figure 5.6. 12-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended
Data
Given:
AMX0SL = 0x00, AMX0CF = 0x00
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0200,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0200 and > 0x0100.
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0x0200.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
> 0x0200 or < 0x0100.
0x0FFF
0x0201
0x0200
0x01FF
0x0101
0x0100
0x00FF
0x0000
AD0WINT=1
AD0WINT
not affected
AD0WINT
not affected
ADC Data
Word
0x0FFF
0x0201
0x0200
0x01FF
0x0101
0x0100
0x00FF
0x0000
AD0WINT=1
AD0WINT
not affected
AD0WINT=1
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0
Input Voltage
(AD0.0 - AGND)
REF x (4095/4096)
REF x (256/4096)
REF x (512/4096)
0
Input Voltage
(AD0.0 - AGND)
REF x (4095/4096)
REF x (256/4096)
REF x (512/4096)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 69
Figure 5.7. 12-Bit ADC0 Window Interrupt Example: Right Justified Differential
Data
0x07FF
0x0101
0x0100
0x00FF
0x0000
0xFFFF
0xFFFE
0xF800
AD0WINT=1
AD0WINT
not af fected
AD0WINT
not af fected
0x07FF
0x0101
0x0100
0x00FF
0x0000
0xFFFF
0xFFFE
0xF800
AD0WINT=1
AD0WINT
not affected
-REF
Input Voltage
(AD0.0 - AD0.1)
AD0WINT=1
REF x (2047/2048)
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC Data
Word
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
REF x (256/2048)
REF x (-1/2048)
-REF
Input Voltag e
(AD0.0 - AD0 .1)
REF x (2047/2048)
REF x (256/2048)
REF x (-1/2048)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0xFFFF.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0100 and > 0xFFFF. (In 2s-complement
math, 0xFFFF = -1.)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0xFFFF,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFFF or > 0x0100. (In 2s-complement
math, 0xFFFF = -1.)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
70 Rev. 1.4
Figure 5.8. 12-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended
Data
0xFFF0
0x2010
0x2000
0x1FF0
0x1010
0x1000
0x0FF0
0x0000
AD0WINT=1
AD0WINT
not af fected
AD0WINT
not af fected
ADC Data
Word
0xFFF0
0x2010
0x2000
0x1FF0
0x1010
0x1000
0x0FF0
0x0000
AD0WINT=1
AD0WINT
not affected
AD0WINT=1
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0
Input Voltag e
(AD0.0 - AG ND)
REF x (4095/4096)
REF x (256/4096)
REF x (512/4096)
0
Input Voltage
(AD0.0 - AGND)
REF x (4095/4096)
REF x (256/4096)
REF x (512/4096)
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0x2000,
ADC0GTH:ADC0GTL = 0x1000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x2000 and > 0x1000.
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’
ADC0LTH:ADC0LTL = 0x1000,
ADC0GTH:ADC0GTL = 0x2000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x1000 or > 0x2000.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 71
Figure 5.9. 12-Bit ADC0 Window Interrupt Example: Left Justified Differential Data
0x7FF0
0x1010
0x1000
0x0FF0
0x0000
0xFFF0
0xFFE0
0x8000
AD0WINT=1
AD0WINT
not af fected
AD0WINT
not af fected
0x7FF0
0x1010
0x1000
0x0FF0
0x0000
0xFFF0
0xFFE0
0x8000
AD0WINT=1
AD0WINT
no t affec ted
-REF
Input Voltage
(AD0.0 - AD0.1)
AD0WINT=1
REF x (2047/2048)
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC Data
Word
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
REF x (256/2048)
REF x (-1/2048)
-REF
Input Voltage
(AD0.0 - AD0.1)
REF x (2047/2048)
REF x (256/2048)
REF x (-1/20 48)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0x1000,
ADC0GTH:ADC0GTL = 0xFFF0.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x1000 and > 0xFFF0. (2s-compleme nt
math.)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0xFFF0,
ADC0GTH:ADC0GTL = 0x1000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFF0 or > 0x1000. (2s-complemen t math.)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
72 Rev. 1.4
Table 5.1. 12-Bit ADC0 Electrical Characteristics (C8051F120/1/4/5)
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
DC Accuracy
Resolution 12 bits
Integral Nonlinearity — — ±1 LSB
Differential Nonlinearity Guar ante ed Mo noto nic — — ±1 LSB
Offset Error — –3±1 — LSB
Full Scale Error Differential mode — –7±3 — LSB
Offset Temperature Coefficient — ±0.25 — ppm/°C
Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps
Signal-to-Noise Plus Distortion 66 — — dB
Total Harmonic Distortion Up to the 5th harmonic —–75— dB
Sp ur io us- F ree Dyn a mic Rang e — 8 0 — dB
Conversion Rate
SAR Clock Frequency — — 2.5 MHz
Conversion Time in SAR Clocks 16 — — clocks
Track/Hold Acquisition Time 1.5 — — µs
Throughput Rate — — 100 ksps
Analog Inputs
Input Voltage Range Single-ended operation 0 — VREF V
*Common-mode Voltage Range Differential operation AGND — AV+ V
Input Capacitance — 10 — pF
Temperature Sensor
Linearity1—±0.2— °C
Offset (Temp = 0 °C) — 776 — mV
Offset Error1, 2 (Temp = 0 °C) — ±8.5 — mV
Slope — 2.86 — mV / °C
Slope Error2— ±0.034 — mV / °C
Power Specifications
Power Supply Current
(AV+ supplied to ADC) Operating Mode, 100 ksps —450900 µA
Power Supply Rejection — ±0.3 — mV/V
Notes:
1. Includes ADC offset, gain, and linearity variations.
2. Represents one standard deviation from the mean.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 73
6. ADC0 (10-Bit ADC, C8051F122/3/6/7 and C8051F13x Only)
The ADC0 subsystem for the C8051F122/3/6/7 and C8051F13x consists of a 9-channel, configurable ana-
log multiplexer (AMUX0), a programmable gain amplifier (PGA0), and a 100 ksps, 10-bit successive-
approximation-register ADC with integrated track-and-hold and Programmable Window Detector (see
block diagram in Figure 6.1). The AMUX0, PGA0, Data Conversion Modes, and Window Detector are all
configurable under software control via the Special Function Registers shown in Figure 6.1. The voltage
reference used by ADC0 is selected as described in Section “9. Voltage Reference” on page 113. The
ADC0 subsystem (ADC0, track-and-hold and PGA0) is enabled only when the AD0EN bit in the ADC0
Control register (ADC0CN) is set to logic 1. The ADC0 subsystem is in low power shut down when this bit is
logic 0.
Figure 6.1. 10-Bit ADC0 Functional Block Diagram
6.1. Analog Multiplexer and PGA
Eight of the AMUX channels are available for external measurements while the ninth channel is internally
connected to an on-chip temperature sensor (temperature transfer function is shown in Figure 6.2). AMUX
input pairs can be programmed to operate in either differential or single-ended mode. This allows the user
to select the best measurement technique for each input channel, and even accommodates mode
changes "on-the-fly". The AMUX defaults to all single-ended inputs upon reset. There are two registers
associated with the AMUX: the Cha nnel Selection register AMX0SL (SFR Definition 6.2), and the Configu-
ration register AMX0CF (SFR Definition 6.1). The table in SFR Definition 6.2 shows AMUX functionality by
channel, for each possible configuration. The PGA amplifies the AMUX output signal by an amount deter-
mined by the states of the AMP0GN2-0 bits in the ADC0 Configuration register, ADC0CF (SFR Definition
6.3). The PGA can be software-programmed for gains of 0.5, 2, 4, 8 or 16. Gain defaults to unity on reset.
10-Bit
SAR
ADC
REF
+
-
AV+
TEMP
SENSOR
10
+
-
+
-
+
-
9-to-1
AMUX
(SE or
DIFF)
AV+
20
10
AD0EN
SYSCLK
+
-
X
AIN0.0
AIN0.1
AIN0.2
AIN0.3
AIN0.4
AIN0.5
AIN0.6
AIN0.7
Start Conversion
AGND
AGND
ADC0L ADC0H
ADC0LTLADC0LTHADC0GTLADC0GTH
AD0CM
Timer 3 Overflow
Timer 2 Overflow
00
01
10
11
AD0BUSY (W)
CNVSTR0
AD0WINT
Comb.
Logic
AMX0SL
AMX0AD0
AMX0AD1
AMX0AD2
AMX0AD3
AMX0CF
AIN01IC
AIN23IC
AIN45IC
AIN67IC
ADC0CF
AMP0GN0
AMP0GN1
AMP0GN2
AD0SC0
AD0SC1
AD0SC2
AD0SC3
AD0SC4
ADC0CN
AD0LJST
AD0WINT
AD0CM0
AD0CM1
AD0BUSY
AD0INT
AD0TM
AD0EN
AD0CM
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
74 Rev. 1.4
The Temperature Sensor transfer function is shown in Figure 6.2. The output voltage (VTEMP) is the PGA
input when the Temperature Sensor is selected by bits AMX0AD3-0 in register AMX0SL; this voltage will
be amplified by the PGA ac cording to the user-p rogrammed PGA se ttings. Typical values fo r the Slope and
Offset parameters can be found in Table 6.1.
Figure 6.2. Typical Temperature Sensor Transfer Function
0-50 50 100
Temperature (Celsius)
Voltage
VTEMP = (Slope x TempC) + Offset
Offset (V at 0 Celsius)
Slope (V / deg C)
TempC = (VTEMP - Offset) / Slope
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 75
6.2. ADC Modes of Operation
ADC0 has a maximum conversion speed of 100 ksp s. T he ADC0 con version clock is der ived from the sys-
tem clock divided by the value held in the ADCSC bits of register ADC0CF.
6.2.1. Starting a Conversion
A conversion can be initiated in one of four ways, depending on the programmed states of the ADC0 Start
of Conversion Mode bits (AD0CM1, AD0CM0) in ADC0CN. Conversions may be initiated by:
1. Writing a ‘1’ to th e AD0BUSY bit of ADC0CN;
2. A Timer 3 overflow (i.e. timed continuous conversions);
3. A rising edge detected on the external ADC convert start signal, CNVSTR0;
4. A Timer 2 overflow (i.e. timed continuous conversions).
The AD0BUSY bit is set to logic 1 during conversion and restored to logic 0 when conversion is complete.
The falling edge of AD0BUSY triggers an interrupt (when enabled) and sets the AD0INT interrupt flag
(ADC0CN.5). Converted dat a is available in the ADC0 dat a word MSB and LSB r egisters, ADC0H, ADC0L.
Converted data can be either left or right justified in the ADC0H:ADC0L register pair (see example in
Figure 6.5) depending on the programmed state of the AD0LJST bit in the ADC0CN register.
When initiating conversions by writing a ‘1’ to AD0BUSY, the AD0INT bit should be polled to determine
when a conversion has completed (ADC0 interrupts may also be used). The recomm ended polling proce-
dure is shown below.
Step 1. Write a ‘0’ to AD0INT;
Step 2. Wr ite a ‘1’ to AD0BUSY;
Step 3. Poll AD0INT for ‘1’;
Step 4. Process ADC0 data.
When CNVSTR0 is used as a co nversion start source, it must be enabled in the crossba r, and the corre-
sponding pin must be set to open-drain, high-impedance mode (see Section “18. Port Input/Output” on
page 235 for more details on Port I/O configuration).
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
76 Rev. 1.4
6.2.2. Tracking Modes
The AD0TM bit in register ADC0CN controls the ADC0 track-and-hold mode. In its default state, the ADC0
input is continuously tracked when a conversion is not in progress. When the AD0TM bit is logic 1, ADC0
operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a tracking
period of 3 SAR clocks (after the start-of-conversion signal). When the CNVSTR0 signal is used to initiate
conversions in low-po wer tracking mode , ADC0 tracks only when CNVSTR0 is low; conversion begins on
the rising edge of CNVSTR0 (see Figure 6.3). Tracking can also be disabled (shutdown) when the entire
chip is in low power standby or sleep modes. Low-power track-and-hold mode is also useful when AMUX
or PGA settings are frequently changed, to ensure that settling time requirements are met (see Section
“6.2.3. Settling Time Requirements” on page 77).
Figure 6.3. ADC0 Track and Conversion Example Timing
12345678910111213141516
CNVSTR0
(AD0CM[1:0]=10)
ADC0TM=1
ADC0TM=0
Timer 2, Timer 3 Overflow;
Write '1' to AD0BUSY
(AD0CM[1:0]=00, 01, 11)
ADC0TM=1
ADC0TM=0
A. ADC Timing for External Trigger Source
B. ADC Timing for Internal Trigger Sources
SAR Clocks
SAR Clocks
1234567891011121314151617 18 19
12345678910111213141516
SAR Clocks
Track Convert Low Powe r M ode
Low Power
or Convert
Track Or Convert Convert Track
Track Convert Low Power Mode
Low Power
or Convert
Track or
Convert Convert Track
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 77
6.2.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This trackin g time is
determined by the ADC0 MUX resistance, the ADC0 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 6.4 shows the equivalent ADC0 input circuits
for both Differential and Single-ended modes. Notice that the equivalent time constant for both input cir-
cuits is the same. The required settling time for a given settling accuracy (SA) may be approximated by
Equation 6.1. When measuring the Temperature Sensor output, RTOTAL reduces to RMUX. An absolute
minimum settling time of 1.5 µs is required after any MUX or PGA selection. Note that in low-power track-
ing mode, three SAR clocks are used for tracking at the start of every conversion. For most applica tions,
these three SAR clocks will meet the tracking requirements.
Equation 6.1. ADC0 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the ADC0 MUX resistance and any external source resist ance.
n is the ADC resolution in bits (10).
Figure 6.4. ADC0 Equivalent Input Circuits
t2n
SA
-------
RTOTALCSAMPLE
ln=
R
MUX
= 5k
RC
Input
= R
MUX
* C
SAMPLE
R
MUX
= 5k
C
SAMPLE
= 10pF
C
SAMPLE
= 10pF
MUX Select
MUX Select
Differe ntial Mode
AIN0.x
AIN0.y
R
MUX
= 5k
C
SAMPLE
= 10pF
RC
Input
= R
MUX
* C
SAMPLE
MUX Select
Single -Ended Mode
AIN0.x
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
78 Rev. 1.4
SFR Definition 6.1. AMX0CF: AMUX0 Configuration
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3: AIN67IC: AIN0.6, AIN0.7 Input Pair Configuration Bit.
0: AIN0.6 and AIN0.7 are independent single-ended input s.
1: AIN0.6, AIN0.7 are (respectively) +, - differen tial input pair.
Bit2: AIN45IC: AIN0.4, AIN0.5 Input Pair Configuration Bit.
0: AIN0.4 and AIN0.5 are independent single-ended input s.
1: AIN0.4, AIN0.5 are (respectively) +, - differen tial input pair.
Bit1: AIN23IC: AIN0.2, AIN0.3 Input Pair Configuration Bit.
0: AIN0.2 and AIN0.3 are independent single-ended input s.
1: AIN0.2, AIN0.3 are (respectively) +, - differen tial input pair.
Bit0: AIN01IC: AIN0.0, AIN0.1 Input Pair Configuration Bit.
0: AIN0.0 and AIN0.1 are independent single-ended input s.
1: AIN0.0, AIN0.1 are (respectively) +, - differen tial input pair.
Note: The ADC0 Data Word is in 2’s complement format for channels configured as differenti al.
SFR Page:
SFR Address: 0
0xBA
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - AIN67IC AIN45IC AIN23IC AIN01IC 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 79
SFR Definition 6.2. AMX0SL: AMUX0 Channel Select
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bits3–0: AMX0AD3–0: AMX0 Address Bits.
0000-1111b: ADC Input s selected per chart below.
SFR Page:
SFR Address: 0
0xBB
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - AMX0AD3 AMX0AD2 AMX0AD1 AMX0AD0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
AMX0AD3-0
0000 0001 0010 0011 0100 0101 0110 0111 1xxx
AMX0CF Bits 3-0
0000 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0001 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0010 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0011 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 AIN0.6 AIN0.7 TEMP
SENSOR
0100 AIN0.0 AIN0.1 AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
0101 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
0110 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
0111 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) AIN0.6 AIN0.7 TEMP
SENSOR
1000 AIN0.0 AIN0.1 AIN0.2 AIN0.3 AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1001 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1010 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1011 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) AIN0.4 AIN0.5 +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1100 AIN0.0 AIN0.1 AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1101 +(AIN0.0)
–(AIN0.1) AIN0.2 AIN0.3 +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1110 AIN0.0 AIN0.1 +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
1111 +(AIN0.0)
–(AIN0.1) +(AIN0.2)
–(AIN0.3) +(AIN0.4)
–(AIN0.5) +(AIN0.6)
–(AIN0.7) TEMP
SENSOR
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
80 Rev. 1.4
SFR Definition 6.3. ADC0CF: ADC0 Configuration
Bits7–3: AD0SC4–0: ADC0 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from sy st em clock by the following equation, where
AD0SC refers to the 5-b it value held in AD0SC4-0, and CLKSAR0 refers to the desired ADC0
SAR clock (Note: the ADC0 SAR Conversion Clock should be less than or equal to
2.5 MHz).
When the AD0SC bits are equal to 00000b, the SAR Conversion clock is equal to SYSCLK
to facilitate faster ADC conversions at slower SYSCLK speeds.
Bits2–0: AMP0GN2–0: ADC0 Internal Amplifier Gain (PGA).
000: Gain = 1
001: Gain = 2
010: Gain = 4
011: Gain = 8
10x: Gain = 16
11x: Gain = 0.5
SFR Page:
SFR Address: 0
0xBC
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0SC4 AD0SC3 AD0SC2 AD0SC1 AD0SC0 AMP0GN2 AMP0GN1 AMP0GN0 11111000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
AD0SC SYSCLK
2CLKSAR0
--------------------------------1–=
AD0SC 00000b
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 81
SFR Definition 6.4. ADC0CN: ADC0 Control
Bit7: AD0EN: ADC0 Enable Bit.
0: ADC0 Disabled. ADC0 is in low-power shutdown.
1: ADC0 Enabled. ADC0 is active and r eady for data conversions.
Bit6: AD0TM: ADC Track Mode Bit.
0: When the ADC is enabled, tracking is continuous unless a conversion is in process.
1: Tracking Defined by ADCM1-0 bits.
Bit5: AD0INT: ADC0 Conversion Complete Interrupt Flag.
This flag must be cleared by software.
0: ADC0 has not completed a data conversion since the last time this flag was cleared.
1: ADC0 has completed a data conversion.
Bit4: AD0BUSY: ADC0 Busy Bit.
Read:
0: ADC0 Conversion is complete or a conversion is not currently in progre ss. AD0INT is set
to logic 1 on the falling edge of AD0BUSY.
1: ADC0 Conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC0 Conversion if AD0CM1-0 = 00b.
Bits3–2: AD0CM1–0: ADC0 Start of Conversion Mode Select.
If AD0TM = 0:
00: ADC0 conversion initiated on every write of ‘1’ to AD0BUSY.
01: ADC0 conversion initiated on overflow of Timer 3.
10: ADC0 conversion initiated on rising edge of external CNVSTR0.
11: ADC0 conversion initiated on overflow of Timer 2.
If AD0TM = 1:
00: Tracking starts with the write of ‘1’ to AD0BUSY and last s for 3 SAR clocks, followe d by
conversion.
01: Tracking started by the overflow of Timer 3 and lasts for 3 SAR clocks, followed by con-
version.
10: ADC0 tracks only when CNVSTR0 input is logic low; conve rsion starts on rising
CNVSTR0 edge.
11: Tracking started by the overflow of Timer 2 and lasts for 3 SAR clocks, followed by con-
version.
Bit1: AD0WINT: ADC0 Window Compare Interrupt Flag.
This bit must be cleared by software.
0: ADC0 Window Compa rison Da ta match has not occurred sin ce th is flag was la st clear ed .
1: ADC0 Window Comparison Data match has occurr ed.
Bit0: AD0LJST: ADC0 Left Justify Select.
0: Data in ADC0H:ADC0L registers are right-ju stif ied .
1: Data in ADC0H:ADC0L registers are left-justified.
SFR Page:
SFR Address: 0
0xE8 (bit addressable)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD0EN AD0TM AD0INT AD0BUSY AD0CM1 AD0CM0 AD0WINT AD0LJST 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
82 Rev. 1.4
SFR Definition 6.5. ADC0H: ADC0 Data Word MSB
SFR Definition 6.6. ADC0L: ADC0 Dat a Word LSB
Bits7–0: ADC0 Da ta Word High-Order Bits.
For AD0LJST = 0: Bit s 7–4 are the sign exte nsion of Bit3. Bits 3–0 are the upper 4 bits of the
10-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–0 are the most-s ignificant bits of the 10-bit ADC0 Data Word.
SFR Page:
SFR Address: 0
0xBF
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: ADC0 Da ta Word Low-Order Bits.
For AD0LJST = 0: Bits 7–0 are the lower 8 bits of the 10-bit ADC0 Data Word.
For AD0LJST = 1: Bits 7–4 are the lower 4 bits of the 10-bit ADC0 Data Word. Bits 3–0 will
always read ‘0’.
SFR Page:
SFR Address: 0
0xBE
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 83
Figure 6.5. ADC0 Data Word Example
10-bit ADC0 Data Word appears in the ADC0 Dat a Word Registers as follows:
ADC0H[1:0]:ADC0L[7:0], if AD0LJST = 0
(ADC0H[7:2] will be sign-extension of ADC0H.1 for a differential reading, otherwise
=000000b).
ADC0H[7:0]:ADC0L[7:6], if AD0LJST = 1
(ADC0L[5:0] = 00b).
Example: ADC0 Data Word Conversion Map , AIN0.0 Input in Single-Ended Mode
(AMX0CF = 0x00, AMX0SL = 0x00)
Example: ADC0 Data Word Conversion Map, AIN0.0-AIN0.1 Differential Input Pair
(AMX0CF = 0x01, AMX0SL = 0x00)
For AD0LJST = 0:
; ‘n’ = 10 for Single-Ended; ‘n’= 9 for Differential.
AIN0.0–AGND
(Volts) ADC0H:ADC0L
(AD0LJST = 0) ADC0H:ADC0L
(AD0LJST = 1)
VREF x (1023/1024) 0x03FF 0xFFC0
VREF / 2 0x0200 0x8000
VREF x (511/1024) 0x01FF 0x7FC0
0 0x0000 0x0000
AIN0.0–AIN0.1
(Volts) ADC0H:ADC0L
(AD0LJST = 0) ADC0H:ADC0L
(AD0LJST = 1)
VREF x (511/512) 0x01FF 0x7FC0
VREF / 2 0x0100 0x4000
VREF x (1/512) 0x0001 0x0040
0 0x0000 0x0000
–VREF x (1/512) 0xFFFF (–1d) 0xFFC0
–VREF / 2 0xFF00 (–256d ) 0xC000
–VREF 0xFE00 (–512d) 0x8000
Code Vin Gain
VREF
---------------
2n
=
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
84 Rev. 1.4
6.3. ADC0 Programmable Window Detector
The ADC0 Programmable Win do w Detector continuou sly compares the ADC0 output to user-prog ramme d
limits, a nd no tifies th e system whe n a n out- of-boun d co ndition is detected. This is especially effective in an
interrupt-driven system, saving code space and CPU bandwidth while delivering faster system response
times. The window detector interrupt flag (AD0WINT in ADC0CN) can also be used in polled mode. The
high and low bytes of the reference words are loaded into the ADC0 Greater-Than and ADC0 Less-Than
registers (ADC0GTH, ADC0GTL, ADC0LTH, and ADC0LTL). Reference comparisons are shown starting
on page 87. Notice that the windo w detecto r flag can be asser ted when the measur ed da t a is inside or out-
side the user-programmed limits, depending on the programming of the ADC0GTx and ADC0LTx regis-
ters.
SFR Definition 6.7. ADC0GTH: ADC0 Greater-Than Data High Byte
SFR Definition 6.8. ADC0GTL: ADC0 Greater-Than Data Low Byte
Bits7–0: High byte of ADC0 Greater-Than Data Word.
SFR Page:
SFR Address: 0
0xC5
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: Low byte of ADC0 Gr ea ter-Than Data Word.
SFR Page:
SFR Address: 0
0xC4
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 85
SFR Definition 6.9. ADC0LTH: ADC0 Less-Than Data High Byte
SFR Definition 6.10. ADC0LTL: ADC0 Less-Than Data Low Byte
Bits7–0: High byte of ADC0 Less-Than Data Word.
SFR Page:
SFR Address: 0
0xC7
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: Low byte of ADC0 Le ss- T ha n Data Word.
SFR Page:
SFR Address: 0
0xC6
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
86 Rev. 1.4
Figure 6.6. 10-Bit ADC0 Window Interrupt Example: Right Justified Single-Ended
Data
Given:
AMX0SL = 0x00, AMX0CF = 0x00
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0200,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0200 and > 0x0100.
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0x0200.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
> 0x0200 or < 0x0100.
0x03FF
0x0201
0x0200
0x01FF
0x0101
0x0100
0x00FF
0x0000
ADWINT=1
ADWINT
not affected
ADWINT
not affected
ADC Data
Word
0x03FF
0x0201
0x0200
0x01FF
0x0101
0x0100
0x00FF
0x0000
ADWINT=1
ADWINT
not affected
ADWINT=1
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0
Input Voltage
(AD0.0 - AGND)
REF x (1023/1024)
REF x (256/1024)
REF x (512/1024)
0
Input Voltage
(AD0.0 - AGND)
REF x (1023/1024)
REF x (256/1024)
REF x (512/1024)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 87
Figure 6.7. 10-Bit ADC0 Window Interrupt Example: Right Justified Differential
Data
0x01FF
0x0101
0x0100
0x00FF
0x0000
0xFFFF
0xFFFE
0xFE00
ADWINT=1
ADWINT
not af fected
ADWINT
not af fected
0x01FF
0x0101
0x0100
0x00FF
0x0000
0xFFFF
0xFFFE
0xFE00
ADWINT=1
ADWINT
not affected
-REF
Input Voltage
(AD0.0 - AD 0.1)
ADWINT=1
REF x (511/512)
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC Data
Word
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
REF x (256/512)
REF x (-1/512)
-REF
Inpu t Voltage
(AD0.0 - AD 0 .1)
REF x (511/512)
REF x (256/512)
REF x (-1/512)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0x0100,
ADC0GTH:ADC0GTL = 0xFFFF.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x0100 and > 0xFFFF. (In 2s-complement
math, 0xFFFF = -1.)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘0’,
ADC0LTH:ADC0LTL = 0xFFFF,
ADC0GTH:ADC0GTL = 0x0100.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFFF or > 0x0100. (In 2s-complement
math, 0xFFFF = -1.)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
88 Rev. 1.4
Figure 6.8. 10-Bit ADC0 Window Interrupt Example: Left Justified Single-Ended
Data
0xFFC0
0x8040
0x8000
0x7FC0
0x4040
0x4000
0x3FC0
0x0000
ADWINT=1
ADWINT
not af fected
ADWINT
not af fected
ADC Data
Word
0xFFC0
0x8040
0x8000
0x7FC0
0x4040
0x4000
0x3FC0
0x0000
ADWINT=1
ADWINT
not affected
ADWINT=1
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC0GTH:ADC0GTL
ADC0LTH:ADC0LTL
0
Inpu t Voltage
(AD0.0 - AGND)
REF x (1023/1024)
REF x (256/1024)
REF x (512/1024)
0
Input Voltage
(AD0.0 - AGND)
REF x (1023/1024)
REF x (256/1024)
REF x (512/1024)
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0x2000,
ADC0GTH:ADC0GTL = 0x1000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x2000 and > 0x1000.
Given:
AMX0SL = 0x00, AMX0CF = 0x00,
AD0LJST = ‘1’
ADC0LTH:ADC0LTL = 0x1000,
ADC0GTH:ADC0GTL = 0x2000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x1000 or > 0x2000.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 89
Figure 6.9. 10-Bit ADC0 Window Interrupt Example: Left Justified Differential Data
0x7FC0
0x2040
0x2000
0x1FC0
0x0000
0xFFC0
0xFF80
0x8000
ADWINT=1
ADWINT
not af fected
ADWINT
not af fected
0x7FC0
0x2040
0x2000
0x1FC0
0x0000
0xFFC0
0xFF80
0x8000
ADWINT=1
ADWINT
no t affec ted
-REF
Input Voltage
(AD0.0 - AD0.1)
ADWINT=1
REF x (511/512)
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
ADC Data
Word
ADC Data
Word
ADC0LTH:ADC0LTL
ADC0GTH:ADC0GTL
REF x (128/512)
REF x (-1/51 2)
-REF
Input Voltage
(AD0.0 - AD0.1)
REF x (511/512)
REF x (128/512)
REF x (-1/512)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0x2000,
ADC0GTH:ADC0GTL = 0xFFC0.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0x2000 and > 0xFFC0. (2s-complement
math.)
Given:
AMX0SL = 0x00, AMX0CF = 0x01,
AD0LJST = ‘1’,
ADC0LTH:ADC0LTL = 0xFFC0,
ADC0GTH:ADC0GTL = 0x2000.
An ADC0 End of Conversion will cause an
ADC0 Window Compare Interrupt (AD0WINT
= ‘1’) if the resulting ADC0 Data Word is
< 0xFFC0 or > 0x2000. (2s-complement
math.)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
90 Rev. 1.4
Table 6.1. 10-Bit ADC0 Electrical Characteristics (C8051F122/3/6/7 and C8051F13x)
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), PGA Gain = 1, –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
DC Accuracy
Resolution 10 bits
Integral Nonlinearity — — ±1 LSB
Differential Nonlinearity Guar ante ed Mo noto nic — — ±1 LSB
Offset Error — ±0.5 — LSB
Full Scale Error Differential mode — –1.5±0.5 — LSB
Offse t Temperature Coefficient — ±0.25 — ppm/°C
Dynamic Performance (10 kHz sine-wave input, 0 to 1 dB below Full Scale, 100 ksps
Signal-to-Noise Plus Distortion 59 — — dB
Total Harmonic Distortion Up to the 5th harmonic — –70 — dB
Sp ur io us- F re e Dyn a mic Rang e — 80 — d B
Conversion Rate
SAR Clock Frequency — — 2.5 MHz
Conversion Time in SAR Clocks 16 — — clocks
Track/Hold Acquisition Time 1.5 — — µs
Throughput Rate — — 100 ksps
Analog Inputs
Input Voltage Range Single-ended operation 0 — VREF V
*Common-mode Voltage Range Differential operation AGND — AV+ V
Input Capacitance — 10 — pF
Temperature Sensor
Linearity1—±0.2— °C
Offset (Temp = 0 °C) — 776 — mV
Offset Error1,2 (Temp = 0 °C) — ±8.5 — mV
Slope — 2.86 — mV/°C
Slope Error2— ±0.034 — mV/°C
Power Specifications
Power Supply Current
(AV+ supplied to ADC) Operating Mode, 100 ksps — 450 900 µA
Power Supply Rejection — ±0.3 — mV/V
Notes:
1. Includes ADC offset, gain, and linearity variations.
2. Represents one standard deviation from the mean.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 91
7. ADC2 (8-Bit ADC, C8051F12x Only)
The C8051F12x devices includ e a second ADC peripheral (ADC2 ), which consists of an 8-channel, config-
urable analog multiplexer, a programmable gain amplif ier, and a 500 ksps, 8-b it successive-a pproximation-
register ADC with integrated track-and-hold (see block diagram in Figure 7.1). ADC2 is fully configurable
under soft ware control via the Special Function Registe rs shown in Figure 7.1. The ADC2 subsystem (8-bit
ADC, track-and-hold and PGA) is enabled only when the AD2EN bit in the ADC2 Control register
(ADC2CN) is set to logic 1. The ADC2 subsystem is in low power shutdown when this bit is logic 0. The
voltage reference used by ADC2 is selected as described in Section “9. Voltage Reference” on
page 113.
Figure 7.1. ADC2 Functional Block Diagram
7.1. Analog Multiplexer and PGA
Eight ADC2 channels are available for measurement, as selected by the AMX2SL register (see SFR Defi-
nition 7.2). The PGA amplifies the ADC2 output signal by an amount determined by the states of the
AMP2GN2-0 bits in t he AD C2 Co n fig ur at ion r e gist er, ADC2CF (SFR Definition 7. 3) . T h e PG A c an be s oft-
ware-programmed for gains of 0.5, 1, 2, or 4. Gain defaults to 0.5 on reset.
Import ant Not e: AIN2 pins also functio n as Port 1 I/O pins, an d must be configu red as ana log inputs when
used as ADC2 inputs. To configure an AIN2 pin for analog input, set to ‘0’ the corresponding bit in register
P1MDIN. Port 1 pins selected as analog inputs are skipped by the Digital I/O Crossbar. See Section
“18.1.5. Configuring Port 1 Pins as Analog Inputs” on page 240 for more information on configuring
the AIN2 pins.
8-Bit
SAR
ADC
REF
+
-
AV+
8
AV+
AD2EN
SYSCLK
X
AGND
ADC2
ADC2CF
AMP2GN0
AMP2GN1
AD2SC0
AD2SC1
AD2SC2
AD2SC3
AD2SC4
AMX2SL ADC2CN
AD2WINT
AD2CM0
AD2CM1
AD2CM2
AD2BUSY
AD2INT
AD2TM
AD2EN
Start Conversion
Timer 3 Overflow
Timer 2 Overflow
000
001
010
011
Write to AD2BUSY
CNVSTR2
1xx Write to AD0BUSY
(synchronized with
ADC0)
AMX2AD0
AMX2AD1
AMX2AD2
8-to-1
AMUX
AIN2.0 (P1.0)
AIN2.1 (P1.1)
AIN2.2 (P1.2)
AIN2.3 (P1.3)
AIN2.4 (P1.4)
AIN2.5 (P1.5)
AIN2.6 (P1.6)
AIN2.7 (P1.7)
+
-
+
-
+
-
+
-
AMX2CF
PIN01IC
PIN23IC
PIN45IC
PIN67IC
ADC2LTHADC2GTH
16 Dig
Comp
AD2WINT
AD2CM
AD2CM
8
8
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
92 Rev. 1.4
7.2. ADC2 Modes of Operation
ADC2 has a maximum conversion speed of 500 ksps. The ADC2 conversion clock (SAR2 clock) is a
divided version of the system clock, determined by the AD2SC bits in the ADC2CF register. The maximum
ADC2 conversion clock is 6 MHz.
7.2.1. Starting a Conversion
A conversion can be initiate d in on e of five ways, de pending on the programmed states of the ADC2 Start
of Conversion Mode bits (AD2CM2-0) in ADC2CN. Conversions may be initia ted by:
1. Writing a ‘1’ to th e AD2BUSY bit of ADC2CN;
2. A Timer 3 overflow (i.e. timed continuous conversions);
3. A rising edge detected on the external ADC convert start signal, CNVSTR2;
4. A Timer 2 overflow (i.e. timed continuous conversions);
5. Writing a ‘1’ to the AD0BUSY of register ADC0 CN (initiate conversion of ADC2 and ADC0 with
a single software command).
During conversion, the AD2BUSY bit is set to logic 1 and restored to 0 when conversion is complete. The
falling edge of AD2BUSY triggers an interrupt (when enabled) and sets the interrupt flag in ADC2CN. Con-
verted data is available in the ADC2 data word, ADC2.
When a conversion is initiated by writing a ‘1’ to AD2BUSY, it is recommended to poll AD2INT to deter mine
when the conversion is complete. The recommende d procedure is:
Step 1. Write a ‘0’ to AD2INT;
Step 2. Wr ite a ‘1’ to AD2BUSY;
Step 3. Poll AD2INT for ‘1’;
Step 4. Process ADC2 data.
When CNVSTR2 is used as a co nversion start source, it must be enabled in the crossba r, and the corre-
sponding pin must be set to open-drain, high-impedance mode (see Section “18. Port Input/Output” on
page 235 for more details on Port I/O configuration).
7.2.2. Tracking Modes
The AD2TM bit in register ADC2CN controls the ADC2 track-and-hold mode. In its default state, the ADC2
input is continuously tracked, except when a conversion is in progress. When the AD2TM bit is logic 1,
ADC2 operates in low-power track-and-hold mode. In this mode, each conversion is preceded by a track-
ing period of 3 SAR clocks (after the start-of-conversion sign al). When th e CNVSTR 2 signal is used to ini-
tiate conversions in low-power tracking mode, ADC2 tracks only when CNVSTR2 is low; conversion
begins on the rising edge of CNVSTR2 (see Figure 7.2). Tracking can also be disabled (shutdown) when
the entire chip is in low power standby or sleep modes. Low-power Track-and-Hold mode is also useful
when AMUX or PGA settings are frequently changed, due to the settling time requirements described in
Section “7.2.3. Settling Time Requirements” on page 94.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 93
Figure 7.2. ADC2 Track and Conversion Example Timing
Write '1' to AD2BUSY,
Timer 3 Overf low,
Timer 2 Overfl ow,
Write '1' to AD0BUSY
(AD2CM[2:0]=000, 001, 011, 1xx)
AD2TM=1
AD2TM=0
SAR Clocks
123456789101112
123456789
SAR Clocks
Track Convert Low Power Mode
Lo w Power
or Convert
Track or
Convert Convert Track
B. ADC Timing for Internal Trigger Source
123456789
CNVSTR2
(AD2CM[2:0]=010)
AD2TM=1
A. ADC Timing for External Trigger Source
SAR Clocks
Track or Convert Convert TrackAD2TM=0
Track Convert Low Power Mode
Lo w Power
or Convert
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
94 Rev. 1.4
7.2.3. Settling Time Requirements
A minimum tracking time is required before an accurate conversion can be performed. This trackin g time is
determined by the ADC2 MUX resistance, the ADC2 sampling capacitance, any external source resis-
tance, and the accuracy required for the conversion. Figure 7.3 shows the equivalent ADC2 input circuit.
The required ADC2 settling time for a given settling accuracy (SA) may be approximated by Equation 7.1.
Note: An absolute minimum settling time of 800 ns required after any MUX selection. In low-power tracking
mode, three SAR2 clocks are used for tracking at the start of every conversion. For most applications,
these three SAR2 clocks will meet the tracking requirements.
Equation 7.1. ADC2 Settling Time Requirements
Where:
SA is the settling accuracy, given as a fraction of an LSB (for example, 0.25 to settle within 1/4 LSB)
t is the required settling time in seconds
RTOTAL is the sum of the ADC2 MUX resistance and any external source resist ance.
n is the ADC resolution in bits (8).
Figure 7.3. ADC2 Equivalent Input Circuit
t2n
SA
-------
RTOTALCSAMPLE
ln=
R
MUX
= 5k
RC
Input
= R
MUX
* C
SAMPLE
R
MUX
= 5k
C
SAMPLE
= 5pF
C
SAMPLE
= 5pF
MUX Select
MUX Select
Differential Mode
AIN2.x
AIN2.y
R
MUX
= 5k
C
SAMPLE
= 5pF
RC
Input
= R
MUX
* C
SAMPLE
MUX Select
Single-Ended Mode
AIN2.x
Note: When the PGA gain i s set to 0.5, C
SAMPLE
= 3pF
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 95
SFR Definition 7.1. AMX2CF: AMUX2 Configuration
Bits7–4: UNUSED. Read = 0000b; Write = don’t care.
Bit3: PIN67IC: AIN2.6, AIN2.7 Input Pair Configuration Bit.
0: AIN2.6 and AIN2.7 are independent single-ended inputs.
1: AIN2.6 and AIN2.7 are (respectively) +, – differential input pa ir.
Bit2: PIN45IC: AIN2.4, AIN2.5 Input Pair Configuration Bit.
0: AIN2.4 and AIN2.5 are independent single-ended inputs.
1: AIN2.4 and AIN2.5 are (respectively) +, – differential input pa ir.
Bit1: PIN23IC: AIN2.2, AIN2.3 Input Pair Configuration Bit.
0: AIN2.2 and AIN2.3 are independent single-ended inputs.
1: AIN2.2 and AIN2.3 are (respectively) +, – differential input pa ir.
Bit0: PIN01IC: AIN2.0, AIN2.1 Input Pair Configuration Bit.
0: AIN2.0 and AIN2.1 are independent single-ended inputs.
1: AIN2.0 and AIN2.1 are (respectively) +, – differential input pa ir.
Note: The ADC2 Data Word is in 2’s complement format for channels configured as differenti al.
SFR Page:
SFR Address: 2
0xBA
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - PIN67IC PIN45IC PIN23IC PIN01IC 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
96 Rev. 1.4
SFR Definition 7.2. AMX2SL: AMUX2 Channel Select
Bits7–3: UNUSED. Read = 00000b; Write = don’t care.
Bits2–0: AMX2AD2–0: AMX2 Address Bits.
000-111b: ADC Inputs selected per chart below.
SFR Page:
SFR Address: 2
0xBB
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - AMX2AD2 AMX2AD1 AMX2AD0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
AMX2AD2–0
000 001 010 011 100 101 110 111
AMX2CF Bits 3–0
0000 AIN2.0 AIN2.1 AIN2.2 AIN2.3 AIN2.4 AIN2.5 AIN2.6 AIN2.7
0001 +(AIN2.0)
–(AIN2.1) AIN2.2 AIN2.3 AIN2.4 AIN2.5 AIN2.6 AIN2.7
0010 AIN2.0 AIN2.1 +(AIN2.2)
–(AIN2.3) AIN2.4 AIN2.5 AIN2.6 AIN2.7
0011 +(AIN2.0)
–(AIN2.1) +(AIN2.2)
–(AIN2.3) AIN2.4 AIN2.5 AIN2.6 AIN2.7
0100 AIN2.0 AIN2.1 AIN2.2 AIN2.3 +(AIN2.4)
–(AIN2.5) AIN2.6 AIN2.7
0101 +(AIN2.0)
–(AIN2.1) AIN2.2 AIN2.3 +(AIN2.4)
–(AIN2.5) AIN2.6 AIN2.7
0110 AIN2.0 AIN2.1 +(AIN2.2)
–(AIN2.3) +(AIN2.4)
–(AIN2.5) AIN2.6 AIN2.7
0111 +(AIN2.0)
–(AIN2.1) +(AIN2.2)
–(AIN2.3) +(AIN2.4)
–(AIN2.5) AIN2.6 AIN2.7
1000 AIN2.0 AIN2.1 AIN2.2 AIN2.3 AIN2.4 AIN2.5 +(AIN2.6)
–(AIN2.7)
1001 +(AIN2.0)
–(AIN2.1) AIN2.2 AIN2.3 AIN2.4 AIN2.5 +(AIN2.6)
–(AIN2.7)
1010 AIN2.0 AIN2.1 +(AIN2.2)
–(AIN2.3) AIN2.4 AIN2.5 +(AIN2.6)
–(AIN2.7)
1011 +(AIN2.0)
–(AIN2.1) +(AIN2.2)
–(AIN2.3) AIN2.4 AIN2.5 +(AIN2.6)
–(AIN2.7)
1100 AIN2.0 AIN2.1 AIN2.2 AIN2.3 +(AIN2.4)
–(AIN2.5) +(AIN2.6)
–(AIN2.7)
1101 +(AIN2.0)
–(AIN2.1) AIN2.2 AIN2.3 +(AIN2.4)
–(AIN2.5) +(AIN2.6)
–(AIN2.7)
1110 AIN2.0 AIN2.1 +(AIN2.2)
–(AIN2.3) +(AIN2.4)
–(AIN2.5) +(AIN2.6)
–(AIN2.7)
1111 +(AIN2.0)
–(AIN2.1) +(AIN2.2)
–(AIN2.3) +(AIN2.4)
–(AIN2.5) +(AIN2.6)
–(AIN2.7)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 97
SFR Definition 7.3. ADC2CF: ADC2 Configuration
Bits7–3: AD2SC4–0: ADC2 SAR Conversion Clock Period Bits.
SAR Conversion clock is derived from sy st em clock by the following equation, where
AD2SC refers to the 5-bit value held in AD2SC4–0, and CLKSAR2 refers to the desired
ADC2 SAR clock (Note: the ADC2 SAR Conversion Clock should be less than or equal to
6MHz).
Bit2: UNUSED. Read = 0b; Write = don’t care.
Bits1–0: AMP2GN1–0: ADC2 Internal Amplifier Gain (PGA).
00: Gain = 0.5
01: Gain = 1
10: Gain = 2
11: Gain = 4
SFR Page:
SFR Address: 2
0xBC
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
AD2SC4 AD2SC3 AD2SC2 AD2SC1 AD2SC0 - AMP2GN1 AMP2GN0 11111000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
AD2SC SYSCLK
CLKSAR2
-----------------------1–=
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
98 Rev. 1.4
SFR Definition 7.4. ADC2CN: ADC2 Control
Bit7: AD2EN: ADC2 Enable Bit.
0: ADC2 Disabled. ADC2 is in low-power shutdown.
1: ADC2 Enabled. ADC2 is active and ready for data conversions.
Bit6: AD2TM: ADC2 Track Mode Bit.
0: Normal Track Mode: When ADC2 is enabled, tracking is continuous unless a c onve rs i on
is in process.
1: Low-power Track Mode: Tracking Defined by AD2CM2-0 bits (see below).
Bit5: AD2INT: ADC2 Conversion Complete Interrupt Flag.
This flag must be cleared by software.
0: ADC2 has not completed a data conversion since the last time this flag was cleared.
1: ADC2 has completed a da ta conversion.
Bit4: AD2BUSY: ADC2 Busy Bit.
Read:
0: ADC2 Conversion is complete or a conversion is not currently in progress. AD2INT is set
to logic 1 on the falling edge of AD2BUSY.
1: ADC2 Conversion is in progress.
Write:
0: No Effect.
1: Initiates ADC2 Conversion if AD2CM2-0 = 000b
Bits3–1: AD2CM2–0: ADC2 Start of Conversion Mode Select.
AD2TM = 0:
000: ADC2 conversion initiated on every write of ‘1’ to AD2BUSY.
001: ADC2 conversion initiated on overflow of Timer 3.
010: ADC2 conversion initiated on rising edge of external CNVSTR2.
011: ADC2 conversion initiated on overflow of Timer 2.
1xx: ADC2 conversion initiated on write of ‘1’ to AD0BUSY (synchronized with ADC0 soft-
ware-commanded conversions).
AD2TM = 1:
000: Tracking initiated on write of ‘1’ to AD2BUSY for 3 SAR2 clocks, followed by conver-
sion.
001: Tracking initiated on overflow of Timer 3 for 3 SAR2 clocks, followed by conversion.
010: ADC2 tracks only when CNVSTR2 input is logic low; conversion starts on rising
CNVSTR2 edge.
011: Tracking initiated on overflow of Timer 2 for 3 SAR2 clocks, followed by conversion.
1xx: Tracking initiated on write of ‘1’ to AD0BUSY an d la sts 3 SAR2 clocks, followed b y con-
version.
Bit0: AD2WINT: ADC2 Window Compare Inte rr upt Flag.
This bit must be cleared by software.
0: ADC2 Window Comparison Data match has not occurred since this flag was last cleared.
1: ADC2 Window Comparison Data match has occurred.
SFR Page:
SFR Address: 2
0xE8 (bit addressable)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
AD2EN AD2TM AD2INT AD2BUSY AD2CM2 AD2CM1 AD2CM0 AD2WINT 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 99
SFR Definition 7.5. ADC2: ADC2 Data Word
Figure 7.4. ADC2 Data Word Example
Bits7–0: ADC2 Da ta Word.
SFR Page:
SFR Address: 2
0xBE
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Single-Ended Example:
8-bit ADC Data Word appears in the ADC2 Data Word Register as follows:
Example: ADC2 Data Word Conversion Map, Single-Ended AIN2.0 Input
(AMX2CF = 0x00; AMX2SL = 0x00)
Differential Example:
8-bit ADC Data Word appears in the ADC2 Data Word Register as follows:
Example: ADC2 Data Word Conversion Map, Diff erential AIN2.0-AIN2.1 Input
(AMX2CF = 0x01; AMX2SL = 0x00)
AIN2.0–AGND
(Volts) ADC2
VREF * (255/256) 0xFF
VREF * (128/256) 0x80
VREF * (64/256) 0x40
00x00
AIN2.0–AIN2.1
(Volts) ADC2
VREF * (127/128) 0x7F
VREF * (64/128) 0x40
00x00
–VREF * (64/128) 0xC0 (-64d)
–VREF * (128/128) 0x80 (-128d)
Code Vin Gain
VREF
---------------
256=
Code Vin Gain
2VREF
-------------------------
256=
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
100 Rev. 1.4
7.3. ADC2 Programmable Window Detector
The ADC2 Programmable Win do w Detector continuou sly compares the ADC2 output to user-prog ramme d
limits, and notifies the system when a desired condition is detected. This is especially effective in an inter-
rupt-driven system, saving code space and CPU bandwidth while delivering faster system response times.
The window detector interrupt flag (AD2WINT in register ADC2CN) can also be used in polled mode. The
ADC2 Greater-Than (ADC2GT) and Less-Than (ADC2LT) registers hold the comparison values. Example
comparisons for Differential and Single-ended modes are shown in Figure 7.6 and Figure 7.5, respectively.
Notice that the window detector flag can be programmed to indicate when measured data is inside or out-
side of the user-p ro g ra mme d limits, de pe ndi n g on the cont en ts of the ADC2LT an d ADC2 GT registers.
7.3.1. Window Detector In Single-Ended Mode
Figure 7.5 shows two example window comparisons for Single-ended mode, with ADC2LT = 0x20 and
ADC2GT = 0x10. Notice that in Single-ended mode, the codes vary from 0 to VREF*(255/256) and are
represented as 8-bit unsigned integers. In the left example, an AD2WINT interrupt will be generated if the
ADC2 conversion word (ADC2) is within the range defined by ADC2GT and ADC2LT
(if 0x10 ADC2 0x20). In the right example, and AD2WINT interrupt will be generated if ADC2 is outside
of the range defined b y ADC2GT and ADC2LT (if ADC2 0x10 or ADC2 0x20).
Figure 7.5. ADC2 Window Compare Examples, Single-Ended Mode
0xFF
0x21
0x20
0x1F
0x11
0x10
0x0F
0x00
0
Input Voltage
(AIN 2.x - AGND)
REF x (255/256)
REF x (32/256)
REF x (16/256)
AD2WINT=1
AD2WINT
not affected
AD2WINT
not affected
ADC2LT
ADC2GT
0xFF
0x21
0x20
0x1F
0x11
0x10
0x0F
0x00
0
Input Voltage
(AIN 2.x - AGND)
REF x (255/256)
REF x (32/25 6)
REF x (16/25 6)
AD2WINT
not affected
ADC2GT
ADC2LT
AD2WINT=1
AD2WINT=1
ADC2 ADC2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 101
7.3.2. Window Detector In Differential Mode
Figure 7.6 shows two example window comparisons for dif ferential mode, with ADC2LT = 0x10 (+16d) and
ADC2GT = 0xFF (-1d). Notice that in Differential mode, the codes vary from -VREF to VREF*(127/128)
and are represented as 8-bit 2’s complement signed integers. In the left example, an AD2WINT interrupt
will be generated if the ADC2 conversion word (ADC2L) is within the range defined by ADC2GT and
ADC2LT (if 0xFF (-1d) < ADC2 < 0x0F (16d)). In the right example, an AD2WINT interrupt will be gener-
ated if ADC2 is outside of the range defined by ADC2GT and ADC2LT (if ADC2 < 0xFF (-1d) or ADC2 >
0x10 (+16d)).
Figure 7.6. ADC2 Window Compare Examples, Differential Mode
0x7F (127d)
0x11 (17d)
0x10 (16d)
0x0F (15d)
0x00 (0d)
0xFF (-1d)
0xFE (-2d)
0x80 (-128d)
-REF
Input Voltage
(AIN2.x - AIN2.y)
REF x (127/128)
REF x (16/128)
REF x (-1/256)
0x7F (127d)
0x11 (17d)
0x10 (16d)
0x0F (15d)
0x00 (0d)
0xFF (-1d)
0xFE (-2d)
0x80 (-128d)
-REF
Input Voltage
(AIN2.x - AIN2.y )
REF x (127/128)
REF x (16/128)
REF x (-1/256)
AD2WINT=1
AD2WINT
not affected
AD2WINT
not affected
ADC2LT
ADC2GT
AD2WINT
not affected
ADC2GT
ADC2LT
AD2WINT=1
AD2WINT=1
ADC2ADC2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
102 Rev. 1.4
SFR Definition 7.6. ADC2GT: ADC2 Greater-Than Data Byte
SFR Definition 7.7. ADC2LT: ADC2 Less-Than Data Byte
Bits7–0: ADC2 Greater-Than Data Word.
SFR Page:
SFR Address: 2
0xC4
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Bits7–0: ADC2 Less-Than Data Word.
SFR Page:
SFR Address: 2
0xC6
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 103
Table 7.1. ADC2 Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, VREF2 = 2.40 V (REFBE = 0), PGA gain = 1, –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
DC Accuracy
Resolution 8 bits
Integral Nonlinearity — — ±1 LSB
Differential Nonlinearity Guar ante ed Mo noto nic — — ±1 LSB
Offse t Er ror — 0.5±0.3 — LSB
Full Scale Error Differential mode — – 1± 0.2 — LSB
Offse t Temperature Coefficient — 10 — ppm/°C
Dynamic Performance (10 kHz sine-wave in put, 1 dB below Full Scale, 500 ksps
Signal-to-Noise Plus Distortion 45 47 — dB
Total Harmonic Distortion Up to the 5th harmonic —-51— dB
Sp ur io us- F re e Dyn a mic Rang e — 52 — dB
Conversion Rate
SAR Clock Frequency — — 6 MHz
Conversion Time in SAR Clocks 8 — — clocks
Track/Hold Acquisition Time 300 — — ns
Throughput Rate — — 500 ksps
Analog Inputs
Input Voltage Range 0 — VREF V
Input Capacitance — 5 — pF
Power Specifications
Power Supply Current
(AV+ supplied to ADC2) Operating Mode, 500 ksps — 420 900 µA
Power Supply Rejection — ±0.3 — mV/V
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
104 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 105
8. DACs, 12-Bit Voltage Mode (C8051F12x Only)
The C8051F12x devices include two on-chip 12-bit voltage-mode Digital-to-Analog Converters (DACs).
Each DAC has an output swing of 0 V to (VREF-1LSB) for a corresponding input code range of 0x000 to
0xFFF. The DACs may be enabled/disabled via their corresponding control registers, DAC0CN and
DAC1CN. While disabled, the DAC output is maintained in a high-impedance state, and the DAC supply
current falls to 1 µA or less. The voltage reference for each DAC is supplied at the VREFD pin
(C8051F120/2/4/6 devices) or the VREF pin (C8051F121/3/5/7 devices). Note that the VREF pin on
C8051F121/3/5/7 devices may be driven by the internal voltage reference or an external source. If the
internal voltage reference is used it must be e nab led in ord er for the DAC outpu ts to be valid. See Section
“9. Voltage Reference” on page 113 for more information on configuring the voltage reference for the
DACs.
8.1. DAC Output Scheduling
Each DAC features a flexible output update mechanism which allows for seamless full-scale changes and
supports jitter-free updates for waveform generation. The follo wing examples are written in terms of DAC0,
but DAC1 operation is identical.
Figure 8.1. DAC Functional Block Diagram
DAC0
AV+
12
AGND
8
8
REF
DAC0
DAC0CN
DAC0EN
DAC0MD1
DAC0MD0
DAC0DF2
DAC0DF1
DAC0DF0
DAC0HDAC0L
Dig. MUX
Latch Latch
8
8
DAC1
AV+
12
AGND
8
8
REF
DAC1
DAC1CN
DAC1EN
DAC1MD1
DAC1MD0
DAC1DF2
DAC1DF1
DAC1DF0
DAC1HDAC1L
Dig. MUX
Latch Latch
8
8
DAC0H
Timer 3
Timer 4
Timer 2
DAC1H
Timer 3
Timer 4
Timer 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
106 Rev. 1.4
8.1.1. Update Output On-Demand
In its default mode (DAC0CN.[4:3] = ‘00’) the DAC0 output is updated “on-demand” on a write to the high-
byte of the DAC0 dat a register (DAC0H). It is import ant to note that writes to DAC0L are held, and have no
effect on the DAC0 output until a write to DAC0H takes place. If writing a full 12-bit word to the DAC data
registers, the 12-bit data word is written to the low byte (DAC0L) and high byte (DAC0H) data registers.
Data is latched into DAC0 after a write to the corresponding DAC0H register, so the write sequence
should be DAC0L followed by DAC0H if the full 12-bit resolution is required. The DAC can be used in 8-
bit mode by initializing DAC0L to the desired value (typically 0x00), and writing data to only DAC0H (also
see Section 8.2 for information on formatting the 12-bit DAC data word within the 16-bit SFR space).
8.1.2. Update Output Based on Timer Overflow
Similar to the ADC operation, in which an ADC conversion can be initiated by a timer overflow indepen-
dently of the processor, the DAC outputs can use a Timer overflow to schedule an output update event.
This feature is useful in systems where the DAC is used to gen erate a waveform of a defined sa mpling rate
by eliminating the effects of variable interrupt latency and instruction execution on the timing of the DAC
output. When the DAC0MD bits (DAC0CN.[4:3]) are set to ‘01’, ‘10’, or ‘11’, writes to both DAC data regis-
ters (DAC0L and DAC0H) are held until an associated Timer overflow event (Timer 3, Timer 4, or Timer 2,
respectively) occurs, at which time the DAC0H:DAC0L content s ar e co pie d to the DAC inpu t latches allow-
ing the DAC output to change to the new value.
8.2. DAC Output Scaling/Justification
In some instances, input data should be shifted prior to a DAC0 write operation to properly justify data
within the DAC input registers. This action would typically require one or more load and shift operations,
adding software overhead and slowing DAC throughput. To alleviate this problem, the data-formatting fea-
ture provides a means for the user to program the orientation of the DAC0 data word within data registers
DAC0H and DAC0L. The three DAC0DF bits (DAC0CN.[2:0]) allow the user to specify one of five data
word orientations as shown in the DAC0CN register definition.
DAC1 is functionally the same as DAC0 described above. The electrical specifications for both DAC0 and
DAC1 are given in Table 8.1.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 107
SFR Definition 8.1. DAC0H: DAC0 High Byte
SFR Definition 8.2. DAC0L: DAC0 Low Byte
Bits7–0: DAC0 Data Word Most Significant Byte.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD3
0
Bits7–0: DAC0 Data Word Least Significant Byte.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD2
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
108 Rev. 1.4
SFR Definition 8.3. DAC0CN: DAC0 Control
Bit7: DAC0EN: DAC0 Enable Bit.
0: DAC0 Disabled. DAC0 Output pin is disabled; DAC0 is in low-po wer shutdown mode.
1: DAC0 Enabled. DAC0 Output pin is active; DAC0 is operational.
Bits6–5: UNUSED. Read = 00b; Write = don’t care.
Bits4–3: DAC0MD 1– 0: DAC0 Mode Bits.
00: DAC output updates occur on a write to DAC0H.
01: DAC output updates occur on Timer 3 overflow.
10: DAC output updates occur on Timer 4 overflow.
11: DAC output updates occur on Timer 2 overflow.
Bits2–0: DAC0DF2–0: DAC0 Data Format Bits:
000: The most signifi cant nibble of the DAC0 Data W ord is in DAC0H[3:0], while the least
significant byte is in DAC0L.
001: The most significant 5-bits of the DAC0 Data Word is in DAC0H[4:0], while the least
significant 7-b i ts are in DAC0 L[ 7:1].
010: The most significant 6-bits of the DAC0 Data Word is in DAC0H[5:0], while the least
significant 6-b i ts are in DAC0 L[ 7:2].
011: The most sig nificant 7-bits of the DAC0 Data Word is in DAC0H[6:0], while the least
significant 5-b i ts are in DAC0 L[ 7:3].
1xx: The most significant 8-bits of the DAC0 Data Word is in DAC0H[7:0], while the least
significant 4-b i ts are in DAC0 L[ 7:4].
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
DAC0EN - - DAC0MD1 DAC0MD0 DAC0DF2 DAC0DF1 DAC0DF0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD4
0
DAC0H DAC0L
MSB LSB
DAC0H DAC0L
MSB LSB
DAC0H DAC0L
MSB LSB
DAC0H DAC0L
MSB LSB
DAC0H DAC0L
MSB LSB
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 109
SFR Definition 8.4. DAC1H: DAC1 High Byte
SFR Definition 8.5. DAC1L: DAC1 Low Byte
Bits7–0: DAC1 Data Word Most Significant Byte.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD3
1
Bits7–0: DAC1 Data Word Least Significant Byte.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD2
1
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
110 Rev. 1.4
SFR Definition 8.6. DAC1CN: DAC1 Control
Bit7: DAC1EN: DAC1 Enable Bit.
0: DAC1 Disabled. DAC1 Output pin is disabled; DAC1 is in low-po wer shutdown mode.
1: DAC1 Enabled. DAC1 Output pin is active; DAC1 is operational.
Bits6–5: UNUSED. Read = 00b; Write = don’t care.
Bits4–3: DAC1MD 1– 0: DAC1 Mode Bits:
00: DAC output updates occur on a write to DAC1H.
01: DAC output updates occur on Timer 3 overflow.
10: DAC output updates occur on Timer 4 overflow.
11: DAC output updates occur on Timer 2 overflow.
Bits2–0: DAC1DF2: DAC1 Data Format Bits:
000: The most signifi cant nibble of the DAC1 Data W ord is in DAC1H[3:0], while the least
significant byte is in DAC1L.
001: The most significant 5-bits of the DAC1 Data Word is in DAC1H[4:0], while the least
significant 7-b i ts are in DAC1 L[ 7:1].
010: The most significant 6-bits of the DAC1 Data Word is in DAC1H[5:0], while the least
significant 6-b i ts are in DAC1 L[ 7:2].
011: The most sig nificant 7-bits of the DAC1 Data Word is in DAC1H[6:0], while the least
significant 5-b i ts are in DAC1 L[ 7:3].
1xx: The most significant 8-bits of the DAC1 Data Word is in DAC1H[7:0], while the least
significant 4-b i ts are in DAC1 L[ 7:4].
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
DAC1EN - - DAC1MD1 DAC1MD0 DAC1DF2 DAC1DF1 DAC1DF0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD4
1
DAC1H DAC1L
MSB LSB
DAC1H DAC1L
MSB LSB
DAC1H DAC1L
MSB LSB
DAC1H DAC1L
MSB LSB
DAC1H DAC1L
MSB LSB
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 111
.
Table 8.1. DAC Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, VREF = 2.40 V (REFBE = 0), No Output Load unless otherwise specified
Parameter Conditions Min Typ Max Units
Static Performance
Resolution 12 bits
Integral Nonlinearity — ±1.5 — LSB
Differential Nonlinearity — — ±1 LSB
Output Noise No Output Filter
100 kHz Output Filter
10 kHz Output Filter
—250
128
41
—µVrms
Offset Error Data Word = 0x014 — ±3 ±30 mV
Offset Tempco — 6 — ppm/°C
Full-Scale Error — ±20 ±60 mV
Full-Scale Error Tempco — 10 — ppm/°C
VDD Power Supply Rejection
Ratio —–60— dB
Output Impedance in Shutdown
Mode DACnEN = 0 —100— k
Output Sink Current — 300 — µA
Output Short-Circuit Current Dat a Word = 0xFFF — 15 — mA
Dynamic Performance
Voltage Output Slew Rate Load = 40 pF — 0.44 — V/µs
Output Settling Time to 1/2 LSB Load = 40 pF, Output swing from
code 0xFFF to 0x014 —10— µs
Output Voltage Swing 0 — VREF-
1LSB V
Startup Time — 10 — µs
Analog Outputs
Load Regulation IL = 0.01 mA to 0.3 mA at code
0xFFF —60— ppm
Power Consumption (each DAC)
Power Supply Current (AV+
supplied to DAC) Dat a Word = 0x 7FF —110400 µA
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
112 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 113
9. Voltage Reference
The voltage reference optio ns available on the C8051F12x and C8051F13x device families vary according
to the device capabilities.
All devices include an internal voltage reference circuit, consisting of a 1.2 V, 15 ppm/°C (typical) bandgap
voltage r eference generato r and a gain-of- two output buf fer amp lifier. The internal refe rence may be routed
via the VREF pin to external syste m component s or to th e volta ge reference inpu t pins. The maximum load
seen by the VREF pin must be less than 200 µA to AGND. Bypass cap acitors of 0.1 µF and 4.7 µF are rec-
ommended from the VREF pin to AGND.
The Reference Control Register, REF0CN enables/disables the internal reference generator and the inter-
nal temperature sensor o n all devices. The BIASE bit in REF0CN enab les the on-bo ard refe rence gener a-
tor while the REFBE bit enables the gain-of-two buffer amplifier which drives the VREF pin. When
disabled, the supply current drawn by the bandgap and buffer amplifier falls to less than 1 µA (typical) and
the output of the buffer amplifier enters a high impedance state. If the internal bandgap is used as the ref-
erence voltage generator, BIASE and REFBE must both be set to logic 1. If the internal reference is not
used, REFBE may be set to logic 0. Note that the BIASE bit must be set to logic 1 if any DACs or ADCs are
used, regardless of whether the voltage reference is derived from the on-chip reference or supplied by an
off-chip source. If no ADCs or DACs are being used, both of these bits can be set to logic 0 to conserve
power.
When enabled, the temperature sensor connects to the highest order input of the ADC0 input multiplexer.
The TEMPE bit within REF0CN enables and disables the temperature sensor. While disabled, the temper-
ature sensor defaults to a high impedance state. Any ADC measurements performed on the sensor while
disabled will result in undefined data.
The electrical specifications for the internal voltage reference are given in Table 9.1.
9.1. Reference Configuration on the C8051F120/2/4/6
On the C8051F120/2/4/6 devices, the REF0CN register also allows selection of the voltage reference
source for ADC0 and ADC2, as shown in SFR Definition 9.1. Bits AD0VRS and AD2VRS in the REF0CN
register select the ADC0 and ADC2 volt age reference sour ces, respectively. Three volt age reference input
pins allow each ADC and the two DACs to reference an external voltage reference or the on-chip voltage
reference output (with an external connection). ADC0 may also reference the DAC0 output internally, and
ADC2 may reference the analog power supply voltage, via the VREF multiplexers shown in Figure 9.1.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
114 Rev. 1.4
Figure 9.1. Voltage Reference Functional Block Diagram (C8051F120/2/4/6)
SFR Definition 9.1. REF0CN: Reference Control (C8051F120/2/4/6)
Recommended Bypass
Capacitors
x2
VREF
DAC0
DAC1
Ref
VREFD
AV+
ADC2
ADC0
VREF2
Ref
Ref
1
0
0
1
VREF0
4.7
F0.1
F
External
Voltage
Reference
Circuit
R1
VDD
DGND
REF0CN
REFBE
BIASE
TEMPE
AD2VRS
AD0VRS
REFBE
BIASE
Bias to
ADCs,
DACs
1.2V
Band-Gap
EN
+
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bit4: AD0VRS: ADC0 Voltage Reference Select.
0: ADC0 voltage reference from VREF0 pin.
1: ADC0 voltage referenc e fro m DAC0 ou tp ut .
Bit3: AD2VRS: ADC2 Voltage Reference Select.
0: ADC2 voltage reference from VREF2 pin.
1: ADC2 voltage reference fro m AV+.
Bit2: TEMPE: Temperat ur e Sen s o r Ena b le Bit.
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
Bit1: BIASE: ADC/DAC Bias Generator Enable Bit. (Mus t be ‘1’ if using ADC, DAC, or VREF).
0: Internal Bias Generator Off.
1: Internal Bias Generator On.
Bit0: REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer Off.
1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
SFR Page:
SFR Address: 0
0xD1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - AD0VRS AD2VRS TEMPE BIASE REFBE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 115
9.2. Reference Configuration on the C8051F121/3/5/7
On the C8051F121/3/5/7 devices, the REF0CN register also allows selection of the voltage reference
source for ADC0 and ADC2, as shown in SFR Definition 9.2. Bits AD0VRS and AD2VRS in the REF0CN
register select the ADC0 and ADC2 voltage reference sources, respectively. The VREFA pin provides a
voltage refer ence input for ADC0 and ADC2, wh ich can be connected to an external precision r eference or
the internal voltage reference. ADC0 may also reference th e DAC0 output internally, and ADC2 may refer-
ence the analog power su pply voltage, via the VREF multiplexers shown in Figure 9.2.
Figure 9.2. Voltage Reference Functional Block Diagram (C8051F121/3/5/7)
Recommended Bypass
Capacitors
x2
VREF
DAC0
DAC1
Ref
AV+
ADC2
ADC0
Ref
Ref
1
0
0
1
VREFA
4.7
F0.1
F
External
Voltage
Reference
Circuit
R1
VDD
DGND
REF0CN
REFBE
BIASE
TEMPE
AD2VRS
AD0VRS
REFBE
BIASE
Bias to
ADCs,
DACs
1.2V
Band-Gap
EN
+
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
116 Rev. 1.4
SFR Definition 9.2. REF0CN: Reference Control (C8051F121/3/5/7)
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bit4: AD0VRS: ADC0 Voltage Reference Select.
0: ADC0 voltage reference from VREFA pin.
1: ADC0 voltage referenc e fro m DAC0 ou tp ut .
Bit3: AD2VRS: ADC2 Voltage Reference Select.
0: ADC2 voltage reference from VREFA pin.
1: ADC2 voltage reference fro m AV+.
Bit2: TEMPE: Temperat ur e Sen s o r Ena b le Bit.
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
Bit1: BIASE: ADC/DAC Bias Generator Enable Bit. (Mus t be ‘1’ if using ADC, DAC, or VREF).
0: Internal Bias Generator Off.
1: Internal Bias Generator On.
Bit0: REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer Off.
1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
SFR Page:
SFR Address: 0
0xD1
R/W R/W R/W R/W R/W R/W R/W R /W Reset Value
- - - AD0VRS AD2VRS TEMPE BIASE REFBE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 117
9.3. Reference Configuration on the C8051F130/1/2/3
On the C8051F130/1/2/3 devices, the VREF0 pin provides a voltage reference input for ADC0, which can
be connected to an external precision reference or the internal voltage refe rence, as sh own in Figure 9.3.
The REF0CN register for the C8051F130/1/2/3 is described in SF R Definition 9.3.
Figure 9.3. Voltage Reference Functional Block Diagram (C8051F130/1/2/3)
SFR Definition 9.3. REF0CN: Reference Control (C8051F130/1/2/3)
Recommended Bypass
Capacitors
x2
VREF
ADC0
Ref
VREF0
4.7F0.1F
External
Voltage
Reference
Circuit
R1
VDD
DGND
Bias to ADC
1.2V
Band-Gap
EN
+
REF0CN
REFBE
BIASE
TEMPE
Bits7–5: UNUSED. Read = 000b; Write = don’t care.
Bits4–3: Reserved: Must be written to 0.
Bit2: TEMPE: Temperat ur e Sen s o r Ena b le Bit.
0: Internal Temperature Sensor Off.
1: Internal Temperature Sensor On.
Bit1: BIASE: ADC/DAC Bias Generato r Ena b le Bit. (M us t be ‘1’ if using ADC or VREF) .
0: Internal Bias Generator Off.
1: Internal Bias Generator On.
Bit0: REFBE: Internal Reference Buffer Enable Bit.
0: Internal Reference Buffer Off.
1: Internal Reference Buffer On. Internal voltage reference is driven on the VREF pin.
SFR Page:
SFR Address: 0
0xD1
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - Reserved Reserved TEMPE BIASE REFBE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
118 Rev. 1.4
Table 9.1. Voltage Reference Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
Analog Bias Generator Power
Supply Current BIASE = 1 —100 — µA
Internal Reference (REFBE = 1)
Output Voltage 25 °C ambient 2.36 2.43 2.48 V
VREF Short-Circuit Current — — 30 mA
VREF Temperature Coefficient — 15 — ppm/°C
Load Regulation Load = 0 to 200 µA to AGND — 0.5 — ppm/µA
VREF Turn-on T ime 1 4.7 µF tant alum, 0.1 µF ceramic
bypass —2 — ms
VREF Turn-on Time 2 0.1 µF ceramic bypass — 20 — µs
VREF Turn-on T ime 3 no bypass cap — 10 — µs
Reference Buffer Power Sup-
ply Current —40 — µA
Power Supply Rejection — 140 — ppm/V
External Reference (REFBE = 0)
Input Voltage Range 1.00 — (AV+) – 0.3 V
Input Current — 0 1 µA
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 119
10. Comparators
Two on-chip programmable volt age comp arators ar e included, as shown in Figu re 10.1. The input s of each
comparator are available at dedicated pins. The output of each comparator is optionally available at the
package pins via the I/O crossbar. When assigned to package pins, each comparator output can be pro-
grammed to operate in open drain or push-pull modes. See Section “18.1. Ports 0 through 3 and the
Priority Crossbar Decoder” on page 238 for Crossbar and port initialization details.
Figure 10.1. Comparator Functional Block Diagram
+
-
Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
Crossbar
Interrupt
Handler
Reset
Decision
Tree
(SYNCHRONIZER)
CP0+
CP0-
AGND
CPT0CN
CP0HYN0
CP0MD
CP0HYN1
CP0HYP0
CP0HYP1
CP0FIF
CP0RIF
CP0OUT
CP0EN
AV+
CPT0MD
CP0MD0
CP0MD1
CP0FIE
CP0RIE
CP0MD
+
-
Q
Q
SET
CLR
D
Q
Q
SET
CLR
D
Crossbar
Interrupt
Handler
(SYNCHRONIZER)
CP1+
CP1-
AGND
CPT1CN
CP1HYN0
CP1MD
CP1HYN1
CP1HYP0
CP1HYP1
CP1FIF
CP1RIF
CP1OUT
CP1EN
AV+
CPT1MD
CP1MD0
CP1MD1
CP1FIE
CP1RIE
CP1MD
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
120 Rev. 1.4
Comparator interrupts can be generated on rising-edge and/or falling-edge output transitions. (For inter-
rupt enable an d priori ty contro l, see Section “11.3. Interrupt Handler” on page 154). The CP0FIF flag is
set upon a Comparator0 falling-edge interrupt, and the CP0RIF flag is set upon the Comparator0 rising-
edge interrupt. Once set, these bits remain set un til cleared by software. The Output State of Comparator0
can be obtained at any time by reading the CP0OUT bit. Comparator0 is enabled by setting the CP0EN
bit to logic 1, and is disabled by clearing this bit to logic 0. Comparator0 can also be programmed as a
reset source; for details, see Section “13.5. Comparator0 Reset” on page 179.
Note that after being enabled, there is a Power-Up time (listed in Ta ble 10.1) during which the comparator
outputs stabilize. The states of the Rising-Edge and Falling-Edge flags are indeterminant after comparator
Power-Up and should be explicitly cleared before the comparator interrupts are enabled or the compara-
tors are configured as a reset source.
Comparator0 response time may be configured in software via the CP0MD1-0 bits in register CPT0MD
(see SFR Definition 10.2). Selecting a longer response time reduces the amount of current consumed by
Comparator0. See Table 10.1 for complete timing and current consumption specifications.
The hysteresis of each comparator is software-programmable via its respective Comparator control regis-
ter (CPT0CN and CPT1CN for Comparator0 and Comp ar ator1, re sp ectively) . The u ser can program bo th
the amount of hysteresis voltage (referred to the input voltage) and the positive and negative-going sym-
metry of this hysteresis around the threshold voltage. The output of the comparator can be polled in soft-
ware, or can be used as an interrupt source. Each comparator can be individually enabled or disabled
(shutdown). When disabled, the comparator output (if assigned to a Port I/O pin via the Crossbar) defaults
to the logic low state, its interrupt capability is suspended and its supply current falls to less than 100 nA.
Comparato r inputs can be externally driven from –0.25 V to (AV+) + 0.25 V without damage or upset.
Comparator0 hysteresis is programmed using bits 3-0 in the Comparator0 Control Register CPT0CN
(shown in SFR Definition 10.1). The amount of negative hysteresis volt a ge is deter mined by the setting s of
the CP0HYN bits. As shown in SFR Definition 10.1, the negative hysteresis can be programmed to three
different settings, or negative hysteresis can be disabled. In a similar way, the amount of positive hystere-
sis is determined by the setting the CP0HYP bits.
The operation of Comparator1 is identical to that of Comparator0, though Comparator1 may not be config-
ured as a reset source. Comparator1 is controlled by the CPT1CN Register (SFR Definition 10.3) and the
CPT1MD Register (SFR Definition 10.4). The complete electrical specifications for the Comparators are
given in Table 10.1.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 121
Figure 10.2. Comparator Hysteresis Plot
Posit ive Hystere sis Vo ltage
(Programmed w ith CP 0H Y P Bi ts)
Negative Hysteresis Voltage
(Programmed by CP0HYN Bits)
VIN-
VIN+
INPUTS
CIRCUIT CONFIGU RATIO N
+
_
CP0+
CP0- CP0
VIN+
VIN- OUT
V
OH
Posit iv e H y ste re sis
Disabled Maximum
Posit ive Hyst er esis
Negative Hysteresis
Disabled Maximum
Negative Hysteresis
OUTPUT
V
OL
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
122 Rev. 1.4
SFR Definition 10.1. CPT0CN: Comparator0 Control
Bit7: CP0EN: Comparator0 En ab le Bit.
0: Comparator0 Disabled.
1: Comparator0 Enabled.
Bit6: CP0OUT: Comparator 0 Ou tp ut State Flag.
0: Voltage on CP0+ < CP0–.
1: Voltage on CP0+ > CP0–.
Bit5: CP0RIF: Comparator 0 Risin g-Ed ge Fla g.
0: No Comparator0 Rising Edge has occurred since this flag was last cleared.
1: Comparator0 Rising Edge has occurred.
Bit4: CP0FIF: Comparator0 Falling-Edge Flag.
0: No Comparator0 Falling-Edge has occurred since this flag was last cleared.
1: Comparator0 Falling-Edge has occurred.
Bits3–2: CP0HYP1–0: Comparator0 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 15 mV.
Bits1–0: CP0HYN1–0 : Comparator0 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 15 mV.
SFR Page:
SFR Address: 1
0x88
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CP0EN CP0OUT CP0RIF CP0FIF CP0HYP1 CP0HYP0 CP0HYN1 CP0HYN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 123
SFR Definition 10.2. CPT0MD: Comparator0 Mode Selection
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit 5: CP0RIE: Comparator 0 Rising-Edge Interrupt Enable Bit.
0: Comparator 0 rising-edge interrupt disa bled.
1: Comparator 0 rising-edge interrupt enabled.
Bit 4: CP0FIE: Comparator 0 Falling-Edge Interrupt Enable Bit.
0: Comparator 0 falling-edge interrupt disabled.
1: Comparator 0 falling-edge interrupt enabl ed.
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CP0MD1–CP0MD0: Comparator0 Mode Select
These bits select the response time for Comparator0.
SFR Page:
SFR Address: 1
0x89
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - CP0RIE CP0FIE - - CP0MD1 CP0MD0 00000010
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Mode CP0MD1 CP0MD0 Notes
0 0 0 Fastest Response Time
101 —
210 —
3 1 1 Lowest Power Consumption
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
124 Rev. 1.4
SFR Definition 10.3. CPT1CN: Comparator1 Control
Bit7: CP1EN: Comparator1 En ab le Bit.
0: Comparator1 Disabled.
1: Comparator1 Enabled.
Bit6: CP1OUT: Comparator 1 Ou tp ut State Flag.
0: Voltage on CP1+ < CP1–.
1: Voltage on CP1+ > CP1–.
Bit5: CP1RIF: Comparator 1 Risin g-Ed ge Fla g.
0: No Comparator1 Rising Edge has occurred since this flag was last cleared.
1: Comparator1 Rising Edge has occurred.
Bit4: CP1FIF: Comparator1 Falling-Edge Flag.
0: No Comparator1 Falling-Edge has occurred since this flag was last cleared.
1: Comparator1 Falling-Edge Interr upt has occurred.
Bits3–2: CP1HYP1–0: Comparator1 Positive Hysteresis Control Bits.
00: Positive Hysteresis Disabled.
01: Positive Hysteresis = 5 mV.
10: Positive Hysteresis = 10 mV.
11: Positive Hysteresis = 15 mV.
Bits1–0: CP1HYN1–0 : Comparator1 Negative Hysteresis Control Bits.
00: Negative Hysteresis Disabled.
01: Negative Hysteresis = 5 mV.
10: Negative Hysteresis = 10 mV.
11: Negative Hysteresis = 15 mV.
SFR Page:
SFR Address: 2
0x88
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CP1EN CP1OUT CP1RIF CP1FIF CP1HYP1 CP1HYP0 CP1HYN1 CP1HYN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 125
SFR Definition 10.4. CPT1MD: Comparator1 Mode Selection
Bits7–6: UNUSED. Read = 00b, Write = don’t care.
Bit 5: CP1RIE: Comparator 1 Rising-Edge Interrupt Enable Bit.
0: Comparator 1 rising-edge interrupt disa bled.
1: Comparator 1 rising-edge interrupt enabled.
Bit 4: CP1FIE: Comparator 0 Falling-Edge Interrupt Enable Bit.
0: Comparator 1 falling-edge interrupt disabled.
1: Comparator 1 falling-edge interrupt enabl ed.
Bits3–2: UNUSED. Read = 00b, Write = don’t care.
Bits1–0: CP1MD1–CP1MD0: Comparator1 Mode Select
These bits select the response time for Comparator1.
SFR Page:
SFR Address: 2
0x89
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - CP1RIE CP1FIE - - CP1MD1 CP1MD0 00000010
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
Mode CP0MD1 CP0MD0 Notes
0 0 0 Fastest Response Time
101 —
210 —
3 1 1 Lowest Power Consumption
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
126 Rev. 1.4
Table 10.1. Comparator Electrical Characteristics
VDD = 3.0 V, AV+ = 3.0 V, –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
Response Time:
Mode 0, VCM* = 1.5 V CPn+ – CPn- = 100 mV — 100 — ns
CPn+ – CPn– = –100 mV — 250 — n s
Response Time:
Mode 1, VCM* = 1. 5 V CPn+ – CPn– = 100 mV — 175 — ns
CPn+ – CPn– = –100 mV — 500 — n s
Response Time:
Mode 2, VCM* = 1. 5 V CPn+ – CPn– = 100 mV — 320 — ns
CPn+ – CPn– = –100 mV — 1100 — ns
Response Time:
Mode 3, VCM* = 1. 5 V CPn+ – CPn– = 100 mV — 1050 — ns
CPn+ – CPn– = –100 mV — 5200 — ns
Common-Mode Rejection
Ratio — 1.5 4 mV/V
Positive Hysteresis 1 CPnHYP1-0 = 00 — 0 1 mV
Positive Hysteresis 2 CPnHYP1-0 = 01 2 4.5 7 mV
Positive Hysteresis 3 CPnHYP1-0 = 10 4 9 13 mV
Positive Hysteresis 4 CPnHYP1-0 = 11 10 17 25 mV
Negative Hysteresis 1 CPnHYN1-0 = 00 — 0 1 mV
Negative Hysteresis 2 CPnHYN1-0 = 01 2 4.5 7 mV
Negative Hysteresis 3 CPnHYN1-0 = 10 4 9 13 mV
Negative Hysteresis 4 CPnHYN1-0 = 11 10 17 25 mV
Inverting or Non-Inverting
Input Voltage Range –0.25 — (AV+)
+ 0.25 V
Input Capacitance — 7 — pF
Input Bias Curren t –5 0.001 +5 n A
Input Offset Voltage –10 — +10 mV
Power Supply
Power-Up Time CPnEN from 0 to 1 — 20 — µs
Power Supply Rejection — 0.1 1 mV/V
Supply Current at DC
(each comparat or )
Mode 0 — 7.6 — µA
Mode 1 — 3.2 — µA
Mode 2 — 1.3 — µA
Mode 3 — 0.4 — µA
*Note: VCM is the common-mode voltage on CPn+ and CPn-.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 127
11. CIP-51 Microcontroller
The MCU system controller core is the CIP-51 microcontroller. The CIP-51 is fully compatible with the
MCS-51™ instruction set; standard 803x/805x assemblers and compilers can be used to develop soft-
ware. The MCU family has a superset of all the peripherals included with a standard 8051. Included are
five 16-bit counter/timers (see description in Section 23), two full-duplex UARTs (see description in Sec-
tion 21 and Section 22), 256 bytes of internal RAM, 128 byte Special Function Register (SFR) address
space (see Section 11.2.6), and 8/4 byte-wide I/O Ports (see description in Section 18). The CIP-51 also
includes on-chip debug hardware (see description in Section 25), and interfaces directly with the MCU’s
analog and d igital subsystems providing a com plete data acquisition or control-system solution in a single
integrated circuit.
The CIP-51 Microcontroller core implements the standard 8051 organization and peripherals as well as
additional custom peripherals and functions to extend its capability (see Figure 11.1 for a block diagram).
The CIP-51 includes the following features:
Performance
The CIP-51 emplo ys a pipeli ned ar chitecture tha t gre atly increases its instruction throughpu t over the st an-
dard 8051 architecture. In a standard 8051, all instructions except for MUL and DIV take 12 or 24 system
clock cycles to execute, and usually have a maximum system clock of 12 MHz. By contrast, the CIP-51
core executes 70% of its instructions in one or two system clock cycles, with no instructions taking more
than eight system clock cycles.
With the CIP-51's system clock running at 100 MHz, it has a peak throughput of 100 MIPS. The CIP-51
has a total of 109 instructions. The table below shows the total number of instructions that require each
execution time.
Clocks to Execute 1 22/333/444/55 8
Number of Instructions 265051473121
- Fully Compatible with MCS-51 Instruction Set
- 100 or 50 MIPS Peak Using the On-Chip PLL
- 256 Bytes of Internal RAM
- 8/4 Byte-Wide I/O Ports
- Extended Interrupt Handler
- Reset Input
- Power Management Modes
- On-chip Debug Logic
- Program and Data Memory Security
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
128 Rev. 1.4
Figure 11.1. CIP-51 Block Diagram
Programming and Debugging Support
A JTAG-based serial interface is provided for in-system programming of the Flash program memory and
communication with on-chip debug support logic. The re-programmable Flash can also be read and
changed by the a pplica tion software using the MOVC and MOVX in stru ctions. This fea ture allows prog ra m
memory to be used for non- volatile data storage as well as upda ting program code under software control.
The on-chip debug support logic facilitates full speed in-circuit debugging, allowing the setting of hardware
breakpoints and watch points, starting, stopping and single stepping through program execution (including
interrupt service routin es), e xaminatio n of the pro gram's call stack, and re ading/writing the content s of reg-
isters and memory. This method of on-chip debug is completely non-intrusive and non-invasive, requiring
no RAM, Stack, timers, or other on-chip r esources.
The CIP-51 is supported by development tools from Silicon Labs and third party vendors. Silicon Labs pro-
vides an integrated development environment (IDE) including editor, macro assembler, debugger and pro-
grammer. The IDE's debugger and programmer interface to the CIP-51 via its JTAG interface to provide
fast and efficient in-system device programming and debugging. Third party macro assemblers and C
compilers are also availa ble .
DATA BUS
TMP1 TMP2
PRGM. ADDRESS REG.
PC INCREMENTER
ALU
PSW
DATA BUS
DATA B US
MEMORY
INTERFACE
MEM_ADDRESS
D8
PIPELINE
BUFFER
DATA POINTER
INTERRUPT
INTERFACE
SYSTEM_IRQs
EMULATION_IRQ
MEM_CONTROL
CONTROL
LOGIC
A16
PROGRAM COUNTER (PC)
STOP
CLOCK
RESET
IDLE POWER CONTROL
REGISTER
DATA BUS
SFR
BUS
INTERFACE
SFR_ADDRESS
SFR_CONTROL
SFR_WRITE_DATA
SFR_READ_DATA
D8
D8
B REGISTER
D8
D8
ACCUMULATOR
D8
D8
D8
D8
D8
D8
D8
D8
MEM_WRITE_DATA
MEM_READ_DATA
D8
SRAM
ADDRESS
REGISTER
SRAM
(256 X 8)
D8
STACK POINTER
D8
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 129
11.1. Instructi on Se t
The instruction set of the CIP-51 System Controller is fully compatible with the standard MCS-51™ instruc-
tion set; standard 8051 development tools can be used to develop software for the CIP-51. All CIP-51
instructions are the binary and functional equivalent of their MCS-51™ counterparts, including opcodes,
addressing modes and effect on PSW flags. However, instruction timing is different than that of the stan-
dard 8051.
11.1.1. Instruction and CPU Timing
In many 8051 implementations, a distinction is made between machine cycles and clock cycles, with
machine cycles varying from 2 to 12 clock cycles in length. However, the CIP-51 implementation is based
solely on clock cycle timing. All instruction timings are specified in terms of clock cycles.
Due to the pipelined architecture of the CIP-51, most instructions execute in the same number of clock
cycles as there are program bytes in the instruction. Conditional branch instructions take one less clock
cycle to complete when the branch is not taken as opposed to when the branch is taken. Table 11.1 is the
CIP-51 Instruction Set Summary, which includes the mnemonic, number of bytes, and number of clock
cycles for each instruction.
11.1.2. MOVX Instruction and Program Memory
In the CIP-51 , the MOVX instr uction serves th ree purposes: accessing on-chip XRAM, accessing off-chip
XRAM, and accessing on-chip program Flash memory. The Flash access feature provides a mechanism
for user software to update program code and use the program memory space for non-volatile data stor-
age (see Section “15. Flash Memory” on page 199). The External Memory Interface provides a fast
access to off-chip XRAM (or memory-mapped peripherals) via the MOVX instruction. Refer to Section
“17. External Data Memory Interface and On-Chip XRAM” on page 219 for details.
Table 11.1. CIP-51 Instructio n Set Summary
Mnemonic Description Bytes Clock
Cycles
Arithmetic Operations
ADD A, Rn Add register to A 1 1
ADD A, direct Add direct byte to A 2 2
ADD A, @Ri Add indirect RAM to A 1 2
ADD A, #data Add immediate to A 2 2
ADDC A, Rn Add register to A with carry 1 1
ADDC A, direct Add direct byte to A with ca rry 2 2
ADDC A, @Ri Add indirect RAM to A with carry 1 2
ADDC A, #data Add immediate to A with carry 2 2
SUBB A, Rn Subtract register from A with borrow 1 1
SUBB A, direct Subtract direct byte from A with borrow 2 2
SUBB A, @Ri Subtract indirect RAM from A with borrow 1 2
SUBB A, #data Subtract immediate from A with borrow 2 2
INC A Increment A 1 1
INC Rn Increment register 1 1
INC direct Increment direct byte 2 2
INC @Ri Increment indirect RAM 1 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
130 Rev. 1.4
DEC A Decrement A 1 1
DEC Rn Decrement register 1 1
DEC direct Decrement direct byte 2 2
DEC @Ri Decrement indirect RAM 1 2
INC DPTR Increment Data Pointer 1 1
MUL AB Multiply A and B 1 4
DIV AB Divide A by B 1 8
DA A Decimal adjust A 1 1
Logical Operations
ANL A, Rn AND Register to A 1 1
ANL A, direct AND direct byte to A 2 2
ANL A, @Ri AND indirect RAM to A 1 2
ANL A, #data AND immediate to A 2 2
ANL direct, A AND A to direct byte 2 2
ANL direct, #data AND immediate to direct byte 3 3
ORL A, Rn OR Register to A 1 1
ORL A, direct OR direct byte to A 2 2
ORL A, @Ri OR indirect RAM to A 1 2
ORL A, #data OR immediate to A 2 2
ORL direct, A OR A to direct byte 2 2
ORL direct, #data OR immediate to direct byte 3 3
XRL A, Rn Exclusive-OR Register to A 1 1
XRL A, direct Exclusive-OR direct byte to A 2 2
XRL A, @Ri Exclusive-OR indirect RAM to A 1 2
XRL A, #data Exclusive-OR immediate to A 2 2
XRL direct, A Exclusive-OR A to direct byte 2 2
XRL direct, #data Exclusive-OR immediate to direct byte 3 3
CLR A Clear A 1 1
CPL A Complement A 1 1
RL A Rotate A left 1 1
RLC A Rotate A left through Carry 1 1
RR A Rotate A right 1 1
RRC A Rotate A right through Carry 1 1
SWAP A Swap nibbles of A 1 1
Data Transfer
MOV A, Rn Move Register to A 1 1
MOV A, direct Move direct byte to A 2 2
MOV A, @Ri Move indirect RAM to A 1 2
MOV A, #data Move immediate to A 2 2
MOV Rn, A Move A to Register 1 1
MOV Rn, direct Move direct byte to Register 2 2
MOV Rn, #data Move immediate to Register 2 2
MOV direct, A Move A to direct byte 2 2
MOV direct, Rn Move Register to direct byte 2 2
MOV direct, direct Move direct byte to direct byte 3 3
Table 11.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic Description Bytes Clock
Cycles
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 131
MOV direct, @Ri Move indirect RAM to direct byte 2 2
MOV direct, #data Move immediate to direct byte 3 3
MOV @Ri, A Move A to indirect RAM 1 2
MOV @Ri, direct Move direct byte to indirect RAM 2 2
MOV @Ri, #data Move immediate to indirect RAM 2 2
MOV DPTR, #data16 Load DPTR with 16-bit constant 3 3
MOVC A, @A+DPTR Move code byte relative DPTR to A 1 3
MOVC A, @A+PC Move code byte relative PC to A 1 3
MOVX A, @Ri Move external data (8-bit address) to A 1 3
MOVX @Ri, A Move A to external data (8-bit addr ess) 1 3
MOVX A, @DPTR Move external data (16-bit address) to A 1 3
MOVX @DPTR, A Move A to external data (16-bit address) 1 3
PUSH direct Push direct byte onto stack 2 2
POP direct Pop direct byte from stack 2 2
XCH A, Rn Exchange Register with A 1 1
XCH A, direct Exchange direct byte with A 2 2
XCH A, @Ri Exchange indirect RAM with A 1 2
XCHD A, @Ri Exchange low nibble of indirect RAM with A 1 2
Boolean Manipulation
CLR C Clear Carry 1 1
CLR bit Clear direct bit 2 2
SETB C Set Carry 1 1
SETB bit Set direct bit 2 2
CPL C Complement Carry 1 1
CPL bit Complement direct bit 2 2
ANL C, bit AND direct bit to Carry 2 2
ANL C, /bit AND complement of direct bit to Carry 2 2
ORL C, bit OR direct bit to carry 2 2
ORL C, /bit OR complement of direct bit to Carry 2 2
MOV C, bit Move direct bit to Carry 2 2
MOV bit, C Move Carry to direct bit 2 2
JC rel Jump if Carry is set 2 2/3*
JNC rel Jump if Carry is not set 2 2/3*
JB bit, rel Jump if direct bit is set 3 3/4*
JNB bit, rel Jump if direct bit is not set 3 3/4*
JBC bit, rel Jump if direct bit is set and clear bit 3 3/4*
Program Branch in g
ACALL addr11 Absolute subroutine call 2 3*
LCALL addr16 Long subrou tin e ca ll 3 4*
RET Return from subroutine 1 5*
RETI Return from interrupt 1 5*
AJMP addr11 Absolute jump 2 3*
LJMP addr16 Long jump 3 4*
SJMP rel Short jump (relative add ress) 2 3*
JMP @A+DPTR Jump indirect relative to DPTR 1 3*
Table 11.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic Description Bytes Clock
Cycles
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
132 Rev. 1.4
JZ rel Jump if A equals zero 2 2/3*
JNZ rel Jump if A does not equal zero 2 2/3*
CJNE A, direct, rel Compare direct byte to A and jump if not equal 3 3/4*
CJNE A, #data, rel Compare immediate to A and jump if not equa l 3 3/4*
CJNE Rn, #data, rel Compare immediate to Registe r and jump if not
equal 33/4*
CJNE @Ri, #data, rel Compare immediate to indirect and jump if not
equal 34/5*
DJNZ Rn, rel Decrement Register and jump if not zero 2 2/3*
DJNZ direct, rel Decrement dir ect byte and jump if not zero 3 3/4*
NOP No operation 1 1
* Branch instructions will incur a cache-miss penalty if the branch target location is not already stored in
the Branch Target Cache. See Section “16. Branch Target Cache” on page 211 for more details.
Table 11.1. CIP-51 Instruction Set Summary (Continued)
Mnemonic Description Bytes Clock
Cycles
Notes on Registers, Operands and Addressing Modes:
Rn - Register R0-R7 of the currently selected register bank.
@Ri - Data RAM location addressed indirectly through R0 or R1.
rel - 8-bit, signed (2s complement) offset relative to the first byte of the following instruction. Used by
SJMP and all conditional jumps.
direct - 8-bit internal data location’s address. This could be a direct-access Data RAM loca tion (0x00-
0x7F) or an SFR (0x80-0xFF).
#data - 8-bit constant
#data16 - 16-bit constant
bit - Direct-accessed bit in Data RAM or SFR
addr11 - 11-bit destination address used by ACALL and AJMP. The destination must be within the same
2K-byte p age of program memory as the first byte of the following instruction.
addr16 - 16-bit destination address used by L CALL and LJMP. The destination may be a nywhere within
the 64K-byte pr og ra m mem o ry space.
There is one unused opcode (0xA5) that performs the same function as NOP.
All mnemonics copyrighted © Intel Corporation 1980.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 133
11.2. Memory Organization
The memory organization of the CIP-51 System Controller is similar to that of a standard 8051. There are
two separate memory spaces: program memory and data memory. Program and data memory share the
same address space but are accessed via different instruction types. There are 256 bytes of internal data
memory and 128k bytes (C8051F12x and C8051F130/1) or 64k bytes (C8051F132/3) of internal program
memory address space implemented within the CIP-51. The CIP-51 memory organization is shown in
Figure 11.2.
Figure 11.2. Memory Map
11.2.1. Program Memory
The C8051F12x and C80 51F130/1 have a 128 kB pr ogram me mory sp ace . The MCU imp lements this pro-
gram memory space as in-system re-programmable Flash memory in four 32 kB code banks. A common
code bank (Bank 0) of 32 kB is always accessible from addresses 0x0000 to 0x7FFF. The three upper
code banks (Bank 1, Bank 2, and Bank 3) are each mapped to addresses 0x8000 to 0xFFFF, depending
on the selection of bits in the PSBANK register, as described in SFR Definition 11.1. The IFBANK bits
select which of the upper banks are used for co de exe cution, wh ile the COBANK bits select the bank to be
used for direct writes and reads of the Flash memory. Note: 1024 bytes of the memory in Bank 3
(0x1FC00 to 0x1FFFF) are reserved and are not available for user program or data storage. The
C8051F132/3 have a 64k byte program memory space implemented as in-system re-programmable Flash
memory, and organized in a contiguous block from address 0x00000 to 0x0FFFF.
Program memory is nor mally assumed to be re ad-only. However, the CIP-51 can write to p rogr am memo ry
by setting the Program S tore Write Enable bit (PSCTL.0) and using the MOVX instruction. This feature pro-
vides a mechanism for the CIP-51 to update program code and use the program memory space for non-
volatile data storage. Refer to Section “15. Flash Memory” on page 199 for further details.
PROGRAM/DATA MEMORY
(FLASH)
FLASH
(In-System
Programmable in 102 4
Byte Sectors)
0x00000
0x1FFFF RESERVED
0x1FC00
0x1FBFF
Scrachpad Memory
(DATA only)
0x200FF
0x20000
(Direct and Indirect
Addressing)
Upper 128 RAM
(Indirect Addressing
Only)
Special Functi on
Registers
(Direct Addressing Only)
DATA MEMORY (RAM)
General Purpose
Registers
Bit Addressable Lower 128 RAM
(Direct and Indirect
Addressing)
INTERNAL DATA ADDRESS SPACE
EXTERNAL DATA ADDRESS SPACE
XRAM - 8192 Bytes
(accessable using MOVX
instruction)
0x0000
0x1FFF
Off-chip XRA M sp ac e
0x2000
0xFFFF
Up To
256 SFR Pages
13
02
C8051F120/1/2/3/4/5/6/7
C8051F130/1
FLASH
(In-System
Programmable in 102 4
Byte Sectors)
0x00000
0x0FFFF
Scrachpad Memory
(DATA only)
0x200FF
0x20000
C8051F132/3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
134 Rev. 1.4
SFR Definition 11.1. PSBANK: Program Space Bank Select
Figure 11.3. Address Memory Map for Instruction Fetches (128 kB Flash Only)
Bits 7–6: Reserved.
Bits 5–4: COBANK: Constant Operations Bank Select.
These bits select which Flash bank is targeted during constant operations (MOVC and Flash
MOVX) involving addresses 0x8000 to 0xFFFF. These bits are ignored when accessing the
Scratchpad memory areas (see Section “15. Flash Memory” on page 199).
00: Constant Operations Target Bank 0 (note that Bank 0 is also mapped between 0x0000 to
0x7FFF).
01: Constant Operations Target Bank 1.
10: Constant Operations Target Bank 2.
11: Constant Operations Target Bank 3.
Bits 3–2: Reserved.
Bits 1–0: IFBANK: Instruction Fetch Operations Bank Select.
These bits select which Flash bank is used for instruction fetches involving addresses 0x8000 to
0xFFFF. These bits can only be changed from code in Bank 0 (see Figure 11.3).
00: Instructions Fetch From Bank 0 (note that Bank 0 is also mapped between 0x0000 to
0x7FFF).
01: Instructions Fetch From Bank 1.
10: Instructions Fetch From Bank 2.
11: Instructions Fetch From Bank 3.
*Note: On the C8051F132/3, the COBANK and IFBANK bits should both remain set to the default setting of ‘01’ to
ensure proper device functionality.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - COBANK - - IFBANK 00010001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xB1
All Pages
Bank 0 Bank 1 Bank 2 Bank 3
Bank 0 Bank 0 Bank 0 Bank 0
IFBANK = 0 IFBANK = 1 IFBANK = 2 IFBANK = 3
Internal
Address
0x0000
0x7FFF
0x8000
0xFFFF
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 135
11.2.2. Data Memory
The CIP-51 implement s 256 bytes of internal RAM mapped into the dat a memory sp ace from 0x00 thro ugh
0xFF. The lower 128 bytes of data memory are used for general purpose registers and memory. Either
direct or indirect addressing may be used to access the lower 128 bytes of data memory. Locations 0x00
through 0x1F are addressable as four banks of general purpose registers, each bank consisting of eight
byte-wide registers. The next 16 bytes, locations 0x20 through 0x2F, may either be addressed as bytes or
as 128 bit locations accessible with the direct addressing mode.
The upper 128 bytes of data memory are accessible only by indirect addressing. This region occupies the
same address space as the Special Function Registers (SFR) but is physically separate from the SFR
space. The addressing mode used by an instruction when accessing locations above 0x7F determines
whether the CP U acce sses the uppe r 12 8 bytes of data mem ory space o r th e SFR ’s. Instruct ions tha t use
direct addressing will access the SFR space. Instructions using indirect addressing above 0x7F access the
upper 128 bytes of data memory. Figure 11.2 illustrates the data memory organization of the CIP-51.
11.2.3. General Purpose Registers
The lower 32 bytes of dat a memory, locations 0x00 through 0x 1F, may be addressed as four banks of gen-
eral-purpose registers. Each bank consists of eight byte-wide registers designated R0 through R7. Only
one of these banks may be ena bled at a time. Two bits in the program st atus word , RS0 (PSW.3) and RS1
(PSW.4), select the active register bank (see description of the PSW in SFR Definition 11.9). This allows
fast context switching when entering su broutin es and interrupt se rvice routine s. Indirect addr essing modes
use registers R0 and R1 as index register s.
11.2.4. Bit Addressable Locations
In addition to direct access to d ata memory organize d as bytes, the sixteen d at a mem ory locations at 0x20
through 0x2F are also accessible as 128 individually addressable bits. Each bit has a bit address from
0x00 to 0x7F. Bit 0 of the byte at 0x20 has bit address 0x00 while bit 7 of the byte at 0x20 has bit address
0x07. Bit 7 of the byte at 0x2F has bit address 0x7F. A bit access is distinguished from a full byte access by
the type of instruction used (bit source or destination operands as opposed to a byte source or destina-
tion). The MCS-51™ assembly language allows an alternate notation for bit addressing of the form XX.B
where XX is the byte address and B is the bit position within the byte.
For example, the instruction:
MOV C, 22.3h
moves the Boolean value at 0x13 (bit 3 of the byte at location 0x2 2) into the Carry flag.
11.2.5. Stack
A programmer's st ack can be located anywhere in the 256 byte dat a memory. The stack area is de signated
using the Stack Pointer (SP, address 0x81) SFR. The SP will point to the last location used. The next value
pushed on the stack is placed at SP+1 and then SP is incremented. A reset initializes the stack pointer to
location 0x07; therefore, the first value pushed on the stack is placed at location 0x08, which is also the
first register (R0) of re gister bank 1. Thus, if more than one register bank is to be used, the SP should be
initialized to a location in the data memory not being used for data storage. The st a ck de pth ca n extend up
to 256 bytes.
The MCUs a lso h ave built- in ha rdwa re f or a stack reco rd w hich is a ccess ed b y th e de bug logic . Th e stack
record is a 32-bit shif t registe r, where each PUSH or increment SP pushes one record bit onto the register,
and each CALL pushes two record bits onto the register. (A POP or decrement SP pops one record bit,
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
136 Rev. 1.4
and a RET pops two record bits, also.) The stack record circuitry can also detect an overflow or underflow
on the 32-bit shift register, and can notify the debug software even with the MCU running at speed.
11.2.6. Special Function Registers
The direct-access data memory locations from 0x80 to 0xFF constitute the special function registers
(SFR’s). The SFR’s provide control and data exchange with the CIP-51's resources and peripherals. The
CIP-51 duplicates the SFR’s found in a typical 8051 implementation as well as implementing additional
SFR’s used to configure and access the sub-systems unique to the MCU. This allows the addition of new
functionality while retaining compatibility with the MCS-51™ instruction set. Table 11.2 lists the SFR’s
implemented in the CIP-51 System Controller.
The SFR registers are accessed whenever the direct addressing mode is used to access memory loca-
tions from 0x80 to 0xFF. SFR’s with addresses ending in 0x0 or 0x8 (e.g. P0, TCON, P1, SCON, IE, etc.)
are bit-addressable as well as byte-addressable. All other SFR’s are byte-addressable only. Unoccupied
addresses in the SFR space are reserved for future use. Accessing these areas will have an indeterminate
effect and should be avoided. Refer to the corresponding pages of the datasheet, as indicated in
Table 11.3, for a detailed description of each register.
11.2.6.1.SFR Paging
The CIP-51 features SFR paging, allowing the device to map many SFR’s into the 0x80 to 0xFF memory
address space. The SF R memory space has 256 pages. In this way, each memory location from 0x80 to
0xFF can access up to 256 SFR’s. The C8051F12x family of devices utilizes five SFR pages: 0, 1, 2, 3,
and F. SFR pages are selected using the Special Function Register Page Selection register, SFRPAGE
(see SFR Definition 11.3). The procedure for reading and writing an SFR is as follows:
1. Select the appropriate SFR page number using the SFRPAGE register.
2. Use direct accessing mode to read or write the special function register (MOV instruction).
11.2.6.2.Interrupts and SFR Paging
When an interrupt occurs, the SFR Page Register will automatically switch to the SFR page containing the
flag bit that caused the interrupt. The automatic SFR Page switch function conveniently removes the bur-
den of switching SFR pages from the interrupt service routine. Upon execution of the RETI instruction, the
SFR page is automatically restored to the SFR Page in use prior to the interrupt. This is accomplished via
a three-byte SFR Page Stack. The top byte of the stack is SFRPA GE, the current SF R Page. The se cond
byte of the S FR Page Stack is SFRNE XT. The third, or bottom byte of the SFR Page Stack is SFRLAST.
On interrupt, the current SFRPAGE value is pushed to the SFRNEXT byte, and the value of SFRNEXT is
pushed to SFRLAST. Hardware then loads SFRPAGE with the SFR Page containing the flag bit associated
with the interrupt. On a return from interrup t, the SFR Page Stack is popped resu lting in the value of SFRN-
EXT returning to the SFRPAGE register, thereby restoring the SFR p age context without so ftware interven-
tion. The value in SFRLAST (0x00 if there is no SFR Page value in the bottom of the stack) of the stack is
placed in SFRNEXT register. If desired, the values stored in SFRNEXT and SFRLAST may be modified
during an interrupt, enabling the CPU to return to a different SFR Page upon execution of the RETI instruc-
tion (on interrupt exit). Modifying registers in the SFR Page Stack does not cause a push or pop of the
stack. Only interrupt calls and returns will cause push/pop operations on the SFR Page Stack.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 137
Figure 11.4. SFR Page Stack
Automatic hardware switching of the SFR Page on interru pts may be enabled or disabled as desired using
the SFR Automatic Page Control Enable Bit located in the SFR Page Control Register (SFRPGCN). This
function defaults to ‘enabled’ upon reset. In this way, the autoswitching function will be enabled unless dis-
abled in software.
A summary of the SFR locations (address and SFR page) is provided in Table 11.2. in the form of an SFR
memory map. Each memory location in the map has an SFR page row, denoting the page in which that
SFR resides. Note that certain SFR’s are accessible from ALL SFR pages, and are denoted by the “(ALL
PAGES)” designation. For example, the Port I/O registers P0, P1, P2, and P3 all have the “(ALL PAGES)”
designation, indic ating th ese SFR’s are acc essible f rom all SF R pages regardless of the SFRPAGE regis -
ter value.
SFRNEXT
SFRPAGE
SFRLAST
CIP-51
Interrupt
Logic
SFRPGCN Bit
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
138 Rev. 1.4
11.2.6.3.SFR Page Stack Example
The following is an example that shows the operation of the SFR Page Stack during interrupts.
In this example, the SFR Page Control is left in the default enabled state (i.e., SFRPGEN = 1), and the
CIP-51 is executing in-line code that is writing value s to Port 5 (SFR “P5” , located at addre ss 0xD8 on SFR
Page 0x0F). The device is also using the Programmable Counter Array (PCA) and the 10-bit ADC (ADC2)
window compar ator to mo nitor a vo ltage. The PCA is timing a critical control function in its interrupt service
routine (ISR), so its interrupt is enabled and is set to high priority. The ADC2 is monitoring a voltage that is
less import an t, bu t to mi nimize the software overhead its window comparator is being used with an associ-
ated ISR that is set to low priority. At this point, the SFR page is set to access the Port 5 SFR (SFRPAGE =
0x0F). See Figure 11.5 below.
Figure 11.5. SFR Page Stack While Using SFR Page 0x0F To Access Port 5
While CIP-51 exec utes in-line code (writing values to Port 5 in this example), ADC2 Window Comparator
Interrupt occurs. The CIP-51 vectors to the ADC2 Window Comparator ISR and pushes the current SFR
Page value (SFR Page 0x0F) into SFRNEXT in the SFR Page Stack. The SFR page needed to access
ADC2’s SFR’s is then automatically placed in the SFRPAGE register (SFR Page 0x02). SFRPAGE is con-
sidered the “top” of the SFR Pag e Stack. Software can now access the ADC2 SFR’s. Software may switc h
to any SFR Page by writing a new value to the SFRPAGE register at any time during the ADC2 ISR to
access SFR’s that are not on SFR Page 0x02. See Figure 11.6 below.
0x0F
(Port 5) SFRPAGE
SFRLAST
SFRNEXT
SFR Page
Stack SFR's
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 139
Figure 11.6. SFR Page Stack After ADC2 Window Comparator Interrupt Occurs
While in the ADC2 ISR, a PCA interrupt occurs. Recall the PCA interrupt is configured as a high priority
interrupt, while the ADC2 interrupt is configured as a low priority interrupt. Thus, the CIP-51 will now vector
to the high priority PCA ISR. Upon doing so, the CIP-51 will automatically place the SFR page needed to
access the PCA’s special function registers into the SFRPAGE register, SFR Page 0x00. The value that
was in the SFRPAGE register before the PCA interrupt (SFR Page 2 for ADC2) is pushed down the stack
into SFRNEXT. Likewise, the value that was in the SFRNEXT register before the PCA interrupt (in this
case SFR Page 0x0F for Port 5) is pushed down to the SFRLAST register, the “bottom” of the stack. Note
that a value stored in SFRLAST (via a previous software write to the SFRLAST register) will be overwritten.
See Figure 11.7 below.
0x02
(ADC2)
0x0F
(Port 5)
SFRPAGE
SFRLAST
SFRNEXT
SFRPAGE
pushed to
SFRNEXT
SFR Page 0x02
Automatically
pushed on stack in
SFRPAGE on ADC2
interrupt
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
140 Rev. 1.4
Figure 11.7. SFR Page Stack Upon PCA Interrupt Occurring During an ADC2 ISR
On exit from the PCA interrupt service routine, the CIP-51 will return to the ADC2 Window Comparator
ISR. On execution of the RETI instruction, SFR Page 0x00 used to access the PCA registers will be auto-
matically popped off of the SFR Page Stack, and the contents of the SFRNEXT register will be moved to
the SFRPAGE register. Software in the ADC2 ISR can continue to access SFR’s as it did prior to the PCA
interrupt. Likewise, the contents of SFRLAST are moved to the SFRNEXT register. Recall this was the
SFR Page value 0x0F being used to access Port 5 before the ADC2 interrupt occurred. See Figure 11.8
below.
Figure 11.8. SFR Page Stack Upon Return From PCA Interrupt
0x00
(PCA)
0x02
(ADC2)
0x0F
(Port 5)
SFRPAGE
SFRLAST
SFRNEXT
SFR Page 0x00
Automatically
pushed on stack in
SFRPAGE on PCA
interrupt
SFRPAGE
pushed to
SFRNEXT
SFRNEXT
pushed to
SFRLAST
0x02
(ADC2)
0x0F
(Port 5)
SFRPAGE
SFRLAST
SFRNEXT
SFR Page 0x00
Automatically
popped off of the
stack on return from
interrupt
SFRNEXT
popped to
SFRPAGE
SFRLAST
popped to
SFRNEXT
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 141
On the execution of the RETI instruction in the ADC2 Window Comparator ISR, the value in SFRPAGE
register is overwritten with the contents of SFRNEXT. The CIP-51 may now access the Port 5 SFR bits as
it did prior to the interrupts occurring. See Figure 11.9 below.
Figure 11.9. SFR Page Stack Upon Return From ADC2 Window Interrupt
Note that in the above example, all three bytes in the SFR Page Stack are accessible via the SFRPAGE,
SFRNEXT, and SFRLAST special function regist er s. If the stack is a l ter e d while servicing an interrupt, it is
possible to return to a different SFR Page upon interrupt exit than selected prior to the interr upt call. Direct
access to the SFR Page stack can be useful to enable real-time operating systems to control and manage
context switching between multiple tasks.
Push operations on the SFR Page Stack only occur on interrupt service, and pop oper ations only occur on
interrupt exit (execution on the RETI instruction). The automatic switching of the SFRPAGE and operation
of the SFR Page Stack as described above can be disabled in software by clearing the SFR Automatic
Page Enable Bit (SFRPGEN) in the SFR Page Control Register (SFRPGCN). See SFR Definition 11.2.
0x0F
(Port 5) SFRPAGE
SFRLAST
SFRNEXT
SFR Page 0x02
Automatically
popped off of the
stack on return from
interrupt
SFRNEXT
popped to
SFRPAGE
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
142 Rev. 1.4
SFR Definition 11.2. SFRPGCN: SFR Page Control
SFR Definition 11.3. SFRPAGE: SFR Page
Bits7–1: Reserved.
Bit0: SFRPGEN: SFR Automatic Page Control Enable.
Upon interrupt, the C8051 Core will vector to the specified interrupt service routine and auto-
matically switch the SFR page to the corresponding p eriphe ra l or fu nction’s SFR page. This
bit is used to control this autopaging function.
0: SFR Automatic Paging disabled. C8051 core will not automatically change to the appro-
priate SFR page (i.e., the SFR page that cont ains the SFR’s for the peripheral/function that
was the source of the interrupt).
1: SFR Automatic Paging enabled. Upon interrupt, the C8051 will switch the SFR page to
the page that contains the SFR’s for the peripheral or function that is the source of the inter-
rupt.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - - - - - SFRPGEN 00000001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x96
F
Bits7–0: SFR Page Bit s: Byte Repr esent s the SFR Page the C8051 MCU u ses when re ading or m od-
ifying SFR’s.
Write: Sets the SFR Page.
Read: Byte is the SFR page the C8051 MCU is using.
When enabled in the SFR Page Control Register (SFRPGCN), the C8051 will automatically
switch to the SFR Page that contains the SFR’ s of the corresponding peripher al/function that
caused the interrupt, and return to the previous SFR page upon return from interrupt (unless
SFR Stack was altered before a returning from the interrupt).
SFRPAGE is the top byte of the SFR Page Stack, and push/pop events of this stack are
caused by interrupts (and not by reading/writing to the SFRPAGE register)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x84
All Pages
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 143
SFR Definition 11.4. SFRNEXT: SFR Next Register
SFR Definition 11.5. SFRLAST: SFR Last Register
Bits7–0: SFR Page Stack Bits: SFR page context is retained upon interrupts/return from interrupts in
a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFR-
LAST is the third entr y. The SFR stack bytes may be used alter the context in th e SFR Page
Stack, and will not cause the stack to ‘push’ or ‘pop’. Only interrupts and return from inter-
rupts cause pushes and pops of the SFR Page Stack.
Write: Sets the SFR Page contained in the second byte of the SFR Stack. This will cause
the SFRPAGE SFR to have this SFR page value upon a re tu rn from interrupt.
Read: Returns the value of the SFR page contained in the second byte of the SFR stack.
This is the value that will go to the SFR Page register upon a return from interrupt.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x85
All Pages
Bits7–0: SFR Page Stack Bits: SFR page context is retained upon interrupts/return from interrupts in
a 3 byte SFR Page Stack: SFRPAGE is the first entry, SFRNEXT is the second, and SFR-
LAST is the third entr y. The SFR stack bytes may be used alter the context in th e SFR Page
Stack, and will not cause the stack to ‘push’ or ‘pop’. Only interrupts and return from inter-
rupts cause pushes and pops of the SFR Page Stack.
Write: Sets the SFR Page in the last entry of the SFR Stack. This will cause the SFRNEXT
SFR to have this SFR page value upon a return from interrupt.
Read: Returns the value of the SFR page contained in the last en try of the SFR stack.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x86
All Pages
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
144 Rev. 1.4
Table 11.2. Special Function Register (SFR) Memory Map
ADDRESS
SFR Page
0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F)
F8
0
1
2
3
F
SPI0CN
P7
PCA0L PCA0H PCA0CPL0 PCA0CPH0 PCA0CPL1 PCA0CPH1 WDTCN
(ALL
PAGES)
F0
0
1
2
3
F
B
(ALL
PAGES)
EIP1
(ALL
PAGES)
EIP2
(ALL
PAGES)
E8
0
1
2
3
F
ADC0CN
ADC2CN
P6
PCA0CPL2 PCA0CPH2 PCA0CPL3 PCA0CPH3 PCA0CPL4 PCA0CPH4 RSTSRC
E0
0
1
2
3
F
ACC
(ALL
PAGES)
PCA0CPL5
XBR0
PCA0CPH5
XBR1 XBR2
EIE1
(ALL
PAGES)
EIE2
(ALL
PAGES)
D8
0
1
2
3
F
PCA0CN
P5
PCA0MD PCA0CPM0 PCA0CPM1 PCA0CPM2 PCA0CPM3 PCA0CPM4 PCA0CPM5
D0
0
1
2
3
F
PSW
(ALL
PAGES)
REF0CN DAC0L
DAC1L DAC0H
DAC1H DAC0CN
DAC1CN
C8
0
1
2
3
F
TMR2CN
TMR3CN
TMR4CN
P4
TMR2CF
TMR3CF
TMR4CF
RCAP2L
RCAP3L
RCAP4L
RCAP2H
RCAP3H
RCAP4H
TMR2L
TMR3L
TMR4L
TMR2H
TMR3H
TMR4H MAC0RNDL
SMB0CR
MAC0RNDH
C0
0
1
2
3
F
SMB0CN
MAC0STA
SMB0STA
MAC0AL
SMB0DAT
MAC0AH
SMB0ADR
MAC0CF
ADC0GTL
ADC2GT
ADC0GTH ADC0LTL
ADC2LT
ADC0LTH
0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 145
B8
0
1
2
3
F
IP
(ALL
PAGES)
SADEN0 AMX0CF
AMX2CF
AMX0SL
AMX2SL
ADC0CF
ADC2CF
ADC0L
ADC2
ADC0H
B0
0
1
2
3
F
P3
(ALL
PAGES)
PSBANK
(ALL
PAGES)
FLSCL
FLACL
A8
0
1
2
3
F
IE
(ALL
PAGES)
SADDR0
P1MDIN
A0
0
1
2
3
F
P2
(ALL
PAGES)
EMI0TC
CCH0CN
EMI0CN
CCH0TN
EMI0CF
CCH0LC P0MDOUT P1MDOUT P2MDOUT P3MDOUT
98
0
1
2
3
F
SCON0
SCON1 SBUF0
SBUF1 SPI0CFG
CCH0MA
SPI0DAT
P4MDOUT
SPI0CKR
P5MDOUT P6MDOUT P7MDOUT
90
0
1
2
3
F
P1
(ALL
PAGES)
SSTA0
MAC0BL MAC0BH MAC0ACC0 MAC0ACC1 MAC0ACC2 MAC0ACC3
SFRPGCN MAC0OVR
CLKSEL
88
0
1
2
3
F
TCON
CPT0CN
CPT1CN
FLSTAT
TMOD
CPT0MD
CPT1MD
PLL0CN
TL0
OSCICN
TL1
OSCICL
TH0
OSCXCN
TH1
PLL0DIV
CKCON
PLL0MUL
PSCTL
PLL0FLT
80
0
1
2
3
F
P0
(ALL
PAGES)
SP
(ALL
PAGES)
DPL
(ALL
PAGES)
DPH
(ALL
PAGES)
SFRPAGE
(ALL
PAGES)
SFRNEXT
(ALL
PAGES)
SFRLAST
(ALL
PAGES)
PCON
(ALL
PAGES)
Table 11.2. Special Function Register (SFR) Memory Map (Continued)
0(8) 1(9) 2(A) 3(B) 4(C) 5(D) 6(E) 7(F)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
146 Rev. 1.4
Table 11.3. Special Function Registers
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address SFR
Page Description Page No.
ACC 0xE0 All Pages Accumulator page 153
ADC0CF 0xBC 0 ADC0 Configuration page 621, page 80 2
ADC0CN 0xE8 0 ADC0 Control page 631, page 812
ADC0GTH 0xC5 0 ADC0 Greater-Than High Byte page 661, page 842
ADC0GTL 0xC4 0 ADC0 Greater-Than Low Byte page 661, page 842
ADC0H 0xBF 0 ADC0 Data Word High Byte page 641, page 822
ADC0L 0xBE 0 ADC0 Data Word Low Byte page 641, page 822
ADC0LTH 0xC7 0 ADC0 Less-Than High Byte page 671, page 852
ADC0LTL 0xC6 0 ADC0 Less-Than Low Byte page 671, page 852
ADC2 0xBE 2 ADC2 Data Word page 993
ADC2CF 0xBC 2 ADC2 Configuration page 973
ADC2CN 0xE8 2 ADC2 Control page 983
ADC2GT 0xC4 2 ADC2 Greater-Than page 1023
ADC2LT 0xC6 2 ADC2 Less-Than page 1023
AMX0CF 0xBA 0 ADC0 Multiplexer Configuration page 601, page 782
AMX0SL 0xBB 0 ADC0 Multiplexer Channel Select page 611, page 792
AMX2CF 0xBA 2 ADC2 Multiplexer Configuration page 953
AMX2SL 0xBB 2 ADC2 Multiplexer Channel Select page 963
B 0xF0 All Pages B Register page 153
CCH0CN 0xA1 F Cache Control page 215
CCH0LC 0xA3 F Cache Lock page 216
CCH0MA 0x9A F Cache Miss Accumulator page 217
CCH0TN 0xA2 F Cache Tuning page 216
CKCON 0x8E 0 Clock Control page 315
CLKSEL 0x97 F System Clock Select page 188
CPT0CN 0x88 1 Comparator 0 Control page 123
CPT0MD 0x89 1 C omparator 0 Configuration page 123
CPT1CN 0x88 2 Comparator 1 Control page 124
CPT1MD 0x89 2 C omparator 1 Configuration page 125
DAC0CN 0xD4 0 DAC0 Control page 1083
DAC0H 0xD3 0 DAC0 High Byte page 1073
DAC0L 0xD2 0 DAC0 Low Byte page 1073
DAC1CN 0xD4 1 DAC1 Control page 1103
DAC1H 0xD3 1 DAC1 High Byte page 1093
DAC1L 0xD2 1 DAC1 Low Byte page 1093
DPH 0x83 All Pages Data Pointer High Byte page 151
DPL 0x82 All Pages Data Pointer Low Byte page 151
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 147
EIE1 0xE6 All Pages Extended Interrup t Enable 1 page 159
EIE2 0xE7 All Pages Extended Interrup t Enable 2 page 160
EIP1 0xF6 All Pages Extended Interrupt Priority 1 page 161
EIP2 0xF7 All Pages Extended Interrupt Priority 2 page 162
EMI0CF 0xA3 0 EMIF Configuration page 221
EMI0CN 0xA2 0 EMIF Control page 220
EMI0TC 0x A1 0 EMIF Timing C on tr ol page 22 6
FLACL 0xB7 F Flash Access Limit page 206
FLSCL 0xB7 0 Flash Scale page 208
FLSTAT 0x88 F Flash Status page 217
IE 0xA8 All Pages Interrupt Enable page 157
IP 0xB8 All Pages Interrupt Priority page 158
MAC0ACC0 0x93 3 MAC0 Accumulator Byte 0 (LSB) page 1744
MAC0ACC1 0x94 3 MAC0 Accumulator Byte 1 page 1734
MAC0ACC2 0x95 3 MAC0 Accumulator Byte 2 page 1734
MAC0ACC3 0x96 3 MAC0 Accumulator Byte 3 (MSB) page 1734
MAC0AH 0xC2 3 MAC0 A Register High Byte page 1714
MAC0AL 0xC1 3 MAC0 A Register Low Byte page 1724
MAC0BH 0x92 3 MAC0 B Register High Byte page 1724
MAC0BL 0x91 3 MAC0 B Register Low Byte page 1724
MAC0CF 0xC3 3 MAC0 Configuration page 1704
MAC0OVR 0x97 3 MAC0 Accumulator Overflow page 1744
MAC0RNDH 0xCF 3 MAC0 Rounding Register High Byte page 1744
MAC0RNDL 0xCE 3 MAC0 Rounding Register Low Byte page 1754
MAC0STA 0xC0 3 MAC0 Status Register page 1714
OSCICL 0x8B F Internal Oscillator Calibration page 186
OSCICN 0x8A F Internal Oscillator Control page 186
OSCXCN 0x8C F External Oscillator Control page 189
P0 0x80 All Pages Port 0 Latch page 248
P0MDOUT 0xA4 F Port 0 Output Mode Configuration page 248
P1 0x90 All Pages Port 1 Latch page 249
P1MDIN 0xAD F Port 1 Input Mode page 249
P1MDOUT 0xA5 F Port 1 Output Mode Configuration page 250
P2 0xA0 All Pages Port 2 Latch page 250
P2MDOUT 0xA6 F Port 2 Output Mode Configuration page 251
P3 0xB0 All Pages Port 3 Latch page 251
P3MDOUT 0xA7 F Port 3 Output Mode Configuration page 252
P4 0xC8 F Port 4 Latch page 254
P4MDOUT 0x9C F Port 4 Output Mode Configuration page 254
P5 0xD8 F Port 5 Latch page 255
P5MDOUT 0x9D F Port 5 Output Mode Configuration page 255
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address SFR
Page Description Page No.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
148 Rev. 1.4
P6 0xE8 F Port 6 Latch page 256
P6MDOUT 0x9E F Port 6 Output Mode Configuration page 256
P7 0xF8 F Port 7 Latch page 257
P7MDOUT 0x9F F Port 7 Output Mode Configuration page 257
PCA0CN 0xD8 0 PCA Control page 335
PCA0CPH0 0xFC 0 PCA Module 0 Capture/Compare High Byte page 339
PCA0CPH1 0xFE 0 PCA Module 1 Capture/Compare High Byte page 339
PCA0CPH2 0xEA 0 PCA Module 2 Capture/Compare High Byte page 339
PCA0CPH3 0xEC 0 PCA Module 3 Capture/Compare High Byte page 339
PCA0CPH4 0xEE 0 PCA Module 4 Capture/Compare High Byte page 339
PCA0CPH5 0xE2 0 PCA Module 5 Capture/Compare High Byte page 339
PCA0CPL0 0xFB 0 PCA Module 0 Capture/Compare Low Byte page 338
PCA0CPL1 0xFD 0 PCA Module 1 Capture/Compare Low Byte page 338
PCA0CPL2 0xE9 0 PCA Module 2 Capture/Compare Low Byte page 338
PCA0CPL3 0xEB 0 PCA Module 3 Capture/Compare Low Byte page 338
PCA0CPL4 0xED 0 PCA Module 4 Capture/Co mpare Low Byte page 338
PCA0CPL5 0xE1 0 PCA Module 5 Capture/Compare Low Byte page 338
PCA0CPM0 0xDA 0 PCA Module 0 Mode page 337
PCA0CPM1 0xDB 0 PCA Module 1 Mode page 337
PCA0CPM2 0xDC 0 PCA Module 2 Mode page 337
PCA0CPM3 0xDD 0 PCA Module 3 Mode page 337
PCA0CPM4 0xDE 0 PCA Module 4 Mode page 337
PCA0CPM5 0xDF 0 PCA Module 5 Mode page 337
PCA0H 0xFA 0 PCA Counter High Byte page 338
PCA0L 0xF9 0 PCA Counter Low Byte page 338
PCA0MD 0xD9 0 PCA Mode page 336
PCON 0x87 All Pages Power Control page 164
PLL0CN 0x89 F PLL Control page 193
PLL0DIV 0x8D F PLL Divider p age 194
PLL0FLT 0x8F F PLL Filter p age 195
PLL0MUL 0 x8E F PLL Multiplier page 194
PSBANK 0xB1 All Pages Flash Bank Select page 134
PSCTL 0x8F 0 Flash Write/Erase Control page 209
PSW 0xD0 All Pages Program Status Word page 152
RCAP2H 0xCB 0 Timer/Counter 2 Capture/Reload High Byte page 323
RCAP2L 0xC A 0 Timer/Counter 2 Capture/Reload Low B yte page 323
RCAP3H 0xCB 1 Timer 3 Capture/Reload High Byte page 323
RCAP3L 0xCA 1 Timer 3 Capture/Reload Low Byte page 323
RCAP4H 0xCB 2 Timer/Counter 4 Capture/Reload High Byte page 323
RCAP4L 0xC A 2 Timer/Counter 4 Capture/Reload Low B yte page 323
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address SFR
Page Description Page No.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 149
REF0CN 0xD1 0 Voltage Reference Control page 1145,
page 1166,
page 1177
RSTSRC 0xEF 0 R eset Source page 182
SADDR0 0xA9 0 UART 0 Slave Address page 298
SADEN0 0xB9 0 UART 0 Slave Address Mask page 298
SBUF0 0x99 0 UART 0 Data Buffer page 298
SBUF1 0x99 1 UART 1 Data Buffer page 305
SCON0 0x98 0 UART 0 Control p age 296
SCON1 0x98 1 UART 1 Control p age 304
SFRLAST 0x86 All Pages SFR Stack Last Page page 143
SFRNEXT 0x85 All Pages SFR Stack Next Page page 143
SFRPAGE 0x84 All Pages SFR Page Select pa ge 142
SFRPGCN 0x96 F SFR Page Control page 142
SMB0ADR 0xC3 0 SMBus Slave Address page 269
SMB0CN 0xC0 0 SMBus Control page 266
SMB0CR 0xCF 0 SMBus Clock Rate page 267
SMB0DAT 0xC2 0 SMBus Data page 268
SMB0STA 0xC1 0 SMBus Status page 269
SP 0x81 All Pages Stack Pointer page 151
SPI0CFG 0x9A 0 SPI Configuration page 280
SPI0CKR 0x9D 0 SPI Clock Rate Control page 282
SPI0CN 0xF8 0 SPI Control page 281
SPI0DAT 0x9B 0 SPI Data page 282
SSTA0 0x91 0 UART 0 Status page 297
TCON 0x88 0 Timer/Counter Control page 313
TH0 0x8C 0 Timer/Counter 0 High Byte page 316
TH1 0x8D 0 Timer/Counter 1 High Byte page 316
TL0 0x8A 0 Timer/Counter 0 Low Byte page 315
TL1 0x8B 0 Timer/Counter 1 Low Byte page 316
TMOD 0x89 0 Timer/Counter Mode pa ge 314
TMR2CF 0xC9 0 Timer/Counter 2 Configuration page 324
TMR2CN 0xC8 0 Timer/Counter 2 Control page 324
TMR2H 0xCD 0 Timer/Counter 2 High Byte page 324
TMR2L 0xCC 0 Timer/Counter 2 Low Byte page 323
TMR3CF 0xC9 1 Timer 3 Configuration page 324
TMR3CN 0xC8 1 Timer 3 Control page 324
TMR3H 0xCD 1 Timer 3 High Byte page 324
TMR3L 0xCC 1 Time r 3 Low Byte page 323
TMR4CF 0xC9 2 Timer/Counter 4 Configuration page 324
TMR4CN 0xC8 2 Timer/Counter 4 Control page 324
TMR4H 0xCD 2 Timer/Counter 4 High Byte page 324
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address SFR
Page Description Page No.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
150 Rev. 1.4
TMR4L 0xCC 2 Timer/Counter 4 Low Byte page 323
WDTCN 0xFF All Pages Watchdog Timer Control page 181
XBR0 0xE1 F Port I/O Crossbar Control 0 page 245
XBR1 0xE2 F Port I/O Crossbar Control 1 page 246
XBR2 0xE3 F Port I/O Crossbar Control 2 page 247
Notes:
1. Refers to a register in the C8051F120/1/4/5 only.
2. Refers to a register in the C8051F122/3/6/7 and C8051F130/1/2/3 only.
3. Refers to a register in the C8051F120/1/2/3/4/5/6/7 only.
4. Refers to a register in the C8051F120/1/2/3 and C8051F130/1/2/3 only.
5. Refers to a register in the C8051F120/2/4/6 only.
6. Refers to a register in the C8051F121/3/5/7 only.
7. Refers to a register in the C8051F130/1/2/3 only.
Table 11.3. Special Function Registers (Continued)
SFRs are listed in alphabetical order. All undefined SFR locations are reserved.
Register Address SFR
Page Description Page No.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 151
11.2.7. Register Descriptions
Following are descriptions of SFRs related to the operation of the CIP-51 System Controller. Reserved bits
should not be set to logic l. Future product versions may use these bit s to implement new features in wh ich
case the reset value of the bit will be logic 0, selecting the feature's default state. Detailed descriptions of
the remaining SFRs are included in the sections of the datasheet associated with their corresponding sys-
tem function.
SFR Definition 11.6. SP: Stack Pointer
SFR Definition 11.7. DPL: Data Pointer Low Byte
SFR Definition 11.8. DPH: Data Pointer High Byte
Bits7–0: SP: Stack Pointer.
The S tack Pointer holds the location of the top of the stack. The stack pointer is incremented
before every PUSH operation. The SP register defaults to 0x07 afte r reset.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x81
All Pages
Bits7–0: DPL: Data Pointer Low.
The DPL register is the low byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x82
All Pages
Bits7–0: DPH: Data Pointer High.
The DPH register is the high byte of the 16-bit DPTR. DPTR is used to access indirectly
addressed XRAM and Flash memory.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x83
All Pages
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
152 Rev. 1.4
SFR Definition 11.9. PSW: Program Status Word
Bit7: CY: Carry Flag.
This bit is set when the last arithmetic operation resulted in a carry (addition) or a borrow
(subtraction). It is cleared to 0 by all other arithmetic operations.
Bit6: AC: Auxiliary Carry Flag
This bit is set when the la st arithmetic operation re sulted in a carry into (additio n) or a borrow
from (subtraction) the high order nibble. It is cleared to 0 by all other arithmetic operations.
Bit5: F0: User Flag 0.
This is a bit-addressable, general purpose flag for use under software con trol.
Bits4–3: RS1–RS0: Register Bank Select.
These bits select which register bank is used during register accesses.
Bit2: OV: Overflow Flag.
This bit is set to 1 under the following circumstances:
• An ADD, ADDC, or SUBB instruction causes a sign-change overflow.
• A MUL instruction results in an overflow (result is greater than 255) .
• A DIV instruction causes a divide-by-zero condition.
The OV bit is cleared to 0 b y the ADD, ADDC, SUBB, MUL, a nd DIV instruction s in all ot her
cases.
Bit1: F1: User Flag 1.
This is a bit-addressable, general purpose flag for use under software con trol.
Bit0: PARITY: Parity Flag.
This bit is set to 1 if the sum of the eight bits in the accumulator is odd and cleared if the sum
is even.
R/W R/W R/W R/W R/W R/W R/W R Reset Value
CY AC F0 RS1 RS0 OV F1 PARITY 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xD0
All Pages
RS1 RS0 Register Bank Address
0 0 0 0x00–0x07
0 1 1 0x08–0x0F
1 0 2 0x10–0x17
1 1 3 0x18–0x1F
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SFR Definition 11.10. ACC: Accumulator
SFR Definition 11.11. B: B Register
Bits7–0: ACC: Accumulator.
This register is the accumulator for arithmetic operations.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ACC.7 ACC.6 ACC.5 ACC.4 ACC.3 ACC.2 ACC.1 ACC.0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xE0
All Pages
Bits7–0: B: B Register.
This register serves as a second accumulator for certain arithmetic ope rations.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
B.7 B.6 B.5 B.4 B.3 B.2 B.1 B.0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xF0
All Pages
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11.3. Interrupt Handler
The CIP-51 includes an extended interrup t system supp orting a total of 20 interrupt source s with two prior-
ity levels. The allocation of interrupt sources between on-chip peripherals and external input pins varies
according to the specific version of th e device. Each in terrupt sou rce has one or more associated interrupt-
pending flag(s) located in an SFR. When a peripheral or external source meets a valid interrupt condition,
the associat ed inte rr up t-pending flag is set to logic 1.
If interrupt s are enable d for the source, an inter rupt request is generated when th e interrupt-p ending flag is
set. As soon as execution of the current instruction is complete, the CPU generates an LCALL to a prede-
termined address to begin execu tion of an interrupt service ro utine (ISR). Each ISR must end with an RETI
instruction, which returns program execution to the next instruction that would have been executed if the
interrupt request h ad not occurred. If inter rupt s are not enabled, the inter rupt-pending flag is ignored by the
hardware and program execution continues as normal. (The interrupt-pending flag is set to logic 1 regard-
less of the interrupt's enable/disable state.)
Each interrupt source can be individually enabled or disabled through the use of an associated interrupt
enable bit in an SFR (IE, EIE1, or EIE2). However, interrupts must first be globally enabled by setting the
EA bit (IE.7) to logic 1 before the individual interrupt enables are recognized. Setting the EA bit to logic 0
disables all interrupt sources regardless of the individual interrupt-enable settings.
Note: Any instruction that clears the EA bit should be immediately followed by an instruction that has two
or more opcode bytes. For example:
// in 'C':
EA = 0; // clear EA bit.
EA = 0; // this is a dummy instruction with two-byte opcode.
; in assembly:
CLR EA ; clear EA bit.
CLR EA ; this is a dummy instruction with two-byte opcode.
If an interrupt is posted during the execution phase of a "CLR EA" opcode (or any instruction which clears
the EA bit), and the instruction is followed by a single-cycle instruction, the interrupt may be taken. How-
ever, a read of the EA bit will return a '0' inside the interrupt service routine. When the "CLR EA" opcode is
followed by a multi-cycle instruction, the interrupt will not be taken.
Some interrupt-pending flags are au tomatically cleared by the hardware when the CPU vectors to the ISR.
However, most are not clear ed by the h ardwar e and mu st be cle ared by software before retur ning fro m the
ISR. If an interrupt-pending flag remains set after the CPU completes the return-from-interrupt (RETI)
instruction, a new interrupt request will be generated immediately and the CPU will re-enter the ISR after
the completion of the next instruction.
11.3.1. MCU Interrupt Sources and Vectors
The MCUs support 20 interrupt sources. Software can simulate an interrupt event by setting any interrupt-
pending flag to logic 1. If interrupts are enabled for the flag, an interrupt request will be generated and the
CPU will vector to the ISR address associated with the interrupt-pending flag. MCU interrupt sources,
associated vector addresses, priority order and control bits are summarized in Table 11.4. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the perip h er al and th e be ha vio r of its interrupt-pen ding flag (s) .
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11.3.2. External Interrupts
Two of the external interrupt sources (/INT0 and /INT1) are configurable as active-low level-sensitive or
active-low edge-sensitive inputs depending on the setting of bits IT0 (TCON.0) and IT1 (TCON.2). IE0
(TCON.1) and IE1 (TCON.3) serve as the interrupt-pending flag for the /INT0 and /INT1 e xternal inte rrupt s,
respectively. If an /INT0 or /INT1 external interrupt is configured as edge-sensitive, the corresponding
interrupt-pending flag is automatically cleared by the hardware when the CPU vectors to the ISR. When
configured as level se nsitive, the interrupt- pending flag follows the st ate of the external interr upt's input pin.
The external interrupt source must hold the input active until the interrupt request is recognized. It must
then deactivate the interrupt request before execution of the ISR completes or another interrupt request
will be generated.
Table 11.4. Interrupt Summary
Interrupt Source Interru
pt
Vector
Priority
Order Pending Flags
Bit addres sa b le?
Cleared by HW?
SFRPAGE (SFRPGEN = 1)
Enable
Flag Priority
Control
Reset 0x0000 Top None N/A N/A 0 Always
Enabled Always
Highest
External Inte rrupt 0 (/INT0) 0x0003 0 IE0 (TCON.1) Y Y 0 EX0 (IE.0) PX0 (IP.0)
Timer 0 Overflow 0x 000B 1 TF0 (TCON.5) Y Y 0 ET0 (IE.1) PT0 (IP.1)
External Inte rrupt 1 (/INT1) 0x0013 2 IE1 (TCON.3) Y Y 0 EX1 (IE.2) PX1 (IP.2)
Timer 1 Overflow 0x 001B 3 TF1 (TCON.7) Y Y 0 ET1 (IE.3) PT1 (IP.3)
UART0 0x0023 4 RI0 (SCON0.0)
TI0 (SCON0.1) Y 0 ES0 (IE.4) PS0 (IP.4)
Timer 2 0x002B 5 TF2 (TMR2CN.7)
EXF2 (TMR2CN.6)
Y 0 ET2 (IE.5) PT2 (IP.5)
Serial Peripheral Interface 0x0033 6
SPIF (SPI0CN.7)
WCOL (SPI0CN.6)
MODF (SPI0CN.5)
RXOVRN (SPI0CN.4)
Y0
ESPI0
(EIE1.0) PSPI0
(EIP1.0)
SMBus Interface 0x003B 7 SI (SMB0CN.3) Y 0 ESMB0
(EIE1.1) PSMB0
(EIP1.1)
ADC0 Window Comp arator 0x0043 8 AD0WINT
(ADC0CN.1) Y0
EWADC0
(EIE1.2) PWADC0
(EIP1.2)
Programmab l e Co un te r
Array 0x004B 9 CF (PCA0CN.7)
CCFn (PCA0CN.n)
Y0
EPCA0
(EIE1.3) PPCA0
(EIP1.3)
Comparator 0 Falling Edge 0x0053 10 CP0FIF (CPT0CN.4) Y 1 ECP0F
(EIE1.4) PCP0F
(EIP1.4)
Comparator 0 Rising Edge 0x005B 11 CP0RIF (CPT0CN.5) Y 1 ECP0R
(EIE1.5) PCP0R
(EIP1.5)
Comparator 1 Falling Edge 0x0063 12 CP1FIF (CPT1CN.4) Y 2 ECP1F
(EIE1.6) PCP1F
(EIP1.6)
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11.3.3. Interrupt Priorities
Each interrupt source can be individua lly pr ogra mmed to one of two priority levels: low or high. A low prior-
ity interrupt service routine can be preempted by a high priority interrupt. A high priority interrupt cannot be
preempted. Each interrupt has an associated interrupt priority bit in an SFR (IP-EIP2) used to configure its
priority level. Low priority is the default. If two interrupts are recognized simultaneously, the interrupt with
the higher priority is serviced first. If both interrupts have the same priority level, a fixed priority order is
used to arbitrate, given in Table 11.4.
11.3.4. Interrupt Latency
Interrupt response time depen ds on the state of the CPU when the interr upt occurs. Pending interru pts are
sampled and priority decoded each system clock cycle. Therefore, the fastest possible response time is
5 system clock cycles: 1 clock cycle to detect the interrupt and 4 clock cycles to complete the LCALL to the
ISR. Additional clock cycles will be required if a cache miss occurs (see Section “16. Branch Target
Cache” on p age 211 for more details). If an interrupt is pending when a RETI is executed, a single instru c-
tion is executed before an LCALL is made to service the pending interrupt. Therefore, the maximum
response time for an interrupt (when no other interrupt is currently being serviced or the new interrupt is of
greater priority) is when the CPU is performing an RETI instruction followed by a DIV as the next instruc-
tion, and a cache miss event also occurs. If the CPU is executing an ISR for an interrupt with equal or
higher priority, the new interrupt will not be serviced until the current ISR completes, including the RETI
and following instruction.
Comparator 1 Rising Edge 0x006B 13 CP1RIF (CPT1CN.5) Y 2 ECP1R
(EIE1.7) PCP1F
(EIP1.7)
Timer 3 0x0073 14 TF3 (TMR3CN.7)
EXF3 (TMR3CN.6)
Y1
ET3
(EIE2.0) PT3
(EIP2.0)
ADC0 End of Conversion 0x007B 15 AD0INT (ADC0CN.5) Y 0 EADC0
(EIE2.1) PADC0
(EIP2.1)
Timer 4 0x0083 16 TF4 (TMR4CN.7)
EXF4 (TMR4CN.7)
Y2
ET4
(EIE2.2) PT4
(EIP2.2)
ADC2 Window Comp arator 0x008B 17 AD2WINT
(ADC2CN.0) Y2
EWADC2
(EIE2.3) PWADC2
(EIP2.3)
ADC2 End of Conversion 0x0093 18 AD2INT (ADC2CN.5) Y 2 EADC2
(EIE2.4) PADC2
(EIP2.4)
RESERVED 0x009B 19 N/A N/A N/A N/A N/A N/A
UART1 0x00A3 20 RI1 (SCON1.0)
TI1 (SCON1.1) Y1
ES1
(EIE2.6) PS1
(EIP2.6)
Table 11.4. Interrupt Summary (Continued)
Interrupt Source Interru
pt
Vector
Priority
Order Pending Flags
Bit addressable?
Cleared by HW?
SFRPAGE (SFRPGEN = 1)
Enable
Flag Priority
Control
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11.3.5. Interrupt Register Descriptions
The SFRs used to enable th e inte rrupt sources an d set their priority le vel ar e descr ibed be low. Refer to the
datasheet section associated with a particular on-chip peripheral for information regarding valid interrupt
conditions for the perip h er al and th e be ha vio r of its interrupt-pen ding flag (s) .
SFR Definition 11.12. IE: Interrupt Enable
Bit7: EA: Enable All Interrupts.
This bit globally en ables/disables all interrupt s. It override s the individual interrupt mask set-
tings.
0: Disable all interrupt source s.
1: Enable each interrupt according to its individual mask setting.
Bit6: IEGF0: Genera l Purpose Flag 0.
This is a general purpose flag for use under software contro l.
Bit5: ET2: Enabler Timer 2 Interrupt.
This bit sets the masking of the Timer 2 interrupt.
0: Disable Timer 2 interrupt.
1: Enable Timer 2 interrupt.
Bit4: ES0: Enable UART0 Interrupt.
This bit sets the masking of the UART0 interrupt.
0: Disable UART0 interrupt.
1: Enable UART0 interrupt.
Bit3: ET1: Enable Timer 1 Interrupt.
This bit sets the masking of the Timer 1 interrupt.
0: Disable Timer 1 interrupt.
1: Enable Timer 1 interrupt.
Bit2: EX1: Enable External Interrupt 1.
This bit sets the masking of External Interrupt 1.
0: Disable External Interrupt 1.
1: Enable External Interrupt 1.
Bit1: ET0: Enable T imer 0 Interrupt.
This bit sets the masking of t he Timer 0 interrupt.
0: Disable Timer 0 interrupts.
1: Enable Timer 0 interrupts.
Bit0: EX0: Enable External Interrupt 0.
This bit sets the masking of External Interrupt 0.
0: Disable External Interrupt 0.
1: Enable External Interrupt 0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
EA IEGF0 ET2 ES0 ET1 EX1 ET0 EX0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xA8
All Pages
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SFR Definition 11.13. IP: Interrupt Priority
Bits7–6: UNUSED. Read = 11b, Write = don't care.
Bit5: PT2: Timer 2 Interrupt Priority Control.
This bit sets the priority of the Timer 2 interrupt.
0: Timer 2 interrupt set to low priority.
1: Timer 2 interrupt set to high priority.
Bit4: PS0: UART0 Interrupt Priority Control.
This bit sets the priority of the UART0 interrupt.
0: UART0 interrupt set to low priority.
1: UART0 interrupts set to high priority.
Bit3: PT1: Timer 1 Interrupt Priority Control.
This bit sets the priority of the Timer 1 interrupt.
0: Timer 1 interrupt set to low priority.
1: Timer 1 interrupts set to high priority.
Bit2: PX1: External Interrupt 1 Priority Control.
This bit sets the priority of the External Interrupt 1 interrupt.
0: External In terrupt 1 set to low priority.
1: External Interrupt 1 set to high priority.
Bit1: PT0: Timer 0 Interrupt Priority Control.
This bit sets the priority of the Timer 0 interrupt.
0: Timer 0 interrupt set to low priority.
1: Timer 0 interrupt set to high priority.
Bit0: PX0: External Interrupt 0 Priority Control.
This bit sets the priority of the External Interrupt 0 interrupt.
0: External In terrupt 0 set to low priority.
1: External Interrupt 0 set to high prior ity.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - PT2 PS0 PT1 PX1 PT0 PX0 11000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xB8
All Pages
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SFR Definition 11.14. EIE1: Extended Interrupt Enable 1
Bit7: ECP1R: Enable Comparat or 1 (CP1) Rising Edge Interrupt .
This bit sets the masking of the CP1 rising edge interrupt.
0: Disable CP1 rising edge interrupts.
1: Enable CP1 rising edge interrupts.
Bit6: ECP1F: Enable Comparator1 (CP1) Falling Edge Interrupt.
This bit sets the masking of the CP1 falling edge interrupt.
0: Disable CP1 falling edge interrupts.
1: Enable CP1 falling edge interrupts.
Bit5: ECP0R: Enable Comparat or 0 (CP0) Rising Edge Interrupt .
This bit sets the masking of the CP0 rising edge interrupt.
0: Disable CP0 rising edge interrupts.
1: Enable CP0 rising edge interrupts.
Bit4: ECP0F: Enable Comparator0 (CP0) Falling Edge Interrupt.
This bit sets the masking of the CP0 falling edge interrupt.
0: Disable CP0 falling edge interrupts.
1: Enable CP0 falling edge interrupts.
Bit3: EPCA0: Enable Programmable Counter Array (PCA0) Interrupt.
This bit sets the masking of the PCA0 interrupts.
0: Disable PCA0 interrupts.
1: Enable PCA0 interrupts.
Bit2: EWADC0: Enable Window Comparison ADC0 Interrupt.
This bit sets the masking of ADC0 Window Compariso n interrupt.
0: Disable ADC0 Window Comparison Interrupt.
1: Enable ADC0 Window Comparison Interrupt.
Bit1: ESMB0: Enable System Management Bus (SMBus0) Interrupt.
This bit sets the masking of the SMBus interrupt.
0: Disable SMBus interrupts.
1: Enable SMBus interrupts.
Bit0: ESPI0: Enable Serial Peripheral Interface (SPI0) Interrupt.
This bit sets the masking of SPI0 interrupt.
0: Disable SPI0 interrupts.
1: Enable SPI0 interrupts.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
ECP1R ECP1F ECP0R ECP0F EPCA0 EWADC0 ESMB0 ESPI0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xE6
All Pages
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SFR Definition 11.15. EIE2: Extended Interrupt Enable 2
Bit7: UNUSED. Read = 0b, Write = don't care.
Bit6: ES1: Enable UART1 Interrupt.
This bit sets the masking of the UART1 interrupt.
0: Disable UART1 interrupts.
1: Enable UART1 interrupts.
Bit5: UNUSED. Read = 0b, Write = don't care.
Bit4: EADC2: Enable ADC2 End Of Conversion Interrupt.
This bit sets the masking of the ADC2 End of Conversion interrupt.
0: Disable ADC2 End of Conversion interrupts.
1: Enable ADC2 End of Conversion Interrupts.
Bit3: EWADC2: Enable Window Comparison ADC2 Interrupt.
This bit sets the masking of ADC2 Window Compariso n interrupt.
0: Disable ADC2 Window Comparison Interrupts.
1: Enable ADC2 Window Comparison Interrupts.
Bit2: ET4: Enable T imer 4 Interrupt
This bit sets the masking of the Timer 4 interrupt.
0: Disable Timer 4 interrupts.
1: Enable Timer 4 interrupts.
Bit1: EADC0: Enable ADC0 End of Conversion Interrupt.
This bit sets the masking of the ADC0 End of Conversion Interrupt.
0: Disable ADC0 End of Conversion Interrupts .
1: Enable ADC0 End of Conversion Interrupts.
Bit0: ET3: Enable Timer 3 Interrupt.
This bit sets the masking of the Timer 3 interrupt.
0: Disable Timer 3 interrupts.
1: Enable Timer 3 interrupts.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- ES1 - EADC2 EWADC2 ET4 EADC0 ET3 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xE7
All Pages
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SFR Definition 11.16. EIP1: Extended Interrupt Priority 1
Bit7: PCP1R: Comparator 1 (CP1) Rising Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 rising interrupt set to low priority.
1: CP1 rising interrupt set to hi gh priority.
Bit6: PCP1F: Comparator1 (CP1) Falling Interrupt Priority Control.
This bit sets the priority of the CP1 interrupt.
0: CP1 falling interrupt set to low priority.
1: CP1 falling interrupt set to high priority.
Bit5: PCP0R: Comparator 0 (CP0) Rising Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 rising interrupt set to low priority.
1: CP0 rising interrupt set to hi gh priority.
Bit4: PCP0F: Comparator0 (CP0) Falling Interrupt Priority Control.
This bit sets the priority of the CP0 interrupt.
0: CP0 falling interrupt set to low priority.
1: CP0 falling interrupt set to high priority.
Bit3: PPCA0: Programmable Counter Array (PCA0) Interrupt Prior i ty Control.
This bit sets the priority of the PCA0 interrupt.
0: PCA0 interrupt set to low priority.
1: PCA0 interrupt set to high priority.
Bit2: PWADC0: ADC0 Window Comparator Interrupt Priority Control.
This bit sets the priority of the ADC0 Window interrup t.
0: ADC0 Window interrupt set to low priority.
1: ADC0 Window interrupt set to high priority.
Bit1: PSMB0: System Management Bus (SMBus0) Interrupt Priority Control.
This bit sets the priority of the SMBus0 interrupt.
0: SMBus interrupt set to low priority.
1: SMBus interrupt set to high priority.
Bit0: PSPI0: Serial Peripheral Interface (SPI0) Interrupt Priority Control.
This bit sets the priority of the SPI0 interrupt.
0: SPI0 interrupt set to low priority.
1: SPI0 interrupt set to high priority.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PCP1R PCP1F PCP0R PCP0F PPCA0 PWADC0 PSMB0 PSPI0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xF6
All Pages
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SFR Definition 11.17. EIP2: Extended Interrupt Priority 2
Bit7: UNUSED. Read = 0b, Write = don't care.
Bit6: ES1: UART1 Interrupt Priority Control.
This bit sets the priority of the UART1 interrupt.
0: UART1 interrupt set to low priority.
1: UART1 interrupt set to high priority.
Bit5: UNUSED. Read = 0b, Write = don't care.
Bit4: PADC2: ADC2 End Of Conversion Interrupt Priority Control.
This bit sets the priority of the ADC2 End of Conversion interrupt.
0: ADC2 End of Conversion interrupt set to low priority.
1: ADC2 End of Conversion interrupt set to high priority.
Bit3: PWADC2: ADC2 Window Compare Interrupt Priority Control.
This bit sets the priority of the ADC2 Window Compare interrupt.
0: ADC2 Window Compare interrupt set to low priority.
1: ADC2 Window Compare interrupt set to high priority.
Bit2: PT4: Timer 4 Interrupt Priority Control.
This bit sets the priority of the Timer 4 interrupt.
0: Timer 4 interrupt set to low priority.
1: Timer 4 interrupt set to high priority.
Bit1: PADC0: ADC0 End of Conversion Interrupt Priority Control.
This bit sets the priority of the ADC0 End of Conversion Interrupt.
0: ADC0 End of Conversion interrupt set to low priority.
1: ADC0 End of Conversion interrupt set to high priority.
Bit0: PT3: Timer 3 Interrupt Priority Control.
This bit sets the priority of the T imer 3 interrupts.
0: Timer 3 interrupt set to low priority.
1: Timer 3 interrupt set to high priority.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- PS1 - PADC2 PWADC2 PT4 PADC0 PT3 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xF7
All Pages
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11.4. Power Management Modes
The CIP-51 core has two software programmable power management modes: Idle and Stop. Idle mode
halts the CPU while leaving the external peripherals and internal clocks active. In St op mode, the CPU is
halted, all interrupts and timers (except the Missing Clock Detector) are inactive, and the system clock is
stopped. Since clocks are running in Idle mode, power consumption is dependent upon the system clock
frequency and the numb er of pe ripherals le f t in active mode before e ntering Id le. Stop mode consumes the
least power. SFR Definit ion 11.1 8 describes the Powe r Control Register (PCON) used to control the CIP-
51's power management modes.
Although the CIP-51 has Idle and Stop modes built in (as with any standard 8051 architecture), power
management of the entire MCU is better accomplished by enabling/disabling individual peripherals as
needed. Each analog peripheral can be disabled when not in use and put into low power mode. Digital
peripherals, such as timers or serial buses, draw little power whenever they are not in use. Turning off the
Flash memory saves power, similar to entering Idle mode. Turning off the oscillator saves even more
power, but re qu ires a reset to restart the MCU .
11.4.1. Idle Mode
Setting the Idle Mode Select bit (PCON.0) causes the CIP-51 to halt the CPU and enter Idle mode as soon
as the instruction that sets the bit completes. All internal registers and memory maintain their original
data. All analog and digital peripherals can remain active during Idle mode.
Idle mode is terminated when an enabled interrupt or RST is asserted. The assertion of an enabled inter-
rupt will cause the Idle Mode Selection bit (PCON.0) to be cleared and the CPU to resume operation. The
pending interrupt will be serviced and the next instruction to be executed after the return from interrupt
(RETI) will be the instruction immediately following the one that set the Idle Mode Select bit. If Idle mode is
terminated by an internal or external reset, the CIP-51 performs a normal reset sequence and begins pro-
gram execution at address 0x00000.
If enabled, the WDT will eventually cause an internal watchdog reset and thereby terminate the Idle mode.
This feature protects the system from an unintended permanent shutdown in the event of an inadvertent
write to the PCON register. If this behavior is not desired, the WDT may be disabled by software prior to
entering the Idle mode if the WDT was initially configured to allow this operation. This provides the oppor-
tunity for additional power savings, allowing the system to remain in the Idle mode indefinitely, waiting for
an external stimulus to wake up the system. Refer to Section 13 for more information on the use and con-
figuration of the WDT.
Note: Any instruction which sets the IDLE bit should be immediately followed by an instruction which has
two or more opcode bytes. For example:
// in ‘C’:
PCON |= 0x01; // Set IDLE bit
PCON = PCON; // ... Followed by a 3-cycle Dummy Instruction
; in assembly:
ORL PCON, #01h ; Set IDLE bit
MOV PCON, PCON ; ... Followed by a 3-cycle Dummy Instruction
If the instruction following the write to the IDLE bit is a sin gle-byte instruction and an interrupt occur s during
the execution of the instruction of th e instruction which sets the IDLE bit, the CPU may not wake from IDLE
mode when a future interrupt occurs.
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11.4.2. Stop Mode
Setting the Stop Mode Select bit (PCON.1) causes the CIP-51 to enter Stop mode as soon as the instruc-
tion that sets the bit completes. In Stop mode, the CPU and oscillators are stopped, effectively shutting
down all digital peripherals. Each analog peripheral must be shut down individually prior to entering Stop
Mode. Stop mode can only be terminated by an internal or external reset. On reset, the CIP-51 performs
the normal reset sequence and begins program execution at address 0x00000.
If enabled, the Missing Clock Detector will cause an internal reset and thereby terminate the Stop mode.
The Missing Clock Detector should be disabled if the CPU is to be put to sleep for longer than the MCD
timeout of 100 µs.
SFR Definition 11.18. PCON: Power Control
Bits7–3: Reserved.
Bit1: STOP: STOP Mode Select.
Writing a ‘1’ to this bit will place the CIP-51 into STOP mode. This bit will always read ‘0’.
1: CIP-51 forced into power-down mode. (Turns off oscillator).
Bit0: IDLE: IDLE Mode Select.
Writing a ‘1’ to this bit will place the CIP-51 into IDLE mode. This bit will always read ‘0’.
1: CIP-51 forced into IDLE mode. (Shuts off clock to CPU, but clock to Timers , Interrupts,
and all peripherals remain active.)
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
------STOPIDLE00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x87
All Pages
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 165
12. Multiply And Accumulate (MAC0)
The C8051F120/1/2/3 and C8051F130/1/2/3 devices include a multiply and accumulate engine which can
be used to speed up many mathematical operations. MAC0 contains a 16-by-16 bit multiplier and a 40-bit
adder, which can perform integer or fractional multiply-accumulate and multiply operations on signed input
values in two SYSCLK cycles. A rounding engine provides a rounded 16-bit fractional result after an addi-
tional (third) SYSCLK cycle. MAC0 also contains a 1-bit arithmetic shifter that will left or right-shift the con-
tents of the 40-bit accumulator in a single SYSCLK cycle. Figure 12.1 shows a block diagram of the MAC0
unit and its associated Special Function Registers.
Figure 12.1. MAC0 Block Diagram
12.1. Special Function Registers
There are thirteen Special Function Register (SFR) locations associated with MAC0. Two of these regis-
ters are related to configuration and operation, while the other eleven are used to store multi-byte input
and output data for MAC0. The Configuration register MAC0CF (SFR Definition 12.1) is used to configure
and control MAC0. The Status register MAC0STA (SFR Definition 12.2) contain s flags to indicate overflow
conditions, as well as zero and negative results. The 16-bit MAC0A (MAC0AH:MAC0AL) and MAC0B
(MAC0BH:MAC0BL) registers are used as inputs to the multiplier. The MAC0 Accumulator register is 40
bits long, and consists of five SFRs: MAC0OVR, MAC0ACC3, MAC0ACC2, MAC0ACC1, and
MAC0ACC0. The primary results of a MAC0 operation are stored in the Accumulator registers. If they are
needed, the rounded results are stored in the 16-bit Rounding Register MAC0RND
(MAC0RNDH:MAC0RNDL).
MAC0CF
MAC0MS
MAC0FM
MAC0SAT
MAC0CA
MAC0SD
MAC0SC
MAC0STA
MAC0N
MAC0SO
MAC0Z
MAC0HO
16 x 16 Multiply
MAC0RNDH MAC0RNDL
MAC0 Rounding Register
MAC0OVR MAC0ACC3 MAC0ACC2 MAC0ACC1 MAC0ACC0
MAC0 Accumula tor
40 bit Add
MAC0MS
1
0
0
Rounding Engine1 bit Shift
MAC0FM
Flag Logic
MAC0BH MAC0BL
MAC0 B Register
MAC0AH MAC0AL
MAC0 A Register
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
166 Rev. 1.4
12.2. Integer and Fractional Math
MAC0 is capable of interpreting the 16-bit inputs stored in MAC0A and MAC0B as signed integers or as
signed fractional numbers. When the MAC0FM bit (MAC0CF.1) is c leared to ‘0’, the in puts are treated as
16-bit, 2’s complement, integer values. After the operation, the accumulator will contain a 40-bit, 2’s com-
plement, integer value. Figure 12.2 shows how integers are stored in the SFRs.
Figure 12.2. Integer Mode Data Representation
When the MAC0FM bit is set to ‘1’, the inpu ts are treated at 16-bit, 2’s complement, fr action al values. The
decimal point is located between bits 15 and 14 of the data word. Af ter the operation, the accumulator will
contain a 40-bit, 2’s complement, fractional value, with the decimal point located between bits 31 and 30.
Figure 12.3 shows how fractional numbers are stored in the SFRs.
Figure 12.3. Fractional Mode Data Representation
-(2
15
) 2
14
2
13
2
12
2
11
2
10
2
9
2
8
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
-(2
39
) 2
38
2
33
2
32
2
31
2
30
2
1
2
0
2
2
2
29
2
3
2
28
2
4
High Byte Low Byte
MAC0OVR MAC0ACC3 : MAC0ACC2 : MAC0ACC1 : MAC0ACC0
MAC0A and MAC0B Bit Weighting
MAC0 Accumulator Bit Weighting
-1 2
-1
2
-2
2
-3
2
-4
2
-5
2
-6
2
-7
2
-8
2
-9
2
-10
2
-11
2
-12
2
-13
2
-14
2
-15
-(2
8
) 2
7
2
2
2
1
2
0
2
-1
2
-30
2
-31
2
-29
2
-2
2
-28
2
-3
2
-27
High Byte Low Byte
MAC0OVR MAC0ACC3 : MAC0A CC2 : MAC0ACC1 : MAC0ACC0
MAC0A, and MAC0B Bit Weighting
MAC0 Accumulator Bit Weighting
MAC0RND Bit Weight i n g
* The MAC0RND re gister contain s the 16 LSBs of a two's complement number. The MAC 0N Fla g can be
used to de t e rmine the sign of the MAC0RND register.
1 2
-1
2
-2
2
-3
2
-4
2
-5
2
-6
2
-7
2
-8
2
-9
2
-10
2
-11
2
-12
2
-13
2
-14
2
-15
High Byte Low Byte
* -2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 167
12.3. Operating in Multiply and Accumulate Mode
MAC0 operates in Multiply and Accumulate (MAC) mode when the MAC0MS bit (MAC0CF.0) is cleared to
‘0’. When operating in MAC mode, MAC0 performs a 16-by-16 bit multiply on the contents of the MAC0A
and MAC0B registers, and adds the result to the contents of the 40-bit MAC0 accumulator. Figure 12.4
shows the MAC0 pipeline. There are three stages in the pipeline, each of which takes exactly one SYS-
CLK cycle to complete. The MAC operation is initiated with a write to the MAC0BL register. After the
MAC0BL register is written, MAC0A and MAC0B are multiplied on the first SYSCLK cycle. During the sec-
ond stage of the MAC0 pipeline, the results of the multiplication are added to the current accumulator con-
tents, and the result of the addition is stored in the MAC0 accumulator. The status flags in the MAC0STA
register are set a fter the end of the second pipe line st age. During the second st age of the pipeline , the next
multiplication can be initiated by writing to the MAC0BL register, if it is desired. The rounded (and option-
ally, saturated) result is available in the MAC0RNDH and MAC0RNDL registers at the end of the third pipe-
line stage. If th e MAC0CA bit (MAC0CF.3) is set to ‘1’ when the MAC operation is initiated, the accum ulator
and all MAC0STA flags will be cleared during the next cycle of the controller’s clock (SYSCLK). The
MAC0CA bit will clear itself to ‘0’ when the clear operation is complete.
Figure 12.4. MAC0 Pipeline
12.4. Operating in Multiply Only Mode
MAC0 operates in Multip ly Only mode when the MAC0MS bit (MAC0CF.0) is set to ‘1’. Multiply Only mode
is identical to Multiply and Accumulate mode, except that the multiplication result is added with a value of
zero before being stored in the MAC0 accumulator (i.e. it overwrites the current accumulator contents).
The result of the multiplication is available in the MAC0 accumulator registers at the end of the second
MAC0 pipeline stage (two SYSCLKs after writing to MAC0BL). As in MAC mode, the rounded result is
available in the MAC0 Rounding Registers after the third pipeline stage. Note that in Multiply Only mode,
the MAC0HO flag is not affected.
12.5. Accumulator Shif t Operations
MAC0 contains a 1-bit arithmetic shift function which can be used to shift the contents of the 40-bit accu-
mulator left or right by one bit. The accumulator shift is initiated by writing a ‘1’ to the MAC0SC bit
(MAC0CF.5), and takes one SYSCLK cycle (the rounded result is available in the MAC0 Rounding Regis-
ters after a second SYSCLK cycle, and MAC0SC is cleared to ‘0’). The direction of the arithmetic shift is
controlled by the MAC0SD bit (MAC0CF.4). When this bit is cleared to ‘0’, the MAC0 accumulator will shift
left. When the MAC0SD bit is set to ‘1’, the MAC0 accumulator will shift right. Right-shift operations are
sign-extended with the current value of bit 39. Note that the status flags in the MAC0STA register are not
affected by shift operations.
Multiply Add Round
Multiply Add Round
Write
MAC0BL
Write
MAC0BL
MAC0 Operation
Begins
Next MAC0
Operation May
Be Initiated
Here
Accumulator
Results Available Rounded Results
Available
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
168 Rev. 1.4
12.6. Rounding and Saturation
A Rounding Engine is included, which can be used to provide a rounded result when operating on frac-
tional numbers. MAC0 uses an unbiased rounding algorithm to round the data stored in bits 31–16 of the
accumulator, as shown in Table 12.1. Rounding occurs during the third stage of the MAC0 pipeline, after
any shift operation, or on a write to the LSB of the accumulator. The rounded results are stored in the
rounding registers: MAC0RNDH (SFR Definition 12.12) and MAC0RNDL (SFR Definition 12.13). The
accumulator registers ar e not af fected by th e rounding engine. Altho ugh rounding is primarily used fo r frac-
tional data, the data in the rounding registers is updated in the same way when operating in integer mode.
The rounding engine can also be used to saturate the results stored in the rounding registers. If the
MAC0SAT bit is set to ‘1’ and the rounding register overflows, the rounding registers will saturate. When a
positive overflow occurs, the rounding registers will show a value of 0x7FFF when saturated. For a nega-
tive overflow, the rounding registers will show a value of 0x8000 when saturated. If the MAC0SAT bit is
cleared to ‘0’, the rounding registers will not saturate.
12.7. Usage Examples
This section details some software examples for using MAC0. Section 12.7.1 shows a series of two MAC
operations using fractional numbers. Section 12.7.2 shows a single operation in Multiply Only mode with
integer numbers. The last example, shown in Section 12.7.3, demonstrates how the left-shift and right-
shift operations can be used to modify the accumulator. All of the examples assume that all of the flags in
the MAC0STA register are initially set to ‘0’.
12.7.1. Multiply and Accumulate Example
The example below implements the equation:
MOV MAC0CF, #0Ah ; Set to Clear Accumulator, Use fractional numbers
MOV MAC0AH, #40h ; Load MAC0A register with 4000 hex = 0.5 decimal
MOV MAC0AL, #00h
MOV MAC0BH, #20h ; Load MAC0B register with 2000 hex = 0.25 decimal
MOV MAC0BL, #00h ; This line initiates the first MAC operation
MOV MAC0BH, #E0h ; Load MAC0B register with E000 hex = -0.25 decimal
MOV MAC0BL, #00h ; This line initiates the second MAC operation
NOP
NOP ; After this instruction, the Accumulator should be equal to 0,
; and the MAC0STA register should be 0x04, indicating a zero
NOP ; After this instruction, the Rounding register is updated
Table 12.1. MAC0 Rounding (MAC0SAT = 0)
Accumulator Bits 15–0
(MAC0ACC1:MAC0ACC0) Accumulator Bits 31–16
(MAC0ACC3:MAC0ACC2) Rounding
Direction Rounded Results
(MAC0RNDH:MAC0RNDL)
Greater Than 0x8000 Anything Up (MAC0ACC3:MAC0ACC2) + 1
Less Than 0x8000 Anything Down (MAC0ACC3:MAC0ACC2)
Equal To 0x8000 Odd (LSB = 1) Up (MAC0ACC3:MAC0ACC2) + 1
Equal To 0x8000 Even (LSB = 0) Down (MAC0ACC3:MAC0ACC2)
0.5 0.250.5 0.25–+ 0.125 0.125–0.0==
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 169
12.7.2. Multiply Only Example
The example below implements the equation:
MOV MAC0CF, #01h ; Use integer numbers, and multiply only mode (add to zero)
MOV MAC0AH, #12h ; Load MAC0A register with 1234 hex = 4660 decimal
MOV MAC0AL, #34h
MOV MAC0BH, #FEh ; Load MAC0B register with FEDC hex = -292 decimal
MOV MAC0BL, #DCh ; This line initiates the Multiply operation
NOP
NOP ; After this instruction, the Accumulator should be equal to
; FFFFEB3CB0 hex = -1360720 decimal. The MAC0STA register should
; be 0x01, indicating a negative result.
NOP ; After this instruction, the Rounding register is updated
12.7.3. MAC0 Accumulator Shift Example
The example below shifts the MAC0 accumulator left one bit, and then right two bi ts:
MOV MAC0OVR, #40h ; The next few instructions load the accumulator with the value
MOV MAC0ACC3, #88h ; 4088442211 Hex.
MOV MAC0ACC2, #44h
MOV MAC0ACC1, #22h
MOV MAC0ACC0, #11h
MOV MAC0CF, #20h ; Initiate a Left-shift
NOP ; After this instruction, the accumulator should be 0x8110884422
NOP ; The rounding register is updated after this instruction
MOV MAC0CF, #30h ; Initiate a Right-shift
MOV MAC0CF, #30h ; Initiate a second Right-shift
NOP ; After this instruction, the accumulator should be 0xE044221108
NOP ; The rounding register is updated after this instruction
4660 292–1360720–=
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
170 Rev. 1.4
SFR Definition 12.1. MAC0CF: MAC0 Configuration
Bits 7–6: UNUSED: Read = 00b, Write = don’t care.
Bit 5: MAC0SC: Accumulator Shift Control.
When set to 1, the 40-bit MAC0 Accumulator register will be shifted during the next SYSCLK
cycle. The direction of the shift (left or right) is controlled by the MAC0RS bit.
This bit is cleared to ‘0’ by hardware when the shift is complete.
Bit 4: MAC0SD: Accumulator Shif t Direction.
This bit controls the direction of the accumulator shift activated by the MAC0SC bit.
0: MAC0 Accumulator will be shifted left.
1: MAC0 Accumulator will be shifted right.
Bit 3: MAC0CA: Clear Accumulator.
This bit is used to reset MAC0 before the next operation.
When set to ‘1’, the MAC0 Accumulator will be cleared to zero and the MAC0 Status regis-
ter will be reset during the next SYSCLK cycle.
This bit will be cleared to ‘0’ by hardware when the reset is complete.
Bit 2: MAC0SAT: Saturate Rounding Register.
This bit controls whether the Rounding Register will saturate. If this bit is set and a Soft
Overflow occurs, the Rounding Register will saturate. This bit does not affect the operation
of the MAC0 Accumulator. See Section 12.6 for mor e det ails about rounding a nd saturation.
0: Rounding Register will not saturate.
1: Rounding Register will saturate.
Bit 1: MAC0FM: Fractional Mode.
This bit selects between Integer Mode and Fractional Mode for MAC0 operations.
0: MAC0 operates in Integer Mode.
1: MAC0 operates in Fractional Mode.
Bit 0: MAC0MS: Mode Select
This bit selects between MAC Mode and Multiply Only Mode.
0: MAC (Multiply and Accumulate) Mode.
1: Multiply Only Mode.
Note: The contents of this register should not be changed by software during the first two MAC0
pipeline stages.
R R R/W R/W R/W R/W R/W R/W Reset Value
- - MAC0SC MAC0SD MAC0CA MAC0SAT MAC0FM MAC0MS 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC3
SFR Page: 3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 171
SFR Definition 12.2. MAC0STA: MAC0 Status
SFR Definition 12.3. MAC0AH: MAC0 A High Byte
Bits 7–4: UNUSED: Read = 0000b, Write = don’t care .
Bit 3: MAC0HO: Hard Overflow Flag.
This bit is set to ‘1’ whenever an overflow out of the MAC0OVR register occurs during a
MAC operation (i.e . when MAC0OVR changes from 0x7F to 0x80 or from 0x80 to 0x7F).
The hard overflow flag m ust b e cleare d in software by directly writing it to ‘0’, or by resettin g
the MAC logic using the MAC0CA bit in register MAC0CF.
Bit 2: MAC0Z: Zero Flag.
This bit is set to ‘1’ if a MAC0 ope ration re sult s in an Accumulator value of ze ro. If the re sult
is non-zero, this bit will be cleared to ‘0’.
Bit 1: MAC0SO: Soft Overflow Flag.
This bit is set to ‘1’ when a MAC ope ration causes an overflow into the sign b it (bit 31) of the
MAC0 Accumulator. If the overflow condition is corrected after a subse quent MAC opera-
tion, this bit is cleared to ‘0’.
Bit 0: MAC0N: Negative Flag.
If the MAC Accumulator result is negative, this bit will be set to ‘1’. If the result is positive or
zero, this flag will be cleared to ‘0’.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
R R R R R/W R/W R/W R/W Reset Value
- - - - MAC0HO MAC0Z MAC0SO MAC0N 00000100
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: 0xC0
SFR Page: 3
Bits 7–0: High Byte (bits 15–8) of MAC0 A Register.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC2
SFR Page: 3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
172 Rev. 1.4
SFR Definition 12.4. MAC0AL: MAC0 A Low Byte
SFR Definition 12.5. MAC0BH: MAC0 B High Byte
SFR Definition 12.6. MAC0BL: MAC0 B Low Byte
Bits 7–0: Low Byte (bits 7–0) of MAC0 A Register.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xC1
SFR Page: 3
Bits 7–0: High Byte (bits 15–8) of MAC0 B Register.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x92
SFR Page: 3
Bits 7–0: Low Byte (bits 7–0) of MAC0 B Register.
A write to this register initiates a Multiply or Multiply and Accumulate operation.
*Note: The contents of this register should not be changed by software during the first MAC0 pipeline stage.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x91
SFR Page: 3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 173
SFR Definition 12.7. MAC0ACC3: MAC0 Accumulator Byte 3
SFR Definition 12.8. MAC0ACC2: MAC0 Accumulator Byte 2
SFR Definition 12.9. MAC0ACC1: MAC0 Accumulator Byte 1
Bits 7–0: Byte 3 (bits 31–24) of MAC0 Accumulator .
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x96
SFR Page: 3
Bits 7–0: Byte 2 (bits 23–16) of MAC0 Accumulator .
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x95
SFR Page: 3
Bits 7–0: Byte 1 (bits 15–8) of MAC0 Accumulator.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x94
SFR Page: 3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
174 Rev. 1.4
SFR Definition 12.10. MAC0ACC0: MAC0 Accumulator Byte 0
SFR Definition 12.11. MAC0OVR: MAC0 Accumulator Overflow
SFR Definition 12.12. MAC0RNDH: MAC0 Rounding Register High Byte
Bits 7–0: Byte 0 (bits 7–0) of MAC0 Accumulator.
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x93
SFR Page: 3
Bits 7–0: MAC0 Accumulator Overflow Bits (bits 39–32).
*Note: The contents of this register should not be changed by software during the first two MAC0 pipeline stages.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0x97
SFR Page: 3
Bits 7–0: High Byte (bits 15–8) of MAC0 Rounding Register.
R R R R R R R R Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCF
SFR Page: 3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 175
SFR Definition 12.13. MAC0RNDL: MAC0 Rounding Register Low Byte
Bits 7–0: Low Byte (bits 7–0) of MAC0 Rounding Register.
RRRRRRRRReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: 0xCE
SFR Page: 3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
176 Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 177
13. Reset Sources
Reset circuitry allows the controller to be easily placed in a predefined default condition. On entry to this
reset state, the following occur:
• CIP-51 halts program execution.
• Special Function Registers (SFRs) are initialized to their defined reset values.
• External port pins are forced to a known configuration.
• Interrupt s and timers are disabled.
All SFRs are reset to the predefined values noted in the SFR detailed descriptions. The contents of internal
data memory are unaffected during a reset; any previously stored data is preserved. However, since the
stack pointer SFR is reset, the stack is effectively lost even though the data on the stack are not altered.
The I/O port latches are reset to 0xFF (all logic 1’s), activating internal weak pullups during and after the
reset. For VDD Monitor resets, the RST pin is driven low until the end of the VDD reset timeout.
On exit from the reset state, the program counter (PC) is reset, and the system clock defaults to the inter-
nal oscillator running at its lowest frequency. Refer to Section “14. Oscillators” on page 185 for informa-
tion on selecting and configuring the system clock source. The Watchdog Timer is enabled using its
longest timeout interva l (see Section “13.7. W atch dog Ti mer Reset” on p age 179). Once the system clock
source is stable, program execution begins at location 0x0000.
There are seven sources for putting the MCU into the reset state: power-on, power-fail, external RST pin,
external CNVSTR0 signal, software command, Comparator0, Missing Clock Detector, and Watchdog
Timer. Each reset source is described in the following sections.
Figure 13.1. Reset Sources
WDT
XTAL1
XTAL2
OSC
Internal
Clock
Generator
System
Clock
CIP-51
Microcontroller
Core
Missing
Clock
Detector
(one-
shot)
WDT
Strobe
Software Reset
Extended Interrupt
Handler
Clock Select
/RST
+
-
VDD
Supply
Reset
Timeout
(wired-OR)
System Reset
Supply
Monitor
PRE
Reset
Funnel
+
-
CP0+
Comparator0
CP0-
(Port
I/O)
Crossbar CNVSTR
(CNVSTR
reset
enable)
(CP0
reset
enable)
EN
WDT
Enable
EN
MCD
Enable
PLL
Circuitry
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
178 Rev. 1.4
13.1. Power-on Reset
The C8051F120/1/2/3/4/5/6/7 family incorporates a power supply monitor that holds the MCU in the reset
state until VDD rises above the VRST level during power-up. See Figure 13.2 for timing diagram, and refer
to Table 13.1 for the Electrical Characteristics of the power supply monitor circuit. The RST pin is asserted
low until the end of the 10 0 ms VDD Monitor timeout in order to allow the VDD supply to stabilize. The VDD
Monitor reset is enabled and disabled using the external V DD monitor enable p in (MONEN). When the VDD
Monitor is enabled, it is selected as a reset source using the PORSF bit. If the RSTSRC reg ister is written
by firmware, PORSF (RSTSRC.1) must be written to ‘1’ for the VDD Monitor to be effective.
On exit from a power-on reset, the PORSF flag (RSTSRC.1) is set by hardware to logic 1. All of the other
reset flags in the RSTSRC Register are indeterminate. PORSF is cleared by all other resets. Since all
resets cau se p rogr am execution to begin at the same loca tion (0x0000 ) sof tware can re ad the PORSF flag
to determine if a power-up was the cause of reset. The contents of internal data memory should be
assumed to be undefined after a power-on reset.
Figure 13.2. Reset Timing
13.2. Power-fail Reset
When a power-down transition or power irregularity causes VDD to drop below VRST, the power supply
monitor will drive the RST pin low and return the CIP-51 to the reset state. When VDD returns to a level
above VRST, the CIP-51 will leave th e reset state in the same manner as that for the power-on reset (see
Figure 13.2). Note that even though internal data memory contents are not altered by the power-fail reset,
it is impossible to determine if VDD dropped below the level r equired fo r dat a retention. If th e PORSF flag is
set to logic 1, the data may no longer be valid.
VDD Monito r Re setPower-On Reset
/RST
t
volts
1.0
2.0
Logic HIGH
Logic LOW
100ms 100ms
VDD
2.70
2.55
V
RST
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13.3. External Reset
The external RST pin provides a means fo r external circuitry to force the MCU into a reset state. Asserting
the RST pin low will cause the MCU to enter the reset state. It may be desirable to provide an external pul-
lup and/or decoupling of the RST pin to avoid erroneous noise-induced resets. The MCU will remain in
reset until at least 12 clock cycles after the active-low RST signal is removed. The PINRSF flag (RST-
SRC.0) is set on exit from an external reset.
13.4. Missing Clock Detector Reset
The Missing Clock Detector is essentially a one-shot circuit that is triggered by the MCU system clock. If
the system clock goes away for more than 100 µs, the one-shot will time out and generate a reset. After a
Missing Clock Detector reset, the MCDRSF flag (RSTSRC.2) will be set, signifying the MSD as the reset
source; otherwise, this bit reads ‘0’. The state of the RST pin is unaffected by this reset. Setting the
MCDRSF bit, RSTSRC.2 (see Section “14. Oscillators” on page 185) enables the Missing Clock Detector .
13.5. Comparator0 Reset
Comparator0 can be configured as a reset input by writing a ‘1’ to the C0RSEF flag (RSTSRC.5).
Comparator0 should be enabled using CPT0CN.7 (see Section “10. Comparators” on page 119) prior to
writing to C0RSEF to prevent any turn-on chatter on the output from generating an unwanted reset. The
Comparator0 reset is active-low: if the non-inverting input voltage (CP0+ pin) is less than the inverting
input voltage (CP0- pin), the MCU is put into the reset state. After a Comparator0 Reset, the C0RSEF flag
(RSTSRC.5) will read ‘1’ signifying Comparator0 as the reset source; otherwise, this bit reads ‘0’. The st ate
of the RST pin is unaffected by this reset.
13.6. External CNVSTR0 Pin Reset
The external CNVSTR0 signal can be configured as a reset input by writing a ‘1’ to the CNVRSEF flag
(RSTSRC.6). The CNVSTR0 signal can appear on any of the P0, P1, P2 or P3 I/O pins as described in
Section “18.1. Ports 0 through 3 and the Priority Crossbar Decoder ” on page 238. Note that the Cross-
bar must be configured for the CNVSTR0 signal to be routed to the appropriate Port I/O. The Crossbar
should be configured and enabled before the CNVRSEF is set. When configured as a reset, CNVSTR0 is
active-low and level sensitive. CNVSTR0 cannot be used to start ADC0 conversions when it is configured
as a reset source. After a CNVSTR0 reset, the CNVRSEF flag (RSTSRC.6) will read ‘1’ signifying
CNVSTR0 as the reset source; otherwise, this bit reads ‘0’. The state of the ⁄RST pin is unaffected by this
reset.
13.7. Watchdog Timer Reset
The MCU includes a programmable Watchdog Timer (WDT) running off the system clock. A WDT overflow
will force the MCU into the reset state. To prevent the reset, the WDT must be restarted by application sof t-
ware before overflow. If the system experiences a software or hardware malfunction preventing the soft-
ware from restarting the WDT, the WDT will overflow and cause a reset. This should prevent the system
from running out of control.
Following a reset the WDT is automatically enabled and running with the default maximum time interval. If
desired the WDT can be disabled by system software or locked on to prevent accidental disabling. Once
locked, the WDT cannot be disabled until the nex t syst em r eset . T he s tate of th e RST pin is unaffected by
this reset.
The WDT consists of a 21-bit timer running from the programmed system clock. The timer measures the
period between specific writes to its control register. If this period exceeds the programmed limit, a WDT
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reset is generated. The WDT can be enabled and disabled as needed in software, or can be permanently
enabled if desired. Watchdog features are controlled via the Watchdog Timer Control Register (WDTCN)
shown in SFR Definition 13.1.
13.7.1. Enable/Reset WDT
The watchdog timer is both enabled and reset by writing 0xA5 to the WDTCN register. The user's applica-
tion software should include periodic writes of 0xA5 to WDTCN as needed to prevent a watchdog timer
overflow. The WDT is enabled and reset as a result of any system reset.
13.7.2. Disable WDT
Writing 0xDE followed by 0xAD to the WDTCN register disables the WDT. The following code segment
illustrates disabling the WDT:
CLR EA ; disable all interrupts
MOV WDTCN,#0DEh ; disable software watchdog timer
MOV WDTCN,#0ADh
SETB EA ; re-enable interrupts
The writes of 0xDE and 0xAD must occur within 4 clock cycles of each other, or the disable operation is
ignored. This means that the prefetch engine should be enabled and interrupts should be disabled during
this procedure to avoid any de lay between the two writes.
13.7.3. Disable WDT Lockout
Writing 0xFF to WDTCN locks out the disable feature. Once locked out, the disable operation is ignored
until the next system reset. W riting 0xFF does not enable or reset the watchdog timer. Applications always
intending to use the watchdog should write 0xFF to WDTCN in the initialization code.
13.7.4. Setting WDT Interval
WDTCN.[2:0] control the watchdog timeout interval. The interval is given by the following equatio n:
; where Tsysclk is the system clock period.
For a 3 MHz system clock, this provides an interval range of 0.021 ms to 349.5 ms. WDTCN.7 must be
logic 0 when setting this interval. Reading WDTCN returns the programmed interval. WDTCN.[2:0] reads
111b after a system reset.
43WDTCN 20–+Tsysclk
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SFR Definition 13.1. WDTCN: Watchdog Timer Control
Bits7–0: WDT Control
Writing 0xA5 both enables and reloads the WDT.
Writing 0xDE followed within 4 system clocks by 0xAD disables the WDT.
Writing 0xFF locks out the disable feature.
Bit4: Watchdog Status Bit (when Read)
Reading the WDTCN.[4] bit indicates the Watchdog Timer Status.
0: WDT is inactive
1: WDT is active
Bits2–0: Watchdog Timeout Interval Bits
The WDTCN.[2:0] bits set the Watchdog Timeout Interval. When writing these bits,
WDTCN.7 must be set to 0.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
xxxxx111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xFF
All Pages
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SFR Definition 13.2. RSTSRC: Reset Source
Bit7: Reserved.
Bit6: CN VRSEF: Convert Start 0 Reset Source Enable and Flag
Write: 0: CNVSTR0 is not a reset source.
1: CNVSTR0 is a reset source (active low).
Read: 0: Source of prior reset was not CNVSTR0.
1: Source of prior reset was CNVSTR0.
Bit5: C0 RSEF: Comparator0 Reset Enable and Flag.
Write : 0: Comparator0 is not a reset source.
1: Comparator0 is a reset source (active low).
Read: 0: Source of last reset was not Comparator0.
1: Source of last reset was Comparator0.
Bit4: SW RSF: Software Reset Force and Flag.
Write: 0: No effect.
1: Forces an internal reset. RST pin is not effected.
Read: 0: Source of last reset was not a write to the SWRSF bit.
1: Source of last reset was a write to the SWRSF bit.
Bit3: WDTRSF: Watchdog Timer Reset Flag.
0: Source of last reset was not WDT timeout.
1: Source of last reset was WDT time out.
Bit2: MCDRSF: Missing Clock Detector Flag.
Write: 0: Missing Clock Detector disabled.
1: Missing Clock Detector enabled; triggers a reset if a missing clock condition is detected.
Read: 0: Source of last reset was not a Missing Clock Detector timeout.
1: Source of last reset was a Missing Clock Detector timeout.
Bit1: PORSF: Power-On Reset Flag.
Write: If the VDD monitor circuitry is enabled (by tying the MONEN pin to a logic high state), this bit can
be written to select or de-select the VDD monitor as a reset source.
0: De-select the VDD monitor as a reset source.
1: Select the VDD monitor as a reset source.
Important: At power-on, the VDD monitor is enabled/disabled using the external VDD monitor
enable pin (MONEN). Th e POR SF bi t does not disable or enable the VDD monitor circuit. It sim-
ply selects the VDD monitor as a reset source.
Read: This bit is set whenever a power-on reset occurs. This may be due to a true power-on reset or a
VDD monitor reset. In either case, data memory should be considered indeterminate following the
reset.
0: Source of last reset was not a power-on or VDD monitor reset.
1: Source of last reset was a power-on or VDD monitor reset.
Note: When this flag is read as '1', al l other reset flags are indeterminate.
Bit0: PINRSF: HW Pin Reset Flag.
Write: 0: No effect.
1: Forces a Power-On Reset. RST is driven low.
Read: 0: Source of prior reset was not RST pin.
1: Source of prior reset was RST pin.
R R/W R/W R/W R R/W R/W R/W Reset Value
- CNVRSEF C0RSEF SWRSEF WDTRSF MCDRSF PORSF PINRSF 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xEF
0
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Table 13.1. Reset Electrical Characteristics
–40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
RST Output Low Voltage IOL = 8.5 mA, VDD = 2.7 to 3.6 V ——0.6V
RST Input High Voltage 0.7 x VDD ——V
RST Input Low Voltage — — 0.3 x VDD
RST Input Leakage Current RST = 0.0 V — 50 — µA
VDD for RST Output Valid 1.0 — — V
AV+ for RST Output Valid 1.0 — — V
VDD POR Threshold (VRST)* 2.40 2.55 2.70 V
Minimum RST Low Time to Gen-
erate a System Reset 10——ns
Reset Time Delay RST rising edge afte r VDD
crosses VRST threshold 80 100 120 ms
Missing Clock Detector Timeout Time from last system clock to
reset initiation 100 220 500 µs
*Note: W hen operating at frequencies above 50 MHz, minimum VDD supply Voltage is 3.0 V.
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NOTES:
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14. Oscillators
The devices include a programmable internal oscillator and an external oscillator drive circuit. The internal
oscillator can be enabled, disabled, and calibrated using the OSCICN and OSCICL registers, as shown in
Figure 14.1. The system clock can be sourced by the external oscillator circuit, the internal oscillator, or the
on-chip phase-locked loop (PLL). The internal oscillator's electrical specifications are given in Table 14.1
on page 185.
Figure 14.1. Oscillator Diagram
14.1. Internal Calibrated Oscillator
All devices include a calibrated internal oscillator that defaults as the system clock after a system reset.
The internal oscillator period can be adjusted via the OSCICL register as defined by SFR Definition 14.1.
OSCICL is factory calibrated to obtain a 24.5 MHz frequency.
Table 14.1. Oscillator Electrical Characteristics
–40°C to +85°C unless otherwise specified.
Parameter Conditions Min Typ Max Units
Calibrated Internal Oscillator
Frequency 24 24.5 25 MHz
Internal Oscillator Supply
Current (from VDD)OSCICN.7 = 1 — 400 — µA
External Clock Frequency 0 — 30 MHz
TXCH (External Clock High Time) 15 — — ns
TXCL (External Clock Low Time) 15 — — ns
OSC
Calibrated
Internal
Oscillator
Input
Circuit
EN
SYSCLK
n
OSCICL OSCICN
IOSCEN
IFRDY
IFCN1
IFCN0
XTAL1
XTAL2
Option 2
VDD
XTAL1
Option 1
Option 4
XTAL1
OSCXCN
XTLVLD
XOSCMD2
XOSCMD1
XOSCMD0
XFCN2
XFCN1
XFCN0
CLKSEL
CLKDIV1
CLKDIV0
CLKSL1
CLKSL0
00
01
PLL 10
Option 3
XTAL1
XTAL2
AGND
AV+
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Electrical specifications for the precision internal oscillator are given in Table 14.1. Note that the system
clock may be derived from the programmed internal oscillator divided by 1, 2, 4, or 8, as defined by the
IFCN bits in register OSCICN.
SFR Definition 14.1. OSCICL: Internal Oscillator Calibration.
SFR Definition 14.2. OSCICN: Internal Oscillator Control
Bits 7–0: OSCICL: Internal Oscillator Calibration Register.
This register calibrates the internal oscillator period. The reset value for OSCICL defines the
internal oscillator base frequency. The reset value is factory calibrated to generate an inter-
nal oscillator frequency of 24.5 MHz.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
Variable
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8B
F
Bit 7: IOSCEN: Internal Oscillator Enable Bit.
0: Internal Oscillator Disabled.
1: Internal Oscillator Enabled.
Bit 6: IFRDY: Internal Oscillator Frequency Ready Flag.
0: Internal Oscillator not running at programmed frequency.
1: Internal Oscillator running at programmed frequency.
Bits 5–2: Re se rved.
Bits 1–0: IFCN1-0: Internal Oscillator Frequency Control Bits.
00: Internal Oscillator is divided by 8.
01: Internal Oscillator is divided by 4.
10: Internal Oscillator is divided by 2.
11: Internal Oscillator is divided by 1.
R/W R R/W R R/W R/W R/W R/W Reset Value
IOSCEN IFRDY - - - - IFCN1 IFCN0 11000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8A
F
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14.2. External Oscillator Drive Circuit
The external oscillator circuit may drive an external crystal, ceramic resonator, capacitor, or RC network. A
CMOS clock m ay also provide a clock inp ut. For a crystal or ceramic resonator configuration, the crystal/
resonator must be wired across the XTAL1 and XTAL2 pins as shown in Option 1 of Figure 14.1. In RC,
capacitor, or CMOS clock configuration, the clock source should be wired to the XTAL2 and/or XTAL1
pin(s) as shown in Option 2, 3, or 4 of Figure 14.1 . The type of external oscillator must be selected in the
OSCXCN register, and the frequency control bits (XFCN) must be selected appropriately (see SFR Defini-
tion 14.4).
14.3. System Clock Selection
The CLKSL1-0 bits in register CLKSEL select which oscillator source generates the system clock.
CLKSL1-0 must be set to ‘01’ for the system clock to run from the external osci llator; however the external
oscillator may still clock certain peripherals, such as the timers and PCA, when the internal oscillator or the
PLL is selected as the system clock. The system clock may be switched on-the-fly between the internal
and external oscillators or the PLL, so long as the selected oscillator source is enabled and settled. The
internal oscillator requires little start-up time, and may be enabled and selected as the system clock in the
same write to OSCICN. External crystals and ceramic resonators typically require a start-up time before
they are settled and ready for use as the system clock. The Crystal Valid Flag (XTLVLD in register
OSCXCN) is set to ‘1’ by hardware when the external oscillator is settled. To avoid reading a false
XTLVLD, in crystal mode software should delay at least 1 ms between enabling the external oscillator and
checking XTLVLD. RC and C modes typically require no startup time. The PLL also requires time to lock
onto the desired frequency, and the PLL Lock Flag (PLLLCK in register PLL0CN) is set to ‘1’ by hardware
once the PLL is locked on the correct frequency.
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SFR Definition 14.3. CLKSEL: System Clock Selection
Bits 7–6: Reserved.
Bits 5–4: CLKDIV1–0: Output SYSCLK Divide Factor.
These bits can be used to pre-divide SYSCLK before it is output to a port pin through the
crossbar.
00: Output will be SYSCLK.
01: Output will be SYSCLK/2.
10: Output will be SYSCLK/4.
11: Output will be SYSCLK/8.
See Section “18. Port Input/Output” on page 235 for more details about routing this out-
put to a port pin.
Bits 3–2: Reserved.
Bits 1–0: CLKSL1–0: System Clock Source Select Bits.
00: SYSCLK derived from the Internal Oscillator, and scaled as per the IFCN bits in
OSCICN.
01: SYSCLK derived from the External Oscillator circuit.
10: SYSCLK derived from the PLL.
11: Reserved.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - CLKDIV1 CLKDIV0 - - CLKSL1 CLKSL0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x97
F
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SFR Definition 14.4. OSCXCN: External Oscillator Control
Bit7: XTLVLD: Crystal Oscillator Valid Flag.
(Valid only when XOSCMD = 11x.)
0: Crystal Oscillator is unused or not yet stable.
1: Crystal Oscillator is running and stable.
Bits6–4: XOSCMD2–0: External Oscillator Mode Bits.
00x: External Oscillator circuit off.
010: External CMOS Clock Mode (External CMOS Clock input on XTAL1 pin).
011: External CMOS Clock Mode with divide by 2 stage (External CMOS Clock input on
XTAL1 pin).
10x: RC/C Oscillator Mode with divide by 2 stage.
110: Crystal Oscillator Mode.
111: Crystal Oscillator Mode with divide by 2 stage.
Bit3: RESERVED. Read = 0, Write = don't care.
Bits2–0: XFCN2–0: External Oscillator Frequency Control Bits.
000-111: see table below:
CRYSTAL MODE (Circuit from Figure 14.1, Option 1; XOSCMD = 11x)
Choose XFCN value to match crystal frequency.
RC MODE (Circuit from Figure 14.1, Option 2; XOSCMD = 10x)
Choose XFCN value to match frequency range:
f=1.23(103) / (R * C), where
f = frequency of oscillation in MHz
C = capacitor value in pF
R = Pullup resistor value in k
C MODE (Circuit from Figure 14.1, Option 3; XOSCMD = 10x)
Choose K Factor (KF) for the oscillation frequency desired:
f=KF / (C * VDD), where
f = frequency of oscillation in MHz
C = capacitor value on XTAL1, XTAL2 pins in pF
VDD = Power Supply on MCU in Volts
R R/W R/W R/W R R/W R/W R/W Reset Value
XTLVLD XOSCMD2 XOSCMD1XOSCMD0 - XFCN2 XFCN1 XFCN0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8C
F
XFCN Crystal (XOSCMD = 11x) RC (XOSCMD = 10x) C (XOSCMD = 10x)
000 f 32 kHz f 25 kHz K Factor = 0.87
001 32 kHz f 84 kHz 25 kHz f 50 kHz K Fact or = 2.6
010 84 kHz f 225 kHz 50 kHz f 100 kHz K Factor = 7.7
011 225 kHz f 590 kHz 100 kHz f 200 kHz K Factor = 22
100 590 kHz f 1.5 MHz 200 kHz f 400 kHz K Factor = 65
101 1.5 MHz f 4 MHz 400 kHz f 800 kHz K Factor = 180
110 4 MHz f 10 MHz 800 kHz f 1.6 MHz K Factor = 664
111 10 MHz f 30 MHz 1.6 MHz f 3.2 MHz K Factor = 1590
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14.4. External Crystal Example
If a crystal or ceramic resonator is used as an external oscillator source for the MCU, the circuit should be
configured as shown in Figure 14.1, Option 1. The External Oscillator Frequency Control value (XFCN)
should be chosen from the Crystal column of the table in SFR Definition 14.4 (OSCXCN register). For
example, an 11.0592 MHz crystal requires an XFCN setting of 111b.
When the crystal oscillator is enabled, the oscillator amplitude detection circuit requires a settle time to
achieve proper bias. Waiting at least 1 ms between enabling the oscillator and checking the XTLVLD bit
will prevent a premature switch to the external oscillator as the system clock. Switching to the external
oscillator before the crystal oscillator has stabilized can result in unpredictable behavior. The recom-
mended procedure is:
Step 1. Enable the external oscillator.
Step 2. Wait at least 1 ms.
Step 3. Poll for XTLVLD => ‘1’.
Step 4. Switch the system clock to the external oscillator.
Important Note on External Crystals: Crystal oscillator circuits are quite sensitive to PCB layout. The
crystal should be placed as close as possible to the XTAL pins on the device. The traces should be as
short as possible and shielded with ground plane from any other traces which could introduce noise or
interference.
14.5. External RC Example
If an RC network is used as an external oscillator source for the MCU, the circuit should be configured as
shown in Figure 14.1, Option 2. The capacitor should be no greater than 100 pF; however for very small
capacitors, the total capacitance may be dominated by parasitic capacitance in the PCB layout. To deter-
mine the required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, first
select the RC network value to produce the desired frequency of oscillation. If the frequency desired is
100 kHz, let R = 246 k and C = 50 pF:
f = 1.23(103)/RC = 1.23 (103)/[246 x 50] = 0.1 MHz = 100 kHz
Referring to the table in SFR Definition 14.4, the required XFCN setting is 010.
14.6. External Capacitor Example
If a capacitor is used as an external oscillator for the MCU, the circuit should be configured as shown in
Figure 14.1, Option 3. The capacitor should be no greater than 100 pF; however for very small capacitors,
the total capacitance may be dominated by parasitic capacitance in the PCB layout. To determine the
required External Oscillator Frequency Control value (XFCN) in the OSCXCN Register, select the capaci-
tor to be used and find the frequency of oscillation from the equations below. Assume VDD =3.0V and
C=50pF:
f = KF/( C x VDD ) = KF/( 50 x 3 )
f=KF/150
If a frequency of roughly 50 kHz is desired, select the K Factor from the table in SFR Definition 14.4
as KF = 7.7:
f = 7 . 7 /15 0 = 0.05 1 MHz, or 51 kHz
Therefore, the XFCN value to use in this example is 010.
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14.7. Phase-Locked Loop (PLL)
A Phase-Locked-Loop (PLL) is included, which is used to multiply the internal oscillator or an external
clock source to achieve higher CPU operating frequencies. The PLL circuitry is designed to produce an
output frequency between 25 MHz and 100 MHz, from a divided reference frequency between 5 MHz and
30 MHz. A block diagram of the PLL is shown in Figure 14.2.
Figure 14.2. PLL Block Diagram
14.7.1. PLL Input Clock and Pre-divider
The PLL circuitry can derive its reference clock from either the internal oscillator or an external clock
source. The PLLSRC bit (PLL0CN.2) controls which clock source is used for the reference clock (see SFR
Definition 14.5). If PLLSRC is set to ‘0’, the internal oscillator source is used. Note that the internal oscilla-
tor divide factor (as specified by bits IFCN1-0 in register OSCICN) will also apply to this clock. When
PLLSRC is set to ‘1’, an external oscillator source will be used. The external oscillator should be active and
settled before it is selected as a reference clock for the PLL circuit. The reference clock is divided down
prior to the PLL circuit, according to the contents of the PLLM4-0 bits in the PLL Pre-divider Register
(PLL0DIV), shown in SFR Definition 14.6.
14.7.2. PLL Multiplication and Output Clock
The PLL circuitry will multiply the divided reference clock by the multiplication factor stored in the
PLL0MUL regist er shown in SFR Definit ion 14.7 . To accomplish this, it uses a fe edback loop consistin g of
a phase/frequency detector, a loop filter, and a current-controlled oscillator (ICO). It is important to config-
ure the loop filter and the ICO for the correct frequency ranges. The PLLLP3–0 bits (PLL0FLT.3–0) should
be set according to the divided reference clock frequency. Likewise, the PLLICO1–0 bits (PLL0FLT.5–4)
should be set according to the desired output frequency range. SFR Definition 14.8 describes the proper
settings to use for the PLLLP3–0 and PLLICO1–0 bits. When the PLL is locked and stable at the desired
frequency, the PLLLCK bit (PLL0CN.5) will be set to a ‘1’. The resulting PLL frequency will be set accord-
ing to the equation:
Where “Reference Frequency” is the selected source clock frequency, PLLN is the PLL Multiplier, and
PLLM is the PLL Pre-divider.
PLL0DIV
PLLM4
PLLM3
PLLM2
PLLM1
PLLM0
PLL0MUL
PLLN7
PLLN6
PLLN5
PLLN4
PLLN3
PLLN2
PLLN1
PLLN0
PLL0CN
PLLLCK
PLLSRC
PLLEN
PLLPWR
PLL0FLT
PLLICO1
PLLICO0
PLLLP3
PLLLP2
PLLLP1
PLLLP0
0
1
Internal
Oscillator
External
Oscillator
Phase /
Frequency
Detection
Loop Filter Current
Controlled
Oscillator
PLL Clock
Output
Divided
Reference
Clock
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14.7.3. Powering on and Initializing the PLL
To set up and use the PLL as the system clock after power-up of the device, the following procedure
should be implemented:
Step 1. Ensure that the reference clock to be used (internal or external) is running and stable.
Step 2. Set the PLLSRC bit (PLL0CN.2) to select the desired clock source for the PLL.
Step 3. Program th e Flash read timing bits, FLRT (FLSCL.5–4) to the appropriate value for the
new clock rate (see Section “15. Flash Memory” on page 199).
Step 4. Enable power to the PLL by setting PLLPWR (PLL0CN.0) to ‘1’.
Step 5. Program the PLL0DIV register to produce the divided reference frequency to the PLL.
Step 6. Program the PLLLP3–0 bits (P LL0FLT.3–0) to the appropriate range for the divided
reference frequency.
Step 7. Program the PLLICO1–0 bits (PLL0FLT.5–4) to the appropriate range for the PLL output
frequency.
Step 8. Program the PLL0MUL register to the desired clock multiplication factor.
Step 9. Wait at least 5 µs, to provide a fast frequency lock.
Step 10. Enable the PLL by setting PLLEN (PLL0CN.1) to ‘1’.
Step 11. Poll PLLLCK (PLL0CN.4) until it chang es from ‘0’ to ‘1’.
Step 12. Switch the System Clock source to the PLL using the CLKSEL register.
If the PLL characteristics need to be changed when the PLL is already running, the following procedure
should be implemented:
Step 1. The system clock should first be switched to either the internal oscillator or an external
clock source that is running and stable, using the CLKSEL register.
Step 2. Ensure that the refe rence clock to be used for the new PLL settin g (intern al or externa l) is
running and stable.
Step 3. Set the PLLSRC bit (PLL0CN.2) to select the new clock source for the PLL.
Step 4. If moving to a faster frequency, program the Flash read timing bi ts, FLRT (FLSCL.5–4) to
the appropriate value for the new clock rate (see Section “15. Flash Memory” on
page 199).
Step 5. Disable the PLL by setting PLLEN ( PLL0CN.1) to ‘0’.
Step 6. Program the PLL0DIV register to produce the divided reference frequency to the PLL.
Step 7. Program the PLLLP3–0 bits (P LL0FLT.3–0) to the appropriate range for the divided
reference frequency.
Step 8. Program the PLLICO1-0 bits (PLL0FLT.5–4) to the appropriate range for the PLL output
frequency.
Step 9. Program the PLL0MUL register to the desired clock multiplication factor.
Step 10. Enable the PLL by setting PLLEN (PLL0CN.1) to ‘1’.
Step 11. Poll PLLLCK (PLL0CN.4) until it chang es from ‘0’ to ‘1’.
Step 12. Switch the System Clock source to the PLL using the CLKSEL register.
Step 13. If moving to a slower frequency, program the Flash read timing bits, FLRT (FLSCL.5–4)
to the appropriate value for the new clock rate (see Section “15. Flash Memory” on
PLL Frequency Reference Frequency PLLN
PLLM
---------------
=
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 193
page 199). Important Note: Cache reads, cache writes, and the prefetch engine
should be disabled whenever the FLRT bit s are changed to a lower setting.
To shut down the PLL, the system clock should be switched to the internal oscillator or a stable external
clock source, using the CLKSEL register. Next, disable the PLL by setting PLLEN (PLL0CN.1) to ‘0’.
Finally, the PLL can be powered off, by setting PLLPWR (PLL0CN.0) to ‘0’. Note that the PLLEN and
PLLPWR bits can be cleared at the same time.
SFR Definition 14.5. PLL0CN: PLL Control
Bits 7–5: UNUSED: Read = 000b; Write = don’t care.
Bit 4: PLLCK: PLL Lock Flag.
0: PLL Frequency is not locked.
1: PLL Frequency is locked.
Bit 3: RESERVED. Must write to ‘0’.
Bit 2: PLLSRC: PLL Reference Clock Source Select Bit.
0: PLL Reference Clock Source is Internal Oscillator.
1: PLL Reference Clock Source is External Oscillator.
Bit 1: PLLEN: PLL Enable Bit.
0: PLL is held in reset.
1: PLL is enabled. PLLPWR must be ‘1’.
Bit 0: PLLPWR: PLL Power Enable.
0: PLL bias generator is de-activated. No static power is consumed.
1: PLL bias generator is active. Must be set for PLL to operate.
R/W R/W R/W R R/W R/W R/W R/W Reset Value
- - - PLLLCK 0 PLLSRC PLLEN PLLPWR 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x89
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
194 Rev. 1.4
SFR Definition 14.6. PLL0DIV: PLL Pre-divider
SFR Definition 14.7. PLL0MUL: PLL Clock Scaler
Bits 7–5: UNUSED: Read = 000b; Write = don’t care.
Bits 4–0: PLLM4–0: PLL Reference Clock Pre-divider.
These bit s select the pre- divide value of the P LL re fe rence clock. When set to a ny non- ze ro
value, the reference clock will be divided by the value in PLLM4–0. When set to ‘00000b’,
the reference clock will be divided by 32.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - PLLM4 PLLM3 PLLM2 PLLM1 PLLM0 00000001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8D
F
Bits 7–0: PLLN7–0: PLL Multiplier.
These bits select the multiplication factor of the divided PLL reference clock. When set to
any non-zero value, the multiplication factor will be equal to the value in PLLN7-0. When set
to ‘00000000b’, the multiplication factor will be equal to 256.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PLLN7 PLLN6 PLLN5 PLLN4 PLLN3 PLLN2 PLLN1 PLLN0 00000001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8E
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 195
SFR Definition 14.8. PLL0FLT: PLL Filter
Table 14.2. PLL Frequency Characteristics
–40 to +85 °C unless otherwise specified
Parameter Conditions Min Typ Max Units
Input Frequency
(Divided Reference Frequency) 530MHz
PLL Output Frequency 25 100* MHz
*Note: The maximum operating frequency of the C8051F124/5/6/7 is 50 MHz
Bits 7–6: UNUSED: Read = 00b; Write = don’t care.
Bits 5–4: PLLICO1-0: PLL Current-Controlled Oscillator Control Bits.
Selection is based on th e desired output frequency, according to the following table:
Bits 3–0: PLLLP3-0: PLL Loop Filter Control Bits.
Selection is based on the divided PLL reference clock, according to the following tabl e:
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - PLLICO1 PLLICO0 PLLLP3 PLLLP2 PLLLP1 PLLLP0 00110001
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8F
F
PLL Output Clock PLLICO1-0
65–100 MHz 00
45–80 MHz 01
30–60 MHz 10
25–50 MHz 11
Divided PLL Reference Clock PLLLP3-0
19–30 MHz 0001
12.2–19.5 MHz 0011
7.8–12.5 MHz 0111
5–8 MHz 1111
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
196 Rev. 1.4
Table 14.3. PLL Lock Timing Characteristics
–40 to +85 °C unless otherwise specified
Input
Frequency Multiplier
(Pll0mul) Pll0flt
Setting Output
Frequency Min Typ Max Units
5MHz
20 0x0F 100 MHz 202 µs
13 0x0F 65 MHz 115 µs
16 0x1F 80 MHz 241 µs
90x1F45MHz116 µs
12 0x2F 60 MHz 258 µs
60x2F30MHz112 µs
10 0x3F 50 MHz 263 µs
50x3F25MHz113 µs
25 MHz
40x01100MHz42 µs
20x0150MHz33 µs
30x1175MHz48 µs
20x1150MHz17 µs
20x2150MHz42 µs
10x2125MHz33 µs
20x3150MHz60 µs
10x3125MHz25 µs
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 197
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
198 Rev. 1.4
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 199
15. Flash Memory
All devices include either 128 kB (C8051F12x and C8051F130/1) or 64 kB (C8051F132/3) of on-chip,
reprogrammable Flash memory for program code or non-volatile data storage. An additional 256-byte
page of F lash is also includ ed for n on-volatile dat a storage. The F lash memory can b e programmed in -sys-
tem through the JTAG interface, or by software using the MOVX write in structions. Once cleared to logic 0,
a Flash bit must be erased to set it back to logic 1. Bytes should be erased (set to 0xFF) before being
reprogrammed. Flash write and erase operations are automatically timed by hardware for proper execu-
tion. During a F las h er ase or wr ite, t he FL BUSY bit in the FLSTAT regis ter is set to ‘1 ’ (see SFR Definition
16.5). During this time, instructions th at are located in the prefetch buffer or the branch target cache can be
executed, but the processor will stall until the erase or write is completed if instruction dat a must be fetched
from Flash memory. Interrupts that have been pre-loaded into the branch target cache can also be ser-
viced at this time, if the current code is also executing from the prefetch engine or cache memory. Any
interrupts that are not pre-loaded into cache, or that occur while the core is halted, will be held in a pending
state during the Flash write/erase operation, and serviced in priority order once the Flash operation has
completed. Refer to Table 15.1 for the electrical characteristics of the Flash memory.
15.1. Programming the Flash Memory
The simplest means of programming the Flash memory is through the JTAG interface using programming
tools provided by Silicon Labs or a third party vendor. This is the only means for programming a non-initial-
ized device. For details on the JTAG commands to program Flash memory, see Section “25. JTAG (IEEE
1149.1)” on page 341.
The Flash memory can be programmed from software using the MOVX write instruction with the address
and data byte to be programmed provided as normal operands. Before writing to Flash memory using
MOVX, Flash write operations must be enabled by setting the PSWE Program Store Write Enable bit
(PSCTL.0) to logic 1. This directs the MOVX writes to Flash memory instead of to XRAM, which is the
default target. The PSWE bit remains set until cleared by software. To avoid errant Flash writes, it is rec-
ommended that interrupts be disabled while the PSWE bit is logic 1.
Flash memory is read using the MOVC instruction. MOVX reads are always directed to XRAM, regardless
of the state of PSWE.
On the devices with 128 kB of Flash, the COBANK bits in the PSBANK register (SFR Definition 11.1)
determine which of th e upper th ree Flash b anks are mapped to the address ra nge 0x08000 to 0x0FFFF for
Flash writes, read s and erases.
For devices with 64 kB of Flash. the COBANK bits should always remain set to ‘01’ to ensure that Flash
write, erase, and read operations are valid.
NOTE: To ensure the integrity of Flash memory contents, it is strongly recommended that the on-
chip VDD monitor be enabled by connecting the VDD monitor enable pin (MONEN) to VDD and set-
ting the PORSF bit in the RSTSRC register to ‘1’ in any system that writes and/or erases Flash
memory from software. See “Reset Sources” on page 177 for more informat ion.
A write to Flash memory can clear bits but cannot set them; only an erase operation can set bits in Flash.
A byte location to be programmed must be erased before a new value can be written.
Write/Erase timing is automatically controlled by hardware. Note that on the 128 k Flash versions, 1024
bytes beginning at location 0x1FC00 are reserved. Flash writes and erases targeting the reserved area
should be avoided.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
200 Rev. 1.4
15.1.1. Non-volatile Data Storage
The Flash memory can be used for non-volatile data storage as well as program code. This allows data
such as calibration coef ficients to b e calculated and stored at run time. Data is written and erased using the
MOVX write instruction (as described in Section 15.1.2 and Section 15.1.3) and read using the MOVC
instruction. The COBANK bits in register PSBANK (SFR Definition 11.1) control which por tion of the Fla sh
memory is targeted by writes and erases o f addresses above 0x07FFF. For devices with 64 kB of Flash.
the COBANK bits should always remain set to ‘01’ to ensure that Flash write, erase, and read operations
are valid.
Two additional 128-byte sectors (256 bytes total) of Flash m emory are included for n on-volatile data stor-
age. The smaller sector size makes them particularly well suited as general purpose, non-volatile scratch-
pad memory. Even tho ugh Flash memory can be written a s ingle byte at a tim e, an entire sector must be
erased first. In order to change a single byte of a multi-byte da t a set, th e dat a must be moved to tempo rary
storage. The 128-byte sector-size facilitates updating data without wasting program memory or RAM
space. The 128-byte sectors are double-mapped over the normal Flash memory for MOVC reads and
MOVX writes only; their addresses range from 0x00 to 0x7F and from 0x80 to 0xFF (see F igure 15 .2). To
access the 128-byte sectors, the SFLE bit in PSCTL must be set to logic 1. Code execution from the 128-
byte Scratchpad areas is not permitted. The 128-byte sectors can be erased individually, or both at the
same time. To erase both sectors simultaneously, the address 0x0400 shou ld be targete d during the erase
operation with SFLE set to ‘1’. See Figure 15.1 for the memory map under different COBANK and SFLE
settings.
Table 15.1. Flash Electrical Characteristics
VDD = 2.7 to 3.6 V; –40 to +85 °C
Parameter Conditions Min Typ Max Units
Flash Size1C8051F12x and C8051F130/1 1313282Bytes
Flash Size1C8051F132/3 65792 Bytes
Endurance 20k 100k Erase/Write
Erase Cycle Time 10 12 14 ms
Write Cycle Time 40 50 60 µs
Notes:
1. Includes 256-byte Scratch Pad Area
2. 1024 Bytes at location 0x1FC00 to 0x1FFFF are reserved.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 201
Figure 15.1. Flash Memory Map for MOVC Read and MOVX Write Operations
15.1.2. Erasing Flash Pages From Software
When erasing Flash memory, an entire page is erased (all bytes in the page are s et to 0xFF) . The Flash
memory is organized in 1024-byte pages. The 256 bytes of Scratchpad area (addresses 0x20000 to
0x200FF) consists of two 128 byte pages. To erase any Flash page, the FLWE, PSWE, and PSEE bits
must be set to ‘1’, and a byte must be written using a MOVX instruction to any address within that page.
The following is the recommended procedure for erasing a Flash page fr om software:
Step 1. Disable interrupts.
Step 2. If erasing a page in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for
the appropriate bank.
Step 3. If erasing a page in the Scratchpad area, set the SFLE bit (PSCTL.2).
Step 4. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software .
Step 5. Set PSEE (PSCTL.1) to enable Flash erases.
Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flas h.
Step 7. Use the MOVX instruction to write a data byte to any location within the page to be
erased.
Step 8. Clear PSEE to disable Flash erases.
Step 9. Clear the PSWE bit to redirect MOVX commands to the XRAM data space.
Step 10. Clear the FLWE bit, to disable Flash writes/erases.
Step 11. If erasing a page in the Scratchpad area, clear the SFLE bit.
Step 12. Re-enable interrupts.
Bank 0 Bank 1 Bank 2 Bank 3
Bank 0 Bank 0 Bank 0 Bank 0
COBANK = 0 COBANK = 1 COBANK = 2 COBANK = 3
SFLE = 0 SFLE = 1 Internal
Address
0x0000
0x7FFF
0x8000
0xFFFF
Undefined
Scratchpad
Areas (2)
0x00FF
128k FLASH devices only.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
202 Rev. 1.4
15.1.3. Writing Flash Memory From Software
Bytes in Flash memory can be written one byte at a time, or in small blocks. The CHBLKW bit in register
CCH0CN (SFR Definition 16.1) co nt ro ls whether a single byte or a block of b yte s is writ ten to Flash duri ng
a write operation. When CHBLKW is cleared to ‘0’, the Flash will be written one byte at a time. When
CHBLKW is set to ‘1’, the Flash will be written in blocks of four bytes for addresses in code space, or
blocks of two bytes for addresses in the Scratchpad area. Block writes are performed in the same amount
of time as single byte writes, which can save time when storing large amounts of data to Flash memory.
For single-byte writes to Flash, bytes are written individually, and the Flash write is performed after each
MOVX write instruction. The recommended procedure for writing Flash in single byte s is as follows:
Step 1. Disable interrupts.
Step 2. Clear CHBLKW (CCH0CN.0) to select single-byte write mode.
Step 3. If writing to bytes in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for
the appropriate bank.
Step 4. If writing to bytes in the Scratchpad area, set the SFLE bit (PSCTL.2).
Step 5. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software .
Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flas h.
Step 7. Use the MOVX instruction to write a data byte to the desired location (repeat as
necessary).
Step 8. Clear the PSWE bit to redirect MOVX commands to the XRAM data space.
Step 9. Clear the FLWE bit, to disable Flash writes/erases.
Step 10. If writing to bytes in the Scratchpad area, clear the SFLE bit.
Step 11. Re-enable interrupts.
For block Flash writes, the Flash write procedure is only performed after the last byte of each block is writ-
ten with the MOVX write instruction. When writing to addresses located in any of the four code banks, a
Flash write block is four bytes long, from ad dresses ending in 00 b to addresses end ing in 11b. Writes must
be performed sequentially (i.e. addresses ending in 00b, 01b, 10b, and 11b must be written in order). The
Flash write will be performed following the MOVX write that targets the address ending in 11b. When writ-
ing to addresses located in the Flash Scratchpad area, a Flash block is two bytes long, from addresses
ending in 0b to addresses ending in 1b. The Flash write will be performed following the MOVX write that
targets the address ending in 1b. If any bytes in the block do not need to be updated in Flash, they should
be written to 0xFF. The recommended procedure for writing Flash in blocks is as follows:
Step 1. Disable interrupts.
Step 2. Set CHBLKW (CCH0CN.0) to select block write mode.
Step 3. If writing to bytes in Bank 1, Bank 2, or Bank 3, set the COBANK bits (PSBANK.5-4) for
the appropriate bank.
Step 4. If writing to bytes in the Scratchpad area, set the SFLE bit (PSCTL.2).
Step 5. Set FLWE (FLSCL.0) to enable Flash writes/erases via user software .
Step 6. Set PSWE (PSCTL.0) to redirect MOVX commands to write to Flas h.
Step 7. Use the MOVX instruction to write data bytes to the desired block. The data bytes must
be written sequentially, and the last byte written must be the high byte of the block (see
text for details, repeat as necessary).
Step 8. Clear the PSWE bit to redirect MOVX commands to the XRAM data space.
Step 9. Clear the FLWE bit, to disable Flash writes/erases.
Step 10. If writing to bytes in the Scratchpad area, clear the SFLE bit.
Step 11. Re-enable interrupts.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 203
15.2. Security Options
The CIP-51 provides security options to protect the Flash memory from inadvertent modification by soft-
ware as well as prevent the viewing of proprietary program code and constants. The Program Store Write
Enable (PSCTL.0), Program Store Erase Enable (PSCTL.1), and Flash Write/Erase Enable (FLACL.0) bits
protect the Flash memory from accidental modification by software. These bits must be explicitly set to
logic 1 before software can write or erase the Flash memory. Additional security features prevent proprie-
tary program code and data constants from being read or altered across the JTAG interface or by software
running on the system controller.
A set of security lock bytes protect the Flash program memory from being read or altered across the JTAG
interface. Each bit in a security lock-byte protects one 16k-byte block of memory. Clearing a bit to logic 0 in
the Read Lock Byte prevents the corresponding block of Flash memory from being read across the JTAG
interface. Clearing a bit in the Write/Erase Lock Byte protects the block from JTAG erasures and/or writes.
The Scratchpad area is read or write/erase locked when all bits in the corresponding security byte are
cleared to logic 0.
On the C8051F12x and C8051F130/1, the security lock bytes are located at 0x1FBFE (Write/Erase Lock)
and 0x1FBFF (Read Lock), as shown in Figure 15.2. On the C8051F132/3, the security lock bytes are
located at 0x0FFFE (Write/Erase Lock) and 0x0FFFF (Read Lock), as shown in Figure 15.3. The 1024-
byte sector containing the lock bytes can be written to, but not erased, by software. An attempted read of a
read-locked byte returns undefined data. Debugging code in a read-locked sector is not possible through
the JTAG interface. Th e lo ck bi ts can always b e re ad from and written to logic 0 regardless of the security
setting applied to the block cont aining the security bytes. This allows add itional blocks to be protected af ter
the block containing the security bytes has been locked.
Important Note: To ensure protection from external access, the block containing the lock bytes
must be Write/Erase locked. On the 128 kB devices (C8051F12x and C8051F130/1), the block con-
taining the security bytes is 0x18000-0x1BFFF, and is locked by clearing bit 7 of the Write/Erase
Lock Byte. On the 64 kB devices (C8051F132/3), the block containing the security bytes is
0x0C000-0x0FFF F, and is locked by clearing bit 3 of th e Write/Erase Lock Byte. If the page contain-
ing the security bytes is not Write/Erase locked, it is still possible to erase this page of Flash mem-
ory through the JTAG port and reset the security bytes.
When the page containing the security bytes h as been W rit e/Erase lock ed, a JTAG full device erase
must be performed to unlock any areas of Flash protected by the security bytes. A JTAG full
device erase is init iated by performing a normal JTAG erase operation on eith er of the security byte
locations. This operation must be initiated through the JTAG port, and cannot be performed from
firmware running on the device.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
204 Rev. 1.4
Figure 15.2. 128 kB Flash Memory Map and Security Bytes
0x1FC00
0x1FBFE
Program/Data
Memory Space
0x00000
0x1FBFF
Read Lock Byte
Write/Erase Lock Byte
Reserved
0x1FFFF
0x1FBFD
SFLE = 0
0x00FF
0x0000
Scratchpad Memory
(Data only)
SFLE = 1
Bit
7
6
5
4
3
2
1
0
Read and Write/Erase Security Bits.
(Bit 7 is MSB.)
Memory Block
0x18000 - 0x1BFFF
0x1C000 - 0x1FBFD
0x14000 - 0x17FFF
0x10000 - 0x13FFF
0x08000 - 0x0BFFF
0x0C000 - 0x0FFFF
0x04000 - 0x07FFF
0x00000 - 0x03FFF Flash Access Limit
Flash Read Lock Byte
Bits7–0: Each bit locks a corresponding block of memory. (Bit7 is MSB).
0: Read oper ations ar e locked ( disabled) fo r co rrespondin g block across the JTAG interface.
1: Read operati on s are unlocked (e na ble d ) fo r corresponding block across the JTAG inter-
face.
Flash Write/Erase Lock Byte
Bits7–0: Each bit locks a corresponding block of memory.
0: Write/Erase operations are locked (disable d) for corresponding block across the JTAG
interface.
1: Write/Erase operations are unlocked (enabl ed) for corresponding block across the JTAG
interface.
NOTE: When the highest block is locked, the security bytes may be written but not erased .
Flash access Limit Register (FLACL)
The Flash Access Limit is defined by th e settin g of the FL ACL register, as described in SFR
Definition 15.1. Firmware running at or above this address is prohibited from using the
MOVX and MOVC instructions to read, write, or erase Flash locations below this address.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 205
Figure 15.3. 64 kB Flash Memory Map and Security Bytes
0x0FFFE
Program/Data
Memory Space
0x00000
0x0FFFF
Read Lock Byte
Write/Erase Lock Byte
Flash Access Limit
0x0FFFD
SFLE = 0
0x00FF
0x0000
Scratchpad Memory
(Data only)
SFLE = 1
Bit
7
6
5
4
3
2
1
0
Read and Write/Erase Security Bits.
(Bit 7 is MSB.)
Memory Block
N/A
N/A
N/A
N/A
0x08000 - 0x0BFFF
0x0C000 - 0x0FFFF
0x04000 - 0x07FFF
0x00000 - 0x03FFF
Flash Read Lock Byte
Bits7–0: Each bit locks a corresponding block of memory. (Bit7 is MSB).
0: Read oper ations ar e locked ( disabled) fo r co rrespondin g block across the JTAG interface.
1: Read operati on s are unlocked (e na ble d ) fo r corresponding block across the JTAG inter-
face.
Flash Write/Erase Lock Byte
Bits7–0: Each bit locks a corresponding block of memory.
0: Write/Erase operations are locked (disable d) for corresponding block across the JTAG
interface.
1: Write/Erase operations are unlocked (enabl ed) for corresponding block across the JTAG
interface.
NOTE: When the highest block is locked, the security bytes may be written but not erased .
Flash access Limit Register (FLACL)
The Flash Access Limit is defined by th e settin g of the FL ACL register, as described in SFR
Definition 15.1. Firmware running at or above this address is prohibited from using the
MOVX and MOVC instructions to read, write, or erase Flash locations below this address.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
206 Rev. 1.4
The Flash Access Lim it security feature (see SFR Definition 15.1) protects proprietary program code and
data from being rea d by so ftware runn ing on th e dev ice. T his fe atur e pro vides supp ort fo r OEM s tha t wish
to program the MCU with proprietary value-added firmware before distribution. The value-added firmware
can be protected while allowing additional code to be programmed in remaining program memory space
later.
The Flash Access Limit (FAL) is a 17-bit address that establishes two logical partitions in the program
memory space. The first is an upper partition consisting of all the program memory locations at or above
the FAL address, and the second is a lower partition consisting of all the program memory locations start-
ing at 0x00000 up to (but excluding) the FAL address. Software in the upper partition can execute code in
the lower partition, but is prohibited from read ing locations in the lower partition using the MOVC instruc-
tion. (Executing a MOVC instruction from the upper partition with a source address in the lower partition
will return indeterminate data.) Software running in the lower partition can access locations in both the
upper and lower partition without restriction.
The Value-added firmware should be p laced in the lowe r partition. On reset, control is passed to the value-
added firmware via the reset vector. Once the value-added firmware completes its initial execution, it
branches to a predetermined location in the upper partition. If entry points are published, software running
in the upper partition may execute program code in the lower partition, but it cannot read or change the
contents of the lower partition. Parameters may be passed to the program code running in the lower parti-
tion either through th e typical method o f placing them on the stack or in registers before th e call o r by pla c-
ing them in prescribed memor y locations in the upper partition.
The FAL address is specified using the content s of the Flash Access Limit Register. The 8 MSBs of the 17-
bit FAL address are determine d by the setting of the FLACL register. Thus, the FAL can be located on 512-
byte boundaries anywhere in program memory space. However, the 1024-byte erase sector size essen-
tially requires that a 1024 boundary be used. The contents of a non-initialized FLACL security byte are
0x00, thereby setting the FAL address to 0x00000 and allowing read access to all locations in program
memory space by default.
SFR Definition 15.1. FLACL: Flash Access Limit
Bits 7–0: FLACL: Flash Access Limit.
This register holds the most significant 8 bits of the 17-b it program memory re ad/write/erase
limit address. The lower 9 bit s o f the read/write/er ase limit are always set to 0. A write to th is
register sets the Flash Access Limit. This register can only be written once af ter any reset.
Any subsequent writes are ignored until the next reset. To fully protect all addresses
below this limit, bit 0 of FLACL should be set to ‘0’ to align the FAL on a 1024-byte
Flash page boundary.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
SFR Address:
SFR Page: 0xB7
F
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Rev. 1.4 207
15.2.1. Summary of Flash Security Options
There are three Flash access methods supported on the C8051F12x and C8051F13x devices; 1) Access-
ing Flash through the JTAG debug interface, 2) Accessing Flash from firmware residing below the Flash
Access Limit, and 3) Accessing Flash fro m firmware residing at or above the Flash Access Limit.
Accessing Flash through the JTAG debug interface:
1. The Read and Write/Erase Lock bytes (security bytes) provide security for Flash access
through the JTAG interface.
2. Any unlocked page may be read from, written to, or erased.
3. Locked pages cannot be read from, written to, or erased.
4. Reading the security bytes is always permitted.
5. Locking additional pages by writing to the security bytes is always permitted.
6. If the page containing the security bytes is unlocked, it can be directly erased. Doing so will
reset the security bytes and unlock all pages of Flash.
7. If the page con tainin g the se curity bytes is locked, it can not be dir ectly erased. To unlock the
page containing the security bytes, a full JTAG device erase is required. A full JTAG
device erase will erase all Flash pages, including the page containing the security bytes and
the security bytes themselves.
8. The Reserved Area cannot be read from, written to, or erased at any time.
Accessing Flash from firmware residing below the Flash Access Limit:
1. The Read and Write/Erase Lock bytes (security bytes) do not restrict Flash access from user
firmware.
2. Any page of Flash except the page containing the security by tes may be read from, written to,
or erased.
3. The page containing the security bytes cannot be erased. Unlocking pages of Flash can
only be performe d via the JTAG inte rf ace.
4. The page containing the secur i ty bytes may be read from or written to. Pages of Flash can be
locked from JTAG access by writing to the security bytes.
5. The Reserved Area cannot be read from, written to, or erased at any time.
Accessing Flash from firmware residing at or above the Flash Access Limit:
1. The Read and Write/Erase Lock bytes (security bytes) do not restrict Flash access from user
firmware.
2. Any page of Flash at or above the Flash Access Limit except the page containing the security
bytes may be read from, written to, or erased.
3. Any page of Flash below the Flash Access Limit cannot be read from, written to, or erased.
4. Code bra n ches to locations be low the Flash Access Limit are pe rm itt ed .
5. The page containing the security bytes cannot be erased. Unlocking pages of Flash can
only be performe d via the JTAG inte rf ace.
6. The page containing the secur i ty bytes may be read from or written to. Pages of Flash can be
locked from JTAG access by writing to the security bytes.
7. The Reserved Area cannot be read from, written to, or erased at any time.
C8051F120/1/2/3/4/5/6/7
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208 Rev. 1.4
SFR Definition 15.2. FLSCL: Flash Memory Control
Bits 7–6 : Unused.
Bits 5–4: FLRT: Flash Read Time.
These bits should be programmed to the smallest allowed value, acco rding to the system
clock speed.
00: SYSCLK < 25 MHz.
01: SYSCLK < 50 MHz.
10: SYSCLK < 75 MHz.
11: SYSCLK < 100 MHz.
Bits 3–1: RESERVED. Read = 000b. Must Write 000b.
Bit 0: FLWE: Flash W rite/Erase Enable.
This bit must be set to allow Flash writes/erasures from user software.
0: Flash writes/erases disabled.
1: Flash writes/erases enabled.
Important Note: When changing the FLRT bits to a lower setting (e.g. when changing from a
value of 11b to 00b), cache reads, cache writes, and the prefetch engine should be
disabled using the CCH0CN register (s ee SFR Definition 16.1).
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
- - FLRT Reserved Reserved Reserved FLWE 10000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR Address:
SFR Address:
SFR Page: 0xB7
0
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Rev. 1.4 209
SFR Definition 15.3. PSCTL: Program Store Read/Write Control
Bits 7–3: UNUSED. Read = 00000b, Write = don't care.
Bit 2: SFLE: Scratchpad Flash Memory Access Enable
When this bit is set, Flash MOVC reads and writes from user software are directe d to th e
two 128-byte Scratchp a d Flash secto rs. When SFLE is set to logic 1, Flash accesses out of
the address range 0x00-0xF F should not be at tem p te d (with the exceptio n of addre s s
0x400, which can be used to simultaneously erase both Scratchpad areas). Reads/Writes
out of this range will yield undefined results.
0: Flash access from user software directed to the Program/Data Flash sector.
1: Flash access from user software directed to the two 128 byte Scratchpad sectors.
Bit 1: PSEE: Program Store Erase Enable.
Setting this bit allows an entire page of the Flash program memory to be erased provided
the PSWE bit is also set. After setting this bit, a write to Flash memory using the MOVX
instruction will erase the entire page that contains the location addressed by the MOVX
instruction. The value of the data byte written does not matter. Note: The Flash page con-
taining the Read Lock By te and Write/Erase Lock Byte cannot be erased by software.
0: Flash program memory erasur e disabled.
1: Flash program memory erasure enabled.
Bit 0: PSWE: Program Store Write Enable.
Setting this bit allows writing a byte of data to the Flash program memory using the MOVX
write instruction. The location must be erased prior to writing data.
0: Write to Flash program memory disabled. MOVX write operations target External RAM.
1: Write to Flash program memory enabled. MOVX write operations target Flash memory.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
- - - - - SFLE PSEE PSWE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 SFR
Address:
SFR Address:
SFR Page: 0x8F
0
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210 Rev. 1.4
NOTES:
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Rev. 1.4 211
16. Branch Target Cache
The C8051F12x and C8051F13x device families incorporate a 63x4 byte branch ta rget cache with a 4-byte
prefetch engine. Because the access time of the Flash memory is 40 Flashns, and th e minimum instruction
time is 10ns (C8051F120/1/2/3 and C8051F130/1/2/3) or 20 ns (C8051F124/5/6/7), the branch target
cache and prefetch engine are necessary for full-speed code execution. Instructions are read from Flash
memory four bytes at a time by the prefetch engine, and given to the CIP-51 processor core to execute.
When running linea r co d e (c od e with ou t a ny jum ps or branches), the prefetch engine alone allows instruc-
tions to be executed at full sp eed. W hen a code branch occurs, a search is performed for the branch tar-
get (destination address) in the cache. If the branch target information is found in the cache (called a
“cache hit”), the instruction data is read from the cache and immediately returned to the CIP-51 with no
delay in code execution. If the branch target is not found in the cache (called a “cache miss”), the proces-
sor may be stalled for up to four clock cycles while the next set of four instructions is retrieved from Flash
memory. Each time a cache miss occurs, the requested instruction data is written to the cache if allowed
by the current cache settings. A data flow diagram of the interaction between the CIP-51 and the Branch
Target Cache and Prefetch Engine is shown in Figure 16.1.
Figure 16.1. Branch Target Cache Data Flow
16.1. Cache and Prefetch Operation
The branch target cache maintains two sets of memory locations: “slots” and “tags”. A slot is where the
cached instruction data from Flash is stored. Each slot holds four consecutive code bytes. A tag contains
the 15 most significant bits of the corresponding Flash address for each four-byte slot. Thus, instruction
data is always cached along four-byte boundaries in code space. A tag also contains a “valid bit”, which
indicates whether a cache location contains valid instruction data. A special cache location (called the lin-
ear tag and slot), is reserved for use by the prefetch engine. The cache organization is shown in
Figure 16.2. Each time a Flash read is requested, the address is compared with all valid cache tag loca-
tions (including the linear tag). If any of the tag locations match the requested address, the data from that
slot is immediately provided to the CIP-51. If the requested address matches a location that is currently
being read by the prefetch engine, the CIP-51 will be stalled until the read is complete. If a match is not
found, the current prefetch operation is abandoned, and a new prefetch operation is initiated for the
requested instruction data. When the prefetch operation is finished, the CIP-51 begins executing the
instructions that were retrieved, and the prefetch engine begins reading the next four-byte word from Flash
memory. If the newly-fetched data also meets the criteria necessary to be cached, it will be written to the
cache in the slot indicated by the current replacement algorithm.
FLASH
Memory Branch Target
Cache
Prefetch
Engine
Instruction
Data
CIP-51
Instruction Address
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212 Rev. 1.4
The replacement algorithm is selected with the Cache Algorithm bit, CHALGM (CCH0TN.3). When
CHALGM is cleared to ‘0’, the cache will use the rebound algorithm to replace cache locations. The
rebound algorithm replaces locations in order from the beginning of cache memory to the end, and then
from the end of cache memory to the beginning. When CHALGM is set to ‘1’, the cache will use the
pseudo-random algorithm to replace cache locations. The pseudo-random algorithm uses a pseudo-ran-
dom number to determine which cache location to replace. The cache can be manually emptied by writing
a ‘1’ to the CHFLUSH bit (CCH0CN.4).
Figure 16.2. Branch Target Cache Organiztion
16.2. Cache and Prefetch Optimization
By default, the branch t arget cache is configur ed to provide cod e speed improveme nts for a broad range of
circumstances. In most applications, the cache control registers should be left in their reset states.
Sometimes it is desirable to optimize the execution time of a specific routine or critical timing loop. The
branch target cache includes options to exclude caching of certain types of data, as well as the ability to
pre-load and lock time-critical branch locations to optimize execution speed.
The most basic level of cache control is implemented with the Cache Miss Penalty Threshold bits, CHM-
STH (CCH0TN.1-0). If the processor is stalled during a prefetch operation for more clock cycles than the
number stored in CHMSTH, the requested data will be cached when it becomes available. The CHMSTH
bits are set to zero by default, meaning that any time the processor is stalled, the new data will be cached.
If, for example, CHMSTH is equal to 2, any cache miss causing a delay of 3 or 4 clock cycles will be
cached, while a cache miss causing a delay of 1-2 clock cycles will not be cached.
SLOT = 4 Instruction
Data Bytes
00
TAG 58 SLOT 58V58
TAG 62 SLOT 62V62 TAG 61 SLOT 61V61
TAG 2 SLOT 2V2 TAG 1 SLOT 1V1 TAG 0 SLOT 0V0
TAG 60 SLOT 60V60 TAG 59 SLOT 59V59
LINEAR TAG LINEAR SLOTVLPrefetch Data
Valid
Bit Address Data
Cache Data
TAG = 15 MSBs of Absolute FLASH Address
A16 A2 A1 A0
10
01
11
Byte 0
Byte 1
Byte 2
Byte 3
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Rev. 1.4 213
Certain types of instruction data or certain blocks of code can also be exclude d from caching. The d estina-
tions of RETI instructions are, by default, excluded from caching. To enable caching of RETI destinations,
the CHRETI bit (CCH0CN.3) can be set to ‘1’. It is generally not beneficial to cache RETI destinations
unless the same instruction is likely to be interrupted repeatedly (such as a code loop that is waiting for an
interrupt to happen). Instructions that are part of an interrupt service routine (ISR) can also be excluded
from caching. By defa ult, ISR instructions are cached, bu t this can be disabled by clearing th e CHISR bit
(CCH0CN.2) to ‘0’. The other information that can be explicitly excluded from caching are the data
returned by MOVC instructions. Clearing the CHMOV bit (CCH0CN.1) to ‘0’ will disable caching of MOVC
data. If MOVC caching is allowed, it can be restricted to only use slot 0 for the MOVC information (exclud-
ing cache push operations). The CHFIXM bit (CCH0TN.2) controls this behavior.
Further cach e contr ol can b e imple men ted by disab ling all cache writes. Cache writes can be disabled by
clearing the CHWREN bit (CCH0CN.7) to ‘0’. Although normal cache writes (such as those after a cache
miss) are disabled, data can still be written to the cache with a cache push operation. Disabling cache
writes can be used to prevent a non-critical section of code from ch anging the cach e contents. Note t hat
regardless of the value of CHWREN, a Flash write or erase operation automatically removes the affected
bytes from the cache. Cache reads and the prefetch engine can also be individually disabled. Disabling
cache reads forces all instructions data to execute from Flash memory or from the prefetch engine. To dis-
able cache reads, the CHRDEN bit (CCH0CN.6) can be cleared to ‘0’. Note that when cache reads are
disabled, cache writes will still occur (if CHWREN is set to ‘1’). Disabling the prefetch engine is accom-
plished using the CHPFEN bit (CCH0CN.5). When this bit is cleared to ‘0’, the prefetch engine will be dis-
abled. If both CHPFEN and CHRDEN are ‘0’, code will execute at a fixed rate, as instructions become
available from the Flash memory.
Cache locations can also be pre-loaded and locked with time-critical branch destinations. For example, in
a system with an ISR that must respond as fast as poss ible, the entry point for the ISR can be locked into
a cache location to minimize the response latency of the ISR. Up to 61 locations can be locked into the
cache at one time. Instructions are locked into cache by enabling cache push operations with the
CHPUSH bit (CCH0LC.7). When CHPUSH is set to ‘1’, a MOVC instruction will cause the four-byte seg-
ment containi ng the dat a byte to be writte n to the cache slot location indicated by CHSLOT (CCH0LC.5-0).
CHSLOT is them decrem ented to point to th e ne xt lo ck able cache location . This pr ocess is called a cach e
push operation. Cache location s that are abo ve CHSLOT are “locked”, and cannot be changed by the pro-
cessor core, as shown in Figure 16.3. Cache locations can be unlocked by using a cache pop operation.
A cache pop is performed by writing a ‘1’ to the CHPOP bit (CCH0LC.6). When a cache pop is initiated,
the value of CHSLOT is incremented. This unlocks the most recently locked cache location, but does not
remove the information from the cache. Note that a cache pop should not be initiated if CHSLOT is equal
to 111110b. Doing so may have an adverse effect on cache performance. Important: Although locking
cache location 1 is not explicitly disabled by hardware, the entire cache will be unlocked when
CHSLOT is equal to 000000b. Therefore, cache locations 1 and 0 must remain unlocked at all
times.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
214 Rev. 1.4
Figure 16.3. Cache Lock Operation
TAG 62 SLOT 62
TAG 61 SLOT 61
TAG 2 SLOT 2
TAG 1 SLOT 1
TAG 0 SLOT 0
TAG 60 SLOT 60
TAG 59 SLOT 59
CHSLOT = 58
LOCKED
LOCKED
LOCKED
UNLOCKED
UNLOCKED
UNLOCKED
Lock Status
Cache Push
Operations
Decrement
CHSLOT
Cache Pop
Operations
Increment
CHSLOT
LOCKED
TAG 58 SLOT 58
UNLOCKED
UNLOCKED
TAG 57 SLOT 57 UNLOCKED
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Rev. 1.4 215
SFR Definition 16.1. CCH0CN: Cache Control
Bit 7: CHWREN: Cache Write Enable.
This bit enables the processor to write to the cache memory.
0: Cache contents are not allowed to change, except during Flash writes/erasures or cache
locks.
1: Writes to cache memory are allowed.
Bit 6: CHRDEN: Cache Read Enable.
This bit enables the processor to read instructions from the cache memory.
0: All instruction data comes from Flash memory or the prefetch engine.
1: Instruction data is obtained from cache (when available).
Bit 5: CHPFEN: Cache Prefetch Enable.
This bit enables the pr efetch engine .
0: Prefetch engine is disabled.
1: Prefetch engine is enabled.
Bit 4: CHFLSH: Cache Flush.
When written to a ‘1’, this bit clears the cache contents. This bit always reads ‘0’.
Bit 3: CHRETI: Cache RETI Destination Enable.
This bit enables the destination of a RETI address to be cached.
0: Destinations of RETI instructions will not be cached.
1: RETI destinations will be cached.
Bit 2: CHISR: Cache ISR Enable.
This bit allows instructions which are part of an Interrupt Service Rountine (ISR) to be
cached.
0: Instructions in ISRs will not be loaded into cache memory.
1: Instructions in ISRs can be cached.
Bit 1: CHMOVC: Cache MOVC Enable.
This bit allows data requested by a MOVC instruction to be loaded into the cache memory.
0: Data requested by MOVC instructions will not be cached.
1: Data requested by MOVC instructions will be loaded into cache memory.
Bit 0: CHBLKW: Block Wr ite Enable.
This bit allows block writes to Flash memory from software.
0: Each byte of a software Flash write is written individually.
1: Flash bytes are written in groups of four (for code space writes) or two (for scratchpad
writes).
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
CHWREN CHRDEN CHPFEN CHFLSH CHRETI CHISR CHMOVC CHBLKW 11100110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA1
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
216 Rev. 1.4
SFR Definition 16.2. CCH0TN: Cache Tuning
SFR Definition 16.3. CCH0LC: Cache Lock Control
Bits 7–4: CHMSCTL: Cache Miss Penalty Accumulator (Bits 4–1).
These are bit s 4-1 of the Cache Miss Penalty Accumu lator . To read these bits, th ey must first
be latched by reading the CHMSCTH bits in the CCH0MA Register (See SFR Definition
16.4).
Bit 3: CHALGM: Cache Algorithm Select.
This bit selects th e cache replacement algorithm.
0: Cache uses Rebound algorithm.
1: Cache uses Pseudo-random algorithm.
Bit 2: CHFIXM: Cache Fix MOVC Enable.
This bit forces MOVC writes to the cache memory to use slot 0.
0: MOVC dat a is written according to the current algorithm se lected by the CHALGM bit.
1: MOVC data is always written to cache slot 0.
Bits 1–0: CHMSTH: Cache Miss Penalty Threshold.
These bits determine when missed instruction data will be cached.
If data takes longer than CHMSTH clocks to obtain, it will be cached.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
CHMSCTL CHALGM CHFIXM CHMSTH 00000100
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA2
F
Bit 7: CHPUSH: Cache Push Enable.
This bit enables cache push operations, which will lock information in cache slots using
MOVC instructions.
0: Cache push operations are disabled.
1: Cache push operations are enabled. When a MOVC read is executed, the requested 4-
byte segment containing the data is locked into the cache at the location indicated by
CHSLOT, and CHSLOT is decremented.
Note that no more than 61 cache slots should be locked at one time, since the entire cache
will be unlocked when CHSLOT is equal to 0.
Bit 6: CHPOP: Cache Pop.
Writing a ‘1’ to this bit will increment CHSLOT and then unlock that location. This bit always
reads ‘0’. Note that Cache Pop operations should not be performed while CHSLOT =
111110b. “Pop”ing more Cache slots than have been “Push”ed will have indeterminate
results on the Cache per formance.
Bits 5–0: CHSLOT: Cache Slot Pointer.
These read-only bit s are the pointer into the cache lock st ack. Locations above CHSLOT are
locked, and will not be changed by the processor, except when CHSLOT equals 0.
R/WR/WRRRRRRReset Value
CHPUSH CHPOP CHSLOT 00111110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA3
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 217
SFR Definition 16.4. CCH0MA: Cache Miss Accumulator
SFR Definition 16.5. FLSTAT: Flash Status
Bit 7: CHMSOV: Cache Miss Penalty Overflow.
This bit indicates when the Cache Miss Penalty Accumulator has overflowed since it was
last written.
0: The Cache Miss Penalty Accumulator has not overflowed since it was last written.
1: An overflow of the Cache Miss Penalty Accumulator has occurred since it was last written.
Bits 6–0: CHMSCTH: Cache Miss Penalty Accumulator (bits 11–5)
These are bits 11-5 of the Cache Miss Penalty Accumulator. The next four bits (bits 4-1 ) are
stored in CHMSCTL in the CCH0TN register.
The Cache Miss Pen alty Accumulator is in cremented e very clock cycle that the pro cessor is
delayed due to a cache miss. This is primarily used as a diagnostic feature, when op timizing
code for executio n speed.
Writing to CHMSCTH clears the lower 5 bits of the Cache Miss Penalty Accumulator.
Reading from CHMSCTH returns the current value of CHMSTCH, and latches bits 4-1 into
CHMSTCL so that they can be read. Because bit 0 of the Cache Miss Penalty Accumulator
is not available, the Cumulative Miss Penalty is equal to 2 * (CCHMSTCH:CCHMSTCL).
R R/WR/WR/WR/WR/WR/WR/WReset Value
CHMSOV CHMSCTH 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9A
F
Bit 7–1: Reserved.
Bit 0: FLBUSY: Flash Busy
This bit indicates when a Flash write or erase operation is in progress.
0: Flash is idle or reading.
1: Flash write/erase operation is currently in progress.
R R/WR/WR/WR/WR/WR/WR/WReset Value
-------FLBUSY00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0x88
F
C8051F120/1/2/3/4/5/6/7
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218 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 219
17. External Data Memory Interface and On-Chip XRAM
There are 8 kB of on-chip RAM m apped into the e xternal dat a memory sp ace (X RAM), as well as an Exter-
nal Data Memory Interface which can be used to access off-chip memories and memory-mapped devices
connected to the GPIO ports. The external memory space may be accessed using the external move
instruction (MOVX) and th e dat a pointer (DPT R), or using the MOVX indirect addre ssing mode using R0 or
R1. If the MOVX instruction is used with an 8- bit address operan d (such as @R1 ), then the high byte of the
16-bit address is provided by the External Memory Interface Control Register (EMI0CN, shown in SFR
Definition 17.1). Note: the MOVX instruction can also be used for writing to the Flash memory. See Sec-
tion “15. Flash Memory” on page 199 for det ails. The MOVX instruction accesses XRAM by default. The
EMIF can be configured to appear on the lower GPIO Ports (P0–P3) or the upper GPIO Ports (P4–P7).
17.1. Accessing XRAM
The XRAM memory space is accessed using the MOVX instruction. The MOVX instruction has two forms,
both of which use an indirect addressing method. The first method uses the Data Pointer, DPTR, a 16-bit
register which contains the effective address of the XRAM location to be read f rom or written t o. The sec-
ond method uses R0 or R1 in combination with the EMI0CN register to generate the effective XRAM
address. Examples of both of these methods are given below.
17.1.1. 16-Bit MOVX Example
The 16-bit form of the MOVX instruction accesses the memory location pointed to by the contents of the
DPTR register. The following series of instructions reads the value of the byte at address 0x1234 into the
accumulator A:
MOV DPTR, #1234h ; load DPTR with 16-bit address to read (0x1234)
MOVX A, @DPTR ; load contents of 0x1234 into accumulator A
The above example uses the 16-bit immediate MOV instruction to set the contents of DPTR. Alternately,
the DPTR can be accessed thro ugh the SFR reg ister s DPH, which contains the upper 8-bits of DPT R, and
DPL, which contains the lower 8-bits of DPTR.
17.1.2. 8-Bit MOVX Example
The 8-bit form of the MOVX instruction use s the cont ents o f the EMI0CN SF R to dete rmine the u pper 8-bit s
of the effective address to be accessed and the contents of R0 or R1 to determine the lower 8-bits of the
effective address to be accessed. The following series of instructions read the contents of the byte at
address 0x1234 into the accumulator A.
MOV EMI0CN, #12h ; load high byte of address into EMI0CN
MOV R0, #34h ; load low b yte of address into R0 (or R1)
MOVX a, @R0 ; load contents of 0x1234 into accumulator A
17.2. Configuring the External Memory Interface
Configuring the External Memory Interface consists of five steps:
1. Select EMIF on Low Ports (P3, P2, P1, and P0) or High Ports (P7, P6, P5, and P4).
2. Configure the Output Modes of the port pins as either push-pull or open-drain (push-pull is
most common).
3. Configure Port latches to “park” the EMIF pins in a dormant state (usually by setting them to
logic ‘1’).
4. Select Multiplexed mode or Non-multiplexed mode.
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220 Rev. 1.4
5. Select the memory mode (on-chip only, split mode without bank select, split mode with bank
select, or off-chip only).
6. Set up timing to interface with off-chip memory or peripherals.
Each of these five steps is explained in detail in the following sections. The Port selection, Multiplexed
mode selection, and Mode bits are located in the EMI0CF register shown in SFR Definition 17.2.
17.3. Port Selection and Configuration
The External Memory Interface can appear on Ports 3, 2, 1, and 0 (All Devices) or on Ports 7, 6, 5, and 4
(100-pin TQFP devices only), depending on the state of the PRTSEL bit (EMI0CF.5). If the lower Ports are
selected, the EMIFLE bit (XBR2.1) must be set to a ‘1’ so that the Crossbar will skip over P0.7 (/WR), P0.6
(/RD), and if multiplexed mode is selected P0.5 (ALE). For more information about the configuring the
Crossbar, see Section “18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 238.
The External Memory Interface claims the associated Port pins for memory operations ONLY during the
execution of an off-chip MOVX instruction. Once the MOVX instruction has completed, control of the Port
pins reverts to the Port latches or to the Crossbar (on Ports 3, 2, 1, and 0). See Section “18. Port Input/
Output” on page 235 for more information about the Crossbar and Port operation and configuration. The
Port latches should be explicitly configured to ‘park’ the External Memory Interface pins in a dor-
mant state, most commonly by setting them to a logic 1.
During the execution of the MOVX instruction, the External Memory Interface will explicitly disable the driv-
ers on all Port pins that are actin g as Inpu ts (Data[7:0] during a READ ope ratio n, for example) . The Ou tput
mode of the Port pins (whether the pin is configured as Open-Drain or Push-Pull) is unaffected by the
External Memory Interface operation, and remains controlled by the PnMDOUT registers. In most cases,
the output modes of all EMIF pins should be configured for push-pull mode. See“Configuring the Output
Modes of the Port Pins” on page 239.
SFR Definition 17.1. EMI0CN: External Memory Interface Control
Bits7–0: PGSEL[7:0]: XRAM Page Select Bits.
The XRAM Page Select Bits provide the high byte of the 16-bit external data memory
address when using an 8-bit MOVX command, effectively selecting a 256-byte page of
RAM.
0x00: 0x0000 to 0x00FF
0x01: 0x0100 to 0x01FF
...
0xFE: 0xFE 0 0 to 0xFEFF
0xFF: 0xFF00 to 0xFFFF
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
PGSEL7 PGSEL6 PGSEL5 PGSEL4 PGSEL3 PGSEL2 PGSEL1 PGSEL0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA2
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 221
SFR Definition 17.2. EMI0CF: External Memory Configuration
Bits7–6: Unu sed. Read = 00b. Write = don’t care.
Bit5: PRTSEL: EMIF Port Select.
0: EMIF active on P0–P3.
1: EMIF active on P4–P7.
Bit4: EMD2: EMIF Multiplex Mode Select.
0: EMIF operates in multiplexed address/data mode.
1: EMIF operates in non-multiplexed mode (separate add ress and data pins).
Bits3–2: EMD1-0: EMIF Operating Mode Select.
These bits control the operating mode of th e External Memory In terface.
00: Internal Only: MOVX accesses on-chip XRAM only. All effective addresses a lias to on-
chip memory space.
01: Split Mode without Bank Select: Accesses below the 8 k boundary are directed on-chip.
Accesses above the 8 k boundary are directed off-chip. 8-bit off-chip MOVX operations use
the current contents of the Address High port latches to resolve upper address byte. Note
that in order to access off-chip sp ace, EMI0CN must be set to a page that is not contained in
the on-chip address space.
10: Split Mode with Bank Select: Accesses below the 8 k boundary are directed on-chip.
Accesses above the 8k boundary are directed off-chip. 8-bit off-chip MOVX operations use
the contents of EMI0 CN to determine the high-byte of the address.
11 : External Only: MOVX ac ces ses off-chip XRAM only. On-chip XRAM is not visible to the
CPU.
Bits1–0: EALE1 –0: ALE Pulse-Width Select Bits (only has effect when EMD2 = 0).
00: ALE high and ALE low pulse width = 1 SYSCLK cycle.
01: ALE high and ALE low pulse width = 2 SYSCLK cycles.
10: ALE high and ALE low pulse width = 3 SYSCLK cycles.
11: ALE high and ALE low pulse width = 4 SYSCLK cycles.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
- - PRTSEL EMD2 EMD1 EMD0 EALE1 EALE0 00000011
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA3
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
222 Rev. 1.4
17.4. Multiplexed and Non-multiplexed Selection
The External Memory Interface is capable of acting in a Multiplexed mode or a Non-multiplexed mode,
depending on the state of the EMD2 (EMI0CF.4) bit.
17.4.1. Multiplexed Configuration
In Multiplexed mode, the Data Bus and the lower 8-bits of the Address Bus share the same Port pins:
AD[7:0]. In this mode, an external latch (74HC373 or equivalent logic gate) is used to hold the lower 8-bits
of the RAM address. The external latch is controlled by the ALE (Address Latch Enable) signal, which is
driven by the External Memory Interface logic. An example of a Multiplexed Configuration is shown in
Figure 17.1.
In Multiplexed mo de, the ex ternal MO VX operatio n can be broken into two phases delineated by the state
of the ALE signal. During the first phase, ALE is high and the lower 8-bits of the Address Bus are pre-
sented to AD[7:0]. During this phase, the address latch is configured such that the ‘Q’ outputs reflect the
states of the ‘D’ inputs. When ALE falls, signaling the beginning of the second phase, the address latch
outputs remain fixed and are no longer dep endent on the latch inputs. Later in the second phase, the Data
Bus controls the state of the AD[7:0 ] po rt at the time /RD or /WR is asserted.
See Section “17.6.2. Multiplexed Mode” on page 230 for more information.
Figure 17.1. Multiplexed Configuration Example
ADDRESS/DATA BUS
ADDRESS BUS
E
M
I
F
A[15:8]
AD[7:0]
/WR
/RD
ALE
64K X 8
SRAM
OE
WE
I/O[7:0]
74HC373
G
DQ
A[15:8]
A[7:0]
CE
V
DD
8
(Optional)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 223
17.4.2. Non-multiplexed Configuration
In Non-multiplexed mode, the Data Bus and the Address Bus pins are not shared. An example of a Non-
multiplexed Configuration is shown in Figure 17.2. See Section “17.6.1. Non-multiplexed Mode” on
page 227 for more information about Non-multiplexed operation.
Figure 17.2. Non-multiplexed Configuration Example
ADDRESS BUS
E
M
I
F
A[15:0]
64K X 8
SRAM
A[15:0]
DATA BUSD[7:0] I/O[7:0]
V
DD
8
/WR
/RD OE
WE
CE
(Optional)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
224 Rev. 1.4
17.5. Memory Mode Selection
The external data memory space can be configured in one of four modes, shown in Figure 17.3, based on
the EMIF Mode bits in the EMI0CF register (SFR Definition 17.2). These modes are summarized below.
More information about the different modes can be found in Section “SFR Definition 17.3. EMI0TC:
External Memory Timing Control” on page 226.
17.5.1. Internal XRAM Only
When EMI0CF.[3:2] are set to ‘00’, all MOVX instructions will target the internal XRAM space on the
device. Memory accesses to addresses beyond the populated space will wrap on 8 k boundaries. As an
example, the addresses 0x2000 and 0x4000 both evaluate to address 0x0000 in on- chip XRAM space.
• 8-bit MOVX operations use the contents of EMI0 CN to determine the high-byte of the effective addr ess
and R0 or R1 to determine the low-byte of the effective address.
• 16-bit MOVX operations use the contents of the 16-bit DPTR to determine the effective address.
17.5.2. Split Mode without Bank Select
When EMI0CF.[3:2] are set to ‘01’, the XRAM memory map is split into two areas, on-chip space and off-
chip space.
• Effective addresses below the 8 k boundary will access on-chip XRAM space.
• Effective addresses above the 8 k boundary will access off-chip space.
• 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-
chip or off-chip. However, in the “No Bank Select” mode, an 8-bit MOVX operation will not drive the
upper 8-bits A[15:8] of the Address Bus durin g an off-chip acces s. Th is allows th e use r to manip ula te
the upper address bits at will by setting the Port state directly via the port latches. This behavior is in
contrast with “Split Mode with Bank Select” described below. The lower 8-bit s of the Add ress Bus
A[7:0] are driven, determined by R0 or R1.
• 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-
chip or off-chip, and unlike 8-bit MOVX operations, the full 16 -bits of the Address Bus A[15:0] ar e
driven during the off-chip transaction.
Figure 17.3. EMIF Operating Modes
EMI0CF[3:2] = 00 0xFFFF
0x0000
EMI0CF[3:2] = 11 0xFFFF
0x0000
EMI0CF[3:2] = 01 0xFFFF
0x0000
EMI0CF[3:2] = 10
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
On-Chip XRAM
Off-Chip
Memory
(No Bank Select)
On-Chip XRAM
0xFFFF
0x0000
Off-Chip
Memory
(Bank Select)
On-Chip XRAM
Off-Chip
Memory
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 225
17.5.3. Split Mode with Bank Select
When EMI0CF.[3:2] are set to ‘10’, the XRAM memory map is split into two areas, on-chip space and off-
chip space.
• Effective addresses below the 8k boundary will access on-chip XRAM space.
• Effective addresses above the 8k boundary will access off-chip space.
• 8-bit MOVX operations use the contents of EMI0CN to determine whether the memory access is on-
chip or off- chip. The upper 8-bits of the Address Bus A[15:8] are dete rmined by EMI0CN, and the lower
8-bits o f the Address Bus A[7:0] are determined by R0 or R1. All 1 6-bits of the Address Bus A[15:0] ar e
driven in “Bank Select” mode.
• 16-bit MOVX operations use the contents of DPTR to determine whether the memory access is on-
chip or off-chip, and the full 16-bits of the Address Bus A[15:0] are driven during the off-chip transac-
tion.
17.5.4. External Only
When EMI0CF[3:2] are set to ‘11’, all MOVX operations are directed to off-chip space. On-chip XRAM is
not visible to the CPU. This mode is useful for accessing of f-chip memo ry loca ted betwee n 0x00 00 and th e
8k boundary.
• 8-bit MOVX operations ignore the contents of EMI0CN. The upper Address bits A[15:8] are n ot driven
(identical behavior to an off-chip access in “Split Mode without Bank Select” described above). This
allows the user to manipulate the upper address bits at will by setting the Port state directly. The lower
8-bits of th e effective address A[7:0] are determined by the contents of R0 or R1.
• 16-bit MOVX operations use th e content s of DPTR to deter mine the effective address A[15:0]. The full
16-bits of the Address Bus A[15:0 ] ar e driven during the off-chip tra ns act ion .
17.6. EMIF Timing
The timing parameters of the External Memory Interface can be configured to enable connection to
devices having different setup and hold time requiremen ts. The Address Setup time, Address Hold time , /
RD and /WR strobe widths, and in multiplexed mode, the width of the ALE pulse are all programmable in
units of SYSCLK periods through EMI0TC, shown in SFR Definition 17.3, and EMI0CF[1:0].
The timing for an off-chip MOVX instruction can be calculated by adding 4 SYSCLK cycles to the timing
parameters defined by the EMI0TC register. Assuming non-multiplexed operation, the minimum execution
time for an off-chip XRAM operation is 5 SYSCLK cycles (1 SYSCLK for /RD or /WR pulse + 4 SYSCLKs).
For multiplexed operations, the Address Latch Enable signal will require a minimum of 2 additional SYS-
CLK cycles. Therefore, the minimum execution time for an off-chip XRAM operation in multiplexed mode
is 7 SYSCLK cycles (2 for /ALE + 1 for /RD or /WR + 4). The programmable setup and hold times default
to the maximum delay settings after a reset. Table 17.1 lists the ac parameters for the External Memory
Interface, and Figure 17.4 through Figure 17.9 show the timing diagrams for the different External Memory
Interface mode s an d MOVX operation s.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
226 Rev. 1.4
SFR Definition 17.3. EMI0TC: External Memory Timing Control
Bits7–6: EAS1–0: EMIF Address Setup Time Bits.
00: Address setup time = 0 SYSCLK cycles.
01: Address setup time = 1 SYSCLK cycle.
10: Address setup time = 2 SYSCLK cycles.
11: Address setup time = 3 SYSCLK cycles.
Bits5–2: EWR3–0: EMIF /WR and /RD Pulse-Width Control Bits.
0000: /WR and /RD pulse width = 1 SYSCLK cycle.
0001: /WR and /RD pulse width = 2 SYSCLK cycles.
0010: /WR and /RD pulse width = 3 SYSCLK cycles.
0011: /WR and /RD pulse width = 4 SYSCLK cycles.
0100: /WR and /RD pulse width = 5 SYSCLK cycles.
0101: /WR and /RD pulse width = 6 SYSCLK cycles.
0110: /WR and /RD pulse width = 7 SYSCLK cycles.
0111: /WR and /RD pulse width = 8 SYSCLK cycles.
1000: /WR and /RD pulse width = 9 SYSCLK cycles.
1001: /WR and /RD pulse width = 10 SYSCLK cycles.
1010: /WR and /RD pulse width = 11 SYSCLK cycles.
1011: /WR and /RD pulse width = 12 SYSCLK cycles.
1100: /WR and /RD pulse width = 13 SYSCLK cycles.
1101: /WR and /RD pulse width = 14 SYSCLK cycles.
1110: /WR and /RD pulse width = 15 SYSCLK cycles.
1111: /WR and /RD pulse width = 16 SYSCLK cycles.
Bits1–0: EAH1–0: EMIF Address Hold Time Bits.
00: Address hold time = 0 SYSCLK cycles.
01: Address hold time = 1 SYSCLK cycle.
10: Address hold time = 2 SYSCLK cycles.
11: Address hold time = 3 SYSCLK cycles.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
EAS1 EAS0 ERW3 EWR2 EWR1 EWR0 EAH1 EAH0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA1
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 227
17.6.1. Non-multiplexed Mode
17.6.1.1.16-bit MOVX: EMI0CF[4:2] = ‘ 101’, ‘110’, or ‘111’
Figure 17.4. Non-multiplexed 16-bit MOVX Timing
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPLP2/P6
P1/P5
P0.7/P4.7
P0.6/P4.6
P3/P7 EMIF WRITE DATA
P2/P6
P1/P5
P0.7/P4.7
P0.6/P4.6
P3/P7
T
ACH
T
WDH
T
ACW
T
ACS
T
WDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
/WR
/RD
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from DPLP2/P6
P1/P5
P0.6/P4.6
P0.7/P4.7
P3/P7
P2/P6
P1/P5
P0.6/P4.6
P0.7/P4.7
P3/P7
T
ACH
T
RDH
T
ACW
T
ACS
T
RDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
/RD
/WR
EMIF READ DATA
Nonmuxed 16-bit WRITE
Nonmuxed 16-bit READ
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
228 Rev. 1.4
17.6.1.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘101’ or ‘111’.
Figure 17.5. Non-multiplexed 8-bit MOVX without Bank Select Timing
EMIF ADDRESS (8 LSBs) from R0 or R1P2/P6
P1/P5
P0.7/P4.7
P0.6/P4.6
P3/P7 EMIF WRITE DATA
P2/P6
P0.7/P4.7
P0.6/P4.6
P3/P7
T
ACH
T
WDH
T
ACW
T
ACS
T
WDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
/WR
/RD
EMIF ADDRESS (8 LSBs) from R0 or R1P2/P6
P1/P5
P0.6/P4.6
P0.7/P4.7
P3/P7
P2/P6
P0.6/P4.6
P0.7/P4.7
P3/P7
T
ACH
T
RDH
T
ACW
T
ACS
T
RDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
/RD
/WR
EMIF READ DATA
Nonmuxed 8-bit WRITE without Bank Select
Nonmuxed 8-bit READ without Bank Select
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 229
17.6.1.3.8-bit MOVX with Bank Select: EMI0CF[4:2 ] = ‘110’.
Figure 17.6. Non-multiplexed 8-bit MOVX with Bank Select Timing
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from R0 or R1P2/P6
P1/P5
P0.7/P4.7
P0.6/P4.6
P3/P7 EMIF WRITE DATA
P2/P6
P1/P5
P0.7/P4.7
P0.6/P4.6
P3/P7
T
ACH
T
WDH
T
ACW
T
ACS
T
WDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
/WR
/RD
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from R0 or R1P2/P6
P1/P5
P0.6/P4.6
P0.7/P4.7
P3/P7
P2/P6
P1/P5
P0.6/P4.6
P0.7/P4.7
P3/P7
T
ACH
T
RDH
T
ACW
T
ACS
T
RDS
ADDR[15:8]
ADDR[7:0]
DATA[7:0]
/RD
/WR
EMIF READ DATA
Nonmuxed 8-bit WRITE with Bank Select
Nonmuxed 8-bit READ with Bank Select
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
230 Rev. 1.4
17.6.2. Multiplexed Mode
17.6.2.1.16-bit MOVX: EMI0CF[4:2] = ‘001’, ‘010’, or ‘011’
Figure 17.7. Multiplexed 16-bit MOVX Timing
P3/P7
P2/P6
P3/P7
ADDR[15:8]
AD[7:0]
P2/P6
P0.7/P4.7
P0.6/P4.6
P0.5/P4.5
P0.7/P4.7
P0.6/P4.6
P0.5/P4.5
T
ACH
T
WDH
T
ACW
T
ACS
T
WDS
ALE
/WR
/RD
EMIF ADDRESS (8 MSBs) from DPH
EMIF WRITE DATA
EMIF ADDRESS (8 LSBs) from
DPL
T
ALEH
T
ALEL
P3/P7
P2/P6
P3/P7
ADDR[15:8]
AD[7:0]
P2/P6
P0.6/P4.6
P0.7/P4.7
P0.5/P4.5
P0.6/P4.6
P0.7/P4.7
P0.5/P4.5
T
ACH
T
ACW
T
ACS
ALE
/RD
/WR
EMIF ADDRESS (8 MSBs) from DPH
EMIF ADDRESS (8 LSBs) from
DPL
T
ALEH
T
ALEL
T
RDH
T
RDS
EMIF READ DATA
Muxed 16-bit WRITE
Muxed 16-bit READ
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 231
17.6.2.2.8-bit MOVX without Bank Select: EMI0CF[4:2] = ‘001’ or ‘011’.
Figure 17.8. Multiplexed 8-bit MOVX without Bank Select Timing
P3/P7
P2/P6
P3/P7
ADDR[15:8]
AD[7:0]
P0.7/P4.7
P0.6/P4.6
P0.5/P4.5
P0.7/P4.7
P0.6/P4.6
P0.5/P4.5
T
ACH
T
WDH
T
ACW
T
ACS
T
WDS
ALE
/WR
/RD
EMIF WRITE DATA
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
T
ALEL
P3/P7
P2/P6
P3/P7
ADDR[15:8]
AD[7:0]
P0.6/P4.6
P0.7/P4.7
P0.5/P4.5
P0.6/P4.6
P0.7/P4.7
P0.5/P4.5
T
ACH
T
ACW
T
ACS
ALE
/RD
/WR
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
T
ALEL
T
RDH
T
RDS
EMIF READ DATA
Muxed 8-bit WRITE Without Bank Select
Muxed 8-bit READ Without Bank Select
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
232 Rev. 1.4
17.6.2.3.8-bit MOVX with Bank Select: EMI0CF[4:2 ] = ‘010’.
Figure 17.9. Multiplexed 8-bit MOVX with Bank Select Timing
P3/P7
P2/P6
P3/P7
ADDR[15:8]
AD[7:0]
P2/P6
P0.7/P4.7
P0.6/P4.6
P0.5/P4.5
P0.7/P4.7
P0.6/P4.6
P0.5/P4.5
T
ACH
T
WDH
T
ACW
T
ACS
T
WDS
ALE
/WR
/RD
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF WRITE DATA
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
T
ALEL
P3/P7
P2/P6
P3/P7
ADDR[15:8]
AD[7:0]
P2/P6
P0.6/P4.6
P0.7/P4.7
P0.5/P4.5
P0.6/P4.6
P0.7/P4.7
P0.5/P4.5
T
ACH
T
ACW
T
ACS
ALE
/RD
/WR
EMIF ADDRESS (8 MSBs) from EMI0CN
EMIF ADDRESS (8 LSBs) from
R0 or R1
T
ALEH
T
ALEL
T
RDH
T
RDS
EMIF READ DATA
Muxed 8-bit WRITE with Bank Select
Muxed 8-bit READ with Bank Select
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 233
Table 17.1. AC Parameters for External Memory Interface
Parameter Description Min Max Units
TACS Address/Control Setup Time 0 3 x TSYSCLK ns
TACW Address/Control Pulse Width 1 x TSYSCLK 16 x TSYSCLK ns
TACH Address/Control Hold Time 0 3 x TSYSCLK ns
TALEH Addres s Latch Enable High Time 1 x TSYSCLK 4xT
SYSCLK ns
TALEL Address Latc h Enable Low Time 1 x TSYSCLK 4xT
SYSCLK ns
TWDS Wr ite Data Setup Time 1 x TSYSCLK 19 x TSYSCLK ns
TWDH Write Data Hold Time 0 3 x TSYSCLK ns
TRDS Read Data Setup T i me 20 — ns
TRDH Read Data Hold Time 0 — ns
Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
234 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 235
18. Port Input/Output
The devices are fully integrated mixed-signal System on a Chip MCUs with 64 digital I/O pins (100-pin
TQFP packaging) or 32 digital I/O pins (64-pin TQFP packaging), organized as 8-bit Ports. All ports are
both bit- and byte-addressable through their corresponding Port Data registers. All Port pins are 5 V-toler-
ant, and all support configurable Open-Drain or Push-Pull output modes and weak pullups. A block dia-
gram of the Port I/O cell is shown in Figure 18.1. Complete Electrical Specifications for the Port I/O pins
are given in Table 18.1.
Figure 18.1. Port I/O Cell Block Diagram
DGND
/PORT-OUTENABLE
PORT-OUTPUT
PUSH-PULL VDD VDD
/WEAK-PULLUP
(WEAK)
PORT
PAD
ANALOG INPUT
Analog Select
(Ports 1, 2, and 3)
PORT-INPUT
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
236 Rev. 1.4
Table 18.1. Port I/O DC Electrical Characteristics
VDD = 2.7 to 3.6 V, –40 to +85 °C unless otherwise specified.
Parameter Conditions Min Typ Max Units
Output High Voltage
(VOH)
IOH = -3 mA, Port I/O Push-Pull
IOH = -10 µA, Port I/O Push-Pull
IOH = -10 mA, Port I/O Push-Pull
VDD –0.7
VDD –0.1 VDD –0.8
V
Output Low Voltage
(VOL)
IOL = 8.5 mA
IOL = 10 µA
IOL = 25 mA 1.0
0.6
0.1 V
Input High Voltage (VIH) 0.7 x VDD
Input Low Voltage (VIL) 0.3 x
VDD
Input Leakage Current DGND < Port Pin < VDD, Pin Tri-state
Weak Pullup Off
Weak Pullup On 10 ±1 µA
Input Capacitance 5 pF
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 237
A wide array of digital resources is available through the four lower I/O Ports: P0, P1, P2, and P3. Each of
the pins on P0, P1, P2, and P3, can be defined as a General-Purpose I/O (GPIO) pin or can be controlled
by a digital peripheral or function (like UART0 or /INT1 for example), as shown in Figure 1 8.2. The system
designer controls which digital functions are assigned pins, limited only by the number of pins available.
This resource assignment flexibility is achieved through the use of a Priority Crossbar Decoder. Note that
the state of a Port I/O pi n can alway s be read from its associated Data register regardless o f whether t hat
pin has been assigned to a digital peripheral or behaves as GPIO. The Port pins on Port 1 can be used as
Analog Inputs to ADC2.
An External Memory Interface which is active during the execu tion of an off-chip MOV X instr uctio n ca n be
active on either the lower Ports or the upper Ports. See Section “17. External Data Memory Interface
and On-Chip XRAM” on page 219 for more information about the External Memory Interface.
Figure 18.2. Port I/O Functional Block Diagram
External
Pins
Digital
Crossbar
Priority
Decoder
SMBus
2
SPI 4
UART0
2
PCA
2
T0, T1,
T2, T2EX,
T4,T4EX
/INT0,
/INT1
P1.0
P1.7
P2.0
P2.7
P0.0
P0.7
Highest
Priority
Lowest
Priority
8
8
Comptr.
Outputs
(Internal Digital Signals)
Highest
Priority
Lowest
Priority
UART1
/SYSCLK divided by 1,2,4, or 8
CNVSTR0/2
7
2
P3.0
P3.7
8
8
P0MDOUT, P1MDOUT,
P2MDOUT, P3MDOUT
Registers
XBR0, XBR1,
XBR2, P1MDIN
Registers
P1
I/O
Cells
P3
I/O
Cells
P0
I/O
Cells
P2
I/O
Cells
8
Port
Latches
P0
P1
P2
8
8
8
P3
8
(P2.0-P2.7)
(P1.0-P1.7)
(P0.0-P0.7)
(P3.0-P3.7)
To ADC 2 Input
(‘F12 x O n ly)
To E xte rn al
Memory
Interface
(EMIF)
2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
238 Rev. 1.4
18.1. Ports 0 through 3 and the Priority Crossbar Decoder
The Priority Crossbar Decoder, or “Crossbar”, allocates and assigns Port pins on Port 0 through Port 3 to
the digital peripherals (UARTs, SMBus, PCA, Timers, etc.) on the device using a priority order. The Port
pins are allocated in order starting with P0.0 and continue through P3.7 if necessary. The digital peripher-
als are assigned Port pins in a priority order which is listed in Figure 18.3, with UART0 having the highest
priority and CNVSTR2 having the lowest priority.
18.1.1. Crossbar Pin Assignment and Allocation
The Crossbar assigns Port pins to a peripheral if the corresponding enable bits of the peripheral are set to
a logic 1 in the Crossbar configuration registers XBR0, XBR1, and XBR2, shown in SFR Definition 18.1,
SFR Definition 18.2, and SFR Definition 18.3. For example, if the UART0EN bit (XBR0.2) is set to a
logic 1, the TX0 and RX0 pins will be mapped to P0.0 and P0.1 respectively.
Figure 18.3. Priority Crossbar Decode Table (EMIFLE = 0; P1MDIN = 0xFF)
Because UART0 has the highest priority, its pins will always be mapped to P0.0 and P0.1 when UAR T0EN
is set to a logic 1. If a digital peripheral’s enable bits are not set to a logic 1, then its ports are not accessi-
ble at the Port pins of the device. Also note that the Crossbar a ssigns pins to all a ssociated functions when
a serial communi cation peripheral is sele cted (i.e. SMBus, SPI, UART). It would be impossible, for exam-
PIN I/O 01234567012345670123456701234567
TX0
●
RX0
●
SCK
●●
MISO
●●
MOSI
●●
NSS
●●NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
SDA
● ●●●●●
SCL
● ●●●●●
TX1
● ●●●●●●●
RX1
● ●●●●●●●
CEX0
● ●●●●●●●●●
CEX1
● ●●●●●●●●●
CEX2
● ●●●●●●●●●
CEX3
● ●●●●●●●●●
CEX4
● ●●●●●●●●●
CEX5
● ●●●●●●●●●
ECI
●●●●●●●●●●●●●●●●●
ECI0E: XBR0.6
CP0
●●●●●●●●●●●●●●●●●●
CP0E: XBR0.7
CP1
●●●●●●●●●●●●●●●●●●●
CP1E: XBR1.0
T0
●●●●●●●●●●●●●●●●●●●●
T0E: XBR1.1
/INT0
●●●●●●●●●●●●●●●●●●●●●
INT0E: XBR1.2
T1
●●●●●●●●●●●●●●●●●●●●●●
T1E: XBR1.3
/INT1
●●●●●●●●●●●●●●●●●●●●●●●
INT1E: XBR1.4
T2
●●●●●●●●●●●●●●●●●●●●●●●●
T2E: XBR1.5
T2EX
●●●●●●●●●●●●●●●●●●●●●●●●●
T2EXE: XBR1.6
T4
●●●●●●●●●●●●●●●●●●●●●●●●●●
T4E: XBR2.3
T4EX
●●●●●●●●●●●●●●●●●●●●●●●●●●●
T4EXE: XBR2.4
/SYSCLK
●●●●●●●●●●●●●●●●●●●●●●●●●●●●
SYSCKE: XBR1.7
CNVSTR0
●●●●●●●●●●●●●●●●●●●●●●●●●●●●●
CNVSTE0: XBR2.0
CNVSTR2
●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●
CNVSTE2: XBR2.5
ALE
/RD
/WR
AIN2.0/A8
AIN2.1/A9
AIN2.2/A10
AIN2.3/A11
AIN2.4/A12
AIN2.5/A13
AIN2.6/A14
AIN2.7/A15
A8m/A0
A9m/A1
A10m/A2
A11m/A3
A12m/A4
A13m/A5
A14m/A6
A15m/A7
AD0/D0
AD1/D1
AD2/D2
AD3/D3
AD4/D4
AD5/D5
AD6/D6
AD7/D7
P0 P1 P2 P3
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
UART1EN:
PCA0ME:
Crossbar Register Bits
XBR0.2
XBR0.1
XBR0.0SMB0EN:
XBR2.2
XBR0.[5:3]
UART0EN:
SPI0EN:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 239
ple, to assign TX0 to a Port pin without assigning RX0 as well. Each combination of enabled peripherals
results in a unique device pinout.
All Port pins on Ports 0 through 3 that are not allocated by the Crossbar can be accessed as General-Pur-
pose I/O (GPIO ) pins by r eading and writing the associat ed Port Data register s (See SFR De finition 18.4,
SFR Definition 18.6, SFR Definition 18.9, and SFR Definition 18.11), a set of SFR’s which are both byte-
and bit-addressabl e. The ou tput states of Port pins that are allocated by the Crossbar are controlled by the
digital peripheral that is mapped to those pins. Writes to the Port Data registers (or associated Port bits)
will have no effect on the states of these pins.
A Read of a Port Data register (or Port bit) will always return the logic state present at the pin it self, regard-
less of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs
during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC,
CLR, SETB, and the bitwise MOV write operation). During the read cycle of the read-modify-write instruc-
tion, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read.
Note that at clock rates above 50 MHz, when a pin is written and the n immediately read (i .e. a write instru c-
tion followed immediately by a read instruction), the propagation delay of the port drivers may cause the
read instruction to return the previous logic level of the pin.
Because the Crossbar registers affect the pinout of the peripherals of the device, they are typically config-
ured in the initialization code of the system before the peripher als themselves are con figured. Once config-
ured, the Crossbar registers are typically left alone.
Once the Crossbar registers have been properly configured, the Crossbar is enabled by setting XBARE
(XBR2.4) to a logic 1. Until XBARE is set to a logic 1, the output drivers on Ports 0 through 3 are
explicitly disabled in order to prevent possible contention on the Port pins while the Crossbar reg-
isters and other registers which can affect the device pinout are being written.
The output drivers on Crossbar-assigned input signals (like RX0, for example) are explicitly disabled; thus
the values of the Port Data registers and the PnMDOUT registers have no effect on the states of these
pins.
18.1.2. Configuring the Output Modes of the Port Pins
The output drivers on Ports 0 through 3 remain disabled until the Crossbar is enabled by setting XBARE
(XBR2.4) to a logic 1.
The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull
configuration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be
driven to GND, and writing a logic 1 will cause the Port pin to be driven to VDD. In the Open-Drain configu-
ration, writing a logic 0 to the associated bit in the Port Data register will cause the Port pin to be driven to
GND, and a logic 1 will cause the Port pin to assume a high-impedance state. The Open-Drain configura-
tion is useful to prevent contention between devices in systems where the Port pin participates in a shared
interconnection in which multiple outp uts are conne cted to th e same physical wire (like the SDA signal on
an SMBus connection).
The output modes of the Port pins on Ports 0 through 3 are determined by the bits in the associated
PnMDOUT registers (See SFR Definition 18.5, SFR Definition 18.8, SFR Definition 18.10 , and SFR Defini-
tion 18.12). For example, a logic 1 in P3MDOUT.7 will configure the output mode of P3.7 to Push-Pull; a
logic 0 in P3MDOUT.7 will configure the output mode of P3.7 to Open-Drain. All Port pins default to Open-
Drain output.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
240 Rev. 1.4
The PnMDOUT registers contro l th e out put m odes of th e p or t pins r ega rd less of wh ethe r the Cro ssbar h as
allocated the Port pin for a digital peripheral or not. The exceptions to this rule are: the Port pin s conne cted
to SDA, SCL, RX0 (if UART0 is in Mode 0), and RX1 (if UART1 is in Mode 0) are always configured as
Open-Drain outputs, regardless of the settings of the associated bit s in the PnMDOUT registers.
18.1.3. Configuring Port Pins as Digital Inputs
A Port pin is configured as a digital input by setting it s output mode to “O pen-Dr ain” and writing a logic 1 to
the associated bit in the Port Data register. For example, P3.7 is configured as a digital input by setting
P3MDOUT.7 to a logic 0 and P3.7 to a logic 1.
If the Port pin has been assigned to a digital peripheral by the Crossbar and that pin functions as an input
(for example RX0, the UART0 receive pin), then the output drivers on that pin are au tomatically disabled.
18.1.4. Weak Pullups
By default, each Port pin has an internal weak pullup device enabled which provides a resistive conne ction
(about 100 k) between the pin and VDD. The weak pullup devices can be globally disabled by writing a
logic 1 to the Weak Pullup Disable bit, (WEAKPUD, XBR2.7). The weak pullup is automatically deactivated
on any pin that is driving a logic 0; that is, an output pin will not contend with its own pullup device. The
weak pullup device can also be explicitly disabled on any Port 1 pin by configuring the pin as an Analog
Input, as described below.
18.1.5. Configuring Port 1 Pins as Analog Inputs
The pins on Port 1 can se rve as analog input s to the ADC2 analog MUX on the C8051F1 2x devices. A Port
pin is configured as an Analog Input by writing a logic 0 to the associated bit in the PnMDIN registers. All
Port pins default to a Digital Input mode. Configuring a Port pin as an analog input:
1. Disables the digital input path from the pin. This prevents additiona l power supp ly curr ent fro m
being drawn when the voltage at the pin is near VDD / 2. A read of the Port Data bit will return
a logic 0 regardless of the voltage at the Port pin.
2. Disabl es the we ak pu llu p device on the pin.
3. Causes the Crossbar to “skip over” the pin when allocating Port pins for digital peripherals.
Note that the output drivers on a pin configured as an Analog Input are not explicitly disabled. Therefore,
the associated P1MDOUT bits of pins configured as Analog Inputs should explicitly be set to logic 0
(Open-Drain output mode), and the associated Port1 Data bits should be set to logic 1 (high-impedance).
Also note that it is not required to configure a Port pin as an Analog Input in order to use it as an input to
ADC2, however, it is strongly recommended. See the ADC2 section in this datasheet for further informa-
tion.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 241
18.1.6. External Memory Interface Pin Assignments
If the External Memory Interface (EMIF) is enab led on the Lo w ports (Po rts 0 through 3), EMIFLE (XBR2.5)
should be set to a logic 1 so that the Crossbar will not assign peripherals to P0.7 (/WR), P0.6 (/RD), and if
the External Memory Interface is in Multiplexed mode, P0.5 (ALE). Figure 18.4 shows an example Cross-
bar Decode Table with EMIFLE=1 and the EMIF in Multiplexed mode. Figure 18.5 shows an example
Crossbar Decode Table with EMIFLE=1 and the EMIF in Non-multiplexed mode.
If the External Memory Interface is enabled on the Low ports and an off-chip MOVX operation occurs, the
External Memory Interface will control the output states of the affected Port pins during the execution
phase of the MOVX instruction, regardless of the settings of the Crossbar registers or the Port Data regis-
ters. The output configuration of the Port pins is not affected by the EMIF operation, except that Read
operations will explicitly disable the output drivers on the Data Bus. See Section “17. External Dat a Mem-
ory Interface and On-Chip XRAM” on page 219 for more information about the External Memory Inter-
face.
Figure 18.4. Priority Crossbar Decode Table (EMIFLE = 1; EMIF in Multiplexed
Mode; P1MDIN = 0xFF)
PIN I/O 01234567012345670123456701234567
TX0 ●
RX0 ●
SCK ●●
MISO ●●
MOSI ●●
NSS ●●
NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
SDA ● ●●● ●●
SCL ● ●● ●●●
TX1 ● ●●● ●●●●
RX1 ● ●● ●●●●●
CEX0 ● ●●● ●●●●●●
CEX1 ● ●● ●●●●●●●
CEX2 ● ● ●●●●●●●●
CEX3 ● ●●●●●●●●●
CEX4 ● ●●●●●●●●●
CEX5 ● ●●●●●●●●●
ECI ●●●●● ●●●●●●●●●●●● ECI0E: XBR0.6
CP0 ●●●●● ●●●●●●●●●●●●● CP0E: XBR0.7
CP1 ●●●●● ●●●●●●●●●●●●●● CP1E: XBR1.0
T0 ●●●●● ●●●●●●●●●●●●●●● T0E: XBR1.1
/INT0 ●●●●● ●●●●●●●●●●●●●●●● INT0E: XBR1.2
T1 ●●●●● ●●●●●●●●●●●●●●●●● T1E: XBR1.3
/INT1 ●●●●● ●●●●●●●●●●●●●●●●●● INT1E: XBR1.4
T2 ●●●●● ●●●●●●●●●●●●●●●●●●● T2E: XBR1.5
T2EX ●●●●● ●●●●●●●●●●●●●●●●●●●● T2EXE: XBR1.6
T4 ●●●●● ●●●●●●●●●●●●●●●●●●●●● T4E: XBR2.3
T4EX ●●●●● ●●●●●●●●●●●●●●●●●●●●●● T4EXE: XBR2.4
/SYSCLK ●●●●● ●●●●●●●●●●●●●●●●●●●●●●● SYSCKE: XBR1.7
CNVSTR0 ●●●●● ●●●●●●●●●●●●●●●●●●●●●●●● CNVSTE0: XBR2.0
CNVSTR2 ●●●●● ●●●●●●●●●●●●●●●●●●●●●●●● CNVSTE2: XBR2.5
ALE
/RD
/WR
AIN2.0/A8
AIN2.1/A9
AIN2.2/A10
AIN2.3/A11
AIN2.4/A12
AIN2.5/A13
AIN2.6/A14
AIN2.7/A15
A8m/A0
A9m/A1
A10m/A2
A11m/A3
A12m/A4
A13m/A5
A14m/A6
A15m/A7
AD0/D0
AD1/D1
AD2/D2
AD3/D3
AD4/D4
AD5/D5
AD6/D6
AD7/D7
XBR2.2
XBR0.[5:3]
UART0EN:
SPI0EN:
Crossbar Register Bits
XBR0.2
XBR0.1
XBR0.0SMB0EN:
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
UART1EN:
PCA0ME:
P0 P1 P2 P3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
242 Rev. 1.4
Figure 18.5. Priority Crossbar Decode Table (EMIFLE = 1; EMIF in Non-Multiplexed
Mode; P1MDIN = 0xFF)
PIN I/O 01234567012345670123456701234567
TX0 ●
RX0 ●
SCK ●●
MISO ●●
MOSI ●●
NSS ●● NSS is not assigned to a port pin when the SPI is placed in 3-wire mode
SDA ● ●●●● ●
SCL ● ●●● ●●
TX1 ● ●●●● ●●●
RX1 ● ●●● ●●●●
CEX0 ● ●●●● ●●●●●
CEX1 ● ●●● ●●●●●●
CEX2 ●●● ●●●●●●●
CEX3 ●● ●●●●●●●●
CEX4 ●●●●●●●●●●
CEX5 ●●●●●●●●●●
ECI ●●●●●● ●●●●●●●●●●● ECI0E: XBR0.6
CP0 ●●●●●● ●●●●●●●●●●●● CP0E: XBR0.7
CP1 ●●●●●● ●●●●●●●●●●●●● CP1E: XBR1.0
T0 ●●●●●● ●●●●●●●●●●●●●● T0E: XBR1.1
/INT0 ●●●●●● ●●●●●●●●●●●●●●● INT0E: XBR1.2
T1 ●●●●●● ●●●●●●●●●●●●●●●● T1E: XBR1.3
/INT1 ●●●●●● ●●●●●●●●●●●●●●●●● INT1E: XBR1.4
T2 ●●●●●● ●●●●●●●●●●●●●●●●●● T2E: XBR1.5
T2EX ●●●●●● ●●●●●●●●●●●●●●●●●●● T2EXE: XBR1.6
T4 ●●●●●● ●●●●●●●●●●●●●●●●●●●● T4E: XBR2.3
T4EX ●●●●●● ●●●●●●●●●●●●●●●●●●●●● T4EXE: XBR2.4
/SYSCLK ●●●●●● ●●●●●●●●●●●●●●●●●●●●●● SYSCKE: XBR1.7
CNVSTR0 ●●●●●● ●●●●●●●●●●●●●●●●●●●●●●● CNVSTE0: XBR2.0
CNVSTR2 ●●●●●● ●●●●●●●●●●●●●●●●●●●●●●●● CNVSTE2: XBR2.5
ALE
/RD
/WR
AIN2.0/A8
AIN2.1/A9
AIN2.2/A10
AIN2.3/A11
AIN2.4/A12
AIN2.5/A13
AIN2.6/A14
AIN2.7/A15
A8m/A0
A9m/A1
A10m/A2
A11m/A3
A12m/A4
A13m/A5
A14m/A6
A15m/A7
AD0/D0
AD1/D1
AD2/D2
AD3/D3
AD4/D4
AD5/D5
AD6/D6
AD7/D7
XBR2.2
XBR0.[5:3]
UART0EN:
SPI0EN:
Crossbar Register Bits
XBR0.2
XBR0.1
XBR0.0SMB0EN:
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
UART1EN:
PCA0ME:
P0 P1 P2 P3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 243
18.1.7. Crossbar Pin Assignment Example
In this example (Figure 18.6), we configure the Crossbar to allocate Port pins for UART0, the SMBus,
UART1, /INT0, and /INT1 (8 pins total). Additionally, we configure the External Memory Interface to oper-
ate in Multiplexed mode and to appear on the Low ports. Further, we configure P1.2, P1.3, and P1.4 for
Analog Input mode so that the voltages at these pins can be measured by ADC2. The configuration steps
are as follows:
1. XBR0, XBR1, and XBR2 are set such that UART0EN = 1, SMB0EN = 1, INT0E = 1,
INT1E = 1, and EMIFLE = 1. Thus: XBR0 = 0x05, XBR1 = 0x14, and XBR2 = 0x02.
2. We configure the External Memory Interface to use Multiplexed mode and to appear on the
Low ports. PRTSEL = 0, EMD2 = 0.
3. We configure the desired Port 1 pins to Analog Input mode by setting P1MDIN to 0xE3
(P1.4, P1.3, and P1.2 are Anal og Inputs, so their associated P1MDIN bits are set to logic 0).
4. We enable the Crossbar by setting XBARE = 1: XBR2 = 0x42.
- UART0 has the highest priori ty, so P0.0 is assigned to TX0, and P0.1 is assigned to RX0 .
- The SMBus is next in priority order, so P0.2 is assigned to SDA, and P0.3 is assigned to
SCL.
- UART1 is next in priority order, so P0.4 is assigned to TX1. Because the External Memory
Interface is selected on the lower Ports, EMIFLE = 1, which causes the Crossbar to skip
P0.6 (/RD) and P0.7 (/WR). Because the External Memory Inter face is con figur ed in Multi-
plexed mode, the Crossbar will also skip P0.5 (ALE). RX1 is assigned to the next non-
skipped pin, which in this case is P1.0.
- /INT0 is next in priority order, so it is assigned to P1.1.
- P1MDIN is set to 0xE3, which configures P1.2, P1.3, and P1.4 as Analog Inputs, causing
the Crossbar to skip these pins.
- /INT1 is next in priority order, so it is assigned to the next non-skipped pin, which is P1.5.
- The External Memory Interface will drive Ports 2 and 3 (denoted by red dots in
Figure 18.6) during the execution of an off-chip MOVX instructio n.
5. We set the UART0 TX pin (TX0, P0.0) and UART1 TX pin (TX1, P0.4) output s to Push-Pull by
setting P0MDOUT = 0x11.
6. We configure all EMIF- controlled pi ns to push-pu ll output mode by setting P0MDOUT |= 0xE0;
P2MDOUT = 0xFF; P3MDOUT = 0xFF.
7. We explicitly disable the output drivers on the 3 Analog Input pins by setting P1MDOUT =
0x00 (configure outputs to Open-Drain) and P1 = 0xFF (a logic 1 selects the high-impedance
state).
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
244 Rev. 1.4
Figure 18.6. Crossbar Example
PIN I/O 01234567012345670123456701234567
TX0 ●
RX0 ●
SCK ●●
MISO ●●
MOSI ●●
NSS ●●
SDA ●●●● ●●
SCL ●●●●●●
TX1 ●●●●●● ●●
RX1 ●●● ●● ●●●
CEX0 ● ●●● ●● ●●●●
CEX1 ●●●●●●●●●●
CEX2 ● ● ●● ●●●●●●
CEX3 ● ●● ●●●●●●●
CEX4 ●●●●●●●●●●●
CEX5 ●● ●●●●●●●●●
ECI ●●●●● ●● ●●●●●●●●●● ECI0E: XBR0.6
CP0 ●●●●● ●● ●●●●●●●●●●● CP0E: XBR0.7
CP1 ●●●●● ●● ●●●●●●●●●●●● CP1E: XBR1.0
T0 ●●●●● ●● ●●●●●●●●●●●●● T0E: XBR1.1
/INT0 ●●●●● ●●●●●●●●●●●●●●●● INT0E: XBR1.2
T1 ●●●●● ●● ●●●●●●●●●●●●●●● T1E: XBR1.3
/INT1 ●●●●● ●● ●●●●●●●●●●●●●●●● INT1E: XBR1.4
T2 ●●●●● ●● ●●●●●●●●●●●●●●●●● T2E: XBR1.5
T2EX ●●●●● ●● ●●●●●●●●●●●●●●●●●● T2EXE: XBR1.6
T4 ●●●●● ●● ●●●●●●●●●●●●●●●●●●● T4E: XBR2.3
T4EX ●●●●● ●● ●●●●●●●●●●●●●●●●●●● T4EXE: XBR2.4
/SYSCLK ●●●●● ●● ●●●●●●●●●●●●●●●●●●● SYSCKE: XBR1.7
CNVSTR0 ●●●●● ●● ●●●●●●●●●●●●●●●●●●● CNVSTE0: XBR2.0
CNVSTR2 ●●●●● ●● ●●●●●●●●●●●●●●●●●●● CNVSTE2: XBR2.5
ALE
/RD
/WR
AIN2.0/A8
AIN2.1/A9
AIN2.2/A10
AIN2.3/A11
AIN2.4/A12
AIN2.5/A13
AIN2.6/A14
AIN2.7/A15
A8m/A0
A9m/A1
A10m/A2
A11m/A3
A12m/A4
A13m/A5
A14m/A6
A15m/A7
AD0/D0
AD1/D1
AD2/D2
AD3/D3
AD4/D4
AD5/D5
AD6/D6
AD7/D7
XBR2.2
XBR0.[5:3]
UART0EN:
SPI0EN:
Crossbar Register Bits
XBR0.2
XBR0.1
XBR0.0SMB0EN:
AIN2 Inputs/Non-muxed Addr H Muxed Addr H/Non-muxed Addr L Muxed Data/Non-muxed Data
UART1EN:
PCA0ME:
P0 P1 P2 P3
(EMIFLE = 1; EMIF in Multiplexed Mode; P1MDIN = 0xE3;
XBR0 = 0x05; XBR1 = 0x14; XBR2 = 0x42)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 245
SFR Definition 18.1. XBR0: Port I/O Crossbar Register 0
Bit7: CP0E: Comparator 0 Output Enable Bit.
0: CP0 unavailable at Port pin.
1: CP0 routed to Port pin.
Bit6: ECI0E: PCA0 External Counter Input Enable Bit.
0: PCA0 External Counter Input unavailable at Port pin.
1: PCA0 External Counter Input (ECI0) routed to Port pin.
Bits5–3: PCA0ME: PCA0 Module I/O Enable Bits.
000: All PCA0 I/O unavailable at port pins.
001: CEX0 routed to port pin.
010: CEX0, CEX1 routed to 2 port pins.
011: CEX0, CEX1, and CEX2 routed to 3 port pins.
100: CEX0, CEX1, CEX2, and CEX3 routed to 4 port pins.
101: CEX0, CEX1, CEX2, CEX3, and CEX4 rout ed to 5 po rt pins.
110: CEX0, CEX1, CEX2, CEX3, CEX4, and CEX5 routed to 6 port pins.
Bit2: UART0EN: UART0 I/O Enable Bit.
0: UART0 I/O unavailable at Port pins.
1: UART0 TX routed to P0.0, and RX routed to P0.1.
Bit1: SPI0EN: SPI0 Bus I/O Enable Bit.
0: SPI0 I/O unavailable at Port pins .
1: SPI0 SCK, MISO, MOSI, and NSS routed to 4 Port pins. Note that the NSS signal is not
assigned to a port pin if the SPI is in 3-wire mode. See Section “ 17. External Data Memory
Interface and On-Chip XRAM” on page 219 for more information.
Bit0: SMB0EN: SMBus0 Bus I/O Enable Bit.
0: SMBus0 I/O unavailable at Port pins.
1: SMBus0 SDA and SCL routed to 2 Port pins.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
CP0E ECI0E PCA0ME UART0EN SPI0EN SMB0EN 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xE1
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
246 Rev. 1.4
SFR Definition 18.2. XBR1: Port I/O Crossbar Register 1
Bit7: SYSCKE: /SYSCLK Output Enable Bit.
0: /SYSCLK unavailable at Port pin.
1: /SYSCLK (divided by 1, 2, 4, or 8) routed to Port pin. divide factor is determined by the
CLKDIV1–0 bits in register CLKSEL (See Section “14. Oscillators” on page 185).
Bit6: T2EXE: T2EX Input Enable Bit.
0: T2EX unavailable at Port pin.
1: T2EX routed to Port pin.
Bit5: T2E: T2 Input Enable Bit.
0: T2 unavailable at Port pin.
1: T2 routed to Port pin.
Bit4: INT1E: /INT1 Input Enable Bit.
0: /INT1 unavaila b l e at Por t pin .
1: /INT1 routed to Port pin.
Bit3: T1E: T1 Input Enable Bit.
0: T1 unavailable at Port pin.
1: T1 routed to Port pin.
Bit2: INT0E: /INT0 Input Enable Bit.
0: /INT0 unavaila b l e at Por t pin .
1: /INT0 routed to Port pin.
Bit1: T0E: T0 Input Enable Bit.
0: T0 unavailable at Port pin.
1: T0 routed to Port pin.
Bit0: CP1E: CP1 Output Enable Bit.
0: CP1 unavailable at Port pin.
1: CP1 routed to Port pin.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
SYSCKE T2EXE T2E INT1E T1E INT0E T0E CP1E 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xE2
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 247
SFR Definition 18.3. XBR2: Port I/O Crossbar Register 2
Bit7: WEAKPUD: Weak Pullup Disable Bit.
0: Weak pullups globally enabled.
1: Weak pullups globally disabled.
Bit6: XBARE: Crossbar Enable Bit.
0: Crossbar disabled. All pins on Ports 0, 1, 2, and 3, are forced to Input mode.
1: Crossbar enabled.
Bit5: CNVST2E: External Convert Start 2 Input Enable Bit.
0: CNVSTR2 unavailab le at Port pin.
1: CNVSTR2 routed to Port pin.
Bit4: T4EXE: T4EX Input Enable Bit.
0: T4EX unavailable at Port pin.
1: T4EX routed to Port pin.
Bit3: T4E: T4 Input Enable Bit.
0: T4 unavailable at Port pin.
1: T4 routed to Port pin.
Bit2: UART1E: UART1 I/O Enable Bit.
0: UART1 I/O unavailable at Port pins.
1: UART1 TX and RX routed to 2 Port pins.
Bit1: EMIFLE: External Memory Inter f a ce Lo w- Port Enable Bit.
0: P0.7, P0.6, and P0. 5 fu nc tion s ar e determined by the Crossbar or the Port latches.
1: If EMI0CF.4 = ‘0’ (External Memory Interface is in Multiplexed mode)
P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) are ‘skipped’ by the Crossbar and their
output states are determined by the Port la tches and the Exter nal Memory Interface.
1: If EMI0CF.4 = ‘1’ (External Memory Interface is in Non-multiplexed mode)
P0.7 (/WR) and P0.6 (/RD) are ‘skipped’ by the Crossbar an d their outpu t states are
determined by the Port latches and the External Memory Interface.
Bit0: CNVST0E: ADC0 External Convert Start Input Enable Bit.
0: CNVST0 for ADC0 unava ilab l e at Port pin.
1: CNVST0 for ADC0 routed to Port pin.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
WEAKPUD XBARE CNVST2E T4EXE T4E UART1E EMIFLE CNVST0E 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xE3
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
248 Rev. 1.4
SFR Definition 18.4. P0: Port0 Data
SFR Definition 18.5. P0MDOUT: Port0 Output Mode
Bits7–0: P0.[7:0]: Port0 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registe rs)
0: Logic Low Output.
1: Logic High Output (open if corr esponding P0MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, an d XBR2 Register settings).
0: P0.n pin is logic low.
1: P0.n pin is logic high.
Note: P0.7 (/WR), P0.6 (/RD), and P0.5 (ALE) can be driven by the External Data Memory Interface.
See Section “17. External Data Memory Interface and On-Chip XRAM” on page 219 for
more information. See also SFR Definition 18.3 for information about configuring the Crossbar
for External Memory accesses.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P0.7 P0.6 P0.5 P0.4 P0.3 P0.2 P0.1 P0.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0x80
All Pages
Bits7–0: P0MDOUT.[7:0]: Port0 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are
always configured as Open-Drain when they appear on Port pins.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA4
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 249
SFR Definition 18.6. P1: Port1 Data
SFR Definition 18.7. P1MDIN: Port1 Input Mode
Bits7–0: P1.[7:0]: Port1 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registe rs)
0: Logic Low Output.
1: Logic High Output (open if corr esponding P1MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, an d XBR2 Register settings).
0: P1.n pin is logic low.
1: P1.n pin is logic high.
Notes: 1.On C8051F12x devices, P1.[7:0] can be configured as inputs to ADC2 as AIN2.[7:0], in which
case they are ‘skipped’ by the Crossbar assignment process and their digital input paths are
disabled, depending on P1MDIN (See SFR Definition 18.7). Note that in analog mode, the
output mode of the pin is determined by the Port 1 latch and P1MDOUT (SFR De finition 18.8).
See Section “7. ADC2 (8-Bit ADC, C8051F12x Only)” on page 91 for more information
about ADC2.
2. P1.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-
multiplexed mode). See Section “17. External Data Memory Interface and On-Chip
XRAM” on page 219 for more in formation about the External Memory Interface.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P1.7 P1.6 P1.5 P1.4 P1.3 P1.2 P1.1 P1.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0x90
All Pages
Bits7–0: P1MDIN.[7:0]: Port 1 Input Mode Bits.
0: Port Pin is configured in Analog Input mode. Th e digital input path is disabled (a read from
the Port bit will always return ‘0’). The weak pullup on the pin is disabled.
1: Port Pin is configured in Digital Input mode. A read from the Port bit will return the logic
level at the Pin. When configured as a digital input, the state of the we ak pu llu p for the por t
pin is determined by the WEAKPUD bit (XBR2.7, see SFR Definition 18.3).
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xAD
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
250 Rev. 1.4
SFR Definition 18.8. P1MDOUT: Port1 Output Mode
SFR Definition 18.9. P2: Port2 Data
Bits7–0: P1MDOUT.[7:0]: Port1 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are
always configured as Open-Drain when they appear on Port pins.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA5
F
Bits7–0: P2.[7:0]: Port2 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registers)
0: Logic Low Output.
1: Logic High Output (open if corresponding P2MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, and XBR2 Register settings).
0: P2.n pin is logic low.
1: P2.n pin is logic high.
Note: P2.[7:0] can be dr iven by the External Dat a Memory Interface (as Address[15:8] in Multiplexed
mode, or as Address[7:0] in Non-multiplexed mode). See Section “17. External Data
Memory Interface and On-Chip XRAM” on page 219 for more information about the
External Memory Interface.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P2.7 P2.6 P2.5 P2.4 P2.3 P2.2 P2.1 P2.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR
Address:
SFR Page:
0xA0
All Pages
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 251
SFR Definition 18.10. P2MDOUT: Port2 Output Mode
SFR Definition 18.11. P3: Port3 Data
Bits7–0: P2MDOUT.[7:0]: Port2 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
Note: SDA, SCL, and RX0 (when UART0 is in Mode 0) and RX1 (when UART1 is in Mode 0) are
always configure d as Open-Drain when they appear on Port pins.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA6
F
Bits7–0: P3.[7:0]: Port3 Output Latch Bits.
(Write - Output appears on I/O pins per XBR0, XBR1, and XBR2 Registe rs)
0: Logic Low Output.
1: Logic High Output (open if corr esponding P3MDOUT.n bit = 0).
(Read - Regardless of XBR0, XBR1, an d XBR2 Register settings).
0: P3.n pin is logic low.
1: P3.n pin is logic high.
Note: P3.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed
mode, or as D[7:0] in Non-multiplexed mode). See Section “17. External Data Memory
Interface and On-Chip XRAM” on pa ge 219 for more information about the Externa l Memory
Interface.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P3.7 P3.6 P3.5 P3.4 P3.3 P3.2 P3.1 P3.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xB0
All Pages
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
252 Rev. 1.4
SFR Definition 18.12. P3MDOUT: Port3 Output Mode
18.2. Ports 4 through 7 (100-pin TQFP devices only)
All Port pins on Ports 4 through 7 can be accessed as General-Purpose I/O (GPIO) pins by reading and
writing the associated Port Data registers (See SFR Definition 18.13, SFR Definition 18.15, SFR Definition
18.17, and SFR Definition 18.19), a set of SFR’s which are both bit and byte-addressable. Note also that
the Port 4, 5, 6, and 7 registers are located on SFR Pa ge F. The SFRPAGE register must be set to 0x0F to
access these Port registers.
A Read of a Port Data register (or Port bit) will always return the logic state present at the pin it self, regard-
less of whether the Crossbar has allocated the pin for peripheral use or not. An exception to this occurs
during the execution of a read-modify-write instruction (ANL, ORL, XRL, CPL, INC, DEC, DJNZ, JBC,
CLR, SETB, and the bitwise MOV write operation). During the read cycle of the read-modify-write instruc-
tion, it is the contents of the Port Data register, not the state of the Port pins themselves, which is read.
Note that at clock rates above 50 MHz, when a pin is written and the n immediately read (i .e. a write instru c-
tion followed immediately by a read instruction), the propagation delay of the port drivers may cause the
read instruction to return the previous logic level of the pin.
18.2.1. Configuring Ports which are not Pinned Out
Although P4, P5, P6, and P7 are not brought out to pins on the 64-pin TQFP devices, the Port Data regis-
ters are still present and can be used by software. Because the digital input paths also remain active, it is
recommended that these pins not be left in a ‘floating’ state in order to avoid unnecessary power dissipa-
tion arising from the inputs floating to non-valid logic levels. This condition can be prevented by any of the
following:
1. Leav e the we ak pullu p de vice s en a ble d by setting WEAKPUD (XBR2.7) to a logic 0.
2. Configure the output modes of P4, P5, P6, and P7 to “P ush-Pull” by writing PnM DOUT = 0xFF.
3. Force the output states of P4, P5, P6, an d P7 to logic 0 by writing zer os to the Por t Dat a regis-
ters: P4 = 0x00, P5 = 0x00, P6= 0x00, and P7 = 0x00.
18.2.2. Configuring the Output Modes of the Port Pins
The output mode of each port pin can be configured to be either Open-Drain or Push-Pull. In the Push-Pull
configuration, a logic 0 in the associated bit in the Port Data register will cause the Port pin to be driven to
GND, and a logic 1 will ca use th e Po rt pin to b e d riven to V DD. In the Ope n- Drain configu ratio n, a logic 0 i n
the associated bit in the Port Data register will cause the Port pin to be driven to GND, and a logic 1 will
cause the Port pin to assume a high-impedance state. The Open-Drain configuration is useful to prevent
contention between devices in systems where the Port pin participates in a shared interconnection in
which multiple outputs are connected to the same physical wire.
Bits7–0: P3MDOUT.[7:0]: Port3 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA7
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 253
The output modes of the Port pins on Ports 4 through 7 are determined by the bits in their respective
PnMDOUT Output Mode Registers. Each bit in PnMDOUT controls the output mode of its corresponding
port pin (see SFR De finition 18.14, SFR Definition 18 .16, SFR Definition 18 .18, an d SF R Defin itio n 1 8.20).
For example, to place Port pin 4.3 in push-pull mode (digital output), set P4MDOUT.3 to logic 1. All port
pins default to open-drain mode upon device reset.
18.2.3. Configuring Port Pins as Digital Inputs
A Port pin is configured as a digital input by setting it s output mode to “O pen-Dr ain” and writing a logic 1 to
the associated bit in the Port Data register. For example, P7.7 is configured as a digital input by setting
P7MDOUT.7 to a logic 0 and P7.7 to a logic 1.
18.2.4. Weak Pullups
By default, each Port pin has an internal weak pullup device enabled which provides a resistive conne ction
(about 100 k) between the pin and VDD. The weak pullup devices can be globally disabled by writing a
logic 1 to the Weak Pullup Disable bit, (WEAKPUD, XBR2.7). The weak pullup is automatically deactivated
on any pin that is driving a logic 0; that is, an output pin will not contend with its own pullup device.
18.2.5. External Memory Interface
If the External Memory Interface (EMIF) is enabled on the High ports (Ports 4 through 7), EMIFLE
(XBR2.5) should be set to a logic 0.
If the External Memory Interface is enabled on the High ports and an off-chip MOVX operation occurs, the
External Memory Interface will control the output states of the affected Port pins during the execution
phase of the MOVX instruction, regardless of the settings of the Port Data registers. The output configura-
tion of the Port pins is not affected by the EMIF operation, except that Read operations will explicitly dis-
able the output drivers on the Data Bus during the MOVX execution. See Section “17. External Data
Memory Interface and On-Chip XRAM” on page 219 for more information about the External Memory
Interface.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
254 Rev. 1.4
SFR Definition 18.13. P4: Port4 Data
SFR Definition 18.14. P4MDOUT: Port4 Output Mode
Bits7–0: P4.[7:0]: Port4 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open-Drain if corresponding P4MDOUT.n bit = 0). See SFR Definition
18.14.
Read - Returns states of I/O pins.
0: P4.n pin is logic low.
1: P4.n pin is logic high.
Note: P4.7 (/WR), P4.6 (/RD), and P4.5 (ALE) can be driven by the External Data Memory Interface.
See Section “17. External Data Memory Interface and On-Chip XRAM” on page 219 for
more information.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P4.7 P4.6 P4.5 P4.4 P4.3 P4.2 P4.1 P4.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xC8
F
Bits7–0: P4MDOUT.[7:0]: Port4 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9C
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 255
SFR Definition 18.15. P5: Port5 Data
SFR Definition 18.16. P5MDOUT: Port5 Output Mode
Bits7–0: P5.[7:0]: Port5 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open- Drain if corresponding P5MDOUT bit = 0). See SFR Definition
18.16.
Read - Returns states of I/O pins.
0: P5.n pin is logic low.
1: P5.n pin is logic high.
Note: P5.[7:0] can be driven by the External Data Memory Interface (as Address[15:8] in Non-
multiplexed mode). See Section “17. External Data Memory Interface and On-Chip
XRAM” on page 219 for more in formation about the External Memory Interface.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P5.7 P5.6 P5.5 P5.4 P5.3 P5.2 P5.1 P5.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xD8
F
Bits7–0: P5MDOUT.[7:0]: Port5 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9D
F
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
256 Rev. 1.4
SFR Definition 18.17. P6: Port6 Data
SFR Definition 18.18. P6MDOUT: Port6 Output Mode
Bits7–0: P6.[7:0]: Port6 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open- Drain if corresponding P6MDOUT bit = 0). See SFR Definition
18.18.
Read - Returns states of I/O pins.
0: P6.n pin is logic low.
1: P6.n pin is logic high.
Note: P6.[7:0] can be driven by th e External Data Me mory Interface (as Address[15:8] in Multiple xed
mode, or as Address[7:0] in Non-multiplexed mode). See Section “17. External Data
Memory Interface and On-Chip XRAM” on page 219 for more information abou t th e
External Memory Interface.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P6.7 P6.6 P6.5 P6.4 P6.3 P6.2 P6.1 P6.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xE8
F
Bits7–0: P6MDOUT.[7:0]: Port6 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9E
F
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SFR Definition 18.19. P7: Port7 Data
SFR Definition 18.20. P7MDOUT: Port7 Output Mode
Bits7–0: P7.[7:0]: Port7 Output Latch Bits.
Write - Output appears on I/O pins.
0: Logic Low Output.
1: Logic High Output (Open- Drain if corresponding P7MDOUT bit = 0). See SFR Definition
18.20.
Read - Returns states of I/O pins.
0: P7.n pin is logic low.
1: P7.n pin is logic high.
Note: P7.[7:0] can be driven by the External Data Memory Interface (as AD[7:0] in Multiplexed
mode, or as D[7:0] in Non-multiplexed mode). See Section “17. External Data Memory
Interface and On-Chip XRAM” on pa ge 219 for more information about the Externa l Memory
Interface.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
P7.7 P7.6 P7.5 P7.4 P7.3 P7.2 P7.1 P7.0 11111111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xF8
F
Bits7–0: P7MDOUT.[7:0]: Port7 Output Mode Bits.
0: Port Pin output mode is configured as Open-Drain.
1: Port Pin output mode is configured as Push-Pull.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9F
F
C8051F120/1/2/3/4/5/6/7
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NOTES:
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19. System Management Bus / I2C Bus (SMBus0)
The SMBus0 I/O interface is a two-wire, bi-directional serial bus. SMBus0 is compliant with the System
Management Bus Specification, version 1.1, and compatible with the I2C serial bus. Reads and writes to
the interface by the system controller are byte oriented with the SMBus0 interface autonomously control-
ling the serial transfer of the data. A method of extending the clock-low duration is available to accommo-
date devices with different speed capabilities on the same bus.
SMBus0 may operate as a m aster and/o r slave, and may function on a b us with multiple ma sters. SMBu s0
provides control of SDA (serial data), SCL (serial clock) generation and synchronization, arbitration logic,
and START/STOP control and generation.
Figure 19.1. SMBus0 Block Diagram
SFR Bus
Data Path
Control
SFR Bus
Write to
SMB0DAT
SMBUS CONTROL LOGIC
Read
SMB0DAT
SMB0ADR
S
L
V
6G
C
S
L
V
5
S
L
V
4
S
L
V
3
S
L
V
2
S
L
V
1
S
L
V
0
C
R
O
S
S
B
A
R
Clock Divide
Logic
SYSCLK
SMB0CR
C
R
7
C
R
6
C
R
5
C
R
4
C
R
3
C
R
2
C
R
1
C
R
0
SCL
FILTER
N
SDA
Control
0000000b
7 MSBs 8
AB
A=B
8
01234567 SMB0DAT
8
SMB0CN
S
T
A
S
IA
AF
T
E
T
O
E
E
N
S
M
B
B
U
S
Y
S
T
O
SMB0STA
S
T
A
4
S
T
A
3
S
T
A
2
S
T
A
1
S
T
A
0
SCL
Control
Status Generation
Arbitration
SCL Synchronization
SCL Generation (Master Mode)
IRQ Generation
S
T
A
5
S
T
A
6
S
T
A
7
AB
A=B
SMBUS
IRQ
Interrupt
Request
Port I/O
1
0
SDA
FILTER
N
7
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Figure 19.2 shows a typical SMBus configuration. The SMBus0 interface will work at any voltage between
3.0 and 5.0 V and different devices on the bus may operate at different voltage levels. The bi-directional
SCL (serial clock) and SDA (serial data) lines must be connected to a positive power supply voltage
through a pullup resistor or similar circuit. Every device connected to the bus must have an open-drain or
open-collector output for both the SCL and SDA lines, so that both are pulled high when the bus is free.
The maximum number of devices on the bus is limited only by the requirement that the rise and fall times
on the bus will not exceed 300 ns and 1000 ns, respectively.
Figure 19.2. Typical SMBus Configuration
19.1. Supporting Documents
It is assumed the reader is familiar with or has access to the following supporting documents:
1. The I2C-bus and how to use it (including specifications), Philips Semiconductor.
2. The I2C-Bus Specification -- Version 2.0, Philips Semiconductor.
3. System Management Bus Specification -- Version 1.1, SBS Implementers Forum.
19.2. SMBus Protocol
Two types of data transfers are possible: data transfers from a master transmitter to an addressed slave
receiver (WRITE), and data transfers from an addressed slave transmitter to a master receiver (READ).
The master device initiates both types of data transfers and provides th e seria l clock pulse s on SCL. Note:
multiple master devices on the same bus are supported. If two or more masters attempt to initiate a data
transfer simultan eously, an arbitration scheme is employed with a single master always winning the arbitra-
tion. Note that it is not necessary to specify one device as the master in a system; any device who trans-
mits a START and a slave address becomes the master for that transfer.
A typical SMBus transaction consists of a START condition followed by an address byte (Bits7–1: 7-bit
slave address; Bit0: R/W direction bit), one or more bytes of data, and a STOP condition. Each byte that is
received (by a master or slave) must be acknowledged (ACK) with a low SDA during a high SCL (see
Figure 19.3). If the receiving device does not ACK, the transmitting device will read a “not acknowledge”
(NACK), which is a high SDA during a high SCL.
The direction bit (R/W) occupies the least-significant bit position of the addr ess. The direction bi t is set to
logic 1 to indicate a "READ" operation and cle ared to logic 0 to indicate a "WRITE" operation.
VDD = 5V
Master
Device Slave
Device 1 Slave
Device 2
VDD = 3V VDD = 5V VDD = 3V
SDA
SCL
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All transactions are initiated by a master, with one or more addressed slave devices as the target. The
master generates the START condition and then transmits the slave address and direction bit. If the trans-
action is a WRITE operation from the master to the slave, the master transmits the data a byte at a time
waiting for an ACK from the slave at the end of each byte. For READ operations, the slave transmits the
data waiting for an ACK from the master at the end of each byte. At the end of the data transfer, the master
generates a STOP condition to terminate the transaction and free the bus. Figure 19. 3 illustrates a typical
SMBus transaction.
Figure 19.3. SMBus Transaction
19.2.1. Arbitration
A master may star t a transfer on ly if the bus is free. The b us is free af ter a STOP condition or af ter the SCL
and SDA lines remain high for a specified time (see Sect ion 19.2.4). In the e ve nt that two o r mo re devices
attempt to begin a transfer at the same time, an arbitration scheme is employed to force o ne master to give
up the bus. The master d evices continue tr ansmitting un til one attempt s a HIGH while the other transmit s a
LOW. Since the bus is open-drain, the bus will be pulled LOW. The master attempting the HIGH will detect
a LOW SDA and give up the bus. The winning master continues its transmission without interruption; the
losing master becomes a slave and receives the rest of the transfer. This arbitration scheme is non-
destructive: one device always wins, and no data is lost.
19.2.2. Clock Low Extension
SMBus provides a clock synchronization mechanism, similar to I2C, which allows devices with different
speed capabilities to coexist on the bus. A clock-low extension is used during a transfer in order to allow
slower slave devices to communicate with faster masters. The slave may temporarily hold the SCL line
LOW to extend the clock low period, effectively decreasing the serial clock frequency.
19.2.3. SCL Low Timeout
If the SCL line is held low by a slave device on the bus, n o further commun ication is possible . Furthermore,
the master ca nnot for ce the SCL lin e high to correc t the error condition. To solve this problem, the SMBus
protocol specifies that devices participating in a transfer must detect any clock cycle held low longer than
25 ms as a “timeout” condition. Devices that have detected the timeout condition must reset the communi-
cation no later than 10 ms af ter detecting the timeout condition.
19.2.4. SCL High (SMBus Free) Timeout
The SMBus specification stipulates that if the SCL and SDA lines remain high for more that 50 µs, the bus
is designated as free. If an SMBus device is waiting to generate a Master START, the START will be gen-
erated following the bus free timeout.
SLA6
SDA SLA5-0 R/W D7 D6-0
SCL
Slave Address + R/W Data ByteSTART ACK NACK STOP
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19.3. SMBus Transfer Modes
The SMBus0 interfa ce may be configure d to op erate as a master a nd/or a slave. At any particular time, the
interface will be operating in one of the following modes: Master Transmitter, Master Receiver, Slave
Transmitter , or Slave Receiver. See Table 19.1 for transfer mode status decoding using the SMB0STA sta-
tus register. The following mode descriptions illustrate an interrupt-driven SMBus0 application; SMBus0
may alternatively be ope rated in polled mode.
19.3.1. Master Transmitter Mode
Serial data is transmitted on SDA while the serial clock is output on SCL. SMBus0 generates a START
condition and then transmits the first byte containing the address of the target slave device and the data
direction bit. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The
SMBus0 interface transmits one or more bytes of serial data, waiting for an acknowledge (ACK) from the
slave after each byte. To indicate the end of the serial transfer, SMBus0 generates a STOP condition.
Figure 19.4. Typical Master Tr ansmitter Sequence
19.3.2. Master Receiver Mode
Serial data is received on SDA while the serial clock is output on SCL. T h e SM Bu s0 interfac e g en er a tes a
START followed by the first data byte containing the address of the target slave and the data direction bit.
In this case the data direction bit (R/W) will be logic 1 to indicate a "READ" operation. The SMBus0 inter-
face receives serial data from the slave and generates the clock on SCL. After each byte is received,
SMBus0 generates an ACK or NACK depending on the state of the AA bit in register SMB0CN. SMBus0
generates a STOP condition to indicate the end of the serial transfer.
Figure 19.5. Typical Master Receiver Sequence
A AAS W PData Byte Data ByteSLA
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt InterruptInterrupt
Data B yteData Byte A NAS R PSLA
S = START
P = STOP
A = ACK
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transm itt ed by
SMBus Interface
Interrupt Interrupt InterruptInterrupt
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19.3.3. Slave Transmitter Mode
Serial dat a is transmitted on SDA while the serial clock is received on SCL. The SMBus0 interface r eceives
a START followed by dat a byte co nt aining the sla ve address and direction bit. If the received sla ve address
matches the address held in register SMB0ADR, the SMBus0 interface generates an ACK. SMBus0 will
also ACK if the general call address (0x00) is received and the General Call Address Enable bit
(SMB0ADR.0) is set to logic 1. In this case the data direction bit (R/W) will be logic 1 to indicate a "READ"
operation. The SMBus0 interface receives the clock on SCL and transmits one or more bytes of serial
data, waiting for an ACK from the master after each byte. SMBus0 exits slave mode after receiving a
STOP condition from the master.
Figure 19.6. Typical Slave Transmitter Seq uence
19.3.4. Slave Receiver Mode
Serial data is received on SDA while the serial clock is received on SCL. The SMBus0 interface re ce ives a
START followed by data byte containing the slave address and direction bit. If the received slave address
matches the address held in register SMB0ADR, the interface generates an ACK. SMBus0 will also ACK if
the general call addre ss (0x00) is received and the G eneral Ca ll Address Ena ble bit (SMB0ADR.0) is set to
logic 1. In this case the data direction bit (R/W) will be logic 0 to indicate a "WRITE" operation. The
SMBus0 interface receives one or more bytes of serial data; after each byte is received, the interface
transmits an ACK or NACK depending on the state of the AA bit in SMB0CN. SMBus0 exits Slave Receiver
Mode after receiving a STOP condition from the master.
Figure 19.7. Typical Slave Receiver Sequence
PRSLASData ByteData Byte A NA
S = START
P = STOP
N = NACK
R = READ
SLA = Slave Address
Received by SMBus
Interface
Transmitted by
SMBus Interface
Interrupt Interrupt Interrupt
Interrupt
PWSLASData ByteData Byte A AA
S = START
P = STOP
A = ACK
W = WRITE
SLA = Slave Address
Receiv ed by S MBus
Interface
Transmitt ed by
SMBus Interface
Interrupt Interrupt Interrupt
Interrupt
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19.4. SMBus Special Function Registers
The SMBus0 serial interface is accessed and controlled through five SFR’s: SMB0CN Control Register,
SMB0CR Clock Rate Register, SMB0ADR Address Register, SMB0DAT Data Register and SMB0STA S t a-
tus Register. The five special function registers related to the operation of the SMBus0 interface are
described in the following sections.
19.4.1. Control Register
The SMBus0 Control register SMB0CN is used to configure and control the SMBus0 interface. All of the
bits in the register can be read or written by software. Two of the control bits are also affected by the
SMBus0 hardware. The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by the hardware when a valid
serial interrupt condition occurs. It can only be cleared by software. The Stop flag (STO, SMB0CN.4) is set
to logic 1 by software. It is cleared to logic 0 by hardware when a STOP condition is detected on the bus.
Setting the EN SMB flag to lo gic 1 enables the SMBus0 in terface. Clea ring the ENSMB f lag to logic 0 dis-
ables the SMBus0 interface and removes it from the bus. Momentarily clearing the ENSMB flag and then
resetting it to logic 1 will reset SMBus0 communication. However, ENSMB should not be used to tempo-
rarily remove a device from the bus since the bus state information will be lost. Instead, the Assert
Acknowledge (AA) flag should be used to temporarily remove the device from the bus (see description of
AA flag below).
Setting the Start flag (STA, SMB0CN.5) to logic 1 will put SMBus0 in a master mode. If the bus is free,
SMBus0 will generate a START condition. If the bus is not free, SMBus0 waits for a ST OP condition to free
the bus and then generates a START condition after a 5 µs delay per the SMB0CR value (In accordance
with the SMBus prot ocol, the SMBus 0 interface also considers the bus free if the b us is idle for 50 µs and
no STOP condition was recognized). If STA is set to logic 1 while SMBus0 is in master mode and one or
more bytes have been transferred, a repeated START condition will be generated.
When the Stop flag (STO, SMB0CN.4) is set to logic 1 while the SMBus0 interface is in master mode, the
interface generates a ST O P condition. In a slave m ode, the ST O flag may be use d to recover from an err or
condition. In this case, a STOP condition is not generated on the bus, but the SMBus hardware behaves
as if a STOP condition has been received and enters the "not addressed" slave receiver mode. Note that
this simulated STOP will not cause th e bus to appear free to SMBus0. Th e bus will remain occupied until a
STOP appears on the bus or a Bus Free Timeout occurs. Hardware automatically clears the STO flag to
logic 0 when a STOP condition is detected on the bus.
The Serial Interrupt flag (SI, SMB0CN.3) is set to logic 1 by hardware when the SMBus0 interface enters
one of 27 possible states. If interrupts are enabled for the SMBus0 interface, an interrupt request is gener-
ated when the SI flag is set. The SI flag must be cleared by software.
Important Note: If SI is set to logic 1 while the SCL line is low, the clock-low period of the serial clock will
be stretched and the serial transfer is suspended until SI is cleared to logic 0. A high level on SCL is not
affected by the setting of the SI flag.
The Assert Acknowledge flag (AA, SMB0CN.2) is used to set the level of the SDA line during the acknowl-
edge clock cycle on the SCL line. Setting the AA flag to logic 1 will cause an ACK (low level on SDA) to be
sent during the acknowledge cycle if the device has been addressed. Setting the AA flag to logic 0 will
cause a NACK (high level on SDA) to be sent during acknowledge cycle. After the transmission of a byte in
slave mode, the slave can be temporarily removed from the bus by clearing the AA flag. The slave's own
address and general call address will be ignored. To resume operation on the bus, the AA flag must be
reset to logic 1 to allow the slave's address to be recognized.
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Setting the SMBus0 Free Timer Enable bit (FTE, SMB0CN.1) to logic 1 enables the timer in SMB0CR.
When SCL goes high, the timer in SMB0CR counts up. A timer overflow indicates a free bus timeout: if
SMBus0 is waiting to generate a START, it will do so after this timeout. The bus free period should be less
than 50 µs (see SFR Definition 19.2, SMBus0 Clock Rate Register).
When the TOE bit in SMB0CN is set to logic 1, Timer 3 is used to detect SCL low timeouts. If Timer 3 is
enabled (see Section “23.2. Timer 2, Timer 3, and Timer 4” on page 317), Timer 3 is forced to reload
when SCL is high, and forced to count when SCL is low. With Timer 3 enabled and configured to overflow
after 25 ms (and TOE set), a Timer 3 overflow indicates a SCL low timeout; the Timer 3 interrupt service
routine can then be used to reset SMBus0 communication in the event of an SCL low timeout.
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SFR Definition 19.1. SMB0CN: SMBus0 Control
Bit7: BUSY: Busy Status Flag.
0: SMBus0 is free
1: SMBus0 is busy
Bit6: ENSMB: SMBus Enable.
This bit enables/disables the SMBus serial interface.
0: SMBus0 disabled.
1: SMBus0 enabled.
Bit5: STA: SMBus Start Flag.
0: No START condition is transmitted.
1: When operating as a master, a START condition is tran smitted if the bus is free. (If the
bus is not free, the START is transmitted after a STOP is received.) If STA is set after one or
more bytes have been transmitted or received and before a STOP is received, a repeated
START condition is transmitted.
Bit4: STO: SMBus Stop Flag.
0: No STOP condition is transmitted.
1: Setting STO to logic 1 causes a STOP condition to be transmitted. When a STOP condi-
tion is received, hardware clears STO to logic 0. If both STA and STO are set, a STOP con-
dition is transmitted followed by a START condition. In slave mode, setting the STO flag
causes SMBus to behave as if a STO P condition was received.
Bit3: SI: SMBus Serial Interrupt Flag.
This bit is set by hardware when one of 27 possible SMBus0 st ate s is entered. (Status code
0xF8 does not cause SI to be set.) When the SI interrupt is enabled, setting this bit causes
the CPU to vector to the SMBus interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
Bit2: AA: SMBus Assert Ackno wledge Flag.
This bit defines the type of acknowled ge retu rned during th e acknowledge cycle on the SCL
line.
0: A "not acknowledge" (high level on SDA) is returned during the acknowledge cycle.
1: An "acknowledge" (low level on SDA) is returned during the acknowledge cycle.
Bit1: FTE: SMBus Free Timer Enable Bit
0: No timeout when SCL is high
1: T imeout when SCL high time exceeds limit specified by the SMB0CR value.
Bit0: TOE: SMBus Timeout Enable Bit
0: No timeout when SCL is low.
1: Timeout when SCL low tim e ex ce ed s limit specified by Timer 3, if enabled.
R R/WR/WR/WR/WR/WR/WR/WReset Value
BUSY ENSMB STA STO SI AA FTE TOE 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xC0
0
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19.4.2. Clock Rate Register
SFR Definition 19.2. SMB0CR: SMBus0 Clock Rate
Bits7–0: SMB0CR.[7:0]: SMBus0 Clock Rate Preset
The SMB0CR Clock Rate register controls the frequency of the serial clock SCL in master
mode. The 8-bit word stored in the SMB0CR Register preloads a dedicated 8-bit timer. The
timer counts up, and when it rolls over to 0x00, the SCL logi c state toggles.
The SMB0CR setting should be bounded by the following equation , where SMB0CR is the
unsigned 8-bit value in register SMB0CR, and SYSCLK is the system clock frequency in
MHz:
The resulting SCL signal high and low times are given by the following equations, where
SYSCLK is the system clock frequency in Hz:
Using the same value of SMB0CR from above, the Bus Free Timeout period is given in the
following equation:
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xCF
0
SMB0CR 288 0.85– SYSCLK
4
----------------------
1.125
TLOW 4 256 SMB0CR–SYSCLK=
THIGH 4258SMB0CR–SYSCLK625ns+
TBFT 10 4 256 SMB0CR–1+
SYSCLK
--------------------------------------------------------------
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19.4.3. Data Re gister
The SMBus0 Data register SMB0DAT holds a byte of serial data to be transmitted or one that has just
been received. Softwar e can read or write to this register while the SI flag is set to logic 1; software should
not attempt to access the SMB0DAT register when the SMBus is enabled and the SI flag reads logic 0
since the hardware may be in the process of shifting a byte of data in or out of the register.
Data in SMB0DAT is always shifted out MSB first. After a byte has been received, the first bit of received
data is located at the MSB of SMB0DAT. While data is being shifted out, data on the bus is simultaneously
being shifted in. Therefore, SMB0DAT always contains the last data byte present on the bus. In the event
of lost arbit ration, the transition fr om master transmitter to slave receiver is ma de with the correct data in
SMB0DAT.
SFR Definition 19.3. SMB0DAT: SMBus0 Dat a
19.4.4. Address Register
The SMB0ADR Address register holds the slave address for the SMBus0 interface. In slave mode, the
seven most-significant bits hold the 7-bi t slav e addre ss. The least significant b it (Bit0) is used to enabl e the
recognition of the general call address (0x00). If Bit0 is set to logic 1, the general call address will be recog-
nized. Otherwise, the general call address is ignored. The contents of this register are ignored when
SMBus0 is operating in master mode.
Bits7–0: SMB0DAT: SMBus0 Data.
The SMB0DAT register contain s a byte of data to be transmitted on th e SMBus0 ser ial in ter-
face or a byte that has just been received on the SMBus0 serial interface. The CPU can
read from or write to this register whenever the SI serial interrupt flag (SMB0CN.3) is set to
logic 1. When the SI flag is not set, the system may be in the process of shif ting data and the
CPU should not attempt to access this register.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xC2
0
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SFR Definition 19.4. SMB0ADR: SMBus0 Address
19.4.5. Status Register
The SMB0STA Status register holds an 8-bit status code indicating the current state of the SMBus0 inter-
face. There ar e 28 po ssible SMBu s0 states, each with a corresponding unique status code. The five most
significant bits of the st atus code vary while the three le ast-significant bit s of a valid st atus code are fixed at
zero when SI = ‘1’. Therefore, all possible st atus codes are multiples of eight. This facilit ates the use of st a-
tus codes in software as an index used to branch to appropriate service routines (allowing 8 bytes of code
to service the state or jump to a more extensive service routine).
For the purposes of user software, the con tents of th e SMB0STA register is only defined when the SI flag is
logic 1. Software should never write to the SMB0STA register; doing so will yield indeterminate result s. The
28 SMBus0 states, al ong with their corresponding status codes, are given in Tab le 1.1.
SFR Definition 19.5. SMB0STA: SMBus0 Status
Bits7–1: SLV6–SLV0: SMBus0 Slave Address.
These bits are loaded with the 7-bit slave address to which SMBus0 will respond when oper-
ating as a slave transmitter or slave receiver. SLV6 is the most significant bit of the address
and corresponds to the first bit of the address byte received.
Bit0: GC: General Call Address Enable.
This bit is used to enable general call address (0x00) recognition.
0: General call address is igno red.
1: General call address is reco gnized.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
SLV6 SLV5 SLV4 SLV3 SLV2 SLV1 SLV0 GC 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xC3
0
Bits7–3: STA7–STA3: SMBus0 Status Code.
These bits contain the SMBus0 Status Code. There are 28 possible status codes; each sta-
tus code corresponds to a single SMBus state. A valid status code is present in SMB0STA
when the SI flag (SMB0CN.3) is set to logic 1. The content of SMB0STA is not defined when
the SI flag is logic 0. Writing to the SMB0STA register at any time will yield indeterminate
results.
Bits2–0: STA2–STA0: The three least significant bits of SMB0STA are always read as logic 0 when
the SI flag is logic 1.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
STA7 STA6 STA5 STA4 STA3 STA2 STA1 STA0 11111000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xC1
0
C8051F120/1/2/3/4/5/6/7
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270 Rev. 1.4
Table 19.1. SMB0STA Status Codes and States
Mode Status
Code SMBus State Typical Action
MT/
MR
0x08 START condition transmitted. Load SMB0DAT with Slave Address +
R/W. Cle ar STA.
0x10 Repe ated START condition transmitted. Load SMB0DAT with Slave Address +
R/W. Cle ar STA.
Master Transmitter
0x18 Sl ave Address + W transmitted. ACK
received. Load SMB0DAT with data to be transmit-
ted.
0x20 Sl ave Address + W transmitted. NACK
received. Acknowledge poll to retry. Set STO +
STA.
0x28 Data byte transmitted. ACK received. 1) Load SMB0DAT with next byte, OR
2) Set STO, OR
3) Clear STO then set STA for repeated
START.
0x30 Data byte transmitted. NACK received. 1) Retry transfer OR
2) Set STO.
0x38 Arbitration Lost. Save current data.
Master Receiver
0x40 Sl ave Address + R transmitted. ACK received. If only receiving one byte, clear AA (send
NACK after received byte). Wait for
received data.
0x48 Sl ave Address + R transmitted. NACK
received. Acknowledge poll to retry. Set STO +
STA.
0x50 Data byte received. ACK transmitted. Read SMB0DAT. Wait for next byte. If
next byte is last byte, clear AA.
0x58 Data byte received. NACK transmitted. Set STO.
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Slave Receiver
0x60 Own slave address + W received. ACK trans-
mitted. Wait for data.
0x68 Arb itration lost in sending SLA + R/W as mas-
ter. Own address + W received . ACK transmit-
ted.
Save current data for retry when bus is
free. Wait for data.
0x70 Gen eral call address received. ACK transmit-
ted. Wait for data.
0x78 Arb itration lost in sending SLA + R/W as mas-
ter. General call address received. ACK trans-
mitted.
Save current data for retry when bus is
free.
0x80 Data byte received. ACK transmitted. Read SMB0DAT. Wait for next byte or
STOP.
0x88 Data byte received. NACK transmitted. Set STO to reset SMBus.
0x90 Data byte received after general call address.
ACK transmitted. Read SMB0DAT. Wait for next byte or
STOP.
0x98 Data byte received after general call address.
NACK transmitted. Set STO to reset SMBus.
0xA0 STOP or repeated START received. No action necessary.
Slave Transmitter
0xA8 Own address + R received. ACK transmitted. Load SMB0DAT with data to transmit.
0xB0 Arbitration lost in tra nsmitting SLA + R/W as
master. Own address + R received. ACK
transmitted.
Save current data for retry when bus is
free. Load SMB0DAT with data to trans-
mit.
0xB8 Data byte transmitted. ACK received. Load SMB0DAT with data to transmit.
0xC0 Data byte transmitted. NACK received. Wa it for STOP.
0xC8 Last data byte transmitted (AA=0). ACK
received. Set STO to reset SMBus.
Slave
0xD0 SCL Clock High Timer per SMB0CR timed out Set STO to reset SMBus.
All
0x00 Bus Error (illegal START or STOP) Set STO to reset SMBus.
0xF8 Idle State does not set SI.
Table 19.1. SMB0STA Status Codes and States (Continued)
Mode Status
Code SMBus State Typical Action
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NOTES:
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 273
20. Enhanced Serial Peripheral Interface (SPI0)
The Enhanced Serial Peripheral Interface (SPI0) provides access to a flexible, full-duplex synchronous
serial bus. SPI0 can operate as a master or slave device in both 3-wire or 4-wire modes, and support s mul-
tiple masters and slaves on a single SPI bus. The slave-select (NSS) signal can be co nf igu re d as an in pu t
to select SPI0 in slave mode, or to disable Master Mode operation in a multi-master environment, avoiding
contention on the SPI bus when more than one master attempts simultaneous data transfers. NSS can
also be configur ed as a ch ip-select outp ut in master mode , or disable d for 3-wire operation. Add itional gen-
eral purpose port I/O pi ns can be used to select multiple slave devices in master mode.
Figure 20.1. SPI Block Diagram
SFR Bus
Data Path
Control
SFR Bus
Write
SPI0DAT
Receive Data Buffer
SPI0DAT
01234567
Shift Register
SPI CONTROL LOGIC
SPI0CKR
SCR7
SCR6
SCR5
SCR4
SCR3
SCR2
SCR1
SCR0
SPI0CFG SPI0CN
Pin Interface
Control
Pin
Control
Logic
C
R
O
S
S
B
A
R
Port I/O
Read
SPI0DAT
SPI IRQ
Tx Data
Rx Data
SCK
MOSI
MISO
NSS
Transmit Data Buffer
Clock Divide
Logic
SYSCLK
CKPHA
CKPOL
SLVSEL
NSSMD1
NSSMD0
SPIBSY
MSTEN
NSSIN
SRMT
RXBMT
SPIF
WCOL
MODF
RXOVRN
TXBMT
SPIEN
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274 Rev. 1.4
20.1. Signal Descriptions
The four signals used by SPI0 (MOSI, MISO, SCK, NSS) are described below.
20.1.1. Master Out, Slave In (MOSI)
The master-out, slave-in (MOSI) signal is an output from a master dev ice an d an in put to s lave d evices. I t
is used to serially trans fer data from the ma ster to th e slave. This signal is an output when SPI0 is operat-
ing as a master and an input when SPI0 is operating as a slave. Data is transferred most-significant bit
first. When configured as a master, MOSI is driven by the MSB of the shift register in both 3- and 4-wire
mode.
20.1.2. Master In, Slave Out (MISO)
The master-in, slave-out (MISO) signal is an output from a slave device and an input to the master device.
It is used to serially transfer data from the slave to the master. This signal is an input when SPI0 is operat-
ing as a master and an output when SPI0 is operating as a slave. Data is transferred most-significant bit
first. The MISO pin is placed in a high-impeda nce st ate when the SPI module is disa bled and when the SPI
operates in 4-wire mode as a slave that is not selected. When acting as a slave in 3-wire mode, MISO is
always driven by the MSB of the shift register.
20.1.3. Serial Clock (SCK)
The serial cloc k (SCK) signal is a n output from t he ma ster device and an input to slave devices. It is used
to synchronize the transfer of data between the master and slave on the MOSI and MISO lines. SPI0 gen-
erates this signal when operating as a master. The SCK signal is ignored by a SPI slave when the slave is
not selected (NSS = 1) in 4-wire slave mode.
20.1.4. Slave Select (NSS)
The function of the slave-select (NSS) signal is dependent on the setting of the NSSMD1 and NSSMD0
bits in the SPI0CN register. There are three possible modes that can be selected with these bits:
1. NSSMD[1:0] = 00: 3-Wire Master or 3-Wire Slave Mode: SPI0 operates in 3-wire mode, and
NSS is disabled. When operating as a slave device, SPI0 is always selected in 3-wire mode.
Since no select signal is present, SPI0 must be the only slave on the bus in 3-wire mode. This
is intended for point-to-poin t communication between a master and one slave.
2. NSSMD[1:0] = 01: 4-Wire Slave or Multi-Master Mode: SPI0 operates in 4-wire mode, and
NSS is enabled as an input. When operating as a slave, NSS selects the SPI0 device. When
operating as a master, a 1-to-0 transition of the NSS signal disables the master function of
SPI0 so that multiple master devices can be use d on the same SPI bus.
3. NSSMD[1:0] = 1x: 4-Wire Master Mode: SPI0 operates in 4-wire mode, and NSS is ena bled as
an output. The setting of NSSMD0 determines what logic level the NSS pin will output. This
configuration should only be used when op erating SPI0 as a master device.
See Figure 20.2, Figure 20.3, and Figure 20.4 for typical connection diagrams of the various operational
modes. Note that the setting of NSSMD bits affects the pinou t of the device. When in 3-wir e maste r or
3-wire slave mode, the NSS pin will not be mapped by the crossbar. In all other modes, the NSS signal will
be mapped to a pin on the device. See Section “18. Port Input/Output” on page 235 for general purpose
port I/O and crossbar information.
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20.2. SPI0 Master Mode Operation
A SPI master device initiates all data transfe r s o n a SPI bu s. SPI0 is p laced in master m ode by se ttin g the
Master Enable flag (MSTEN, SPI0CN.6). Writing a byte of data to the SPI0 data register (SPI0DAT) when
in master mode writes to the transmit buffer. If the SPI shift register is empty, the byte in the transmit buffer
is moved to the shift register, and a data transfer begins. The SPI0 master immediately shifts out the data
serially on the MOSI line while providing the serial clock on SCK. The SPIF (SPI0CN.7) flag is set to logic
1 at the end of the transfer. If interrupts are enabled, an interrupt request is generated when the SPIF flag
is set. While the SPI0 master transfers data to a slave on the MOSI line, the addressed SPI slave device
simultaneously transfers the contents of its shif t register to th e SPI master on the MISO line in a full-dup lex
operation. Therefore, the SPIF flag serves as both a transmit-complete and receive-data-ready flag. The
data byte received from the slave is transferred MSB-first into the master's shift register. When a byte is
fully shifted into the register, it is moved to the receive buffer where it can be read by the processor by
reading SPI0DAT.
When configured as a master, SPI0 can operate in one of three dif ferent mo des: multi-master mode, 3-wir e
single-master mode, and 4-wire single-master mode. The default, multi-master mode is active when
NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In this mode, NSS is an input to the device, and
is used to disable the master SPI0 when another master is accessing the bus. When NSS is pulled low in
this mode, MSTEN (SPI0CN.6) and SPIEN (SPI0CN.0) are set to 0 to disable the SPI master device, and
a Mode Fault is generated (MODF, SPI0CN.5 = 1). Mode Fault will generate an interrupt if enabled. SPI0
must be manually re -en ab led in software under th ese circumst ances. In multi-master systems, devices will
typically default to being sla ve devices wh ile they are not a cting as the system master device. In multi-ma s-
ter mode, slave devices can be addressed individually (if needed) using general-purpose I/O pins.
Figure 20.2 shows a connection diagram between two master devices in multiple-master mode.
3-wire single-m aster mod e is active wh en NSSMD1 (SPI0CN.3) = 0 and NS SMD0 (SPI0CN.2) = 0. In this
mode, NSS is not used, and is not mapped to an external por t pin through the crossbar. Any slave devices
that must be addressed in this mode should be selected using general-purpose I/O pins. Figure 20.3
shows a connection diagram between a master device in 3-wire master mode an d a slave device.
4-wire single-master mo de is active when NSSMD1 (SPI0 CN.3) = 1. In this mode, NSS is configure d as an
output pin, and can be used as a slave-select signal for a single SPI device. In this mode, the output value
of NSS is controlled (in software) with the bit NSSMD0 (SPI0CN.2). Additional slave devices can be
addressed using gene ral-pur pose I/O pins. F igure 20.4 shows a connection diagram for a master de vice in
4-wire master mode and two slave devices.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
276 Rev. 1.4
Figure 20.2. Multiple-Master Mode Connection Diagram
Figure 20.3. 3-Wire Single Master and Slave Mode Connection Diagram
Figure 20.4. 4-Wire Single Master and Slave Mode Connection Diagram
Master
Device 2
Master
Device 1
MOSI
MISO
SCK
MISO
MOSI
SCK
NSS
GPIO NSS
GPIO
Slave
Device
Master
Device
MOSI
MISO
SCK
MISO
MOSI
SCK
Slave
Device
Master
Device
MOSI
MISO
SCK
MISO
MOSI
SCK
NSS NSS
GPIO
Slave
Device
MOSI
MISO
SCK
NSS
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 277
20.3. SPI0 Slave Mode Operation
When SPI0 is enabled and not configured as a master, it will operate as a SPI slave. As a slave, bytes are
shifted in through the MOSI pin and out through the MISO pin by a master device controlling the SCK sig-
nal. A bit coun ter in the SPI0 logic cou nts SCK edges. When 8 bits have been shifted through the shift reg-
ister, the SPIF flag is set to logic 1, and the byte is copied into the receive buffer. Data is read from the
receive buffer by reading SPI0DAT. A slave device cannot initiate transfers. Data to be transferred to the
master device is pre-loaded into the shift register by writing to SPI0DAT. Writes to SPI0DAT are double-
buffe red, and a re placed in the transmit bu f fer first. If the shif t registe r is empty, the content s of th e transmit
buffer will immediately be transferred into the shift register. When the shift register already contains data,
the SPI will load the shift register with the transmit buffer’s contents after the last SCK edge of the next (or
current) SPI transfer.
When configured as a slave, SPI0 can be configured for 4-wire or 3-wire operation. The default, 4-wire
slave mode, is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 1. In 4-wire mod e, the
NSS signal is routed to a port pin and configured as a digital input. SPI0 is enabled when NSS is logic 0,
and disabled when NSS is logic 1. The bit counter is reset on a falling edge of NSS. Note that the NSS sig-
nal must be driven low at least 2 system clocks before the first active edge of SCK for each byte transfer.
Figure 20.4 shows a connection diagram between two slave devices in 4-wire slave mode and a master
device.
3-wire slave mode is active when NSSMD1 (SPI0CN.3) = 0 and NSSMD0 (SPI0CN.2) = 0. NSS is not
used in this mode, and is no t mapped to an externa l port pin thro ugh the crossbar. Since there is no way of
uniquely addressing the device in 3-wire slave mode, SPI0 must be the only slave device present on the
bus. It is important to note that in 3-wire sla ve mode there is no external means of resetting the bit counter
that determines when a full byte has been received. The bit counter can only be reset by disabling and re-
enabling SPI0 with the SPI EN bit. Figure 20.3 shows a co nnection diagram between a slave device in 3-
wire slave mod e and a ma ster device.
20.4. SPI0 Interrupt Sources
When SPI0 interrupts are enabled, the following four flags will generate an interrupt when they are set to
logic 1:
Note that all of the following bits must be cleared by software.
1. The SPI Interrupt Flag, SPIF (SPI0CN.7) is set to logic 1 at the end of each byte transfer. This
flag can occur in all SPI0 modes.
2. The Write Collision Flag, WCOL (SPI0CN.6) is set to logic 1 if a write to SPI0DAT is attempted
when the transmit buffer has not been emptied to the SPI shift register. When this occurs, the
write to SPI0DAT will be ignored, and the transmit buffer will not be written.This flag can occur
in all SPI0 modes.
3. The Mode Fault Flag MODF (SPI0CN.5) is set to logic 1 when SPI0 is configured as a master,
and for multi-master mode and the NSS pin is pulled low. When a Mode Fault occurs, the
MSTEN and SPIEN bits in SPI0CN are set to logic 0 to disable SPI0 and allow another master
device to access the bus.
4. The Receive Overrun Flag RXOVRN (SPI0CN.4) is set to logic 1 when configured as a slave,
and a transfer is completed and the receive buffer still holds an unread byte from a previous
transfer. The new byt e is no t tr an sf er re d to th e r ece ive bu ffer, allowing the pre vio usly received
data byte to be read. The data byte which caused the overrun is lost.
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278 Rev. 1.4
20.5. Serial Clock Timing
Four combinations of serial clock phase and polarity can be selected using the clock control bits in the
SPI0 Configuration Register (SPI0CFG). The CKPHA bit (SPI0CFG.5) selects one of two clock phases
(edge used to latch the data). The CKPOL bit (SPI0CFG.4) selects between an active-high or active-low
clock. Both master and slave devices must be configured to use the same cloc k phase and polar ity. SPI0
should be disabled (by clearing the SPIEN bit, SPI0CN.0) when changing the clock phase or polarity. The
clock and data line relationships for master mode are shown in Figure 20.5. For slave mode, the clock and
data relationships are shown in Figure 20.6 and Figure 20.7. Note that CKPHA must be set to ‘0’ on both
the master and slave SPI when communicating between two of the following devices: C8051F04x,
C8051F06x, C8051F12 x/1 3x, C8051F31x, C8051F32x, and C8051F33x
The SPI0 Clock Rate Register (SPI0CKR) as shown in SFR Definition 20.3 controls the master mode
serial clock frequency. This register is ignored when operating in slave mode. When the SPI is configured
as a master, the maximum dat a transfer rate (bits/sec) is one-half the system clock frequency or 12.5 MHz,
whichever is slower. When the SPI is configured as a slave, the maximum data transfer rate (bits/sec) for
full-duplex operation is 1/10 the system clock frequency, provided that the master issues SCK, NSS (in 4-
wire slave mode), and the serial input data synchronously with the slave’s system clock. If the master
issues SCK, NSS, and the serial input data asynchronously, the maximum data transfer rate (bits/sec)
must be less than 1/10 the system clock frequency. In the special case where the master only wants to
transmit data to the sla ve and does not n eed to receive data from the slave (i.e. half-duplex oper ation), the
SPI slave can receive data at a maximum data transfer rate (bits/sec) of 1/4 the system clock frequency.
This is provided that the master issues SCK, NSS, and the serial inpu t data synchronously with the slave’s
system clock.
Figure 20.5. Master Mode Data/Clock Timing
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=1, CKPHA=1)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO/MOSI
NSS (Must Remain High
in Multi-Master Mode)
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C8051F130/1/2/3
Rev. 1.4 279
Figure 20.6. Slave Mode Dat a/Clock Timing (CKPHA = 0)
Figure 20.7. Slave Mode Dat a/Clock Timing (CKPHA = 1)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO
NSS (4-Wire Mode)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MOSI
SCK
(CKPOL=0, CKPHA=0)
SCK
(CKPOL=1, CKPHA=0)
SCK
(CKPOL=0, CKPHA=1)
SCK
(CKPOL=1, CKPHA=1)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MISO
NSS (4-Wi re Mode)
MSB Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0MOSI
C8051F120/1/2/3/4/5/6/7
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280 Rev. 1.4
20.6. SPI Special Function Registers
SPI0 is accessed and controlled through four special function registers in the system controller: SPI0CN
Control Register, SPI0DAT Data Register, SPI0CFG Configuration Register, and SPI0CKR Clock Rate
Register. The four special function registers related to the operation of the SPI0 Bus are described in the
following figures.
SFR Definition 20.1. SPI0CFG: SPI0 Configuration
Bit 7: SPIBSY: SPI Busy (read only).
This bit is set to logic 1 when a SPI transfer is in progress (Master or slave Mode).
Bit 6: MSTEN: Master Mode Enable.
0: Disable master mode. Operate in slave mode.
1: Enable master mode. Operate as a master.
Bit 5: CKPHA: SPI0 Clock Phase.
This bit controls the SPI0 clock phase.
0: Data centered on first edge of SCK period.*
1: Data centered on second edge of SCK pe riod.*
Bit 4: CKPOL: SPI0 Clock Polarity.
This bit controls the SPI0 clock polarity.
0: SCK line low in idle state.
1: SCK line high in idle state.
Bit 3: SLVSEL: Slave Selected Flag (read only).
This bit is set to logic 1 whenever the NSS pin is low indicating SPI0 is the selected slave. It
is cleared to logic 0 when NSS is high (slave not selected). This bit does not indicate the
instantaneous value at the NSS pin, but rather a de-glitched version of the pin input.
Bit 2: NSSIN: NSS Instantaneous Pin Input (read only).
This bit mimics the instantaneou s value that is present on the NSS port pin at the time that
the register is read. Th is input is not de-glitched.
Bit 1: SRMT: Shift Register Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when all data has been transferred in/out of the shift register,
and there is no new information available to read from the transmit buff er or write to the
receive buffer. It returns to logic 0 when a data byte is transfe rred to the shift register from
the transmit buffer or by a transition on SCK.
NOTE: SRMT = 1 when in Master Mode.
Bit 0: RXBMT: Receive Buffer Empty (Valid in Slave Mode, read only).
This bit will be set to logic 1 when the receive buffer has been read and contains no new
information. If there is new information availa ble in the receive buf fer that ha s not been read,
this bit will return to logic 0.
NOTE: RXBMT = 1 when in Master Mode.
*Note: In slave mode, data on MOSI is sampled in the center of each data bit. In master mode, data
on MISO is sampled one SYSCLK before the end of each data bit, to provide maximum
settling time for the slave device. See Table 20.1 for timing parameters.
R R/W R/W R/W R R R R Reset Value
SPIBSY MSTEN CKPHA CKPOL SLVSEL NSSIN SRMT RXBMT 00000111
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9A
0
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Rev. 1.4 281
SFR Definition 20.2. SPI0CN: SPI0 Control
Bit 7: SPIF: SPI0 Interrupt Flag.
This bit is set to logic 1 by hardware at the end of a data transfer. If interrupts are enabled,
setting this bit causes the CPU to vector to the SPI0 interrupt service routine. This bit is not
automatically cleared by hardware. It must be cleared by software.
Bit 6: WCOL: Write Collision Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) to indicate a write to
the SPI0 data register was attempted while a data transfer was in progress. It must be
cleared by software.
Bit 5: MODF: Mode Fault Flag.
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when a master mode
collision is detected (NSS is low, MSTEN = 1, and NSSMD[1:0] = 01). This bit is not auto-
matically cleared by hardware. It must be cleared by sof tware.
Bit 4: RXOVRN: Receive Overrun Flag (Slave Mode only).
This bit is set to logic 1 by hardware (and generates a SPI0 interrupt) when the receive
buffer still holds unread data from a previous transfer and the last bit of the current transfer is
shifted into the SPI0 shift register. This bit is not automatically cleared by hardware. It must
be cleared by software.
Bits 3–2: NSSMD1–NSSMD0: Slave Select Mode.
Selects between the following NSS operation modes:
(See Section “20.2. SPI0 Master Mode Operation” on p age 275 and Section “20.3. SPI0
Slave Mode Operation” on page 277).
00: 3-Wire Slave or 3-wire Master Mode. NSS signal is not routed to a port pin.
01: 4-Wire Slave or Multi-Master Mode (Default). NSS is always an input to the device.
1x: 4-Wire Single-Master Mode. NSS signal is mapped as an output from the device and will
assume the value of NSSMD0.
Bit 1: TXBMT: Transmit Buffer Empty.
This bit will be set to logic 0 when new data has been written to the transmit buffer. When
data in the transmit buffer is transferred to the SPI shift register, this bit will be set to logic 1,
indicating that it is safe to write a new byte to the transmit buf fer.
Bit 0: SPIEN: SPI0 Enable.
This bit enables/disables the SPI.
0: SPI disabled.
1: SPI enabled.
R/WR/WR/WR/WR/WR/W R R/WReset Value
SPIF WCOL MODF RXOVRN NSSMD1 NSSMD0 TXBMT SPIEN 00000110
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0xF8
0
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282 Rev. 1.4
SFR Definition 20.3. SPI0CKR: SPI0 Clock Rate
SFR Definition 20.4. SPI0DAT: SPI0 Data
Bits 7–0: SCR7–SCR0: SPI0 Clock Rate.
These bits determine the frequency of the SCK output when the SPI0 module is configured
for master mode operation. The SCK clock frequency is a divided version of the system
clock, and is given in the following equation , where SYSCLK is the system clock frequency
and SPI0CKR is the 8-bit value he ld in the SPI0CKR register.
for 0 <= SPI0CKR <= 255
Example: If SYSCLK = 2 MHz and SPI0CKR = 0x04,
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SCR7 SCR6 SCR5 SCR4 SCR3 SCR2 SCR1 SCR0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9D
0
fSCK SYSCLK
2 SPI0CKR 1+
-----------------------------------------------
=
fSCK 2000000
241+
--------------------------
=
fSCK 200kHz=
Bits 7–0: SPI0DAT: SPI0 Transmit and Receive Data.
The SPI0DAT register is used to transmit and receive SPI0 data. Writing data to SPI0DAT
places the data into the transmit buffer and initiates a transfer when in Master Mode. A read
of SPI0DAT returns the contents of the receive buffer.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x9B
0
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 283
Figure 20.8. SPI Master Timing (CKPHA = 0)
Figure 20.9. SPI Master Timing (CKPHA = 1)
SCK*
T
MCKH
T
MCKL
MOSI
T
MIS
MISO
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
MIH
SCK*
T
MCKH
T
MCKL
MISO
T
MIH
MOSI
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
MIS
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284 Rev. 1.4
Figure 20.10. SPI Slave Timing (CKPHA = 0)
Figure 20.11. SPI Slave Timing (CKPHA = 1)
SCK*
T
SE
NSS
T
CKH
T
CKL
MOSI
T
SIS
T
SIH
MISO
T
SD
T
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
SEZ
T
SDZ
SCK*
T
SE
NSS
T
CKH
T
CKL
MOSI
T
SIS
T
SIH
MISO
T
SD
T
SOH
* SCK is shown for CKPOL = 0. SCK is the opposite polarity for CKPOL = 1.
T
SLH
T
SEZ
T
SDZ
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Rev. 1.4 285
Table 20.1. SPI Slave Timing Parameters
Parameter Description Min Max Units
Master Mode Timing* (See Figure 20.8 and Figure 20.9)
TMCKH SCK High Time 1xT
SYSCLK ns
TMCKL SCK Low Time 1xT
SYSCLK ns
TMIS MISO Valid to SCK Shift Edge 1xT
SYSCLK + 20 ns
TMIH SCK Shift Edge to MISO Change 0 ns
Slave Mode Timing* (See Figure 20.10 and Figure 20.11)
TSE NSS Falling to First SCK Edge 2xT
SYSCLK ns
TSD Last SCK Edge to NSS Rising 2xT
SYSCLK ns
TSEZ NSS Falling to MISO Valid 4xT
SYSCLK ns
TSDZ NSS Rising to MISO High-Z 4xT
SYSCLK ns
TCKH SCK High Time 5xT
SYSCLK ns
TCKL SCK Low Time 5xT
SYSCLK ns
TSIS MOSI Valid to SCK Sample Edge 2xT
SYSCLK ns
TSIH SCK Sample Edge to MOSI Change 2xT
SYSCLK ns
TSOH SCK Shift Edge to MISO Change 4xT
SYSCLK ns
TSLH Last SCK Edge to MISO Change
(CKPHA = 1 ONLY) 6xT
SYSCLK 8xT
SYSCLK ns
*Note: TSYSCLK is equal to one period of the device system clock (SYSCLK).
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NOTES:
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Rev. 1.4 287
21. UART0
UART0 is an enhanced serial port with frame error detection and address recognition hardware. UART0
may operate in full-duplex asynchronous or half-duplex synchronous modes, and mutiproccessor commu-
nication is fully supported. Receive data is buffered in a holding register, allowing UART0 to start reception
of a second incoming data byte before software has finished reading the previous data byte. A Receive
Overrun bit indicates when new received data is latched into the receive buffer before the previously
received byte ha s be en rea d .
UART0 is acce ssed via it s associated SFR’ s, Serial Control (SCON0) and Serial Data Buffer (SBUF0). The
single SBUF0 locati on provides access to both transmit and receive registers. Reading SCON0 accesses
the Receive registe r and writ ing SCON0 accesses the Transmit re gis te r.
UART0 may be operated in polled or interrupt mode. UART0 has two sources of interrupts: a Transmit
Interrupt flag, TI0 (SCON0.1) set when transmission of a data byte is complete, and a Receive Interrupt
flag, RI0 (SCON0.0) set when reception of a data byte is complete. UART0 interrupt flags are not cleared
by hardware when the CPU vectors to the interr upt service routine; they must be cleared manually by soft-
ware. This allows software to determine the cause of the UART0 interrupt (transmit complete or receive
complete).
Figure 21.1. UART0 Block Diagram
Tx Control
Tx Clock Tx IRQ
Zero Detector
Send
Shift
SET
QD
CLR
Stop Bit
Gen.
TB80
Start
Data
Write to
SBUF0
Crossbar
TX0
Port I/O
Serial Port
(UART0) Interrupt
Rx Control
Start
Rx Clock Load
SBUF
0x1FFShift
EN Rx IRQ
UART0
Baud Rate Generation
Logic
SFR Bus
Input Shift Register
(9 bits)
Frame Error
Detection
SBUF0
Read
SBUF0
SFR Bus
SADDR0
SADEN0
Match Detect
RB80
Load
SBUF0
Crossbar
RX0
SBUF0
Address
Match
SCON 0
S
M
2
0
T
B
8
0
R
B
8
0
T
I
0
R
I
0
S
M
1
0
S
M
0
0
R
E
N
0
SSTA0
T
X
C
O
L
0
S
0
T
C
L
K
1
S
0
T
C
L
K
1
S
0
R
C
L
K
1
S
0
R
C
L
K
1
R
X
O
V
0
F
E
0
S
M
O
D
0
TI0
RI0
C8051F120/1/2/3/4/5/6/7
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288 Rev. 1.4
21.1. UART0 Operational Modes
UART0 provides four operating modes (one synchronous and three asynchronous) selected by setting
configuration bits in the SCON0 register. These four modes offer different baud rates and communication
protocols. The four modes are summarized in Table 21.1.
21.1.1. Mode 0: Synchronous Mode
Mode 0 provides synchronous, half-duplex communication. Serial data is transmitted and received on the
RX0 pin. The TX0 pin provides the shift clock for both transmit and receive. The MCU must be the master
since it generates the shift clock for transmission in both directions (see the interconnect diagram in
Figure 21.3).
Data transmission be gins when an in stru ction writ es a data byte to th e SBUF 0 re giste r. Eight da ta bits are
transferred LSB first (see the timing diagram in Figure 21.2), and the TI0 Transmit Interrupt Flag
(SCON0.1) is set at the end of the eighth bit time. Data reception begins when the REN0 Receive Enable
bit (SCON0.4) is set to logic 1 and the RI0 Receive Interrupt Flag (SCON0.0) is cleared. One cycle after
the eighth bit is shifted in, the RI0 flag is set and reception stops until software clears the RI0 bit. An inter-
rupt will occur if enabled when either TI0 or RI0 are set.
The Mode 0 baud rate is SYSCLK / 12. RX0 is forced to open-drain in Mode 0, and an external pullup will
typically be required.
Figure 21.2. UART0 Mode 0 Timing Diagram
Figure 21.3. UART0 Mode 0 Interconnect
Table 21.1. UART0 Modes
Mode Synchronization Baud Clock Data Bits Start/Stop Bits
0 Synchronous SYSCLK / 12 8 None
1 Asynchronous Timer 1, 2, 3, or 4 Overflow 8 1 Start, 1 Stop
2 Asynchronous SYSCLK / 32 or SYSCLK / 64 9 1 Start, 1 Stop
3 Asynchronous Timer 1, 2, 3, or 4 Overflow 9 1 Start, 1 Stop
D1D0 D2 D3 D4 D5 D6 D7
RX (data out) MODE 0 TRANSMIT
D0
MODE 0 RECEIVE
RX (data in)
D1 D2 D3 D4 D5 D6 D7
TX (clk out)
TX (clk out)
Shift
Reg.
CLK
C8051Fxxx
RX
TX
DATA
8 Extra Outputs
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Rev. 1.4 289
21.1.2. Mode 1: 8-Bit UART, Variable Baud Rate
Mode 1 provides standard asynchronous, full duplex communication using a total of 10 bits per data byte:
one start bit, eight data bits (LSB first), and one stop bit. Data are transmitted from the TX0 pin and
received at the RX0 pin. On receive, the eight data bits are stored in SBUF0 and the stop bit goes into
RB80 (SCON0.2).
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Re ceive Enable bit (SCON0.4) is set to logic 1. After the stop
bit is received, the data byte will be loaded into the SBUF0 receive register if the following conditions are
met: RI0 must be logic 0, and if SM20 is logic 1, the stop bit must be logic 1.
If these conditions ar e me t, the eight bits of data is stored in SBUF0, the stop bit is stored in RB80 and the
RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the RI0 flag will not
be set. An interrupt will occur if enabled when either TI0 or RI0 are set.
Figure 21.4. UART0 Mode 1 Timing Diagram
The baud rate generated in Mode 1 is a function of timer overflow. UART0 can use Timer 1 operating in 8-
Bit Auto-Reload Mode, or Timer 2, 3, or 4 operating in Auto-reload Mode to generate the baud rate (note
that the TX and RX clocks are selected separately). On each timer overflow event (a rollover from all ones
- (0xFF for Timer 1, 0xFFFF for Timer 2, 3, or 4) - to zero) a clock is sent to the baud rate logic.
Timers 1, 2, 3, or 4 are selected as the baud rate source with bits in the SSTA0 register (see SFR Defini-
tion 21.2). The transmit baud rate clock is selected using the S0TCLK1 and S0TCLK0 bit s, and the rece ive
baud rate clock is selected using the S0RCLK1 and S0RCLK0 bits.
When T imer 1 is selected as a baud rate source, the SMOD0 bit (SSTA0.4) selects whether or not to divide
the Timer 1 overflow ra te by two. On reset, the SMOD0 bit is logic 0, thus select ing the low er speed ba ud
rate by default. The SMOD0 bit affects the baud rate generated by Timer 1 as shown in Equation 21.1.
The Mode 1 baud rate equations are shown below, where T1M is bit4 of register CKCON, TH1 is the 8-bit
reload register for Timer 1, and [RCAPnH , RCAPnL] is the 16-bit reload register for Timer 2, 3, or 4.
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE
Equation 21.1. Mode 1 Baud Rate using Timer 1
Mode1_BaudRate 1 32Timer1_OverflowRate=
When SMOD0 = 0:
Mode1_BaudRate 1 16Timer1_OverflowRate=
When SMOD0 = 1:
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290 Rev. 1.4
The Timer 1 overflow rate is determine d by the Timer 1 clock source (T1CLK) and reload value (TH1). Th e
frequency of T1C LK is selected as descr ibed in Section “23.1. Timer 0 and Timer 1” on page 309. The
Timer 1 overflow rate is calculated as shown in Equation 21.2.
When Timers 2, 3, or 4 are selected as a baud rate source, the baud rate is generated as shown in
Equation 21.3.
The overflow rate for Timer 2, 3, or 4 is determined by the clock source for the timer (TnCLK) and the 16-
bit reload value stored in the RCAPn register (n = 2, 3, or 4), as shown in Equation 21.4.
Equation 21.2. Timer 1 Overflow Rate
Timer1_OverflowRate T1CLK 256 TH1–=
Equation 21.3. Mode 1 Baud Rate using Timer 2, 3, or 4
Mode1_BaudRate 1 16Timer234_OverflowRate=
Equation 21.4. Timer 2, 3, or 4 Overflow Rate
Timer234_OverflowRate TnCLK 65536 RCAPn–=
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Rev. 1.4 291
21.1.3. Mode 2: 9-Bit UART, Fixed Baud Rate
Mode 2 provides asyn chronous, full-du plex communicatio n using a tot al of eleven bits per da ta byte: a st art
bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. Mode 2 supports multiprocessor
communications and hardware address recognition (see Section 21.2). On transmit, the ninth data bit is
determined by the valu e in TB80 (SCON0.3 ). It can be assigned the value of the p arity flag P in th e PSW or
used in multiprocessor communications. On receive, the ninth data bit goes into RB80 (SCON0.2) and the
stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF0 register. The TI0 Transmit
Interrupt Flag (SCON0.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN0 Re ceive Enable bit (SCON0.4) is set to logic 1. After the stop
bit is received, the data byte will be loaded into the SBUF0 receive register if RI0 is logic 0 and one of the
following requirements are met:
1. SM20 is logic 0
2. SM20 is logic 1, the received 9th bit is logic 1, and the received address matches the UART0
address as described in Section 21.2.
If the above conditions are satisfied, the eight bits of data are stored in SBUF0, the ninth bit is stored in
RB80 and the RI0 flag is set. If these conditions are not met, SBUF0 and RB80 will not be loaded and the
RI0 flag will not be set. An interrupt will occur if enabled when either TI0 or RI0 are set.
The baud rate in Mode 2 is either SYSCLK / 32 or SYSCLK / 64, according to the value of the SMOD0 bit
in register SSTA0.
Figure 21.5. UART0 Modes 2 and 3 Timing Diagram
Equation 21.5. Mode 2 Baud Rate
BaudRate 2SMOD0SYSCLK
64
----------------------
=
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE D8
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
292 Rev. 1.4
Figure 21.6. UART0 Modes 1, 2, and 3 Interconnect Diagram
21.1.4. Mode 3: 9-Bit UART, Variable Baud Rate
Mode 3 uses the Mode 2 transmission protocol with the Mode 1 baud rate generation. Mode 3 operation
transmits 11 bits: a start bit, 8 data bits (LSB first), a programmable ninth data bit, and a stop bit. The baud
rate is derived from Timer 1 or Timer 2, 3, or 4 overflows, as defined by Equation 21.1 and Equation 21.3.
Multiprocessor communications an d hardware addr ess recognition are supporte d, as described in Section
21.2.
OR
RS-232
C8051Fxxx
RS-232
LEVEL
XLTR
TX
RX
C8051Fxxx
RX
TX
MCU
RX
TX
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 293
21.2. Multiprocessor Communications
Modes 2 and 3 su pport multip rocesso r communication be tween a ma ster processor and one or mo re slave
processors by special use of the ninth data bit and the built-in UART0 address recognition hardware. When
a master processor wants to transmit to one or more slaves, it first sends an address byte to select the t a r-
get(s). An address byte differs from a data byte in that its ninth bit is logic 1; in a data byte, the ninth bit is
always set to logic 0. UART0 will recognize as “valid” (i.e., capable of causing an interrupt) two types of
addresses: (1) a masked address and (2) a broadcast address at any given time. Both are described
below.
21.2.1. Configuration of a Masked Address
The UART0 address is configured via two SFR’s: SADDR0 (Serial Address) and SADEN0 (Serial Address
Enable). SADEN0 sets the bit mask for the address held in SADDR0: bits set to logic 1 in SADEN0 corre-
spond to bit s in SADDR0 tha t are che cked against the received ad dress byte; bits set to logic 0 in SADEN0
correspond to “don’t care” bits in SADDR0.
Setting the SM20 bit (SCON0.5) conf igures UART0 such that wh en a stop bit is received, UART0 will gen-
erate an interrupt only if the ninth bit is logic 1 (RB80 = ‘1’) and the received data byte matches the UART0
slave address. Following the received address interrupt, the slave will clear its SM20 bit to enable interrupts
on the reception of the following data byte(s). Once the entire message is received, the addressed slave
resets its SM20 bit to ignore all transmissions until it receives the next address byte. While SM20 is logic 1,
UART0 ignores all bytes that do not match the UART0 address and include a ninth bit that is logic 1.
21.2.2. Broadcast Addressing
Multiple addresses can be ass igned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The broadcast
address is the logical OR of registers SADDR0 and SADEN0, and ‘0’s of the result are treated as “don’t
cares”. Typically a broadcast address of 0xFF (hexadecimal) is acknowledged by all slaves, assuming
“don’t care” bi ts as ‘1’s. The master processo r can be co nfigure d to receive a ll transmiss ions or a pr otoc ol
can be implemented such that the master/slave role is temporarily reversed to enable half-duplex trans-
mission between th e or iginal master and s lave ( s)..
Note in the above examples 4, 5, and 6, each slave would recognize as “valid” an address of 0xFF as a
broadcast address. Also note that examples 4, 5, and 6 uses the same SADDR0 and SADEN0 register
values as shown in the examples 1, 2, and 3 respectively (slaves #1, 2, and 3). Thus, a master could
address each slave device individually using a masked address, and also broadcast to all three slave
devices. For example, if a Master were to send an address “11110101”, only slave #1 would recognize the
address as valid. If a master were to then send an address of “11111111”, all three slave devices would rec-
ognize the add re ss as a va lid br oa dcast addres s.
Example 1, SLAVE #1 Example 2, SLAVE #2 Example 3, SLAVE #3
SADDR0 = 00110101 SADDR0 = 00110101 SADDR0 = 00110101
SADEN0 = 00001111 SADEN0 = 11110011 SADEN0 = 11000000
UART0 Address = xxxx0101 UART0 Address = 0011xx01 UART0 Address = 00xxxxxx
Example 4, SLAVE #1 Example 5, SLAVE #2 Example 6, SLAVE #3
SADDR0 = 00110101 SADDR0 = 00110101 SADDR0 = 00110101
SADEN0 = 00001111 SADEN0 = 11110011 SADEN0 = 11000000
Broadcast Address = 00111111 Broadcast Address = 11110111 Broadcast Address = 11110101
Where all ZEROES in the Broadcast address are don’t cares.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
294 Rev. 1.4
Figure 21.7. UART Multi-Processor Mode Interconnect Diagram
21.3. Frame and Transmission Error Detectio n
All Modes:
The Transmit Collision bit (TXCOL0 bit in register SSTA0) reads ‘1’ if user software writes data to the
SBUF0 register while a transmit is in progress.
Modes 1, 2, and 3:
The Receive Overrun bit (RXOV0 in registe r SSTA0) reads ‘1’ if a new data byte is latched into the re ce ive
buffer before software has read the previous byte. The Frame Error bit (FE0 in register SSTA0) reads ‘1’ if
an invalid (low) STOP bit is detected.
Master
Device Slave
Device
TXRX RX TX
Slave
Device
RX TX
Slave
Device
RX TX
+5V
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 295
Table 21.2. Oscillator Frequencies for Standard Baud Rates
System Clock
Frequency (MHz) Divide Factor Timer 1 Reload
Value1
Timer2,3,or
4 Reload
Value Resulting Baud Rate (Hz)2
100.0 864 0xCA 0xFFCA 115200 (115741)
99.5328 864 0xCA 0xFFCA 115200
50.0 432 0xE5 0xFFE5 115200 (115741)
49.7664 432 0xE5 0xFFE5 115200
24.0 208 0xF3 0xFFF3 115200 (115384)
22.1184 192 0xF4 0xFFF4 115200
18.432 160 0xF6 0xFFF6 115200
11.0592 96 0xFA 0xFFFA 115200
3.6864 32 0xFE 0xFFFE 115200
1.8432 16 0xFF 0xFFFF 115200
100.0 3472 0x27 0xFF27 28800 (28802)
99.5328 3456 0x28 0xFF28 28800
50.0 1744 0x93 0xFF93 28800 (28670)
49.7664 1728 0x94 0xFF94 28800
24.0 832 0xCC 0xFFCC 28800 (28846)
22.1184 768 0xD0 0xFFD0 28800
18.432 640 0xD8 0xFFD8 28800
11.0592 348 0xE8 0xFFE8 28800
3.6864 128 0xF8 0xFFF8 28800
1.8432 64 0xFC 0xFFFC 28800
100.0 10416 - 0xFD75 9600 (9601)
99.5328 10368 - 0xFD78 9600
50.0 5216 - 0xFEBA 9600 (9586)
49.7664 5184 - 0xFEBC 9600
24.0 2496 0x64 0xFF64 9600 (9615 )
22.1184 2304 0x70 0xFF70 9600
18.432 1920 0x88 0xFF88 9600
11.0592 1152 0xB8 0xFFB8 9600
3.6864 384 0xE8 0xFFE8 9600
1.8432 192 0xF4 0xFFF4 9600
Notes:
1. Assumes SMOD0 = 1 and T1M = 1.
2. Numbers in parenthesis show the actual baud rate.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
296 Rev. 1.4
SFR Definition 21.1. SCON0: UART0 Control
Bits7–6: SM00–SM10: Serial Port Operation Mode:
Write:
When written, these bits select the Serial Port Operation Mode as follows:
Reading these bits returns the current UART0 mode as defined above.
Bit5: SM20: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port Operation Mode.
Mode 0: No effect
Mode 1: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI0 will only be activated if stop bit is logic level 1.
Mode 2 and 3: Multipro cessor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI0 is set and an interrupt is generated only when the ninth bit is logic 1 and the
received address matches the UART0 address or the broadcast ad dress.
Bit4: REN0: Receive Enable.
This bit enables/disable s the UART0 receiver.
0: UART0 reception disabled.
1: UART0 reception enabled.
Bit3: TB80: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in Modes 2 and 3. It is
not used in Modes 0 and 1. Set or cleared by software as required.
Bit2: RB80: Ninth Receive Bit.
The bit is assigned the logic level of the ninth bit received in Modes 2 and 3. In Mode 1, if
SM20 is logic 0, RB80 is assigned the lo gic level of the received stop bit. RB8 is not used in
Mode 0.
Bit1: TI0: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART0 (after the 8th bit in
Mode 0, or at the beginning of the stop bit in other modes). When the UART0 interrupt is
enabled, setting this bit ca us es th e CPU to ve ctor to the UART0 interrupt service rout ine.
This bit must be cleare d manually by software
Bit0: RI0: Receive Interrupt Flag.
Set by hardware when a byte of data has been received by UART0 (as selected by the
SM20 bit). When the UART0 interrupt is enabled, setting this bit causes the CPU to vector
to the UART0 interrupt service routine. This bit must be cleared manually by software.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
SM00 SM10 SM20 REN0 TB80 RB80 TI0 RI0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0x98
0
SM00 SM10 Mode
0 0 Mode 0: Synchronous Mode
0 1 Mode 1: 8-Bit UART, Variable Baud Rate
1 0 Mode 2: 9-Bit UART, Fixed Baud Rate
1 1 Mode 3: 9-Bit UART, Variable Baud Rate
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Rev. 1.4 297
SFR Definition 21.2. SSTA0: UART0 Status and Clock Selection
Bit7: FE0: Frame Error Flag.*
This flag indicates if an invalid (low) STOP bit is detected.
0: Frame Error has not been detected
1: Frame Error has been detected.
Bit6: RXOV0: Receive Overru n Flag.*
This flag indicates new data has been latched into the receive buffer before software has
read the prev iou s byte.
0: Receive overrun has not been detected.
1: Receive Overrun has been detected.
Bit5: TXCOL0: Transmit Collision Flag.*
This flag indicates user software has written to the SBUF0 register while a transmission is
in progress.
0: Transmission Collision has not been detected.
1: Transmission Collision has been detected.
Bit4: SMOD0: UART0 Baud Rate Doubler Enable.
This bit enables/disable s the divide-by-two function of the UAR T0 baud rate logic fo r config-
urations described in th e UART0 section.
0: UART0 baud rate divide-by-two enabled.
1: UART0 baud rate divide-by-two disabled.
Bits3–2: UART0 Transmit Baud Rate Clock Selection Bits
.
Bits1–0: UART0 Receive Baud Rate Clock Selection Bits
*Note: FE0, RXOV0, and TXCOL0 are flags only, and no interrupt is generated by these conditio ns.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
FE0 RXOV0 TXCOL0 SMOD0 S0TCLK1 S0TCLK0 S0RCLK1 S0RCLK0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x91
0
S0TCLK1 S0TCLK0 Serial Tr ansmit Baud Rate Clock Source
0 0 Timer 1 generates UART0 TX Baud Rate
0 1 Timer 2 Overflow generates UART0 TX baud rate
1 0 Timer 3 Overflow generates UART0 TX baud rate
1 1 Timer 4 Overflow generates UART0 TX baud rate
S0RCLK1 S0RCLK0 Serial Receive Baud Rate Clock Source
0 0 T i mer 1 generates UART0 RX Baud Rate
0 1 Timer 2 Overflow generates UART0 RX baud rate
1 0 Timer 3 Overflow generates UART0 RX baud rate
1 1 Timer 4 Overflow generates UART0 RX baud rate
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
298 Rev. 1.4
SFR Definition 21.3. SBUF0: UART0 Data Buffer
SFR Definition 21.4. SADDR0: UART0 Slave Address
SFR Definition 21.5. SADEN0: UART0 Slave Address Enable
Bits7–0: SBUF0.[7:0]: UART0 Buffer Bits 7–0 (MSB–LSB)
This is actually two registers; a transmit and a receive buffer register. When data is moved
to SBUF0, it goes to the transmit buffer and is held for serial transmission. Moving a byte to
SBUF0 is what initiates the transmission. When data is moved from SBUF0, it comes from
the receive buffer.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x99
0
Bits7–0: SADDR0.[7:0]: UART0 Slave Address
The content s of this register are used to define the UAR T0 slave address. Register SADEN0
is a bit mask to determine which bits of SADDR0 are checked against a received address:
corresponding bits set to logic 1 in SADEN0 are checked; corresponding bits set to logic 0
are “don’t cares”.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xA9
0
Bits7–0: SADEN0.[7:0]: UART0 Slave Address Enable
Bits in this register enable corresponding bits in register SADDR0 to determine the UART0
slave address.
0: Corresponding bit in SADDR0 is a “don’t care”.
1: Corresponding bit in SADDR0 is checked against a received address.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xB9
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 299
22. UART1
UART1 is an asynchronous, full duplex serial port offering modes 1 and 3 of the standard 8051 UART.
Enhanced baud rate su pport allows a wide r ange o f clock sour ces to gene rate st andard baud r ates (det ails
in Section “22.1. Enhanced Baud Rate Generation” on page 300). Received data buffering allows
UART1 to st art rece ption of a se cond incomi ng dat a byte befo re sof tware has finishe d reading the previous
data byte.
UART1 has two associated SFRs: Serial Control Register 1 (SCON1) and Serial Data Buffer 1 (SBUF1).
The single SBUF1 location provides access to both transmit and receive registers. Reading SBUF1
accesses the buffered Receive register; writing SBUF1 accesses the Transmit register.
With UART1 interrupts enabled, an interrupt is generated each time a transmit is completed (TI1 is set in
SCON1), or a data byte has been received (RI1 is set in SCON1). The UART1 interrupt flags are not
cleared by hardwa re when the CPU vectors to th e interr upt service routine. They must be cleared manually
by software, allowing software to dete rmine the cause of the UAR T1 interrupt ( transmit complete or rece ive
complete).
Figure 22.1. UART1 Block Diagram
UART1 Baud
Rate Generator
RI1
SCON1
RI1
TI1
RB81
TB81
REN1
MCE1
S1MODE
Tx Control
Tx Clock Send
SBUF1
(TX Shift)
Start
Data
Write to
SBUF1
Crossbar
TX1
Shift
Zero Detector
Tx IRQ
SET
QD
CLR
Stop Bit
TB81
SFR Bus
Serial
Port
Interrupt
TI1
Port I/O
Rx Control
Start
Rx Clock
Load
SBUF1
Shift 0x1FF RB81
Rx IRQ
Input Shift Regist er
(9 bits)
Load SBUF1
Read
SBUF1
SFR Bus
Crossbar
RX1
SBUF1
(RX Latch)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
300 Rev. 1.4
22.1. Enhanced Baud Rate Generation
The UART1 baud rate is generated by Timer 1 in 8-bit auto-reload mode. The TX clock is generated by
TL1; the RX clock is generated by a copy of TL1 (shown as RX Timer in Figure 22.2), which is not user-
accessible. Both TX and RX Timer overflows are divided by two to generate the TX and RX baud rates.
The RX Timer runs when Timer 1 is enabled, and uses the same reload value (TH1). However, an
RX Timer reload is forced when a START condition is detected on the RX pin. This allows a receive to
begin any time a START is detected, independent of the TX Timer state.
Figure 22.2. UART1 Baud Rate Logic
Timer 1 should be configured for Mode 2, 8-bit auto-reload (see Section “23.1.3. Mode 2: 8-bit Counter/
Timer with Auto-Reload” on page 311). The Timer 1 reload value should be set so that overflows will
occur at two times the desired baud rate. Note that Timer 1 may be clocked by one of five sources: SYS-
CLK, SYSCLK / 4, SYSCLK / 12, SYSCLK / 48, or the external oscillator clock / 8. For any given Timer 1
clock source, the UART1 baud rate is determined by Equation 22.1.
Where T1CLK is the frequency of the clock supplied to Timer 1, and T1H is the high byte of Timer 1 (reload
value). Timer 1 clock frequency is selected as described in Section “23.1. Timer 0 and Timer 1” on
page 309. A quick reference for typical baud rates and system clock frequencies is given in Table 22.1
through Table 22.5. Note that the internal oscillator or PLL may still generate the system clock when the
external oscillator is driving Timer 1 (see Section “23.1. Timer 0 and Timer 1” on page 309 for more
details).
RX Timer
Start
Detected
Overflow
Overflow
TH1
TL1
TX Clock
2
RX Cl ock
2
Timer 1 UART1
Equation 22.1. UART1 Baud Rate
UARTBaudRate T1CLK
256 T1H–
-------------------------------1
2
---
=
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Rev. 1.4 301
22.2. Operational Modes
UART1 provides standard asynchronous, full duplex communication. The UART mode (8-bit or 9-bit) is
selected by the S1MODE bit (SCON1.7). Typical UART connection options are shown below.
Figure 22.3. UART Interconnect Diagram
22.2.1. 8-Bit UART
8-Bit UART mode uses a total of 10 bits per data byte: one start bit, eight data bits (LSB first), and one stop
bit. Data are transmitted LSB first from the TX1 pin and received at the RX1 pin. On receive, the eight data
bits are stored in SBUF1 and the stop bit goes into RB81 (SCON1.2).
Data transmission begins when software writes a data byte to the SBUF1 register. The TI1 Transmit Inter-
rupt Flag ( SCON1.1) is set at th e end of the tran smission (the beginning of the stop-bit time). Data recep-
tion can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to logic 1. After the stop bit is
received, the data byte will be loaded into the SBUF1 receive register if the following conditions are met:
RI1 must be logic 0, and if MCE1 is logic 1, the sto p bit must be logic 1. In the event of a receive data over-
run, the first received 8 bits are la tched into the SBUF1 receive register and the following overrun data bits
are lost.
If these conditions ar e me t, the eight bits of data is stored in SBUF1, the stop bit is stored in RB81 and the
RI1 flag is set. If these conditions are not met, SBUF1 and RB81 will not be loaded and the RI1 flag will not
be set. An interrupt will occur if enabled when either TI1 or RI1 is set.
Figure 22.4. 8-Bit UART Timing Diagram
OR
RS-232
C8051Fxxx
RS-232
LEVEL
XLTR
TX
RX
C8051Fxxx
RX
TX
MCU RX
TX
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK
STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
302 Rev. 1.4
22.2.2. 9-Bit UART
9-bit UART mode uses a total of eleven bits per data byte: a start bit, 8 data bits (LSB first), a programma-
ble ninth data bit, and a stop bit. The state of the ninth transmit data bit is determined by the value in TB81
(SCON1.3), which is assigned by use r sof t ware . It can be assigned the value of the parity fla g (bit P in reg-
ister PSW) for error detection, or used in multiprocessor communications. On receive, the ninth data bit
goes into RB81 (SCON1.2) and the stop bit is ignored.
Data transmission begins when an instruction writes a data byte to the SBUF1 register. The TI1 Transmit
Interrupt Flag (SCON1.1) is set at the end of the transmission (the beginning of the stop-bit time). Data
reception can begin any time after the REN1 Receive Enable bit (SCON1.4) is set to ‘1’. After the stop bit
is received, the data byte will be loaded into the SBUF1 receive register if the following conditions are met:
(1) RI1 must be logic 0, and (2) if MCE1 is logic 1, the 9th bit must be logic 1 (when MCE1 is logic 0, the
state of the ninth data bit is unimportant). If these conditions are met, the eight bits of data are stored in
SBUF1, the ninth bit is stored in RB81, and the RI1 flag is set to ‘1’. If the above conditions are not met,
SBUF1 and RB81 will not be loaded and the RI1 flag will not be set to ‘1’. A UART1 interrupt will occur if
enabled when either TI1 or RI1 is set to ‘1’.
Figure 22.5. 9-Bit UART Timing Diagram
D1D0 D2 D3 D4 D5 D6 D7
START
BIT
MARK
STOP
BIT
BIT TIMES
BIT SAMPLING
SPACE
D8
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Rev. 1.4 303
22.3. Multiprocessor Communications
9-Bit UART mode supports multiprocessor communication between a master processor and one or more
slave processors by special use of the ninth dat a bit. When a master p rocessor wa nts to transmit to one or
more slaves, it first sends an address byte to select the target(s). An address byte differs from a data byte
in that its ninth bit is logic 1; in a data byte, the ninth bit is always set to logic 0.
Setting the MCE1 bit (SCON.5) of a slave processor configures its UART such that when a stop bit is
received, the UART will generate an interrupt only if the ninth bit is logic one (RB81 = 1) signifying an
address byte has been received. In the UART interrupt handler, software should compare the received
address with the slave's own assigned 8-bit address. If the addresses match, the slave should clear its
MCE1 bit to enable interrupts on the reception of the following data byte(s). Slaves that weren't addressed
leave their MCE1 bits set and do not generate interrupts on the reception of the following data bytes,
thereby ignoring the data. Once the entire message is received, the addressed slave should reset its
MCE1 bit to ignore all transmissions until it receives the next address byte.
Multiple addresses can be ass igned to a single slave and/or a single address can be assigned to multiple
slaves, thereby enabling "broadcast" transmissions to more than one slave simultaneously. The master
processor can be configured to receive all transmissions or a protocol can be implemented such that the
master/slave role is temporarily reversed to enable half-duplex transmission between the original master
and slave(s).
Figure 22.6. UART Multi-Processor Mode Interconnect Diagram
Master
Device Slave
Device
TXRX RX TX
Slave
Device
RX TX
Slave
Device
RX TX
+5V
C8051F120/1/2/3/4/5/6/7
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304 Rev. 1.4
SFR Definition 22.1. SCON1: Serial Port 1 Control
Bit7: S1MODE: Serial Port 1 Operation Mode.
This bit selects the UART1 Operation Mode.
0: Mode 0: 8-bit UART with Variable Baud Rate
1: Mode 1: 9-bit UART with Variable Baud Rate
Bit6: UNUSED. Read = 1b. Write = don’t care.
Bit5: MCE1: Multiprocessor Communication Enable.
The function of this bit is dependent on the Serial Port 0 Operation Mode.
Mode 0: Checks for valid stop bit.
0: Logic level of stop bit is ignored.
1: RI1 will only be activated if stop bit is logic level 1.
Mode 1: Multiproce ssor Communications Enable.
0: Logic level of ninth bit is ignored.
1: RI1 is set and an interrupt is generated only when the ninth bit is logic 1.
Bit4: REN1: Receive Enable.
This bit enables/disables the UART receiver.
0: UART1 reception disabled.
1: UART1 reception enabled.
Bit3: TB81: Ninth Transmission Bit.
The logic level of this bit will be assigned to the ninth transmission bit in 9-bit UART Mode. It
is not used in 8-bit UART Mode. Set or cleared by software as required.
Bit2: RB81: Ninth Receive Bit.
RB81 is assigned the value of the STOP bit in Mode 0; it is assigned the value of the 9th
data bit in Mode 1.
Bit1: TI1: Transmit Interrupt Flag.
Set by hardware when a byte of data has been transmitted by UART1 (after the 8th bit in 8-
bit UAR T Mode, or at the beginning o f the STOP bit in 9-bit UAR T Mode). Wh en the UAR T1
interrupt is enable d, setting this bit causes the CPU to vector to the UAR T1 interru pt service
routine. This bit must be cleare d manually by software
Bit0: RI1: Receive Interrupt Flag.
Set to ‘1’ by hardware wh en a byte of data ha s been received by UAR T1 (set at the STO P bit
sampling time). When the UART1 interrupt is enabled, setting th is bi t to ‘1’ causes the CPU
to vector to the UART1 interrupt service routine. This bit must be cleared manually by soft-
ware.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
S1MODE - MCE1 REN1 TB81 RB81 TI1 RI1 01000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0x98
1
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 305
SFR Definition 22.2. SBUF1: Serial (UART1) Port Data Buffer
Table 22.1. Timer Settings for Standard Baud Rates Using The Internal 24.5 MHz
Oscillator
Frequency: 24.5 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error Oscilla-
tor Divide
Factor
Timer Clock
Source SCA1-SCA0
(pre-scale
select)*
T1M* Timer 1
Reload
Value (hex)
SYSCLK from
Internal Osc.
230400 -0.32% 106 SYSCLK XX 1 0xCB
115200 -0.32% 212 SYSCLK XX 1 0x96
57600 0.15% 426 SYSCLK XX 1 0x2B
28800 -0.32% 848 SYSCLK / 4 01 0 0x96
14400 0.15% 1704 SYSCLK / 12 00 0 0xB9
9600 -0.32% 2544 SYSCLK / 12 00 0 0x96
2400 -0.32% 10176 SYSCLK / 48 10 0 0x96
1200 0.15% 20448 SYSCLK / 48 10 0 0x2B
X=Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Bits7–0: SBUF1[7:0]: Serial Data Buffer Bits 7-0 (MSB-LSB)
This SFR accesses two registers; a transmit shift register and a receive latch register. When
data is written to SBUF1, it goes to th e transmit shift reg ister and is held for serial transmis-
sion. W riting a byte to SBUF1 is what initiates the transmission. A read of SBUF1 return s the
contents of the receive lat c h .
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x99
1
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
306 Rev. 1.4
Table 22.2. Timer Settings for Standard Baud Rates Using an External 25.0 MHz
Oscillator
Frequency: 25.0 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error Oscilla-
tor Divide
Factor
Timer Clock
Source SCA1-SCA0
(pre-scale
select)*
T1M* Timer 1
Reload
Valu e (h ex )
SYSCLK from
External Osc.
230400 -0.47% 108 SYSCLK XX 1 0xCA
115200 0.45% 218 SYSCLK XX 1 0x93
57600 -0.01% 434 SYSCLK XX 1 0x27
28800 0.45% 872 SYSCLK / 4 01 0 0x93
14400 -0.01% 1736 SYSCLK / 4 01 0 0x27
9600 0.15% 2608 EXTCLK / 8 11 0 0x5D
2400 0.45% 10464 SYSCLK / 48 10 0 0x93
1200 -0.01% 20832 SYSCLK / 48 10 0 0x27
SYSCLK from
Internal Osc.
57600 -0.47% 432 EXTCLK / 8 11 0 0xE5
28800 -0.47% 864 EXTCLK / 8 11 0 0xCA
14400 0.45% 1744 EXTCLK / 8 11 0 0x93
9600 0.15% 2608 EXTCLK / 8 11 0 0x5D
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Table 22.3. Timer Settings for S t andard Baud Rates Using an External 22.1 184 MHz
Oscillator
Frequency: 22.1184 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error Oscilla-
tor Divide
Factor
Timer Clock
Source SCA1-SCA0
(pre-scale
select)*
T1M* Timer 1
Reload
Value (hex)
SYSCLK from
External Osc.
230400 0.00% 96 SYSCLK XX 1 0xD0
115200 0.00% 192 SYSCLK XX 1 0xA0
57600 0.00% 384 SYSCLK XX 1 0x40
28800 0.00% 768 SYSCLK / 12 00 0 0xE0
14400 0.00% 1536 SYSCLK / 12 00 0 0xC0
9600 0.00% 2304 SYSCLK / 12 00 0 0xA0
2400 0.00% 9216 SYSCLK / 48 10 0 0xA0
1200 0.00% 18432 SYSCLK / 48 10 0 0x40
SYSCLK from
Internal Osc.
230400 0.00% 96 EXTCLK / 8 11 0 0xFA
115200 0.00% 192 EXTCLK / 8 11 0 0xF4
57600 0.00% 384 EXTCLK / 8 11 0 0xE8
28800 0.00% 768 EXTCLK / 8 11 0 0xD0
14400 0.00% 1536 EXTCLK / 8 11 0 0xA0
9600 0.00% 2304 EXTCLK / 8 11 0 0x70
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 307
Table 22.4. Timer Settings for Standard Baud Rates Using the PLL
Frequency: 50.0 M Hz
Target
Baud Rate
(bps)
Baud Rate
% Error Oscilla-
tor Divide
Factor
Timer Clock
Source SCA1-SCA0
(pre-scale
select)*
T1M* Timer 1
Reload
Value (hex)
230400 0.45% 218 SYSCLK XX 1 0x93
115200 -0.01% 434 SYSCLK XX 1 0x27
57600 0.45% 872 SYSCLK / 4 01 0 0x93
28800 -0.01% 1736 SYSCLK / 4 01 0 0x27
14400 0.22% 3480 SYSCLK / 12 00 0 0x6F
9600 -0.01% 5208 SYSCLK / 12 00 0 0x27
2400 -0.01% 20832 SYSCLK / 48 10 0 0x27
X=Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1.
Table 22.5. Timer Settings for Standard Baud Rates Using the PLL
Frequency: 100.0 MHz
Target
Baud Rate
(bps)
Baud Rate
% Error Oscilla-
tor Divide
Factor
Timer Clock
Source SCA1-SCA0
(pre-scale
select)*
T1M* Timer 1
Reload
Value (hex)
230400 -0.01% 434 SYSCLK XX 1 0x27
115200 0.45% 872 SYSCLK / 4 01 0 0x93
57600 -0.01% 1736 SYSCLK / 4 01 0 0x27
28800 0.22% 3480 SYSCLK / 12 00 0 0x6F
14400 - 0.47% 6912 SYSCLK / 48 10 0 0xB8
9600 0.45% 10464 SYSCLK / 48 10 0 0x93
X = Don’t care
*Note: SCA1-SCA0 and T1M bit definitions can be found in Section 23.1 .
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
308 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 309
23. Timers
Each MCU includes 5 counter/timers: Timer 0 and Timer 1 are 16-bit counter/timers compatible with those
found in the standard 8051. Timer 2, Timer 3, and Timer 4 are 16-bit auto-reload and capture counter/tim-
ers for use with the ADCs, DACs, square-wave generation, or for general-purpose use. These timers can
be used to measure time intervals, count external events and gener ate per iodic inter rupt re qu ests. Timer 0
and Timer 1 are nearly identical and have four primary modes of operation. Timer 3 offers 16-bit auto-
reload and capture. Timers 2 and 4 are identical, and offer not only 16-bit auto-reload and capture, but
have the ability to produce a 50% duty-cycle square-wave (toggle output) at an external port pin.
Timers 0 and 1 may be clocked by one of five sources, determined by the Timer Mode Select bits (T1M-
T0M) and the Clock Scale bits (SCA1-SCA0). The Clock Scale bits define a pre-scaled clock by which
Timer 0 and/or Timer 1 may be clocked (See SFR Definition 23.3 for pre-scaled clock selection). Timers 0
and 1 can be configured to use either the pre-scaled clock signal or the system clock directly. Timers 2, 3,
and 4 may be clocked by the system clock, the system clock divided by 12, or the external oscillator clock
source divided by 8.
Timer 0 and Timer 1 may also be operated as counters. When functioning as a counter, a counter/timer
register is incremented on each high-to-low transition at the selected input pin. Events with a frequency of
up to one-fourth the system clock's frequency can be counted. The input signal need not be periodic, but it
should be held at a given logic level for at least two full system clock cycles to ensure the leve l is properly
sampled.
23.1. T imer 0 and Timer 1
Each timer is implemented as a 16-bit register accessed as two separate 8-bit SFRs: a low byte (TL0 or
TL1) and a high byte (TH0 or TH1). The Counter/Timer Control register (TCON) is used to enable Timer 0
and Timer 1 as well as indicate their status. Timer 0 interrupts can be enabled by setting the ET0 bit in the
IE register (Section “11.3.5. Interrupt Register Descriptions” on page 157); Timer 1 interrupts can be
enabled by setting the ET1 bit in the IE register (Section 11.3.5). Both counter/timers operate in one of
four primary modes selected by setting the Mode Select bits T1M1–T0M0 in the Counter/Timer Mode reg-
ister (TMOD). Both timers can be configured independently.
23.1.1. Mode 0: 13-bit Counter/Timer
Timer 0 and Timer 1 operate as 13-bit counter/timers in Mode 0. The following describes the configuration
and operation of Timer 0. However, both timers operate identically, and Timer 1 is configured in the same
manner as described for Timer 0.
The TH0 register holds the eight MSBs of the 13-bit counter/timer. TL0 holds the five LSBs in bit positions
TL0.4–TL0.0. The three upper bits of TL0 (TL0.7–TL0.5) are indeterminate and should be masked out or
ignored when reading the TL0 register. As the 13-bit timer register increments and overflows from 0x1FFF
(all ones) to 0x0000, the timer overflow flag TF0 (TCON.5) is set and an interrupt will occur if T imer 0 inter-
rupts are enabled.
Timer 0 and Timer 1 Modes: Timer 2, 3 and 4 Modes:
13-bit counter/timer 16-bit counter/timer with auto-reload
16-bit counter/timer 16-bit counter/timer with capture
8-bit counter/timer with auto-reload Toggle Output (Timer 2 and 4 only)
Two 8-bit counter/timers (Timer 0 only)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
310 Rev. 1.4
The C/T0 bit (TMOD.2) selects the counter/timer's clock source. When C/T0 is set to logic 1, high-to-low
transitions at the selected Timer 0 input pin (T0) increment the timer register (Refer to Section
“18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on page 238 for information on selecting
and configuring externa l I/O pins). Clearing C/T select s the clock defined by the T0M bit (CKCON.3). When
T0M is set, Timer 0 is clocked by the system clock. When T0M is cleared, Timer 0 is clocked by the source
selected by the Clock Scale bit s in CKCON (see SFR Definition 23.3).
Setting the TR0 bit (TCON.4) enables the timer when either GATE0 (TMOD.3) is logic 0 or the input signal
/INT0 is logic-level 1. Setting GATE0 to ‘1’ allows the timer to be controlled by the external input signal /
INT0 (see Section “11.3.5. Interrupt Register Descriptions” on page 157), facilitating pulse width mea-
surements.
Setting TR0 does not force the timer to reset. The timer registers should be loaded with the desired initial
value before the timer is enabled.
TL1 and TH1 fo rm the 13-b it re gister fo r Timer 1 in the same ma nner as descri bed a bove for TL0 a nd TH0.
Timer 1 is configured and controlled using the relevant TCON and TMOD bits just as with Timer 0. The
input signal /INT1 is used with T imer 1.
Figure 23.1. T0 Mode 0 Block Diagram
TR0 GATE0 /INT0 Counter/Timer
0 X X Disabled
1 0 X Enabled
110Disabled
111Enabled
X = Don't Care
TCLK
TL0
(5 bits) TH0
(8 bits)
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
TR0
0
1
0
1
SYSCLK
Pre-scaled Clock
CKCON
S
C
A
0
S
C
A
1
T
1
M
T
0
M
TMOD
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
GATE0
/INT0
T0
Crossbar
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 311
23.1.2. Mode 1: 16-bit Counter/Timer
Mode 1 opera tion is the same as Mode 0, except that the counter/timer registers use all 16 bits. The coun-
ter/timers are enabled and configured in Mode 1 in the same manner as for Mode 0.
23.1.3. Mode 2: 8-bit Counter/Timer with Auto-Reload
Mode 2 configures Timer 0 or Timer 1 to operate as 8-bit counter/timers with automatic reload of the start
value. TL0 holds the count and TH0 holds the reload value. When the cou n te r in T L0 ov er flo w s f ro m 0x FF
to 0x00, the timer overflow flag TF0 (TCON.5) is set and the counter in TL0 is reloaded from TH0. If Timer
0 interrupts are enabled, an interrupt will occur when the TF0 flag is set. The reload value in TH0 is not
changed. TL0 must b e initialized to the desired value before enabling the timer for the first count to be cor-
rect. When in Mode 2, Timer 1 operates identically to Timer 0.
Both counter/timers are enabled and configured in Mode 2 in the same manner as Mode 0. Setting the
TR0 bit (TCON.4) enables th e timer when either GATE0 (TMOD.3) is logic 0 or when th e input signal /INT0
is low
.
Figure 23.2. T0 Mode 2 Block Diagram
TCLK
TMOD
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
TL0
(8 bits)
Reload
TH0
(8 bits)
0
1
0
1
SYSCLK
Pre-scaled Clock
CKCON
S
C
A
0
S
C
A
1
T
1
M
T
0
M
TR0
GATE0
/INT0
T0
Crossbar
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
312 Rev. 1.4
23.1.4. Mode 3: Two 8-bit Counter/Timers (Timer 0 Only)
In Mode 3, Timer 0 is configured as t wo separate 8-bit counter /timers held in TL0 and TH0. The count er/
timer in TL0 is controlled using the Timer 0 control/status bits in TCON and TMOD: TR0, C/T0, GATE0 and
TF0. TL0 can use either the system clock or an external input signal as its timebase. The TH0 register is
restricted to a timer function sourced by the system clock or prescaled clock. TH0 is enabled using the
Timer 1 run control bit TR1. TH0 sets the Timer 1 overflow flag TF1 on overflow and thus controls the
Timer 1 interrupt.
Timer 1 is inactive in Mode 3. When Timer 0 is operating in Mode 3, Timer 1 can be operated in Modes 0,
1 or 2, but cannot be clocked by external signals nor set the TF1 flag and generate an interrupt. However,
the Timer 1 overflow can be used to generate baud rates for the SMBus and/or UART, and/or initiate ADC
conversions. While Timer 0 is operating in Mode 3, Timer 1 run control is handled through its mode set-
tings. To run Timer 1 while Timer 0 is in Mode 3, set the Timer 1 Mode as 0, 1, or 2. To disable Timer 1,
configure it for Mode 3.
Figure 23.3. T0 Mode 3 Block Diagram
TL0
(8 bits)
TMOD
0
1
TCON
TF0
TR0
TR1
TF1
IE1
IT1
IE0
IT0
Interrupt
Interrupt
0
1
SYSCLK
Pre-scaled Clock TR1 TH0
(8 bits)
CKCON
S
C
A
0
S
C
A
1
T
1
M
T
0
M
T
1
M
1
T
1
M
0
C
/
T
1
G
A
T
E
1
G
A
T
E
0
C
/
T
0
T
0
M
1
T
0
M
0
TR0
GATE0
/INT0
T0
Crossbar
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 313
SFR Definition 23.1. TCON: Ti mer Control
Bit7: TF1: Timer 1 Overflow Flag.
Set by hardware when Timer 1 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 1 interru pt servic e ro utine.
0: No Timer 1 over flo w det ected.
1: Timer 1 has overflowed.
Bit6: TR1: Timer 1 Run Control.
0: Timer 1 disab l ed .
1: Timer 1 enabled.
Bit5: TF0: Timer 0 Overflow Flag.
Set by hardware when Timer 0 overflows. This flag can be cleared by software but is auto-
matically cleared when the CPU vectors to the Timer 0 interru pt servic e ro utine.
0: No Timer 0 over flo w det ected.
1: Timer 0 has overflowed.
Bit4: TR0: Timer 0 Run Control.
0: Timer 0 disab l ed .
1: Timer 0 enabled.
Bit3: IE1: External Interrupt 1.
This flag is set by hardware when an edge/le vel of type defined by IT1 is de tected. It can be
cleared by soft ware but is automatica lly cleared when the CPU vectors to the Externa l Inter-
rupt 1 service routine if IT1 = 1. This flag is the inverse of the /INT1 signal.
Bit2: IT1: Interrupt 1 Type Select.
This bit selects whether the configured /INT1 interrupt will be falling-edge sensitive or
active-low.
0: /INT1 is level triggered, active-low.
1: /INT1 is edge triggered, falling-edge.
Bit1: IE0: External Interrupt 0.
This flag is set by hardware when an edge/le vel of type defined by IT0 is de tected. It can be
cleared by soft ware but is automatica lly cleared when the CPU vectors to the Externa l Inter-
rupt 0 service routine if IT0 = 1. This flag is the inverse of the /INT0 signal.
Bit0: IT0: Interrupt 0 Type Select.
This bit selects whether the configured /INT0 interrupt will be falling-edge sensitive or
active-low.
0: /INT0 is level triggered, active logic -low.
1: /INT0 is edge triggered, falling-edge.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address:
SFR Page: 0x88
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
314 Rev. 1.4
SFR Definition 23.2. TMOD: Timer Mode
Bit7: GATE1: Timer 1 Gate Control.
0: Timer 1 enabled wh en TR1 = 1 irrespe ctive of /INT1 logic level.
1: Timer 1 enabled only when TR1 = 1 AND /INT1 = logic 1.
Bit6: C/T1: Counter/Timer 1 Select.
0: Timer Function: Timer 1 incremented by clock defined by T1M bit (CKCON.4).
1: Counter Function: Timer 1 incremented by high-to-low transitions on external input pin
(T1).
Bits5–4: T1 M1–T1M0: Timer 1 Mode Select.
These bits select the Timer 1 operation mode.
Bit3: GATE0: Timer 0 Gate Control.
0: Timer 0 enabled wh en TR0 = 1 irrespe ctive of /INT0 logic level.
1: Timer 0 enabled only when TR0 = 1 AND /INT0 = logic 1.
Bit2: C/T0: Counter/Timer Select.
0: Timer Function: Timer 0 incremented by clock defined by T0M bit (CKCON.3).
1: Counter Function: Timer 0 incremented by high-to-low transitions on external input pin
(T0).
Bits1–0: T0 M1–T0M0: Timer 0 Mode Select.
These bits select the Timer 0 operation mode.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
GATE1 C/T1 T1M1 T1M0 GATE0 C/T0 T0M1 T0M0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x89
0
T1M1 T1M0 Mode
0 0 Mode 0: 13-bit counter/timer
0 1 Mode 1: 16-bit counter/timer
1 0 Mode 2: 8-bit counter/timer with auto-reload
1 1 Mode 3: Timer 1 inactive
T0M1 T0M0 Mode
0 0 M o de 0: 13-bit counter/timer
0 1 M o de 1: 16-bit counter/timer
1 0 Mode 2: 8-bit counter/timer with auto-reload
1 1 Mode 3: Two 8-bit counter/timers
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 315
SFR Definition 23.3. CKCON: Clock Control
SFR Definition 23.4. TL0: Timer 0 Low Byte
Bits7–5: UNUSED. Read = 000b, Write = don’t care.
Bit4: T1M: Timer 1 Clock Select.
This select the clock source supplied to Timer 1. T1M is ignored when C/T1 is set to logic 1.
0: Timer 1 uses the clock defined by the prescale bits, SCA1–SCA0.
1: Timer 1 uses the system clock.
Bit3: T0M: Timer 0 Clock Select.
This bit selects the clock source supplied to Timer 0. T0M is ignored when C/T0 is set to
logic 1.
0: Counter/Timer 0 uses the clock defined by the prescale bits, SCA1-SCA0.
1: Counter/Timer 0 uses the system clock.
Bit2: UNUSED. Read = 0b, Write = don’t care.
Bits1–0: SCA1–SCA0: Timer 0/1 Prescale Bits
These bit s control the division of the clock supplied to Timer 0 and/or Timer 1 if configured
to use prescaled clock inputs.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
- - - T1M T0M - SCA1 SCA0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8E
0
SCA1 SCA0 Prescaled Clock
0 0 System clock divided by 12
0 1 System clock divided by 4
1 0 System clock divided by 48
1 1 External clock divided by 8*
*Note: External clock divided by 8 is synchronized with the system
clock, and external clock must be less than or equal to the
system clock frequency to operate the timer in this mode.
Bits 7–0: TL0: Timer 0 Low Byte.
The TL0 register is the low byte of the 16-bit Timer 0.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8A
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
316 Rev. 1.4
SFR Definition 23.5. TL1: Timer 1 Low Byte
SFR Definition 23.6. TH0: Timer 0 High Byte
SFR Definition 23.7. TH1: Timer 1 High Byte
Bits 7–0: TL1: Timer 1 Low Byte.
The TL1 register is the low byte of the 16-bit Timer 1.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8B
0
Bits 7–0: TH0: Timer 0 High Byte.
The TH0 register is the high byte of the 16-bit Timer 0.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8C
0
Bits 7–0: TH1: Timer 1 High Byte.
The TH1 register is the high byte of the 16-bit Timer 1.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0x8D
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 317
23.2. Timer 2, Timer 3, and Timer 4
Timers 2, 3, and 4 are 16-bit counter/timers, each formed by two 8-bit SFR’s: TMRnL (low byte) and
TMRnH (high byte) where n = 2, 3, and 4 for timers 2, 3, and 4 respectively. Timers 2 and 4 feature auto-
reload, capture, and toggle output modes with the ability to count up or down. Timer 3 features auto-reload
and capture modes, with the ability to count up or down. Capture Mode and Auto-reload mode are selected
using bits in the Timer 2, 3, and 4 Control registers (TMRnCN). Toggle output mode is selected using the
Timer 2 or 4 Configuration registers (TMRnCF). These timers may also be used to generate a square-
wave at an external pin. As with Timers 0 and 1, Timers 2, 3, and 4 can use either the system clock
(divided by one, two, or twelve), exte rnal clock (divided by eight) or transitions on an external input pin as
its clock source. Timer 2 and 3 can be used to start an ADC Data Conversion and Timers 2, 3, and 4 can
schedule DAC outputs. Timers 1, 2, 3, or 4 may be used to gener ate ba ud ra tes for UART 0. On ly Timer 1
can be used to generate baud rates for UART 1.
The Counter/Timer Select bit C/Tn bit (TMRnCN.1) configures the peripheral a s a counter or timer. Clear-
ing C/Tn configures the Timer to be in a timer mode (i.e., the system clock or transitions on an external pin
as the input for the timer). When C/Tn is set to 1, the timer is configured as a counter (i.e., high -to-low tran-
sitions at the Tn input pin increment (or decrement) the counter/timer register. Timer 3 and Timer 2 share
the T2 input pin. Refer to Section “18.1. Ports 0 through 3 and the Priority Crossbar Decoder” on
page 238 for information on selecting and configuring external I/O pins for digital peripherals, such as the
Tn pin.
T imer 2, 3, and 4 can use either SYSCLK, SYSCLK divided by 2, SYSCLK divided by 12, an external clock
divided by 8, or high-to-low transitions on the Tn input pin as its clock source when operating in Counter/
Timer with Capture mode. Clearing the C/Tn bit (TMRnCN.1) selects the system clock/external clock as
the input for the timer. The Timer Clock Select bits TnM0 and TnM1 in TMRnCF can be used to select the
system clock undivided, system clock divided by two, system clock divided by 12, or an external clock pro-
vided at the XTAL1/XTAL2 pins divided by 8 (see SFR Definition 23.13). When C/Tn is set to logic 1, a
high-to-low tran sition at the Tn input pin increments the counter/timer register (i.e., configured as a coun-
ter).
23.2.1. Configuring Timer 2, 3, and 4 to Count Down
Timers 2, 3, and 4 have the ability to count down. When the timer ’s Decrement Enable Bit (DCENn) in the
Timer Configur ation Register (Se e SFR Definition 2 3.13) is set to ‘1’, the timer can then count up or down.
When DCENn = 1, the direction of the timer’s count is controlled by the TnEX pin’s logic level (Timer 3
shares the T2EX pin with Timer 2). When TnEX = 1, the counter/timer will count up; when TnEX = 0, the
counter/timer will count down. To use this feature, TnEX must be enabled in the digital crossbar and config-
ured as a digital input.
Note: When DCENn = 1, other functions of the TnEX input (i.e., capture and auto-reload) are not
available. TnEX will only control the direction of the timer when DCENn = 1.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
318 Rev. 1.4
23.2.2. Capture Mode
In Capture Mode, Timer 2, 3, and 4 will operate as a 16-bit counter/timer with capture facility. When the
Timer External Enable bit (found in the TMRnCN register) is set to ‘1’, a high-to-low transition on the TnEX
input pin (Timer 3 shares the T2EX pin with Timer 2) causes the 16-bit value in the associated timer (THn,
TLn) to be loaded into the capture registers (RCAPnH, RCAPnL). If a capture is triggered in the counter/
timer, the Timer External Flag (TMRnCN.6) will be set to ‘1’ and an interrupt will occur if the interrupt is
enabled. See Section “11.3. Interrupt Handler” on page 154 for further information concerning the con-
figuration of interrupt sources.
As the 16-bit timer register increments and overflows TMRnH:TMRnL, the TFn Timer Overflow/Underflow
Flag (TMRnCN.7) is set to ‘1’ and an interrupt will occur if the interrupt is enabled. The timer can be config-
ured to count down by setting the Decrement Enable Bit (TMRnCF.0) to ‘1’. This will cause the timer to
decrement with every timer clock/count event and underflow when the timer transitions from 0x0000 to
0xFFFF. Just as in overflows, the Overflow/Underflow Flag (TFn) will be set to ‘1’, and an interrupt will
occur if enabled.
Counter/Timer with Capture mode is selected by setting the Capture/Reload Select bit CP/RLn
(TMRnCN.0) and the Timer 2, 3, and 4 Run Control bit TRn (TMRnCN.2) to logic 1. The Timer 2, 3, and 4
respective External Enable EXENn (TMRnCN.3) must also be set to logic 1 to enable captures. If EXENn
is cleared, transitions on TnEX will be ignored.
Figure 23.4. T2, 3, and 4 Capture Mode Block Diagram
TMRnL TMRnH
TRn
TCLK
Interrupt
TMRnCN
EXFn
EXENn
TRn
C/Tn
CP/RLn
TFn
SYSCLK 12
2
TMRnCF
D
C
E
n
T
n
O
E
T
O
G
n
T
n
M
1
T
n
M
0
Toggle Logic
Tn
(Port Pin)
0
1
1
0
EXENn
Crossbar
TnE
X
RCAPnL RCAPnH
0xFF 0xFF
8
External Clock
(XTAL1)
Tn Crossbar
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 319
23.2.3. Auto-Reload Mode
In Auto-Reload Mode, the counter/timer can be configured to count up or down and cause an interrupt/flag
to occur upon an overflow/underflow event. When counting up, the counter/timer will set its overflow/under-
flow flag (TFn) and cause an interrupt (if enabled) upon overflow/underflow, and the values in the Reload/
Capture Registers (RCAPnH and RCAPnL) are loaded into the timer and the timer is restarted. When the
Timer External Enable Bit (EXENn) bit is set to ‘1’ and the Decrement Enable Bit (DCENn) is ‘0’, a falling
edge (‘1’-to-‘0’ transition) on the TnEX pin will cause a timer reload. Note that timer overflows will also
cause auto-relo ads. When DCENn is set to ‘1’, the st at e of the TnEX pin controls whether the counte r/timer
counts up (increment s) or down (decrements), and will not cause an auto-reload or interrupt event (T imer 3
shares the T2EX p in with Timer 2). See Section 23.2.1 for information concerning configuration of a timer
to count down.
When counting down, the counter/timer will set its overflow/underflow flag (TFn) and cause an interrupt (if
enabled) when the value in the TMRnH and TMRnL registers matches the 16-bit value in the Reload/Cap-
ture Registers (RCAPnH and RCAPnL). This is considered an underflow event, and will cause the timer to
load the value 0xFFFF. The timer is automatically restarted when an underflow occurs.
Counter/Timer with Auto-Reload mode is selected by clearing the CP/RLn bit. Setting TRn to logic 1
enables and starts the timer.
In Auto-Reload Mode, the External Flag (EXFn) toggles upon every overflow or underflow and does not
cause an interrupt. The EXFn flag can be used as the most significant bit (MSB) of a 17-bit counter.
.
Figure 23.5. Tn Auto-reload (T2,3,4) and Toggle Mode (T2,4) Block Diagram
TMRnL TMRnH
TRn
TCLK
Reload Interrupt
EXENn
Crossbar
TnE
X
TMRnCN
EXFn
EXENn
TRn
C/Tn
CP/RLn
TFn
SYSCLK 12
2
TMRnCF D
E
C
E
n
T
n
O
E
T
O
G
n
T
n
M
1
T
n
M
0
Toggle Logic Tn
(Port Pin)
0
1
1
0
RCAPnL RCAPnH
0xFF 0xFF
OVF
8
External Clock
(XTAL1)
Tn Crossbar
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
320 Rev. 1.4
23.2.4. Toggle Output Mode (Timer 2 and Timer 4 Only)
Timers 2 and 4 have the capability to toggle the state of their respective output port pins (T2 or T4) to pro-
duce a 50% duty cycle waveform output. The port pin state will change upon the overflow or underflow of
the respective timer (depending on whether the timer is counting up or down). The toggle frequency is
determined by the clock source of the timer and the values loaded into RCAPnH and RCAPnL. When
counting DOWN, the auto-reload value for the timer is 0xFFFF, and underflow will occur when the value in
the timer matches the value stored in RCAPnH:RCAPnL. When counting UP, the auto-reload value for the
timer is RCAPnH:RCAPnL, and overflow will occur when the value in the timer transitions from 0xFFFF to
the reload value.
To output a square wave, the timer is placed in reload mode (the Capture/Reload Select Bit in TMRnCN
and the Timer/Counter Select Bit in TMRnCN are cleared to ‘0’). The timer output is enabled by setting the
Timer Output Enable Bit in TMRnCF to ‘1’. The timer should be configured via the timer clock source and
reload/underflow values such that the timer overflow/underflows at 1/2 the desired output frequency. The
port pin assigned by the crossbar as the timer ’s output pin should be configured as a digital output (see
Section “18. Port Input/Output” on page 235). Setting the timer’s Run Bit (TRn) to ‘1’ will start the toggle
of the pin. A Read/Write of the Timer’s Toggle Output State Bit (TMRnCF.2) is used to read the state of the
toggle output, or to fo rce a value of the outp ut. This is useful wh en it is d esired to st art the to ggle of a pin in
a known sta te, or to force the pin into a desired state when the toggle mode is halted.
Fsq
FTCLK
265536RCAPn–
------------------------------------------------------
=
Equation 23.1. Square Wave Frequency (Timer 2 and Timer 4 Only)
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 321
SFR Definition 23.8. TMRnCN: Timer 2, 3, and 4 Control
Bit7: TFn: Timer 2, 3, and 4 Overflow/Underflow Flag.
Set by hardware when either the Timer overflows from 0xFFFF to 0x0000, underflows from
the value placed in RCAPnH:RCAPnL to 0xFFFF (in Auto-reload Mode), or underflows from
0x0000 to 0xFFFF (in Capture Mode). When the Timer interrupt is enabled, setting this bit
causes the CPU to vector to the Timer interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
Bit6: EXFn: Timer 2, 3, or 4 External Flag.
Set by hardware when either a capture or reload is caused by a high-to-low tra nsition on the
TnEX input pin and EXENn is logic 1. When the Timer interrupt is enabled, setting this bit
causes the CPU to vector to the Timer Interrupt service routine. This bit is not automatically
cleared by hardware and must be cleared by software.
Bit5–4: Reserved.
Bit3: EXENn: Timer 2, 3, and 4 External Enable.
Enables high-to-low transitions on TnEX to trigger captures, reloads, and control the direc-
tion of the timer/counter (up or down count). If DCENn = 1, TnEX will determine if the timer
counts up or down when in Auto-reload Mode. If EXENn = 1, TnEX should be configured as
a digital input.
0: Transitions on the TnEX pin are ignored.
1: Transitions on the TnEX pin cause capture, reload, or control the direction of timer count
(up or down) as follows:
Capture Mode: ‘1’-to-’0’ Transition on TnEX pin causes RCAPnH:RCAPnL to capture timer
value.
Auto-Reload Mode:
DCENn = 0: ‘1’-to-’0’ transition causes reload of timer an d sets the EXFn Flag.
DCENn = 1: TnEX logic level controls direction of timer (up or down).
Bit2: TRn: Timer 2, 3, and 4 Run Control.
This bit enables/disables the respective Timer.
0: Timer disabled.
1: Timer enabled and running/counting.
Bit1: C/Tn: Counter/Timer Select.
0: Timer Function: Timer incremented by clock defined by TnM1:TnM0
(TMRnCF.4:TMRnCF.3).
1: Counter Function: Timer incremented by high-to-low transitions on external input pin.
Bit0: CP/RLn: Capture/Reload Select.
This bit selects wh ether the Timer functions in capture or auto-reload mode.
0: Timer is in Auto-Reload Mode.
1: Timer is in Capture Mode.
Note: Timer 3 and T i mer 2 share the T2 and T2EX pins.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
TFn EXFn - - EXENn TRn C/Tn CP/RLn 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Bit
Addressable
SFR Address: TMR2CN:0xC8;TMR3CN:0xC8;TMR4CN:0xC8
SFR Page: TMR2CN: page 0;TMR3CN: page 1;TMR4CN: page 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
322 Rev. 1.4
SFR Definition 23.9. TMRnCF: Timer 2, 3, and 4 Configuration
Bit7–5: Reserved.
Bit4–3: TnM1 and TnM0: Timer Clock Mode Select Bits.
Bits used to select the Timer clock source. The sources can be the System Clock
(SYSCLK), SYSCLK divided by 2 or 12, or the external clock divided by 8. Clock source is
selected as follows:
00: SYSCLK/12
01: SYSCLK
10: EXTERNAL CLOCK/8 (Synchronized to the System Clock)
11: SYSCLK/2
Bit2: TOGn: Toggle output state bit.
When timer is used to toggle a por t pin, this bit can be used to read the state o f the output, or
can be written to in order to force the state of the output (Timer 2 and Tim er 4 Only).
Bit1: TnOE: Timer output enable bit.
This bit enables the timer to output a 50% du ty cycle output to th e timer’s assigned extern al
port pin.
NOTE: A timer is configured for Square Wave Output as follows:
CP/RLn= 0
C/Tn = 0
TnOE = 1
Load RCAPnH:RCAPnL (See “Square Wave Frequency (Timer 2 and Timer 4 Only)” on
page 320.)
Configure Port Pin to output squarewave (See Section “18. Port Input/Output” on
page 235)
0: Output of toggle mode not available at Timers’s assigned port pin.
1: Output of toggle mode available at Ti mers’s assigned port pin.
Bit0: DCENn: Decrement Enable Bit.
This bit enables the timer to count up or down as determined by the stat e of TnEX.
0: Timer will count up, regardless of the state of TnEX.
1: Timer will count up or down depending on the state of TnEX as follows:
if TnEX = 0, the timer counts DOWN.
if TnEX = 1, the timer counts UP.
Note: Timer 3 and T i mer 2 share the T2 and T2EX pins.
R/W R/W R/W R/W R/W Reset Value
- - - TnM1 TnM0 TOGn TnOE DCENn 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: TMR2CF:0xC9;TMR3CF:0xC9;TMR4CF:0xC9
SFR Page TMR2CF: page 0;TMR3CF: page 1;TMR4CF: Page 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 323
SFR Definition 23.10. RCAPnL: Timer 2, 3, and 4 Captu re Register Low Byte
SFR Definition 23.11. RCAPnH: Timer 2, 3, and 4 Capture Register High Byte
SFR Definition 23.12. TMRnL: Timer 2, 3, and 4 Low Byte
Bits 7–0: RCAP2, 3, and 4L: Timer 2, 3, and 4 Capture Register Low Byte.
The RCAP2, 3, and 4L register captures the low byte of Timer 2, 3, and 4 when Timer 2, 3,
and 4 is configured in capture mode. When T imer 2, 3, and 4 is configured in auto-reload
mode, it holds the low byte of the reload value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: RCAP2L: 0xCA; RCAP3L: 0xCA; RCAP4L: 0xCA
SFR Page: RCAP2L: page 0; RCAP3L: page 1; RCAP4L: page 2
Bits 7–0: RCAP2, 3, and 4H: Timer 2, 3, and 4 Capture Register High Byte.
The RCAP2, 3, and 4H register captures the high byte of Timer 2, 3, and 4 when Timer 2, 3,
and 4 is configured in capture mode. When T imer 2, 3, and 4 is configured in auto-reload
mode, it holds the high byte of the reload value.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: RCAP2H: 0xCB; RCAP3H: 0xCB; RCAP4H: 0xCB
SFR Page: RCAP2H: page 0; RCAP3H: page 1; RCAP4H: page 2
Bits 7–0: TL2, 3, and 4: Timer 2, 3, and 4 Low Byte.
The TL2, 3, and 4 register contains the low byte of the 16-bit Timer 2, 3, and 4
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: TMR2L: 0xCC; TMR3L: 0xCC; TMR4L: 0xCC
SFR Page: TMR2L: page 0; TMR3L: page 1; TMR4L: page 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
324 Rev. 1.4
SFR Definition 23.13. TMRnH Timer 2, 3, and 4 High Byte
Bits 7–0: TH2, 3, and 4: Timer 2, 3, and 4 High Byte.
The TH2, 3, and 4 register contains the high byte of the 16-bit Timer 2, 3, and 4
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: TMR2H: 0xCD; TMR3H: 0xCD; TMR4H: 0xCD
SFR Page: TMR2H: page 0; TMR3H: page 1; TMR4H: page 2
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 325
24. Programmable Counter Array
The Programmable Counter Array (PCA0) provides enhanced timer functionality while requiring less CPU
intervention than the standard 8051 counter/timers. PCA0 consists of a dedicated 16-bit counter/timer and
six 16-bit capture/compare modules. Each capture/compare module has its own associated I/O line
(CEXn) which is routed through the Crossbar to Port I/O when enabled (See Section “18.1. Ports 0
through 3 and the Prio rity Cros sbar Decoder” on page 238). The counter/timer is driven by a pro gram-
mable timebase that can select between six inputs as its source: system clock, system clock divided by
four, system clock div ided by twelve, the external oscillator clock source divided by 8, Timer 0 overflow, or
an external clock signal on the ECI line. Each capture/compare module may be configured to operate inde-
pendently in one of six modes: Edge-Triggered Capture, Software Timer, High-Speed Output, Frequency
Output, 8-Bit PWM, or 16-Bit PWM (each is described in Section 24.2). The PCA is configured and con-
trolled through the system controller's Special Function Registers. The basic PCA block diagram is shown
in Figure 2 4.1.
Figure 24.1. PCA Block Diagram
Capture/Compare
Module 1
Capture/Compare
Module 0 Capture/Compare
Module 2 Capture/Compare
Module 3
CEX1
ECI
Crossbar
CEX2
CEX3
CEX0
Port I/O
16-Bit Counter/Timer
PCA
CLOCK
MUX
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
SYSCLK
External Clock/8
Capture/Compare
Module 4
CEX4
Capture/Compare
Module 5
CEX5
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
326 Rev. 1.4
24.1. PCA Counter/Timer
The 16-bit PCA counter/timer consists of two 8-bit SFRs: PCA0L and PCA0H. PCA0H is the high byte
(MSB) of the 16-bit counter/timer and PCA0L is the low byte (LSB). Reading PCA0L automatically latches
the value of PCA0H into a “snapshot” register; the following PCA0H read accesses this “snapshot” register .
Reading the PCA0L Register first guara ntees an accu rate reading of the entir e 16-bit PCA0 counter. Read-
ing PCA0H or PCA0L does not disturb the counter operation. The CPS2–CPS0 bits in the PCA0MD regis-
ter select the timebase for the counter/timer as shown in Table 24.1.
When the counter/timer overflows from 0xFFFF to 0x0000, the Counter Overflow Flag (CF) in PCA0MD is
set to logic 1 and an interrupt request is generated if CF interrupts are enabled. Setting the ECF bit in
PCA0MD to logic 1 enables the CF flag to generate an interrupt request. The CF bit is not automatically
cleared by hardware when the CPU vectors to the interrupt service routine, and must be cleared by soft-
ware (Note: PCA0 interrupts must be globally enabled before CF interrupts are recognized. PCA0 inter-
rupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit in EIE1 to logic 1). Clearing the
CIDL bit in the PCA0MD register allows the PCA to continue normal operation while the CPU is in Idle
mode.
Figure 24.2. PCA Counter/Timer Block Diagram
Table 24.1. PCA Timebase Input Options
CPS2 CPS1 CPS0 Timebase
0 0 0 System clock divided by 12
0 0 1 System clock divided by 4
0 1 0 Timer 0 overflow
0 1 1 High-to-low transitions on ECI (max rate = system clock divided by 4)
1 0 0 System clock
1 0 1 External oscillator source divided by 8*
*Note: External clock divided by 8 is synchronized with the system clock.
PCA0MD
C
I
D
L
W
D
T
E
E
C
F
C
P
S
1
C
P
S
0
W
D
L
C
K
C
P
S
2
IDLE
0
1
PCA0H PCA0L
Snapshot
Register
To SFR Bus
Overflow To PCA Interrupt System
CF
PCA0L
read
To PCA Modules
SYSCLK/12
SYSCLK/4
Timer 0 Overflow
ECI
000
001
010
011
100
101
SYSCLK
External Clock/8
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 327
Important Note About the PCA0CN Register: If the main PCA counter (PCA0H : PCA0L) overflows dur-
ing the execution phase of a read-modify-write instruction (bit-wise SETB or CLR, ANL, ORL, XRL) that
targets the PCA0CN register, the CF (Counter Overflow) bit will not be set. If the CF flag is used by soft-
ware to keep track of counter overflows, the following steps should be taken when performing a bit-wise
operation on the PCA0CN register:
Step 1. Disable global interrupts.
Step 2. Read PCA0L. This will latch the value of PCA0H.
Step 3. Read PCA0H, saving the value.
Step 4. Execute the bit-wise operat ion on CCFn (for example, CLR CCF0, or CCF0 = 0;).
Step 5. Read PCA0L.
Step 6. Read PCA0H, saving the value.
Step 7. If the value of PCA0H read in Step 3 is 0xFF and the value for PCA0H read in Step 6 is
0x00, then manually set the CF bit in software (for example, SETB CF, or CF = 1;).
Step 8. Re-enable interrupts.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
328 Rev. 1.4
24.2. Capture/Compare Modules
Each module can be configured to operate independently in one of six operation modes: Edge-triggered
Capture, Software Timer, High Speed Output, Frequency Output, 8-Bit Pulse Width Modulator, or 16-Bit
Pulse Width Modulator. Each module has Special Function Registers (SFRs) associated with it in the CIP-
51 system controller. These registers are used to exchange dat a with a module and configu re the modu le's
mode of operation.
Table 24.2 summarizes the bit settings in th e PCA0CP Mn registers used to select the PCA0 capture/com-
pare module’s operating modes. Setting the ECCFn bit in a PCA0CPMn register enables the module's
CCFn interrupt. Note: PCA0 interrupts must be globally enabled before individual CCFn interrupts are rec-
ognized. PCA0 interrupts are globally enabled by setting the EA bit (IE.7) and the EPCA0 bit (EIE1.3) to
logic 1. See Figure 24.3 for details on the PCA interrupt configuration.
Figure 24.3. PCA Interrupt Block Diagram
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
PCA0MD
C
I
D
L
E
C
F
C
P
S
1
C
P
S
0
C
P
S
2
0
1
PCA Module 0
(CCF0)
PCA Module 1
(CCF1)
ECCF1
0
1
ECCF0
0
1
PCA Module 2
(CCF2)
ECCF2
0
1
PCA Module 3
(CCF3)
ECCF3
ECCF4
PCA Counter/
Timer Overflow
0
1
Interrupt
Priority
Decoder
EPCA0
(EIE.3)
PCA0CPMn
(for n = 0 to 5)
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
1
PCA Module 4
(CCF4)
0
1
PCA Module 5
(CCF5)
0
1
EA
(IE.7)
0
1
ECCF5
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 329
24.2.1. Edge-triggered Capture Mode
In this mode, a valid transition on the CEXn pin causes PCA0 to capture the value of the PCA0 counter/
timer and load it into the corresponding module's 16-bit capture/compare register (PCA0CPLn and
PCA0CPHn). The CAPPn and CAPNn bits in the PCA0CPMn registe r are u sed to select th e type o f tran si-
tion that triggers the capture: low-to-high transition (positive edge), high-to-low transition (negative edge),
or either transition (positive or negative edge). When a capture occurs, the Capture/Compare Flag (CCFn)
in PCA0CN is set to logic 1 and an interrup t requ est is generated if CCF interr upts are enabled. The CCFn
bit is not automatically cleared by hardware when the CPU vectors to the interrupt service routine, and
must be cleared by software.
Figure 24.4. PCA Capture Mode Diagram
Note: The signal at CEXn must be high or low for at least 2 system clock cycles in order to be valid.
Table 24.2. PCA0CPM Register Settings for PCA Capture/Compare Modules
PWM16 ECOM CAPP CAPN MAT TOG PWM ECCF Operation Mode
X X 10000X
Capture triggered by positive edge
on CEXn
X X 01000X
Capture triggered by negative
edge on CEXn
X X 11000X
Capture triggered by transitio n on
CEXn
X 1 00100X Software Timer
X 1 00110X High Speed Output
X 1 00011X Frequency Output
0 1 000010 8-Bit Pulse Width Modulator
1 1 00001016-Bit Pulse Width Modulator
X = Don’t Care
PCA0L
PCA0CPLn
PCA
Timebase
CEXn
CrossbarPort I/O
PCA0H
Capture
PCA0CPHn
0
1
0
1
(to CCFn)
PCA Interrupt
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
330 Rev. 1.4
24.2.2. Software Timer (Compare) Mode
In Software Timer mode, the PCA0 counter/timer is compa red to the module' s 16-b it captur e/compare reg-
ister (PCA0CPHn and PCA0CPLn). When a match occurs, the Capture/Compare Flag ( CCFn) in PCA0CN
is set to logic 1 and an interrupt request is generated if CCF interrupts are enabled. The CCFn bit is not
automatically cleared by hardware when the CPU vectors to the interrupt service routine, and must be
cleared by software. Setting the ECOMn and MATn bits in the PCA0CPMn register enables Software
Timer mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 24.5. PCA Software Timer Mode Diagram
Match
16-bit Comparator
PCA0H
PCA0CPHn
Enable
PCA0L
PCA
Timebase
PCA0CPLn
00 00
PCA
Interrupt
0
1
x
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 331
24.2.3. High Speed Output Mode
In High Speed Output mode, a module’s associated CEXn pin is toggled each time a match occurs
between the PCA Counter and the module's 16-bit capture/compare register (PCA0CPHn and
PCA0CPLn) Setting the TOGn, MATn, and ECOMn bits in the PCA0CPMn register enables the High-
Sp ee d Ou tp ut mode.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 24.6. PCA High Speed Output Mode Diagram
Match
16-bit Comparator
PCA0H
PCA0CPHn
Enable
PCA0L
PCA
Timebase
PCA0CPLn
PCA
Interrupt
0
1
00 0x
ENB
ENB
0
1
Write to
PCA0CPLn
Write to
PCA0CPHn
Reset
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
x
CEXn
Crossbar Port I/O
Toggle
0
1
TOGn
PCA0CN
C
FC
RC
C
F
0
C
C
F
2
C
C
F
1
C
C
F
5
C
C
F
4
C
C
F
3
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
332 Rev. 1.4
24.2.4. Frequency Output Mode
Frequency Output Mode produces a programmable-frequency square wave on the module’s associated
CEXn pin. The capture/compare module high byte holds the number of PCA clocks to count before the out-
put is toggled. The frequency of the square wave is then defined by Equation 24.1.
Where FPCA is the frequency of the clock selected by the CPS2–0 bits in the PCA mode register,
PCA0MD. The lower byte of the capture/compare module is compared to the PCA0 counter low byte; on a
match, CEXn is toggled and the offset held in the high byte is added to the matche d value in PCA0CPLn .
Frequency Output Mode is enabled by setting the ECOMn, TOGn, and PWMn bits in the PCA0CPMn reg-
ister.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 24.7. PCA Frequency Output Mode
Equation 24.1. Square Wave Frequency Output
Fsqr FPCA
2PCA0CPHn
-----------------------------------------
=
Note: A value of 0x00 in the PCA0CPHn register is equal to 256 for this equation.
8-bit
Comparator
PCA0L
Enable
PCA Timebase
000 0
match
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
PCA0CPHn8-bit AdderPCA0CPLn
Adder
Enable
CEXn
Crossbar Port I/O
Toggle
0
1
TOGn
1
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 333
24.2.5. 8-Bit Pulse Width Modulator Mode
Each module can be used independently to generate pulse width modulated (PWM) outputs on its associ-
ated CEXn pin. The freque ncy o f th e output is de pendent on the timebase for the PCA0 coun te r/timer. The
duty cycle of the PWM output signal is varied using the module's PCA0CPLn capture/compare register.
When the value in the low byte of the PCA0 counter/timer (PCA0L) is eq ual to the value in PCA0CPLn, the
output on the CEXn pin will be high. When the count value in PCA0L overflows, the CEXn output will be
low (see Figure 24.8). Also, when the counter/timer low byte (PCA0L) overflows from 0xFF to 0x00,
PCA0CPLn is reloaded automatically with the value stored in the counter/timer's high byte (PCA0H) with-
out software intervention. Setting the ECOMn and PWMn bits in the PCA0CPMn register enables 8-Bit
Pulse Width Modulator mode. The duty cycle for 8-Bit PWM Mode is given by Equation 24.2.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 24.8. PCA 8-Bit PWM Mode Diagram
DutyCycle 256 PCA0CPHn–
256
---------------------------------------------------
=
Equation 24.2. 8-Bit PWM Duty Cycle
8-bit
Comparator
PCA0L
PCA0CPLn
PCA0CPHn
CEXn
Crossbar Port I/O
Enable
Overflow
PCA Timebase
0000 0
Q
Q
SET
CLR
S
R
match
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
334 Rev. 1.4
24.2.6. 16-Bit Pulse Width Modulator Mode
Each PCA0 module may also be operated in 16-Bit PWM mode. In this mode, the 16-bit capture/compare
module defines the number of PCA0 clocks for the low time of the PWM signal. When the PCA0 counter
matches the module contents, the output on CEXn is asserted high; when the counter overflows, CEXn is
asserted low. To output a varying duty cycle, new value writes should be synchronized with PCA0 CCFn
match interrupts. 16-Bit PWM Mode is enabled by setting the ECOMn, PWMn, and PWM16n bits in the
PCA0CPMn register. For a varying duty cycle, CCFn should also be set to logic 1 to enable match inter-
rupts. The duty cycle for 16-Bit PWM Mode is given by Equation 24.3.
Important Note About Capture/Compare Registers: When writing a 16-bit value to the PCA0 Capture/
Compare register s, the low byte should always be written first. W riting to PCA0CPLn clears the ECOMn bit
to ‘0’; writing to PCA0CPHn sets ECOMn to ‘1’.
Figure 24.9. PCA 16-Bit PWM Mode
Equation 24.3. 16-Bit PWM Duty Cycle
DutyCycle 65536 PCA0CPn–
65536
-----------------------------------------------------
=
PCA0CPLnPCA0CPHn
Enable
PCA Timebase
0000 0
PCA0CPMn
P
W
M
1
6
n
E
C
O
M
n
E
C
C
F
n
T
O
G
n
P
W
M
n
C
A
P
P
n
C
A
P
N
n
M
A
T
n
1
16-bit Comparator
CEXn
Crossbar Port I/O
Overflow
Q
Q
SET
CLR
S
R
match
PCA0H PCA0L
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 335
24.3. Register Descriptions for PCA0
Following are detailed descriptions of the special function registers related to the operation of PCA0.
SFR Definition 24.1. PCA0CN: PCA Control
Bit7: CF: PCA Counter/Timer Overflow Flag.
Set by hardware when the PCA0 Counter/Timer overflows from 0xFFFF to 0x0000. When
the Counter/T imer Overflow (CF) interrupt is enabled, setting this bit causes the CPU to vec-
tor to the CF interrupt service routine. This bit is not automatically cleared by hardware and
must be cleared by software.
Bit6: CR: PCA0 Counter/T imer Run Control.
This bit enables/disables the PCA0 Counter/Timer.
0: PCA0 Counter/Timer disabled.
1: PCA0 Counter/Timer enabled.
Bit5: CCF5: PCA0 Module 5 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit4: CCF4: PCA0 Module 4 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit3: CCF3: PCA0 Module 3 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit2: CCF2: PCA0 Module 2 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit1: CCF1: PCA0 Module 1 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
Bit0: CCF0: PCA0 Module 0 Capture/Compare Flag.
This bit is set by hardware when a match or capture occurs. When the CCF interrupt is
enabled, setting this bit causes the CPU to vector to the CCF interrupt service routine. This
bit is not automatically cleared by hardware and must be cleared by software.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
CF CR CCF5 CCF4 CCF3 CCF2 CCF1 CCF0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD8
0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
336 Rev. 1.4
SFR Definition 24.2. PCA0MD: PCA0 Mode
Bit7: CIDL: PCA0 Counter/Timer Idle Control.
Specifies PCA0 behavior when CPU is in Idle Mode.
0: PCA0 continues to function normally while the system controller is in Idle Mode.
1: PCA0 operation is suspended while the system controller is in Idle Mode.
Bits6–4: UNUSED. Read = 000b, Write = don't care.
Bits3–1: CPS2-CPS0: PCA0 Counter/Timer Pulse Select.
These bits select the timebase source for the PCA0 counter
Bit0: ECF: PCA Counter/Timer Overflow Interrupt Enable.
This bit sets the masking of the PCA0 Counter/Timer Overflow (CF) interrupt.
0: Disable the CF interrup t.
1: Enable a PCA0 Counter/Timer Overflow interrupt request when CF (PCA0CN.7) is set.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
CIDL - - - CPS2 CPS1 CPS0 ECF 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xD9
0
CPS2 CPS1 CPS0 Timebase
0 0 0 System clock divided by 12
0 0 1 System clock divided by 4
0 1 0 Timer 0 overflow
011
High-to-low transitions on ECI (max rate = system clock
divided by 4)
100System clock
1 0 1 External clock divided by 8 (synchronized with system clock)
1 1 0 Reserved
1 1 1 Reserved
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 337
SFR Definition 24.3. PCA0CPMn: PCA0 Capture/Compare Mode
Bit7: PWM16n: 16-bit Pulse Width Modulation Enable
This bit selects 16-bit mode when Pulse Width Modulatio n mode is enabled (PWMn = 1).
0: 8-bit PWM selected.
1: 16-bit PWM selected.
Bit6: ECOMn: Comparator Function Enable.
This bit enables/disables the comparator function for PCA0 module n.
0: Disabled.
1: Enabled.
Bit5: CAPPn: Capture Positive Function Enable.
This bit enables/disables the positive edge capture for PCA0 module n.
0: Disabled.
1: Enabled.
Bit4: CAPNn: Captur e Ne ga tive Func tion E nable .
This bit enables/disables the negative edge capture for PCA0 module n.
0: Disabled.
1: Enabled.
Bit3: MATn: Match Function Enable.
This bit enables/disa bles the match function for PCA0 module n . When ena bled, matches o f
the PCA0 counter with a module's captu re/compare register cause th e CCFn bit in PCA0MD
register to be set to logic 1.
0: Disabled.
1: Enabled.
Bit2: TOGn: Toggle Function Enable.
This bit enables/disables the toggle function for PCA0 module n. When enabled, matches of
the PCA0 counter with a module's capture/compare register cause the logic level on the
CEXn pin to togg le. If the PWMn b it is a lso se t to logic 1, the m odule op era tes in Freq ue ncy
Output Mode.
0: Disabled.
1: Enabled.
Bit1: PWMn: Pulse Width Modulation Mode Enable.
This bit enables/disables the PWM function for PCA0 module n. When en ab led , a pu lse
width modulated signal is output on the CEXn pin. 8-bit PWM is used if PWM16n is logic 0;
16-bit mode is used if PWM16n logic 1. If the TOGn bit is also set, the module operates in
Frequency Output Mode.
0: Disabled.
1: Enabled.
Bit0: ECCFn: Capture/Compare Flag Interrupt Enable.
This bit sets the masking of the Capture/Compare Flag (CCFn) interrupt.
0: Disable CCFn interrupts.
1: Enable a Capture/Compare Flag interrupt request when CCFn is set.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
PWM16n ECOMn CAPPn CAPNn MATn TOGn PWMn ECCFn 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR
Address: PCA0CPM0: 0xDA, PCA0CPM1: 0xDB, PCA0CPM2: 0xDC, PCA0CPM3: 0xDD, PCA0CPM4: 0xDE,
PCA0CPM5: 0xDF
SFR Page: PCA0CPM0: page 0, PCA0CPM1: page 0, PCA0CPM2: page 0, PCA0CPM3: 0, PCA0CPM4: page 0,
PCA0CPM5: page 0
C8051F120/1/2/3/4/5/6/7
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338 Rev. 1.4
SFR Definition 24.4. PCA0L: PCA0 Counter/Timer Low Byte
SFR Definition 24.5. PCA0H: PCA0 Counter/Timer High Byte
SFR Definition 24.6. PCA0CPLn: PCA0 Capture Module Low Byte
Bits 7–0: PCA0L: PCA0 Counter/Timer Low Byte.
The PCA0L register holds the low byte (LSB) of the 16-bit PCA0 Counter/Timer.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xF9
0
Bits 7–0: PCA0H: PCA0 Counter/Timer High Byte.
The PCA0H register holds the hi gh byte (MSB) of the 16-bit PCA0 Counter/Timer.
R/WR/WR/WR/WR/WR/WR/WR/WReset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address:
SFR Page: 0xFA
0
Bits7–0: PCA0CPLn: PCA0 Capture Module Low Byte.
The PCA0CPLn register holds the low byte (LSB) of the 16-bit capture module n.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: PCA0CPL0: 0xFB, PCA0CPL1: 0xFD, PCA0CPL2: 0xE9, PCA0CPL3: 0xEB, PCA0CPL4: 0xED, PCA0CPL5:
0xE1
SFR Page: PCA0CPL0: page 0, PCA0CPL1: page 0, PCA0CPL2: page 0, PCA0CPL3: page 0, PCA0CPL4: page 0,
PCA0CPL5: page 0
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 339
SFR Definition 24.7. PCA0CPHn: PCA0 Capture Module High Byte
Bits7–0: PCA0CPHn: PCA0 Capture Module High Byte.
The PCA0CPHn register holds the high byte (MSB) of the 16-bit capture module n.
R/W R/W R/W R/W R/W R/W R/W R/W Reset Value
00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR Address: PCA0CPH0: 0xFC, PCA0CPH1: 0xFD, PCA0CPH2: 0xEA, PCA0CPH3: 0xEC, PCA0CPH4: 0xEE, PCA0CPH5:
0xE2
SFR Page: PCA0CPH0: page 0, PCA0CPH1: page 0, PCA0CPH2: page 0, PCA0CPH3: page 0, PCA0CPH4: page 0,
PCA0CPH5: page 0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
340 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 341
25. JTAG (IEEE 1149.1)
Each MCU has an on-chip JTAG interface and logic to support boundary scan for production and in-sys-
tem testing, Flash read/write operations, and non-intrusive in-circuit debug. The JTAG interface is fully
compliant with the IEEE 1149.1 specification. Refer to this specification for det ailed description s of the Test
Interface and Boundary-Scan Architecture. Access of the JTAG Instruc tion Register (IR) and Data Regis-
ters (DR) are as described in the Test Access Port and Operation of the IEEE 1149.1 specification.
The JTAG interface is accessed via four dedicated pins on the MCU: TCK, TMS, TDI, and TDO.
Through the 16-bit JTAG Instruction Register (IR), any of the eight instructions shown in Figure 25.1 can
be commanded. There are three DR’s associated with JTAG Boundary-Scan, and four associated with
Flash read/write operations on the MCU.
JTAG Register Definition 25.1. IR: JTAG Instruction Register
Reset Value
0x0000
Bit15 Bit0
IR Value Instruction Description
0x0000 EXTEST Selects the Boundary Data Register for control and observability of all
device pins
0x0002 SAMPLE/
PRELOAD Selects the Boundary Data Register for observability and presetting the
scan-path latches
0x0004 IDCODE Selects device ID Regist er
0xFFFF BYPASS Selects Bypass Data Register
0x0082 Flash Control Selects FLASHCON Register to control how the interface logic responds
to reads and writes to the FLASHDAT Register
0x0083 Flash Data Selects FLASHDAT Register for reads and writes to the Flash memory
0x0084 Flash Address Selects FLASHADR Register which holds the address of all Flash read,
write, and erase operations
0x0085 Flash Scale Selects FLASHSCL Register which controls the Flash one-shot timer and
read-always enable
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342 Rev. 1.4
25.1. Boundary Scan
The DR in the Boundary Scan path is an 134-bit shift register. The Boundary DR provides control and
observability of all the device pins as well as the SFR bus and Weak Pullup feature via the EXTEST and
SAMPLE commands.
Table 25.1. Boundary Data Register Bit Definitions
EXTEST provides access to both capture and update actions, while Sample only performs a capture.
Bit Action Target
0 Capture Reset Enable from MCU (64-pin TQFP devices)
Update Reset Enable to RST pin (64-pin TQFP devices)
1Capture
Reset input from RST pin (64-pin TQFP devices)
Update Reset output to RST pin (64-pin TQFP devices)
2Capture
Reset Enable from MCU (100-pin TQFP de vices)
Update Reset Enable to RST pin (100-pin TQFP devices)
3Capture
Reset input from RST pin (100-pin TQFP devices)
Update Reset output to RST pin (100-pin TQFP devices)
4 Captu re External Clock from XTAL1 pin
Update Not used
5 Captu re Weak pullup enable from MCU
Update Weak pullup enable to Port Pins
6, 8, 10, 12, 14,
16, 18, 20 Capture P0.n output enable from MCU (e.g. Bit6=P0.0, Bit8=P0.1, etc.)
Update P0.n output enable to pin (e.g. Bit6=P0.0oe, Bit8=P0.1oe, etc.)
7, 9, 11, 13, 15,
17, 19, 21 Capture P0.n input from pin (e.g. Bit7=P0.0, Bit9=P0.1, etc.)
Update P0.n output to pin (e.g. Bit7=P0.0, Bit9=P0.1, etc.)
22, 24, 26, 28, 30,
32, 34, 36 Capture P1.n output enable from MCU
Update P1.n output enable to pin
23, 25, 27, 29, 31,
33, 35, 37 Capture P1.n input from pin
Update P1.n output to pin
38, 40, 42, 44, 46,
48, 50, 52 Capture P2.n output enable from MCU
Update P2.n output enable to pin
39, 41, 43, 45, 47,
49, 51, 53 Capture P2.n input from pin
Update P2.n output to pin
54, 56, 58, 60, 62,
64, 66, 68 Capture P3.n output enable from MCU
Update P3.n output enable to pin
55, 57, 59, 61, 63,
65, 67, 69 Capture P3.n input from pin
Update P3.n output to pin
70, 72, 74, 76, 78,
80, 82, 84 Capture P4.n output enable from MCU
Update P4.n output enable to pin
71, 73, 75, 77, 79,
81, 83, 85 Capture P4.n input from pin
Update P4.n output to pin
86, 88, 90, 92, 94,
96, 98, 100 Capture P5.n output enable from MCU
Update P5.n output enable to pin
87, 89, 91, 93, 95,
97, 99, 101 Capture P5.n input from pin
Update P5.n output to pin
102, 104, 106,
108, 1 10, 1 12, 1 14,
116
Capture P6.n output enable from MCU
Update P6.n output enable to pin
C8051F120/1/2/3/4/5/6/7
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Rev. 1.4 343
25.1.1. EXTEST Instruction
The EXTEST instruction is accessed via the IR. The Boundary DR provides control and observability of all
the device pins as well as the Weak Pullup feature. All inputs to on-chip logic are set to logic 1.
25.1.2. SAMPLE Instruction
The SAMPLE instruction is accessed via the IR. The Boundary DR provides observability and presetting of
the scan-path latches.
25.1.3. BYPASS Instruction
The BYPASS instruction is accessed via the IR. It provides access to the standard JTAG Bypass data reg-
ister.
25.1.4. IDCODE Instruction
The IDCODE instruction is accessed via the IR. It provides access to the 32-bit Device ID register.
JTAG Register Definition 25.2. DEVICEID: JTAG Device ID
Bit Action Target
103, 105, 107,
109, 1 11, 1 13, 1 15,
117
Capture P6.n input from pin
Update P6.n output to pin
118, 120, 122,
124, 126, 128,
130, 132
Capture P7.n output enable from MCU
Update P7.n output enable to pin
119, 121, 123,
125, 127, 129,
131, 133
Capture P7.n input from pin
Update P7.n output to pin
Table 25.1. Boundary Data Register Bit Definitions (Continued)
Version = 0000b
Part Number = 0000 0000 0000 0111b (C8051F120/1/2/3/4/5/6/7 or C8051F130/1/2/3)
Manufacturer ID = 0010 0100 001b (Silicon Labs)
Reset Value
Version Part Number Manufacturer ID 1 0xn0003243
Bit31 Bit28 Bit27 Bit12 Bit11 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
344 Rev. 1.4
25.2. Flash Programming Commands
The Flash memory can be programmed directly over the JTAG interface using the Flash Control, Flash
Data, F l ash Address, and Flash Scale registers. These Indirect Data Registers are accessed via the JTAG
Instruction Register. Read and write operations on indirect data registers are performed by first setting the
appropriate DR address in the IR register. Each read or write is then initiated by writing the appropriate
Indirect Operation Code (IndOpCode) to the selected data register. Incoming commands to this register
have the following format:
IndOpCode: These bit set the operation to perform according to the following table:
The Poll operation is used to check the Busy bit as described below. Although a Capture-DR is performed,
no Update-DR is allowed for the Poll operation. Since updates are disabled, polling can be accomplished
by shifting in/o ut a single bit.
The Read operation initia te s a r ead from th e reg ister a ddressed by th e DRAddress. Re ad s can be initiate d
by shifting only 2 bits into the indirect register. After the read operation is initiated, polling of the Busy bit
must be performed to determine when the operation is complete.
The write operation initiates a write of WriteData to the registe r addres sed by DRAddress. Registers of any
width up to 18 bits can be written. If the register to be written contains fewer than 18 bit s, the data in Write-
Data should be left-justified, i.e. its MSB should occupy bit 17 above. This allows shorter registers to be
written in fewer JTAG clock cycles. For example, an 8- bit register could be written by shifting only 10 bits.
After a Write is initiated, the Busy bit should be polled to determine when the next operation can be initi-
ated. The content s of the Instruction Re gister shou ld not b e altered wh ile either a r ead o r write o peration is
busy.
Outgoing data from the indirect Data Register has the following format:
The Busy bit indicates that the curr ent operation is not complete. It goe s high when an operatio n is initiated
and returns low when complete. Read and Write commands are ignored while Busy is high. In fact, if poll-
ing for Busy to be low will be followed by another read or write operation, JTAG writes of the next operation
can be made while checking for Busy to be low. They will be ignored until Busy is read low, at which time
the new operation will initiate. This bit is placed ate bit 0 to allow polling by single-bit shifts. When waiting
for a Read to complete and Busy is 0, the following 18 bits can be shifted out to obtain the resulting data.
ReadData is always right-justified. This allows registers shorter than 18 bits to be read using a reduced
number of shif ts. For example, the results from a byte-read requires 9 bit shifts (Busy + 8 bits).
19:18 17:0
IndOpCode WriteData
IndOpCode Operation
0x Poll
10 Read
11 Write
19 18:1 0
0 ReadData Busy
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 345
JTAG Register Definition 25.3. FLASHCON: JTAG Flash Control
This register determines how the Flash interface logic will respond to reads and writes to the FLASH-
DAT Register.
Bit7: SFLE: Scratchpad Flash Memory Access Enable
When this bit is set, Flash reads and writes are direc te d to th e two 128-byte Scratchpad
Flash sectors. When SFLE is set to logic 1, Flash accesses out of the address range 0x00-
0xFF should not be attempted (with the exception of address 0x400, which can be used to
simultaneously erase both Scratchpad areas). Reads/Writes out of this range will yield
undefined re su lts.
0: Flash access directed to the Program/Data Flash sector.
1: Flash access directed to the two 128 byte Scratchpad sectors.
Bits6–4: WRMD2–0: Write Mode Select Bits.
The Write Mod e Select Bits control how the interface logic responds to writes to the FLASH-
DAT Register per the following values:
000: A FLASHDAT write replaces the data in the FLASHDAT register, but is otherwise
ignored.
001: A FLASHDAT write initiates a write of FLASHDAT into the memory address by the
FLASHADR register. FLASHADR is incremented by one when complete.
010: A FLASHDAT write initiates an erasure (sets all bytes to 0xFF) of the Flash page
containing the address in FLASHADR. The data written must be 0xA5 for the erase
to occur. FLASHADR is not affected. If FLASHADR = 0x1FBFE – 0x1FBFF, the
entire user space will be erased (i.e. entire Flash memory except for Reserved area
0x1FC00 – 0x1FFFF).
(All other value s for WR MD 2- 0 are reserved .)
Bits3–0: RDMD3–0: Rea d Mode Select Bits.
The Read Mode Select Bits control how the interface logic responds to reads from the
FLASHDAT Register per the following values:
0000: A FLASHDAT read provides the data in the FLASHDAT register, bu t is othe rw ise
ignored.
0001: A FLASHDAT read initiates a read of the byte addressed by the FLASHADR register
if no operation is currently active. This mode is used for block reads.
0010: A FLASHDAT read initiates a read of the byte addressed by FLASHADR only if no
operation is active and any data from a previous read has already been read from
FLASHDAT. This mode allows single bytes to be read (or the last byte of a block)
without initiating an extra read.
(All other value s for RD MD 3– 0 are reserved .)
Reset Value
SFLE WRMD2 WRMD1 WRMD0 RDMD3 RDMD2 RDMD1 RDMD0 00000000
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
346 Rev. 1.4
JTAG Register Definition 25.4. FLASHDAT: JTAG Flash Data
JTAG Register Definition 25.5. FLASHADR: JTAG Flash Address
This register is used to read or write data to the Flash memory across the JTAG interface.
Bits9–2: DATA7–0: Flash Data Byte.
Bit1: FAIL: Flash Fail Bit.
0: Previous Flash memory oper ation was successful.
1: Previous Flash memory oper ation failed. Usually indicates the associated memory loca-
tion was locked.
Bit0: BUSY: Flash Busy Bit.
0: Flash inter fa ce log i c is not bus y.
1: Flash interface logic is processing a request. Reads or writes while BUSY = 1 will not ini-
tiate another operation.
Reset Value
0000000000
Bit9 Bit0
This register holds the address for all JTAG Flash read, write, and erase operations. This register
autoincrements after each read or write, regar dless of whether the operation succeeded or failed.
Bits15–0: Flash Operation 17-bit Address.
Reset Value
0x00000
Bit16 Bit0
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 347
25.3. Debug Support
Each MCU has on-chip JTAG and debug logic that provides non-intrusive, full speed, in-circuit debug sup-
port using the production part inst alled in the end application, via the four pin JTAG I/F. Silicon Labs' debug
system supports inspection and modification of memory and registers, breakpoints, and single stepping.
No additional target RAM, program memory, or communications channels are required. All the digital and
analog peripherals are functional and work correctly (remain synchronized) while debugging. The Watch-
dog Timer (WDT) is disa bled when the MCU is halted during single stepping or at a breakpo int.
The C8051F120DK is a development kit with all the hardware and software necessary to develop applica-
tion code and perform in-circuit debug with each MCU in the C8051F12x and C8051F13x device families.
Each kit includes development software for the PC, a Serial Adapter (for connection to JTAG) and a target
application board with a C8051F120 installed. Serial cables and wall-mount power supply are also
included.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
348 Rev. 1.4
NOTES:
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
Rev. 1.4 349
DOCUMENT CHANGE LIST
Revision 1.3 to Revision 1.4
• Added new paragraph tags: SFR Definition and JTAG Register Definition.
• Product Selection Guide Table 1.1: Added RoHS-compliant ordering information.
• Overview Chapter, Figure 1.8, “On-Chip Memory Map”: Co rrected o n- chip XRAM size to “ 8192 Bytes”.
• SAR8 Chapter: Table 7.1, “ADC2 Electrical Characteristics”: Track/Hold minimu m sp ec corrected to
“300 ns”.
• SAR8 Chapter: Table 7.1, “ADC2 Electrical Characteristics”: Total Harmonic Distortion typical spec
corrected to “-51 dB”.
• Oscillators Chapter, Figure 14.1, “Oscillator Diagram”: Corrected location of IOSCEN arrow.
• CIP51 Chapter, Section 11.3: Added note describing EA change behavior when followed by single-
cycle instruction.
• CIP51 Chapter, Interrupt Summary Table: Added “SFRPAGE” column and SFRPAGE value for each
interrupt source.
• CIP-51 Chapter, Figure 11.2, “Memory Map”: Corrected on-chip XRAM size to “8192 Bytes”.
• Port I/O Chapter, Crossbar Priority Figures: Character formatting problem corrected.
• Port I/O Chapter, P7MDOUT Register Description: Removed references to UART and SMBus periph-
erals.
• Port I/O Chapter, P3MDOUT Register Description: Corrected text to read “P3MDOUT.[7:0]”.
• Timers Chapter: References to “TnCON” corrected to read “TMRnCN”.
• PCA0 Chapter, Section 24.1: Added note about PCA0CN Register and ef fects of read-modify-write
instructions on the CF bit.
C8051F120/1/2/3/4/5/6/7
C8051F130/1/2/3
350 Rev. 1.4
CONTACT INFORMATION
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Tel: 1+(512) 416-8500
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Email: MCUinfo@silabs.com
Internet: www.silabs.com
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notice. Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences
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