Sense & Control
Datasheet
Revision 1.1, 2012-04-03
SP37T
High integrated single-chip TPMS sensor with a low power embedded micro-
controller and wireless FSK/ASK UHF transmitter
SP37T Version A4
1300kPa
TPMS
Tire Pressure Monitoring Sensor
Edition 2012-04-03
Published by
Infineon Technologies AG
81726 Munich, Germany
© 2012 Infineon Technologies AG
All Rights Reserved.
Legal Disclaimer
The information given in this document shall in no event be regarded as a guarantee of conditions or
characteristics. With respect to any examples or hints given herein, any typical values stated herein and/or any
information regarding the application of the device, Infineon Technologies hereby disclaims any and all warranties
and liabilities of any kind, including without limitation, warranties of non-infringement of intellectual property rights
of any third party.
Information
For further information on technology, delivery terms and conditions and prices, please contact the nearest
Infineon Technologies Office (www.infineon.com).
Warnings
Due to technical requirements, components may contain dangerous substances. For information on the types in
question, please contact the nearest Infineon Technologies Office.
Infineon Technologies components may be used in life-support devices or systems only with the express written
approval of Infineon Technologies, if a failure of such components can reasonably be expected to cause the failure
of that life-support device or system or to affect the safety or effectiveness of that device or system. Life support
devices or systems are intended to be implanted in the human body or to support and/or maintain and sustain
and/or protect human life. If they fail, it is reasonable to assume that the health of the user or other persons may
be endangered.
SP37T
Tire Pressure Monitoring Sensor
Datasheet 3 Revision 1.1, 2012-04-03
Trademarks of Infineon Technologies AG
AURIX™, C166™, CanPAK™, CIPOS™, CIPURSE™, EconoPACK™, CoolMOS™, CoolSET™,
CORECONTROL™, CROSSAVE™, DAVE™, EasyPIM™, EconoBRIDGE™, EconoDUAL™, EconoPIM™,
EiceDRIVER™, eupec™, FCOS™, HITFET™, HybridPACK™, I²RF™, ISOFACE™, IsoPACK™, MIPAQ™,
ModSTACK™, my-d™, NovalithIC™, OptiMOS™, ORIGA™, PRIMARION™, PrimePACK™, PrimeSTACK™,
PRO-SIL™, PROFET™, RASIC™, ReverSave™, SatRIC™, SIEGET™, SINDRION™, SIPMOS™,
SmartLEWIS™, SOLID FLASH™, TEMPFET™, thinQ!™, TRENCHSTOP™, TriCore™.
Other Trademarks
Advance Design System™ (ADS) of Agilent Technologies, AMBA™, ARM™, MULTI-ICE™, KEIL™,
PRIMECELL™, REALVIEW™, THUMB™, µVision™ of ARM Limited, UK. AUTOSAR™ is licensed by AUTOSAR
development partnership. Bluetooth™ of Bluetooth SIG Inc. CAT-iq™ of DECT Forum. COLOSSUS™,
FirstGPS™ of Trimble Navigation Ltd. EMV™ of EMVCo, LLC (Visa Holdings Inc.). EPCOS™ of Epcos AG.
FLEXGO™ of Microsoft Corporation. FlexRay™ is licensed by FlexRay Consortium. HYPERTERMINAL™ of
Hilgraeve Incorporated. IEC™ of Commission Electrotechnique Internationale. IrDA™ of Infrared Data
Association Corporation. ISO™ of INTERNATIONAL ORGANIZATION FOR STANDARDIZATION. MATLAB™ of
MathWorks, Inc. MAXIM™ of Maxim Integrated Products, Inc. MICROTEC™, NUCLEUS™ of Mentor Graphics
Corporation. Mifare™ of NXP. MIPI™ of MIPI Alliance, Inc. MIPS™ of MIPS Technologies, Inc., USA. muRata™
of MURATA MANUFACTURING CO., MICROWAVE OFFICE™ (MWO) of Applied Wave Research Inc.,
OmniVision™ of OmniVision Technologies, Inc. Openwave™ Openwave Systems Inc. RED HAT™ Red Hat, Inc.
RFMD™ RF Micro Devices, Inc. SIRIUS™ of Sirius Satellite Radio Inc. SOLARIS™ of Sun Microsystems, Inc.
SPANSION™ of Spansion LLC Ltd. Symbian™ of Symbian Software Limited. TAIYO YUDEN™ of Taiyo Yuden
Co. TEAKLITE™ of CEVA, Inc. TEKTRONIX™ of Tektronix Inc. TOKO™ of TOKO KABUSHIKI KAISHA TA.
UNIX™ of X/Open Company Limited. VERILOG™, PALLADIUM™ of Cadence Design Systems, Inc. VLYNQ™
SP37T High integrated single-chip TPMS sensor with a low power embedded micro-controller and
wireless FSK/ASK UHF transmitter
Revision History: 2012-04-03, Revision 1.1
Previous Revision: Revision 1.0
Page Subjects (major changes since last revision)
Page 78 Update LF Receiver Input Select
Page 148 Update Pressure Measurement Error
Page 156 Temperature Conditions Updated
Page 158 Temperature Conditions Updated
We Listen to Your Comments
Any information within this document that you feel is wrong, unclear or missing at all?
Your feedback will help us to continuously improve the quality of this document.
Please send your proposal (including a reference to this document) to:
sensors@infineon.com
SP37T
Tire Pressure Monitoring Sensor
Datasheet 4 Revision 1.1, 2012-04-03
of Texas Instruments Incorporated. VXWORKS™, WIND RIVER™ of WIND RIVER SYSTEMS, INC. ZETEX™ of
Diodes Zetex Limited.
Last Trademarks Update 2011-02-24
SP37T
Tire Pressure Monitoring Sensor
Table of Contents
Datasheet 5 Revision 1.1, 2012-04-03
Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
1.2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2 Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.2 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
2.3 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
2.4 Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2.5 Operating Modes and States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.5.1 Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.5.2 Resets and Operating Mode Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2.5.3 NORMAL Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.3.1 INIT State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.3.2 RUN State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.3.3 IDLE State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.3.4 POWER DOWN State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2.5.3.5 THERMAL SHUTDOWN State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5.3.6 State Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.5.3.7 Status of SP37T Blocks in Different States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
2.6 Fault Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.1 Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.2 VMIN Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.3 ADC Measurement Overflow & Underflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.4 ADC Selftest . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.5 Bond Wire Surveillance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.6 Sensor Integrity Check . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.6.7 TMAX Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.7 Functional Block Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.7.1 Sensors and Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.7.1.1 Pressure Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.7.1.2 Acceleration Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.7.1.3 Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.7.1.4 Battery Voltage Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.7.1.5 Data Acquisition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.7.2 Memory Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.7.2.1 ROM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.7.2.1.1 ROM Library Functions and Reset/Wakeup Handlers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.7.2.1.2 ROM Protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
2.7.2.2 FLASH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.7.2.2.1 FLASH Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.7.2.2.2 FLASH Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.7.2.3 RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3 Special Function Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.1 Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Table of Contents
SP37T
Tire Pressure Monitoring Sensor
Table of Contents
Datasheet 6 Revision 1.1, 2012-04-03
3.2 General Purpose Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3 System Configuration Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3.4 System Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
3.5 Interval Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
3.6 Interval Timer Precounter / Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
3.7 Clock Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.8 Crystal Pulling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3.9 RF 315/434 MHz FSK/ASK Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
3.10 Manchester/BiPhase Encoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
3.11 LF Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
3.12 LF Receiver Analog Front End . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
3.13 LF Attenuator (AGC) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
3.14 LF Carrier Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
3.15 LF Receiver On/Off Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
3.16 LF Receiver Baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
3.17 Wakeup Pattern Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
3.18 LF Receiver Data Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
3.19 16 Bit CRC (Cyclic Redundancy Check) Generator/Checker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
3.20 Pseudo Random Number Generator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
3.21 Timer Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
3.22 General Purpose Input/Output (GPIO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
3.23 I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
3.23.1 Programming mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
3.23.1.1 FLASH Write Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
3.23.1.2 FLASH Erase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
3.23.1.3 FLASH Check Erase Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
3.23.1.4 FLASH Read Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
3.23.1.5 Read Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
3.23.1.6 FLASH Check CRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
3.23.1.7 FLASH Set User Configuration Sector Lock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
3.23.1.8 Measure Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
3.23.1.9 Measure Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
3.23.1.10 Measure Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
3.23.1.11 Measure Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
3.23.2 DEBUG Mode Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
3.23.2.1 Debug Special Function Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
3.23.2.2 Debugging Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
3.23.2.3 Debugger Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
3.23.2.3.1 SetSFR - Set an SFR to a User-defined Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
3.23.2.3.2 ReadSFR - Read the Value of One SFR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
3.23.2.3.3 SetMemory - Set one Byte in RAM to a User-defined Value . . . . . . . . . . . . . . . . . . . . . . . . . 140
3.23.2.3.4 ReadMemory - Read One Byte of the RAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
3.23.2.3.5 SetPC - Set the Program Counter to a user-defined value . . . . . . . . . . . . . . . . . . . . . . . . . . 140
3.23.2.3.6 ReadPC - Read the Program Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
3.23.2.3.7 SingleStep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
3.23.2.3.8 Run Interruptible . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
3.23.2.3.9 Run to Next Breakpoint . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
4 Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
4.1 Test Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
4.1.1 SP37T Test Board Schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
4.1.2 SP37T Test Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
SP37T
Tire Pressure Monitoring Sensor
Table of Contents
Datasheet 7 Revision 1.1, 2012-04-03
4.1.3 SP37T Test Board Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
4.1.4 SP37T Test Board Bill of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
4.2 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
4.3 Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
4.4 Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
4.4.1 Pressure Sensor (1300kPa variant) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
4.4.2 z-axis Acceleration Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
4.4.3 Temperature Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
4.4.4 Battery Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
4.4.5 Supply Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
4.4.6 RF Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
4.4.7 LF Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
4.4.8 LF Test Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
4.4.9 Crystal Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4.4.10 12 MHz RC HF Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
4.4.11 2 kHz RC LP Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
4.4.12 Interval Timer & LF On/Off Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
4.4.13 Voltage Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
4.4.14 Power On Reset / Brown Out Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
4.4.15 VMIN Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
4.4.16 FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
4.4.17 TMAX Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
4.4.18 Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
4.4.19 Digital I/O pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
4.4.20 I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
5 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.1 Package Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
5.2 Identification Code . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
5.2.1 Identification Code Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
SP37T
Tire Pressure Monitoring Sensor
List of Figures
Datasheet 8 Revision 1.1, 2012-04-03
Figure 1 Pin Configuration PG-DSOSP-14-6 (Top View, Figure not to Scale) . . . . . . . . . . . . . . . . . . . . . . . 14
Figure 2 SP37T Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Figure 3 Available Operating Modes if Lockbyte 2 is not Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 4 Available Operating Modes if Lockbyte 2 is Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Figure 5 Power On Reset / Brown Out Reset / Operating Mode Selection . . . . . . . . . . . . . . . . . . . . . . . . . 20
Figure 6 NORMAL Mode State Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Figure 7 Device Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figure 8 Memory Map. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Figure 9 Interval Timer Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Figure 10 SP37T Clock Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Figure 11 FSK using the internal capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Figure 12 ASK using the internal capacitor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
Figure 13 FSK using only external capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Figure 14 ASK using only an external capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Figure 15 RF Transmitter Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Figure 16 Manchester/BiPhase Encoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
Figure 17 RF PA Control Logic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Figure 18 Diagram of the Different RF Encoder Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Figure 19 LF Receiver Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Figure 20 LF Receiver AFE Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
Figure 21 AGC Timing diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Figure 22 LF Receiver Carrier Detector Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Figure 23 LF Carrier Detector Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
Figure 24 Carrier Detector Threshold Calibration Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Figure 25 LF Receiver Baseband . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Figure 26 LF Receiver Baseband Configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Figure 27 LF Telegram Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Figure 28 LF Decoder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
Figure 29 LF Receiver Baseband Telegram Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Figure 30 CRC (Cyclic Redundancy Check) Generator/Checker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Figure 31 Example for CRC16 usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Figure 32 Example for serial CRC generation/checking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Figure 33 Shift Register Implementation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Figure 34 Timer Mode 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Figure 35 Timer Mode 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Figure 36 Timer Mode 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Figure 37 Timer Mode 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
Figure 38 Timer mode 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
Figure 39 Timer Mode 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Figure 40 Timer Mode 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
Figure 41 Synchronization Stage & Spike Suppression Examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Figure 42 PROGRAMMING Mode State Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Figure 43 I2C Legend - PROGRAMMING Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
Figure 44 FLASH Write Line I2C Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Figure 45 FLASH Erase Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Figure 46 FLASH Check Erase Status Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Figure 47 FLASH Read Line Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Figure 48 FLASH Read Status Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Figure 49 FLASH Check CRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
List of Figures
SP37T
Tire Pressure Monitoring Sensor
List of Figures
Datasheet 9 Revision 1.1, 2012-04-03
Figure 50 FLASH Set User Configuration Sector Lock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Figure 51 Measure Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Figure 52 Measure Acceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Figure 53 Measure Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Figure 54 Measure Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Figure 55 I2C Legend - DEBUG Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Figure 56 DEBUG SetSFR Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Figure 57 DEBUG ReadSFR Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
Figure 58 DEBUG SetMemory Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Figure 59 DEBUG ReadMemory Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Figure 60 DEBUG SetPC Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Figure 61 DEBUG ReadPC Command. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Figure 62 DEBUG SingleStep Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
Figure 63 DEBUG Run Interruptible Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Figure 64 DEBUG Run to Next Breakpoint Command . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
Figure 65 SP37T Test Circuit / Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Figure 66 SP37T Test Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Figure 67 SP37T Test Board Placement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Figure 68 LF Receiver Special Function Register Settings for Telegram Mode . . . . . . . . . . . . . . . . . . . . . . 156
Figure 69 LF Receiver Special Function Register Settings for Carrier Detection . . . . . . . . . . . . . . . . . . . . . 157
Figure 70 Test Circuit for large LF signal measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Figure 71 Test Circuit for small LF signal measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Figure 72 PG-DSOSP-14-6 Package Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Figure 73 PG-DSOSP-14-6 marking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
SP37T
Tire Pressure Monitoring Sensor
List of Tables
Datasheet 10 Revision 1.1, 2012-04-03
Table 1 IPin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 2 SP37T - Operating Modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Table 3 State Transitions in NORMAL Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Table 4 Status of SP37T Blocks in Different States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Table 5 Register Naming Convention Wakeup / Reset Value. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 6 Registers Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 7 Registers Access Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Table 8 Register 0 to F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Table 9 Crystal Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Table 10 GPIO Port Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Table 11 External Wakeup Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Table 12 I/O Port 1 - Alternative Functionality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
Table 13 FLASH Write Line Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Table 14 FLASH Erase Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127
Table 15 FLASH Check Erase Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Table 16 FLASH Check Erase Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Table 17 FLASH Read Line Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Table 18 FLASH Read Line Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Table 19 FLASH Read Status Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
Table 20 FLASH Check CRC Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Table 21 Measure Pressure Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Table 22 Measure Pressure Return Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Table 23 Measure Acceleration Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Table 24 Measure Acceleration Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Table 25 Measure Temperature Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Table 26 Measure Supply Voltage Return values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Table 27 DEBUG mode SFRs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
Table 28 SP37T Test Board Bill of Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Table 29 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145
Table 30 Operating Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
Table 31 Pressure Sensor (1300 kPa variant) , Vbat = 2.1 V...3.3 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Table 32 z-axis Acceleration Sensor, Vbat = 2.1 V...3.3 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149
Table 33 Temperature Sensor, Vbat = 2.1 V...3.6 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Table 34 Battery Sensor, Vbat = 2.1 V...3.6 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Table 35 Supply Currents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
Table 36 RF Transmitter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153
Table 37 LF Receiver, Vbat = 2.1 V...3.6 V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
Table 38 LF Receiver Telegram, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz . . . . . . . . . . . . . . . . . . . . . 156
Table 39 LF Receiver Telegram, Vbat = 2.1 V...3.6 V, T = -20 °C...90 °C, fLF = 120 kHz...130 kHz . . . . . . 156
Table 40 LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz . . . . . . . . . . . . . . . 157
Table 41 LF Receiver Carrier Detection, Vbat = 2.3 V...3.3 V, T = -20 °C...90 °C, fLF = 120 kHz...130 kHz 158
Table 42 Crystal Oscillator, fCrystal = 18 MHz...20 MHz . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
Table 43 12 MHz RC HF Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Table 44 2 kHz RC LP Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Table 45 Interval Timer / LF On/Off Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
Table 46 Voltage Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163
Table 47 Power On Reset / Brown Out Reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Table 48 VMIN Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Table 49 FLASH Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
List of Tables
SP37T
Tire Pressure Monitoring Sensor
List of Tables
Datasheet 11 Revision 1.1, 2012-04-03
Table 50 TMAX Detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
Table 51 Watchdog Timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Table 52 Digital I/O pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
Table 53 I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 166
SP37T
Product Name Product Type Ordering Code Package
SP37T Tire Pressure Monitoring Sensor SP370-23-156-0 PG-DSOSP-14-6
Tire Pressure Monitoring Sensor SP37T
Datasheet 12 Revision 1.1, 2012-04-03
1 Introduction
1.1 Overview
The SP37T is a sensor for air pressure measurements designed for TPMS
applications. With its microcontroller and integrated peripherals, the
SP37T offers a single package solution for TPMS applications. It requires
only few external components. The SP37T features
• Pressure sensor for ambient pressure measurement
• Z-axis acceleration sensor for motion detection
• Temperature and supply voltage sensor
• 8051 based microcontroller
• Advanced system controller to minimize power consumption
• RF Transmitter
• LF Receiver
Measurements of pressure, acceleration, temperature, and battery voltage are performed under software control,
and the data can be formatted and prepared for RF transmission by the microcontroller.
An intelligent wakeup mechanism is available to reduce power consumption. An Interval Timer controls the timing
of measurements and transmissions. The circuitry can be programmed to wakeup at regular intervals or it can be
woken up by the integrated LF Receiver, which furthermore enables SP37T to receive data. Additionally, wakeup
is possible by an external wakeup source connected to a General Purpose Input/Output (GPIO).
The integrated microcontroller is instruction set compatible to the standard 8051 processor. It is equipped with
various peripherals (e.g. a hardware Manchester/BiPhase Encoder/Decoder and CRC Generator/Checker)
enabling an easy implementation of customer-specific applications.
The low power consumption RF Transmitter for 315 and 434 MHz contains a fully integrated PLL synthesizer, an
ASK/FSK modulator and an efficient power amplifier. Fine tuning of the center frequency can be done either using
the on-chip capacitors bank or adding external capacitors.
On-chip FLASH memory is integrated to store:
• The customer specific application program code
• A unique ID-Number
• The calibration data for the sensors
Additional on-chip ROM memory is available that holds the ROM library functions (developed by Infineon) which
covers standard tasks used by the application. The available ROM Library functions are described in a separate
document (see [1]).
SP37T
Tire Pressure Monitoring Sensor
Introduction
Datasheet 13 Revision 1.1, 2012-04-03
1.2 Features
Main features:
• Supply voltage range from 1.9 V up to 3.6 V
• Operating temperature range -40 to +125 °C
• Low supply current
• Pressure sensor for 1300kPa range
• Z-axis acceleration sensor for motion detection
• Temperature sensor
• THERMAL SHUTDOWN mode for device protection at high temperatures
• Battery voltage sensor
• Integrated RF Transmitter for ISM Band 315/434 MHz
• Selectable output power 5 or 8 dBm (transformed into 50 Ohm load)
• Configurable RF transmission data rates up to 10 kbit/s Manchester coded (20 kchips/s)
• ASK/FSK modulation capability
• Frequency deviation up to 50 kHz in FSK mode
• Fully integrated VCO and PLL Synthesizer
• On chip crystal oscillator tuning
• LF Receiver with very high input sensitivity
• LF Receiver data rate 3.9 kbit/s
• 8051 instruction set compatible microcontroller (cycle-optimized)
• 6 kByte FLASH memory (for application code)
• 16 kByte ROM (for ROM library functions)
• 256 Bytes RAM
• Wakeup from POWER DOWN state using the Interval Timer, the LF Receiver or an external wakeup source
connected via a GPIO pin
•I
2C programming/debugging interface
• Hardware Manchester/BiPhase Encoder for RF Transmitter
• Hardware Manchester Decoder for LF Receiver
• 16 Bit Hardware CRC generator
• 8 Bit Pseudo Random Number Generator
• Watchdog timer
• 3 bidirectional GPIO pins
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 14 Revision 1.1, 2012-04-03
2 Functional Description
2.1 General
2.2 Pin Configuration
Figure 1 Pin Configuration PG-DSOSP-14-6 (Top View, Figure not to Scale)
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 15 Revision 1.1, 2012-04-03
2.3 Pin Description
Table 1 IPin Description
Pin
No.
Name Pin
Type
Buffer Type Function
1 PP0 Digital
I/0 GPIO PP0 / I2C Clock / OpMode0
Note: Internal pull-up/pull-down
switchable
2 PP1 Digital
I/0 GPIO PP1 / I2C Data / OpMode1
Note: Internal pull-up/pull-down
switchable
3 PP2 Digital
I/0 GPIO PP2 / TxData
Note: Internal pull-up/pull-down
switchable
4PA Analog
RF Transmitter Output
5 PGND Supply
RF Transmitter Ground
7 GND Supply Ground
8 GND Supply Ground
12 XGND Supply Crystal Oscillator Ground
P1In
P1 D ir
P1Out
Data
Tristate
500
Data
PPx
VBat
GND
VBat
P1 Sens
Pullup
Pulldown
Tristate
Pulling
Resistor
VBat
GND
GND
PA
PGND PGND
10
S
C
R
GND
XGND
PGND
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 16 Revision 1.1, 2012-04-03
6 VBAT Supply Battery Supply Voltage
9 VREG Supply Internal voltage regulator
output
Note: Connect to decoupling
capacitor (CBCAP=100nF)
10 LF Analog Differential LF Receiver Input 1
11 XLF Analog Differential LF Receiver Input 2
13 XTAL Analog Crystal Oscillator Input
14 XTALCAP Analog Crystal Oscillator Load
Capacitance
Table 1 IPin Description (cont’d)
Pin
No.
Name Pin
Type
Buffer Type Function
VBat
VReg
Voltage
Regulator
GND
GND
(X)LF
GND
50 15 k
GND GND
R
input, LF
/ 2
VReg
XGND
500
XGND
XTAL
≈0.9 Vdc
Bypass
XGND
VReg VReg
VReg
XTALCAP
XGN D XGN D
10
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 17 Revision 1.1, 2012-04-03
2.4 Block Diagram
Figure 2 SP37T Block Diagram
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 18 Revision 1.1, 2012-04-03
2.5 Operating Modes and States
The SP37T can be operated in four different operating modes.
•NORMALmode
• PROGRAMMING mode
• DEBUG mode
• (internal production TEST mode)
The operating mode selection is done at Power On Reset by setting the GPIO pins PP0 and PP1 according to the
following table:
Note: Since PP0 and PP1 have their internal pull-up resistors enabled at Power On Reset, the default startup
mode is NORMAL mode if the PP0 and PP1 pins are left unconnected.
Table 2 SP37T - Operating Modes
PP0 PP1 Operating mode Device controlled by
1 1 NORMAL mode FLASH Program at 4000H
0 1 PROGRAMMING mode ROM firmware / external I2C Master
1 0 DEBUG mode ROM firmware / external I2C Master
0 0 Internal production test mode1)
1) IMPORTANT: Do not enter this mode since unpredictable behavior of the device might result
ROM firmware / external I2C Master
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 19 Revision 1.1, 2012-04-03
2.5.1 Operating Modes
The operating modes depend on the setting of Lockbyte 2, which protects the FLASH Sector 0 (Code Sector)
against overwriting, erasing and read-out to prevent reverse engineering of the application code. Figure 3 shows
the mode diagram if the Lockbyte 2 is not set.
Figure 3 Available Operating Modes if Lockbyte 2 is not Set
For security reasons some operating modes are not accessible anymore after the Lockbyte 2 (see “FLASH” on
Page 29) is set. Figure 4 shows the behavior of the SP37T once the Lockbyte 2 is set. All mode selections (except
the internal production TEST mode) lead to NORMAL mode.
Figure 4 Available Operating Modes if Lockbyte 2 is Set
DEBUG
mode
PP0=0
PP1=0
PP0=1
PP1=0
PP0=0
PP1=1
Power On Reset
Software Reset
Brown Out Reset
SYSTEM RESET
PP0=1
PP1=1
Internal
production
TEST mode
NORMAL
mode
PROGRAMMING
mode
INIT
PP0=0
PP1=0
PP0=0 PP0=1 PP0=1
PP1=1 PP1=0 PP1=1
Power On Reset
Software Reset
Brown Out Reset
SYSTEM RESET
INIT
Reduced
Internal
production
TEST mode
NORMAL
mode
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 20 Revision 1.1, 2012-04-03
2.5.2 Resets and Operating Mode Selection
Figure 5 Power On Reset / Brown Out Reset / Operating Mode Selection
Three kinds of resets can occur which cause an operating mode selection:
• The Power On Reset circuit is activated if VREG rises above VPOR. The internal blocks are held in RESET state
until VREG has risen above VTHR.
• The Brown Out Reset circuit is activated if VREG drops below VBRD. The internal blocks are held in RESET state
until VREG has risen above VBRD again.
• The SP37T’s Software Reset can be forced by SP37T setting SRF bit CFG2.0[RESET].
When the Internal Reset state is released (after tPOR is elapsed), a further period tMODE is required for reading the
states applied to PP0 and PP1 to determine the operation mode of the device according to Table 2 “SP37T -
Operating Modes” on Page 18. The levels on these pins must be stable during the whole tMODE period. After
tMODE has elapsed, the device starts operation in the selected mode.
The Watchdog Reset is a special case and it does not result in a mode selection. The Watchdog Reset affects
only the CPU core and forces a program restart.
V_REG
Internal Reset
Signal
(active low )
V
POR
V
THR
V
BRD
=
t
POR
t
POR
t
POR
PP0, PP1
(OpMode 0,
OpMode 1)
t
mode
t
mode
Stable
Levels
Req.
Stable
Levels
Req.
t
mode
Stable
Levels
Req.
t
mode
Stabl e
Levels
Req.
Application
forces SW
Reset
Brownout
Reset
Power On
Reset
Power On
Reset
t
POR
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 21 Revision 1.1, 2012-04-03
2.5.3 NORMAL Mode Operation
After a startup in NORMAL mode the system controller handles the different states as shown in the state transition
diagram below.
Figure 6 NORMAL Mode State Diagram
2.5.3.1 INIT State
The INIT state is entered after every System Reset (either Power On Reset, Brown Out Reset or Software Reset)
to determine the desired operation mode (see “Operating Modes” on Page 19) and to initialize the SP37T. The
INIT state is entered as well if a wakeup or watchdog timeout occurs, but no operation mode selection is done after
a wakeup and RUN state is entered immediately.
2.5.3.2 RUN State
In RUN state, the microcontroller is executing the application program from the FLASH. In this state the watchdog
is active to prevent software-deadlocks. The microcontroller (CPU) clock source is always based on the
12MHz RC HF Oscillator.
2.5.3.3 IDLE State
In IDLE state the microcontroller clock is stopped to reduce the current consumption, while the peripherals
Timer 0, ADC, RF Transmitter and LF Receiver can continue normal operation.
After a resume event is triggered by one of the enabled peripherals, the microcontroller continues the operation
where it was interrupted. The resume event source can be identified by reading SFR REF (see “Resume Event
Flag Register” on Page 50).
2.5.3.4 POWER DOWN State
In POWER DOWN state, the system controller takes control of the SP37T microcontroller and most peripherals
are switched off.
Transitions
WU - Wakeup
PE - Enter POWER DOWN state
TE - Enter THERMAL SHUTDOWN state
WD - Watchdog wakeup
IFLG -Enter IDLE state
RS - Resume event
IDLE state
RUN state
WD
WD
PE
TE
WU
WU
IFLG
RS
POWER
DOWN state
THERMAL
SHUTDOWN state
INIT
(App. Restart )
SR
SR - Sytem Reset
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 22 Revision 1.1, 2012-04-03
In POWER DOWN state the active peripherals (Interval Timer, LF On/Off timer,...) are clocked by the
2kHz RC LP Oscillator.
After a wakeup occurred, the wakeup source can be identified by reading SFR WUF (see “Wakeup Flag
Register” on Page 48).
2.5.3.5 THERMAL SHUTDOWN State
The application can enter THERMAL SHUTDOWN state if the temperature is above the TMAX threshold
temperature. Once the device is in THERMAL SHUTDOWN state, only the TMAX circuit can provide a wakeup
event. All other wakeup sources are disabled. The device will remain in this state until the temperature falls below
the TREL threshold (see “TMAX Detector” on Page 24 for details).
2.5.3.6 State Transitions
With reference to Figure 6 “NORMAL Mode State Diagram” on Page 21, the following state transitions can
occur:
2.5.3.7 Status of SP37T Blocks in Different States
Depending on the current state in NORMAL mode the internal blocks of the SP37T are active, inactive or are not
supplied with supply voltage to minimize the current consumption. The following table gives an overview over of
the individual blocks in the different states.
Table 3 State Transitions in NORMAL Mode
State transition Description
RUN state
=> IDLE state
The application program can set SFR bit CFG0.5 [IDLE] to enter
IDLE state.
(see “Configuration Register 0” on Page 41)
Note: If no peripheral that can create a RESUME event is active,
IDLE state will not be entered and the application will continue un-
interrupted.
IDLE state
=> RUN state
A peripheral unit (Timer 0, ADC, RF Transmitter, LF Receiver) creates a
resume event. The application automatically resumes where it was
interrupted when entering IDLE state (see “Resume Event Flag
Register” on Page 50)
IDLE state
=> INIT state
RUN state
=> INIT state
Overflow of the watchdog timer. The application will restart. The
watchdog wakeup is indicated in the SFR WUF. “Wakeup Flag
Register” on Page 48
RUN state
=> THERMAL SHUDOWN state
The application program can call a ROM Library function to enter
THERMAL SHUTDOWN state.
RUN state
=> POWER DOWN state
The application program can call a ROM Library function to enter
POWER DOWN state.
POWERDOWNstate
=> RUN state
THERMAL SHUTDOWN state
=> RUN state
A wakeup event will restart the application, and set the SFR WUF
accordingly. (see “Wakeup Flag Register” on Page 48)
INIT state
=> RUN state
This state change is initiated automatically by the system controller as
soon as the initialization is finished.
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 23 Revision 1.1, 2012-04-03
Table 4 Status of SP37T Blocks in Different States
Unit Run state IDLE state POWER DOWN state THERMAL SHUT-
DOWN state
Power On Reset Active1)
1) Active: block is powered, active and keeps its register contents.
Active Active Active
Brown Out Detector Active Active Inactive Inactive
TMAX Detector Handled by
ROM Library functions2)
2) The ADC, the Sensor and VMIN Detector are controlled by ROM Library functions described in [1].
Inactive3)
3) Inactive: block is powered, cannot be used, but keeps its register contents.
Inactive Active
Voltage Regulator (VREG) Active Active Active Active
System controller Active Active Active Active
Microcontroller Active Inactive No supply4)
4) No supply: block is not powered, cannot be used and all register content is lost.
No supply
Manchester/
BiPhase encoder, Timer
Active Active No supply No supply
Peripheral modules CRC,
I2C, Pseudo Random
Number Generator
Selectable inactive or
active
Inactive No supply No supply
Watchdog timer Active Active No supply No supply
Upper 128Bytes RAM Active Inactive No supply No supply
Lower 128Bytes RAM Active Inactive Selectable
No supply or inactive
Selectable
No supply or inactive
FLASH Active Inactive No supply No supply
ROM Active Inactive No supply No supply
Crystal oscillator Selectable inactive or
active
Selectable
inactive or
active
No supply No supply
2kHz RC LP Oscillator Active Active Active Inactive
12MHz RC HF Oscillator Active Active No supply No supply
Interval Timer Active Active Active Inactive
LF Receiver Selectable inactive or
active
Selectable
inactive or
active
Selectable inactive or
active
Inactive
RF Transmitter Selectable inactive or
active
Selectable
inactive or
active
Inactive Inactive
Sensor Handled by
ROM Library functions
Handled by
ROM Library
functions
No supply No supply
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 24 Revision 1.1, 2012-04-03
2.6 Fault Protection
The SP37T features multiple fault protections which prevent the application from unexpected behavior and
deadlocks. This chapter gives a brief overview of the available fault protections. Detailed explanation of the usage
can be found later in this document and in [1].
2.6.1 Watchdog Timer
For operation security a watchdog timer is available to avoid application software deadlocks. The watchdog timer
is only active in NORMAL mode and DEBUG mode and must be reset periodically by the application, otherwise
the timer generates a wakeup and forces a restart of SP37T application program. Setting
SFR bit CFG2.1[WDRES] resets the watchdog timer (see “Configuration Register 2” on Page 43)
The watchdog timeout period is fixed (see Table 51 “Watchdog Timer” on Page 166). The accuracy depends
on the accuracy of the 2kHz RC LP Oscillator which is used to clock the watchdog timer.
Upon wakeup the watchdog timer is automatically reset. The watchdog timer is not, however, automatically reset
upon entry into IDLE state. Therefore care must be taken so that the application does not remain in IDLE state
longer than the minimum watchdog timeout period.
2.6.2 VMIN Detector
This circuit will detect if the supply voltage is very close to the minimum required value. The ROM library functions
which perform measurements will return the VMIN status in a status byte with the measurement result (see [1]).
2.6.3 ADC Measurement Overflow & Underflow
The ROM Library functions which perform measurements will return the over/underflow status in a status byte with
the measurement result. (see [1])
2.6.4 ADC Selftest
A dedicated ROM Library function is able to perform a selftest of the ADC (see [1]).
2.6.5 Bond Wire Surveillance
The continuity of the bond wire connection between the ASIC die and the sensor die is checked as part of every
pressure and acceleration measurement. The ROM library routines which perform the measurements will return
the bond wire status in a status byte with the measurement result (see [1]).
2.6.6 Sensor Integrity Check
An integrity check of the acceleration sensor is performed as part of every measurement. The ROM library routine
which performs acceleration measurements will return the integrity status in the status byte with the measurement
result (see [1]).
2.6.7 TMAX Detector
The TMAX detector is used to wakeup the SP37T from THERMAL SHUTDOWN state if the ambient temperature
falls below the release trigger level TREL.
Entering THERMAL SHUTDOWN state is initiated by a ROM Library function described in [1].
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 25 Revision 1.1, 2012-04-03
2.7 Functional Block Description
2.7.1 Sensors and Data Acquisition
The SP37T has four sensors to acquire environmental data:
2.7.1.1 Pressure Sensor
The pressure sensor consists of a single-crystal silicon, bulk micro machined membrane with an integrated full
Wheatstone piezo-resistive bridge. The piezo-resistors are placed inside a vacuum reference chamber, whilst the
pressure media to be measured in the application is applied to the opposite side of the membrane. This gives good
long-term properties as the measurement bridge is protected from the environment. Pressure measurement is
performed by a dedicated ROM library function (see [1]).
2.7.1.2 Acceleration Sensor
The acceleration sensor consists of a single-crystal silicon, bulk micro machined beam and mass with an
integrated full Wheatstone piezo-resistive bridge. The whole beam and mass are placed inside a hermetically
sealed chamber and are therefore well protected from the environment. A diagnostic resistor is integrated along
the edge of the beam to be used to check the mechanical integrity of the beam. Acceleration measurement is
performed by a dedicated library ROM library function (see [1]). Figure 7 shows the direction of the sensitive axis
for the accelerometer. If the SP37T is mounted on the wheel as shown in Figure 7, it will measure a positive
acceleration when the wheel rotates.
Figure 7 Device Orientation
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 26 Revision 1.1, 2012-04-03
2.7.1.3 Temperature Sensor
The temperature sensor is placed on the ASIC. This is read by the ADC referenced to a fixed (band gap) voltage.
Temperature measurement is performed by a dedicated ROM library function (see [1]).
2.7.1.4 Battery Voltage Sensor
The battery voltage sensor is a circuit which provides a signal proportional to the supply voltage. The voltage is
read by the ADC referenced to a fixed (band gap) voltage. Supply Voltage measurement is performed by a
dedicated ROM library function (see [1]).
2.7.1.5 Data Acquisition
The analog data is acquired and digitized by the internal 10 Bit ADC.
Measurement routines for acquiring the environmental data are available within the ROM library functions that are
described in [1].
Characteristic of the individual sensors can be found in “Characteristics” on Page 148.
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 27 Revision 1.1, 2012-04-03
2.7.2 Memory Organization
Figure 8 Memory Map
The following memory blocks are implemented:
• 16 kByte ROM memory
• 6 kByte FLASH memory
• 256 Byte RAM memory
• 128 Byte SFR register
Code
memory
FFFF
H
Not used
5880
H
587 F
H
5800
H
User Configuration
57 FF
H
5780
H
Coefficients
577 F
H
Program Code 4000
H
3FF7
H
Revision number, CRC Sum
0000
H
Data
memory
FF
H
SFR
80
H
7F
H
00
H
Data
Indir ect
addr essing
Direct
addressing
Data
FLASH
RAM
256
byte
58 BF
H
5900
H
Reference cells
128 B
128 B
64 B Flash Configuration
58 C0
H
58 FF
H
64 B
Lockbyte 1
CRC Sum + Lockbyte 2
XTAL Freq + Lockbyte 3
6kB
ROM
16k
0080
H
ROM Librar y Functions
Vector Table
Reserved
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 28 Revision 1.1, 2012-04-03
2.7.2.1 ROM
A 16 kB ROM memory is located in the address range 0000H to 3FF7H.
2.7.2.1.1 ROM Library Functions and Reset/Wakeup Handlers
The ROM contains the reset handler, operation mode handler, wakeup handler, internal test and debug routines
and the ROM Library functions (see in [1]).
2.7.2.1.2 ROM Protections
To protect the ROM code against readout a hardware mechanism is implemented, thus no read operations can
be performed on the ROM.
Direct jumping into the ROM area is prevented by a hardware mechanism, thus access to the
ROM library functions is granted only via a vector table at the bottom of the ROM address space.
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 29 Revision 1.1, 2012-04-03
2.7.2.2 FLASH
2.7.2.2.1 FLASH Organization
The FLASH is divided into five sectors. Each sector can be erased and written individually.
Sectors 0 and 1 are accessible for customer usage.
Sectors 2, 3 and 4 are written in the Infineon production site and cannot be erased or re-written by the customer.
•4000H -- 577FH (6016 Bytes) Code sector (0): The code sector contains the application software including a
CRC16 Checksum (to be written to 577DH -- 577EH) and the Lockbyte 2 (to be written to 577FH).
•5780H -- 57FFH (128 Bytes) User Configuration sector (1):The User Configuration sector can store
individual device configuration data. It also contains the crystal frequency which is needed as a timebase for
ROM Library functions (to be written to 57FAH -- 57FCH) and the Lockbyte 3 (to be written to 57FFH).
•5800H -- 587FH (128 Bytes) Coefficients sector (2): This sector is written during the sensor calibration
process and contains calibration coefficients, the unique Sensor ID and Lockbyte 1 (to be written to 587FH).
•5880H -- 58BFH (64 Bytes) FLASH Configuration sector (3): This sector contains the FLASH driver
parameters and other device configuration parameters.
•58C0H -- 58FFH (64 Bytes) Reference Cell sector (4): This sector contains the reference cells for FLASH
reading.
2.7.2.2.2 FLASH Protection
To protect the FLASH against unauthorized access three FLASH Lockbytes are available.
Note: The Lockbytes are set, if the value in the appropriate FLASH address is programmed to D1H. Setting the
Lockbyte to 00H will result in a unlocked FLASH area. Any other value must not be written to these locations.
After programming a Lockbyte, the SP37T has to be reset before the FLASH lock takes effect.
•Lockbyte 1 (587FH)
This Lockbyte protects the FLASH sectors 2, 3 and 4 against overwriting and erasing. This Lockbyte is
programmed at the Infineon production site.
•Lockbyte 2 (577FH)
This Lockbyte protects the FLASH sector 0 (Code Sector) against overwriting, erasing (except reduced internal
production test mode) and read-out to prevent reverse engineering of the application code.
This Lockbyte has to be set at the end of the programming sequence of the Code Sector via the I2C Interface
(when writing the highest FLASH Line starting at 5760H). Once it is set, the available operating modes are reduced
according to Figure 4 “Available Operating Modes if Lockbyte 2 is Set” on Page 19.
•Lockbyte 3 (57FFH)
This Lockbyte protects the FLASH sector 1 (User Configuration Sector) against overwriting and erasing (except
reduced internal production test mode).
The Lockbyte can be set either via I2C in PROGRAMMING mode in the same programming sequence as Lockbyte
2 is set, or by using a dedicated ROM Library function in NORMAL mode by the application software (see [1]).
SP37T
Tire Pressure Monitoring Sensor
Functional Description
Datasheet 30 Revision 1.1, 2012-04-03
2.7.2.3 RAM
The RAM is available as volatile data storage for the application program. Some RAM locations are required by
the ROM Library Functions and therefore not freely available for use by the application program. For more details
please refer to the ROM Library function guide [1].
The upper 128 bytes of RAM are switched off in POWER DOWN state and THERMAL SHUTDOWN state and
lose their contents.
The lower 128 bytes of RAM can be powered during POWER DOWN state and THERMAL SHUTDOWN state.
This is selectable using SFR bit CFG2.4[PDLMB].
If not powered in these states, this RAM loses the content, otherwise it can be used as battery buffered storage
like the General Purpose Registers (see “General Purpose Registers” on Page 39).
Note: The RAM is not reset at a System Reset or watchdog timeout.
After a Brown Out Reset this feature may be used to possibly recover data.
After Power On Reset the application has to initialize the RAM if needed.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 31 Revision 1.1, 2012-04-03
3 Special Function Registers
Special Function Registers (SFR) are used to control and monitor the state of the SP37T and its peripherals.
The following table shows the naming convention for the SFR descriptions that are used throughout this document
Table 6 provides links within this document to detailed description of the application relevant SFRs. In addition to
register names and offset addresses, this table indicates how each SFR behaves after wakeup and reset events.
The Wakeup Value column applies in the case of a wakeup event, which includes a watchdog timeout. The Reset
Value column applies in the case of a Power On Reset, Brownout Reset or Software Reset event.
Table 5 Register Naming Convention Wakeup / Reset Value
State Symbol Description
Low 0 Register value is 0B
High 1 Register value is 1B
Undefined X Register value is undefined
Unchanged U Register value is unchanged
Table 6 Registers Overview
Register Short
Name
Register Long Name Offset
Address
Wakeup Value Reset Value
Microcontroller
ACC Accumulator E0H00H00H
BRegister B F0H00H00H
DPH Data Pointer (high) 83H00H00H
DPL Data Pointer (low) 82H00H00H
PSW Program Status Word D0H00H00H
SP Stack Pointer 81H07H07H
General Purpose Registers1)
GPR0 General Purpose Register 0 B8HUUHXXH
GPR1 General Purpose Register 1 B0HUUHXXH
GPR2 General Purpose Register 2 A8HUUHXXH
GPR3 General Purpose Register 3 F1HUUHXXH
GPR4 General Purpose Register 4 F2HUUHXXH
GPR5 General Purpose Register 5 F3HUUHXXH
GPR6 General Purpose Register 6 F5HUUHXXH
GPR7 General Purpose Register 7 F6HUUHXXH
GPR8 General Purpose Register 8 F7HUUHXXH
GPR9 General Purpose Register 9 F9HUUHXXH
GPRA General Purpose Register 10 FAHUUHXXH
GPRB General Purpose Register 11 FBHUUHXXH
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 32 Revision 1.1, 2012-04-03
GPRC General Purpose Register 12 FCHUUHXXH
GPRD General Purpose Register 13 FDHUUHXXH
GPRE General Purpose Register 14 FEHUUHXXH
GPRF General Purpose Register 15 FFHUUHXXH
System Configuration Registers
CFG0 Configuration Register 0 F8H0000U000B00H
CFG1 Configuration Register 1 E8H000U000UB00H
CFG2 Configuration Register 2 D8H000U1000B18H
DSR Diagnosis and Status Register D9H0XUU00XUB0XXX0000B
System Controller
WUF Wakeup Flag Register C0HXXH00H
WUM Wakeup Mask Register C1HUUHFFH
REF Resume Event Flag Register D1H00H00H
Interval Timer
ITPR Interval Timer Period Register BCHUUH01H
Interval Timer Precounter / Calibration
ITPH Interval Timer Precounter Register (High
Byte)
BBH0000UUUUB03H
ITPL Interval Timer Precounter Register (Low
Byte)
BAHUUHE8H
Clock Controller
DIVIC Internal Clock Divider B9H000000UUB00H
Crystal Pulling
XTAL0 XTAL Frequency Register (FSKLOW) C4HUUHFFH
XTAL1 XTAL Frequency Register (FSKHIGH/ASK) C3HUUHFFH
RF 315/434 MHz FSK/ASK Transmitter
RFC RF-Transmitter Control Register C8H00H00H
RFTX RF-Transmitter Configuration Register AEHUUU0UUUUB87H
Manchester/BiPhase Encoder
RFENC RF-Encoder Tx Control Register CAHE0HE0H
RFD RF-Encoder Tx Data Register C9H00H00H
RFS RF-Encoder Tx Status Register CBH02H02H
LF Receiver
LFRXC LF Receiver Control Register 98H0UUUUU00B00H
LF Receiver Analog Front End
LFRX0 LF Receiver Configuration Register 0 B7HUUH38H
LF Attenuator (AGC)
LFRX1 LF Receiver Configuration Register 1 B6HUUH00H
Table 6 Registers Overview (cont’d)
Register Short
Name
Register Long Name Offset
Address
Wakeup Value Reset Value
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 33 Revision 1.1, 2012-04-03
LFRX2 LF Receiver Configuration Register 2 AFHUUH77H
LF Carrier Detector
LFCDFLT LF Carrier Detect Filtering B2HUUH00H
LFCDM0 LF Carrier Detector Mode Register 0 B5HUUUUUUU0B00H
LF Receiver On/Off Timer
LFOOT LF On/Off Timer Configuration Register C6HUUH00H
LFOOTP LF OnOff Timer Precounter C5HUUH64H
LF Receiver Baseband
LFDIV LF Bitrate Divider Factor B4H00UUUUUUB17H
Wakeup Pattern Detector
LFPCFG LF Pattern Detection Configuration Register C7H00UU00UUB00H
LFP0H LF Pattern 0 Detector Sequence Data MSB CDHUUHFFH
LFP0L LF Pattern 0 Detector Sequence Data LSB CCHUUHFFH
LFP1H LF Pattern 1 Detector Sequence Data MSB CFHUUHFFH
LFP1L LF Pattern 1 Detector Sequence Data LSB CEHUUHFFH
LF Receiver Data Interface
LFRXD LF Receiver Data Register A5HUUH00H
LFRXS LF Receiver Status Register A4HXUXUUUUUBX0X00000B
16 Bit CRC (Cyclic Redundancy Check) Generator/Checker
CRCC CRC Control Register A9H02H02H
CRCD CRC Data Register AAH00H00H
CRC0 CRC Preload/Result Register 0 (low byte) ACH00H00H
CRC1 CRC Preload/Result Register 1 (high byte) ADH00H00H
Pseudo Random Number Generator
RNGD Random Number Generator Data Register ABHUUH55H
Timer Unit
TCON Timer Control Register 88H00H00H
TMOD Timer Mode Register 89H00H00H
TH0 Timer 0 Register High Byte 8CH00H00H
TL0 Timer 0 Register Low Byte 8AH00H00H
TH1 Timer 1 Register High Byte 8DH00H00H
TL1 Timer 1 Register Low Byte 8BH00H00H
General Purpose Input/Output (GPIO)
P1DIR IO-Port 1 Direction Register 91HUUHFFH
P1IN IO-Port 1 Data In Register 92H00000XXXB00000XXXB
P1OUT IO-Port 1 Data Out Register 90HUUHFFH
P1SENS IO-Port 1 Sensitivity Register 93H00000UUUB00H
I2C Interface
Table 6 Registers Overview (cont’d)
Register Short
Name
Register Long Name Offset
Address
Wakeup Value Reset Value
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 34 Revision 1.1, 2012-04-03
The register is addressed bytewise.
I2CD I2C Data Register 9AH00H00H
I2CS I2C Status Register 9BH00H00H
Debug Special Function Register
DBCH0 Debug Compare Register 0 (high byte) 95H00H00H
DBCL0 Debug Compare Register 0 (low byte) 94H00H00H
DBCH1 Debug Compare Register 1 (high byte) 9DH00H00H
DBCL1 Debug Compare Register 1 (low byte) 9CH00H00H
DBTH0 Debug Target Register 0 (high byte) 97H00H00H
DBTL0 Debug Target Register 0 (low byte) 96H00H00H
DBTH1 Debug Target Register 1 (high byte) 9FH00H00H
DBTL1 Debug Target Register 1 (low byte) 9EH00H00H
1) Reset Value for GRP0 - GPRF is typically undefined (X) except in the case of Software Reset, which leaves the GPR
content unchanged (U).
Table 7 Registers Access Types
Mode Symbol Description Hardware (HW) Description Software (SW)
Basic Access Types
write/read wr Register is used as input for the HW Register is read and writable by SW
read only r Register is written by HW Value written by SW is ignored by HW; that
is, SW may write any value to this field
without affecting HW behavior
write only w Register is written by software and
affects hardware behavior with every
write by software.
Register is writable by SW. When read, the
register does not return the value that has
been written previously, but the reset value
instead.
UNUSED - Register is not used by HW. Value written by SW is ignored by HW; that
is, SW may write any value to this field
without affecting HW behavior.
Reserved Register is used as input for internal
HW; Access Type is not documented.
Value must be kept by SW. SW read or write
any value to this field affecting HW behavior.
Special Access Types1)
1) Optional types
Read
self clearing
rc Register is used as input for the HW,
the register will be cleared due to a HW
mechanism.
Reading from the register generates a
strobe signal for the HW. Register is
readable by SW.
Write
self clearing
wc Register is used as input for the HW,
the register will be cleared due to a HW
mechanism.
Writing to the register generates a strobe
signal for the HW. Register is writable by
SW.
Table 6 Registers Overview (cont’d)
Register Short
Name
Register Long Name Offset
Address
Wakeup Value Reset Value
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 35 Revision 1.1, 2012-04-03
3.1 Microcontroller
The SP37T incorporates an 8051 instruction set compatible microcontroller. It offers an 8-bit data path, several
addressing modes (direct, register, register indirect, immediate, index), and accesses the built-in peripherals
through SFRs. To handle the sequential nature of TPMS applications efficiently, wakeup and resume mechanisms
are implemented instead of an interrupt controller.
The microcontroller incorporates the following basic SFRs: Accumulator (ACC), Register B (B) and Program
Status Word (PSW) are bit addressable registers used to perform arithmetical and logical operations. The Stack
Pointer (SP) and Data Pointer (DPTR) are included to allow basic programming structures. The Data Pointer
(DPTR) is determined by SFR DPH and SFR DPL.
SFR PSW holds the status of basic arithmetic operations.
Accumulator
Register B
Data Pointer (high)
ACC Offset Wakeup Value Reset Value
Accumulator E0H00H00H
Field Bits Type Description
ACC 7:0 wr Accumulator
Reset: 00H
B Offset Wakeup Value Reset Value
Register B F0H00H00H
Field Bits Type Description
B7:0wrRegister B 7-0
Reset: 00H
7 07 0
wr
ACC
7 07 0
wr
B
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 36 Revision 1.1, 2012-04-03
Data Pointer (low)
DPH Offset Wakeup Value Reset Value
Data Pointer (high) 83H00H00H
Field Bits Type Description
DPH 7:0 wr Data Pointer (high)
Reset: 00H
DPL Offset Wakeup Value Reset Value
Data Pointer (low) 82H00H00H
Field Bits Type Description
DPL 7:0 wr Data Pointer (low)
Reset: 00H
7 07 0
wr
DPH
7 07 0
wr
DPL
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 37 Revision 1.1, 2012-04-03
Program Status Word
PSW Offset Wakeup Value Reset Value
Program Status Word D0H00H00H
Field Bits Type Description
CY 7 wr Carry
Reset: 0H
AC 6 wr Auxiliary Carry
Carry-out for BCD operations
Reset: 0H
F0 5 wr Flag 0
Available for general purpose use.
Reset: 0H
RS 4:3 wr Register Bank Select
00B Bank 0 (00H - 07H )
01B Bank 1(08H - 0FH )
10B Bank 2(10H - 17H )
11B Bank 3(18H - 1FH )
Reset: 0H
OV 2 wr Overflow
Reset: 0H
F1 1 wr Flag 1
Available for general purpose use.
Reset: 0H
P0rParity
Set or cleared each instruction cycle to indicate an odd or even number
of 1 bits in the accumulator
Reset: 0H
7 077
wr
CY
66
wr
AC
55
wr
F0
43
wr
RS
22
wr
OV
11
wr
F1
00
r
P
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 38 Revision 1.1, 2012-04-03
Stack Pointer
SP Offset Wakeup Value Reset Value
Stack Pointer 81H07H07H
Field Bits Type Description
SP 7:0 wr Stack Pointer (SP)
SP is incremented before data is pushed and decremented after data is
popped. SP always points to the last valid stack byte.
Reset: 07H
7 07 0
wr
SP
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 39 Revision 1.1, 2012-04-03
3.2 General Purpose Registers
The SP37T incorporates 16 general purpose registers that can be used by the application to store data beyond a
POWER DOWN state / THERMAL SHUTDOWN state period. The GPR Registers are not cleared after a System
Reset. After a Power On Reset, the GPR contents will be undefined.
General Purpose Register 0
General Purpose Registers 0 - F are freely available for application program use. GPR0, GPR1, GPR2 are located
at Offset Addresses that make them well suited for bit manipulation. Placing bit variables in these GPRs will result
in more efficient CPU operation.
GPR0 Offset Wakeup Value Reset Value
General Purpose Register 0 B8HUUHXXH
Field Bits Type Description
GPR0 7:0 wr General Purpose
Reset: XXH
Table 8 Register 0 to F1)
Register Short Name Register Long Name Offset Address Wakeup Value Reset Value
GPR0 General Purpose Register 0 B8HUUHXXH
GPR1 General Purpose Register 1 B0HUUHXXH
GPR2 General Purpose Register 2 A8HUUHXXH
GPR3 General Purpose Register 3 F1HUUHXXH
GPR4 General Purpose Register 4 F2HUUHXXH
GPR5 General Purpose Register 5 F3HUUHXXH
GPR6 General Purpose Register 6 F5HUUHXXH
GPR7 General Purpose Register 7 F6HUUHXXH
GPR8 General Purpose Register 8 F7HUUHXXH
GPR9 General Purpose Register 9 F9HUUHXXH
GPRA General Purpose Register 10 FAHUUHXXH
GPRB General Purpose Register 11 FBHUUHXXH
GPRC General Purpose Register 12 FCHUUHXXH
GPRD General Purpose Register 13 FDHUUHXXH
7 07 0
wr
GPR0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 40 Revision 1.1, 2012-04-03
GPRE General Purpose Register 14 FEHUUHXXH
GPRF General Purpose Register 15 FFHUUHXXH
1) Reset Value for GRP0 - GPRF is typically undefined (X) except in the case of Software Reset, which leaves the GPR
content unchanged (U).
Table 8 Register 0 to F1) (cont’d)
Register Short Name Register Long Name Offset Address Wakeup Value Reset Value
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 41 Revision 1.1, 2012-04-03
3.3 System Configuration Registers
The system configuration registers can be used for:
• Initiating state transitions (SFR CFG0)
• Enabling or disabling peripherals (SFR CFG1 and SFR CFG2)
• Monitoring the operation mode, the system state and peripherals (SFR DSR)
Configuration Register 0
CFG0 Offset Wakeup Value Reset Value
Configuration Register 0 F8H0000U000B00H
Field Bits Type Description
PDWN 7 wr Enter POWER DOWN State
If set to 1 by software the POWER DOWN state is entered; This bit is
automatically reset to 0 by the system controller after a wakeup. Entering
POWER DOWN state is handled by a ROM Library function. It is not
recommended to set this bit manually.
Reset: 0H
TSHDWN 6 wr Enter THERMAL SHUTDOWN State
If set to 1 by software the THERMAL SHUTDOWN state is entered; This
bit is automatically reset to 0 by the system controller after wakeup.
Entering THERMAL SHUTDOWN state is handled by a ROM Library
function. It is not recommended to set this bit manually.
Reset: 0H
IDLE 5 wr Enter IDLE State
If set to 1 by software the IDLE state is entered; This bit is automatically
reset to 0 by the system controller after a resume event occurs.
Reset: 0H
ENXOSC 4 wr Enable XTAL Oscillator
Control of XTAL oscillator enable is handled by a ROM Library function.
It is not recommended to change this bit manually.
0B XTAL oscillator disable
1B XTAL oscillator enable
Reset: 0H
FTM 3 wr Enable Functional Test Mode
This mode is used only during internal device testing.
0B FTM disabled
1B FTM enable
Reset: 0H
7 077
wr
PDWN
66
wr
TSHDWN
55
wr
IDLE
44
wr
ENXOSC
33
wr
FTM
22
Res
11
-
UNUSED
00
Res
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 42 Revision 1.1, 2012-04-03
Configuration Register 1
Res 2 Reserved
This bit must be set to 0B.
Reset: 0H
UNUSED 1 - UNUSED
Reset: 0H
Res 0 Reserved
This bit must be set to 0B.
Reset: 0H
CFG1 Offset Wakeup Value Reset Value
Configuration Register 1 E8H000U000UB00H
Field Bits Type Description
Res 7 Reserved
This bit must be set to 0B.
Reset: 0H
I2CEN 6 wr I2C Enable
0B Standard I/O Port functionality
1B I2C functionality on Pins PP0/SCL and PP1/SDA
Reset: 0H
RNGEN 5 wc Random Number Generator Enable
0B Cleared automatically after random number is generated
1B Initiates generation of a new pseudo random number
Reset: 0H
RFTXPEN 4 wr Transmitter Data Port Output Enable
If this bit is set the RF transmission baseband data is made available on
PP2, and the RF Manchester/BiPhase Encoder does not turn on the PA.
If RF transmission in parallel with PP2 mirroring is desired , the PA must
be enabled by the application prior to RF transmission (RFC.0 = 1).
0B Standard I/O Port functionality
1B Echoes RF transmission baseband data on port PP2/TXData
Reset: 0H
Res 3 Reserved
This bit must be set to 0B.
Reset: 0H
Field Bits Type Description
7 077
Res
66
wr
I2CEN
55
wc
RNGEN
44
wr
RFTXPEN
33
Res
22
wr
ITRD
11
r
ITINIT
00
wr
ITEN
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 43 Revision 1.1, 2012-04-03
Configuration Register 2
ITRD 2 wr Interval Timer Read Enable
To safely read SFR ITPR, this bit should be set to 1 prior to reading ITPR.
After the ITPR contents are read, this bit should be checked.
0B SFR ITPR read result is not valid
1B SFR ITPR read result is valid
Reset: 0H
ITINIT 1 r Interval Timer Initialization
When the wakeup interval is changed by programming ITPR, ITPL or
ITPH with a new value, this bit is set to 1 until the new value has taken
effect. The application should not leave RUN state while this bit is 1
otherwise the ITPR setting does not take effect. This bit is automatically
cleared after initialization is complete.
0B Interval Timer Initialization complete
1B Interval Timer Initialization in progress
Reset: 0H
ITEN 0 wr Interval Timer Enable
Interval Timer is always enabled in NORMAL mode, setting or clearing
ITEN bit has no effect.
0B Disable Interval Timer (TEST/DEBUG mode only)
1B Enable Interval Timer
Reset: 0H
CFG2 Offset Wakeup Value Reset Value
Configuration Register 2 D8H000U1000B18H
Field Bits Type Description
UNUSED 7 - UNUSED
Reset: 0H
I2CGCEN 6 wr I2C General Call Enable
0B Disabled
1B Enabled
Reset: 0H
UNUSED 5 - UNUSED
Reset: 0H
Field Bits Type Description
7 077
-
UNUSED
66
wr
I2CGCEN
55
-
UNUSED
44
wr
PDLMB
33
Res
22
-
UNUSED
11
wc
WDRES
00
wc
RESET
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 44 Revision 1.1, 2012-04-03
PDLMB 4 wr Lower RAM Memory Block (00H-7FH) Power Control
0B Lower RAM retains power in POWER DOWN and THERMAL
SHUTDOWN states
1B Lower RAM is not powered in POWER DOWN and THERMAL
SHUTDOWN states
Reset: 1H
Res 3 Reserved
This bit must be set to 1B.
Reset: 1H
UNUSED 2 - UNUSED
Reset: 0H
WDRES 1 wc Reset Watchdog Counter
0B Cleared automatically after reset of watchdog counter
1B Watchdog counter is reset
Reset: 0H
RESET 0 wc System Reset
0B Cleared automatically after software reset is performed
1B A software reset is performed
Reset: 0H
Field Bits Type Description
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 45 Revision 1.1, 2012-04-03
Diagnosis and Status Register
DSR Offset Wakeup Value Reset Value
Diagnosis and Status Register D9H0XUU00XUB0XXX0000B
Field Bits Type Description
Res 7 Reserved
This bit must be set to 0B.
Reset: 0H
TGOOD 6 r TMAX Detector Status
Entering THERMAL SHUTDOWN state is handled by a ROM Library
function.
0B Temperature > TMAX
1B Temperature < TMAX
Reset: XB
OPMODE 5:4 r Operating Mode
00B TEST Mode
01B DEBUG Mode
10B PROGRAMMING Mode
11B NORMAL Mode
Reset: XXB
Res 3:2 Reserved
These bits must be set to 00B.
Reset: 0H
WUPEND 1 r Wakeup Pending in SFR WUF
0B SFR WUF contents have not changed since the last read
1B SFR WUF contents have changed since the last read
Reset: 0H
Res 0 Reserved
This bit must be set to 0B.
Reset: 0H
7 077
Res
66
r
TGOOD
54
r
OPMODE
32
Res
11
r
WUPEND
00
Res
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 46 Revision 1.1, 2012-04-03
3.4 System Controller
While the microcontroller controls the SP37T in RUN state, the system controller takes over control in
POWER DOWN state, IDLE state and THERMAL SHUTDOWN state.
The system controller handles wakeup / resume events and system resets. It is clocked by the
2kHz RC LP Oscillator.
Difference between System Reset and Wakeup:
•System Reset - The digital circuit is reset. Program execution starts at address 0000H to perform reset
initialization routines (including operation mode selection) and will jump to the FLASH at address 4000H to
execute the application program.
•Wakeup - Only the program counter of the microcontroller and its peripheral units are reset. Program
Execution starts at address 0000H to perform wakeup initialization routines and jumps to the FLASH at 4000H
to execute the application program.
Wakeup Event Handling
Whenever a wakeup occurs, the SP37T leaves POWER DOWN state and enters RUN state to execute the
application program. This transition can be initiated from various sources. The wakeup source can be identified by
reading SFR WUF.
The wakeup sources can be enabled or disabled by setting the appropriate bits in SFR WUM. The bits WDOG,
TMAX and ITIM are always enabled. Setting these bits have no effect in NORMAL/DEBUG modes.
The bits in SFR WUF are cleared upon read (read-clear). If subsequent wakeup source activity is detected, the
SFR DSR.WUPEND bit and the corresponding SFR WUF bit(s) will be set. Note that wakeup sources that have a
mask bit set (disabled) in SFR WUM will always be cleared (inactive) in SFR WUF.
The SFR WUF is not automatically cleared when entering the POWER DOWN state. For this reason it is a good
practice to have the application software read WUF and handle any pending wakeup events before entering
POWER DOWN. Otherwise, any flags in SFR WUF will remain marked as pending upon the next device wakeup.
Note that only new wakeup source activity, occurring after entering POWER DOWN, will cause a device wakeup
to occur.
Watchdog Wakeup
A watchdog wakeup occurs after the watchdog timer has elapsed.
See “Watchdog Timer” on Page 24 for details about the watchdog timer.
TMAX Wakeup
A TMAX wakeup occurs only if the device was in THERMAL SHUTDOWN state and the temperature falls below
the threshold release temperature TREL.
See “TMAX Detector” on Page 24 for details about the TMAX wakeup.
LF Receiver Wakeup Event
The LF Receiver wakeup can be enabled by setting one of following bits:
• SFR bit WUM.5 [LFCD] or
• SFR bit WUM.4 [LFSY] or
• SFR bit WUM.3[LFPM1] and/or SFR bitWUM.2 [LFPM0]
The wakeup source can be read in the SFR WUF.
The LF Receiver has to be configured appropriate for the particular wakeup modes. See “LF Receiver” on
Page 74 for details.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 47 Revision 1.1, 2012-04-03
External PP2 Wakeup Event
I/O Port PP2 can be configured to wakeup the SP37T from POWER DOWN state by an external source.
PP2 has to be configured according to “External Wakeup on PP2” on Page 118 for this feature.
Interval Timer Wakeup Event
When the Interval Timer elapses, a wakeup event is generated and POWER DOWN state is left. The wakeup can
be identified by the application software reading SFR bit WUF.0[ITIM].
The Interval Timer is reloaded automatically with the actual value from SFR ITPR and immediately restarted. The
Interval Timer is also counting during RUN state which leads to accurate wakeup intervals even if RUN state
periods vary in execution time.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 48 Revision 1.1, 2012-04-03
Wakeup Flag Register
WUF Offset Wakeup Value Reset Value
Wakeup Flag Register C0HXXH00H
Field Bits Type Description
WDOG_FLAG 7 rc Watchdog Wakeup
Reset: 0H
TMAX_FLAG 6 rc Thermal Shutdown (TMAX) Release Wakeup
Reset: 0H
LFCD_FLAG 5 rc LF Carrier Wakeup
Reset: 0H
LFSY_FLAG 4 rc LF Sync Match Wakeup
Reset: 0H
LFPM1_FLAG 3 rc LF Pattern 1 Match Wakeup
Reset: 0H
LFPM0_FLAG 2 rc LF Pattern 0 Match Wakeup
Reset: 0H
EXT_FLAG 1 rc I/O-Port PP2 External Wakeup
Reset: 0H
ITIM_FLAG 0 rc Interval Timer Wakeup
Reset: 0H
7 077
rc
WDOG_FL
AG
66
rc
TMAX_FL
AG
55
rc
LFCD_FL
AG
44
rc
LFSY_FL
AG
33
rc
LFPM1_F
LAG
22
rc
LFPM0_F
LAG
11
rc
EXT_FLA
G
00
rc
ITIM_FL
AG
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 49 Revision 1.1, 2012-04-03
Wakeup Mask Register
WUM Offset Wakeup Value Reset Value
Wakeup Mask Register C1HUUHFFH
Field Bits Type Description
WDOG_MASK 7 wr Disable Watchdog Reset
Watchdog is always enabled, setting this bit has no effect in
NORMAL/DEBUG modes.
Reset: 1H
TMAX_MASK 6 wr Disable Thermal Shutdown (TMAX) Release Wakeup
TMAX Wakeup is handled by ROM Library Functions, setting this bit has
no effect in NORMAL/DEBUG modes.
Reset: 1H
LFCD_MASK 5 wr Disable LF Carrier Wakeup
0B Enable LF Carrier wakeup
1B Disable LF Carrier wakeup
Reset: 1H
LFSY_MASK 4 wr Disable LF Sync Match Wakeup
0B Enable LF Sync Match wakeup
1B Disable LF Sync Match wakeup
Reset: 1H
LFPM1_MASK 3 wr Disable LF Pattern 1 Match Wakeup
0B Enable LF Pattern 1 Match wakeup
1B Disable LF Pattern 1 Match wakeup
Reset: 1H
LFPM0_MASK 2 wr Disable LF Pattern 0 Match Wakeup
0B Enable LF Pattern 0 Match wakeup
1B Disable LF Pattern 0 Match wakeup
Reset: 1H
EXT_MASK 1 wr Disable I/O-Port PP2 External Wakeup
0B Enable I/O-Port PP2 wakeup
1B Disable I/O-Port PP2 wakeup
Reset: 1H
ITIM_MASK 0 wr Disable Interval Timer Wakeup
Interval Timer Wakeup is always enabled in NORMAL mode, setting this
bit has no effect in NORMAL/DEBUG modes.
Reset: 1H
7 077
wr
WDOG_MA
SK
66
wr
TMAX_MA
SK
55
wr
LFCD_MA
SK
44
wr
LFSY_MA
SK
33
wr
LFPM1_M
ASK
22
wr
LFPM0_M
ASK
11
wr
EXT_MAS
K
00
wr
ITIM_MA
SK
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 50 Revision 1.1, 2012-04-03
Resume Event Flag Register
Note: SFR DIVIC must be 00b in order to reliably read SFR REF
REF Offset Wakeup Value Reset Value
Resume Event Flag Register D1H00H00H
Field Bits Type Description
UNUSED 7:6 - UNUSED
Reset: 0H
READC 5 rc A/D Conversion complete
This bit is for use by ROM Library functions.
Reset: 0H
RELFO 4 rc LF Receive Buffer full
Data can be read by the application software.
Reset: 0H
RERFF 3 rc RF Transmission complete
All bits in the transmitter shift register have been transmitted.
Reset: 0H
RERFU 2 rc RF Transmit Buffer empty
Next byte to be transmitted may be loaded to SFR RFD.
Reset: 0H
UNUSED 1 - UNUSED
Reset: 0H
RET0 0 rc Timer 0 Underflow
Reset: 0H
7 076
-
UNUSED
55
rc
READC
44
rc
RELFO
33
rc
RERFF
22
rc
RERFU
11
-
UNUSED
00
rc
RET0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 51 Revision 1.1, 2012-04-03
3.5 Interval Timer
Figure 9 Interval Timer Block Diagram
The Interval Timer is responsible to wakeup the SP37T from the POWER DOWN state after a predefined time
interval. It is clocked by the 2kHz RC LP Oscillator and incorporates two dividers:
• Precounter: can be calibrated and represents the timebase; please refer to “Interval Timer Precounter /
Calibration” on Page 53
• Postcounter: configures the Interval Timer duration in multiples of the timebase.
The Precounter (ITPH/L) is a 16 bit register with 12 significant bits. The precounter values 0001H up to 0FFFH
corresponds to 1dec up to 4095dec. The maximum precounter value 0000H corresponds to 4096D.
To increase the timer accuracy, it is recommended to use a ROM library function which calibrates the precounter
dependent on the actual frequency of the 2kHz RC LP Oscillator. See [1] for details.
The Postcounter (ITPR) is an 8 bit register. 01H up to FFH corresponds to a multiplication of the timebase with 1dec
up to 255dec. The maximum postcounter value 00H corresponds to 256D.
The Interval Timer duration is determined by the SFR ITPR. The desired value can be calculated by using the
following equation
(1)
(2)
Writing to the Postcounter (ITPR) establishes the counter reload value.
Reading from the Postcounter (ITPR) returns the counter value, not the counter reload value. The Interval Timer
is asynchronous from the CPU, so care must be taken when reading its contents. To safely read the ITPR, the
SFR CFG1 ITRd bit should be set to one prior to reading ITPR. After the ITPR contents are read, the
SFR CFG1 ITRd bit should be checked: If the ITPR read result is valid, the SFR CFG ITRd bit will still be set. If
the SFR CFG1 ITRd bit is cleared during ITPR read, the ITPR read result is not valid.
Interval Timer
2kHz RC LP Oscillator
(uncalibrated) Precounter Postcounter Interval Wakeup
ITPL/ITPH ITPR
][][][ ITPRrpostcountestimebasesmerperiodIntervalti
•
=
[]
⎥
⎦
⎤
⎢
⎣
⎡
=
s
l
illatorkHzRCLPOsc
f
HITPLprecounter
stimebase
2
/
][
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 52 Revision 1.1, 2012-04-03
Interval Timer Period Register
ITPR Offset Wakeup Value Reset Value
Interval Timer Period Register BCHUUH01H
Field Bits Type Description
ITPR 7:0 wr Interval Timer Period Register
To safely read ITPR, SFR CFG1.2 should be set to 1 prior to reading
ITPR. If the ITPR read was successful, SFR CFG1.2 will remain set to 1.
Reset: 01H
7 07 0
wr
ITPR
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 53 Revision 1.1, 2012-04-03
3.6 Interval Timer Precounter / Calibration
Calibration is done by counting clock cycles from the crystal oscillator during one 2kHz RC LP Oscillator period.
In the case that the crystal oscillator is not available (not running), the 12 MHz RC HF Oscillator is used instead.
The calibration is performed automatically by a ROM library function (see [1]).
Notes
1. SFR ITPL and SFR ITPH can be modified manually for using other (uncalibrated) precounter values than the
ones determined by the ROM Library function.
2. After writing SFR ITPR, SFR ITPL or SFR ITPH some time is needed to activate the new setting.
SFR bit CFG1.1[ITInit] is cleared automatically when the new setting takes effect.
3. Reading SFR ITPL or SFR ITPH returns the low byte or the high byte of the Precounter reload value,
respectively.
Interval Timer Precounter Register (High Byte)
ITPH Offset Wakeup Value Reset Value
Interval Timer Precounter Register (High
Byte)
BBH0000UUUUB03H
Field Bits Type Description
UNUSED 7:4 - UNUSED
Reset: 0H
ITPH 3:0 wr Interval Timer Precounter Register (High Byte)
Reset: 3H
7 074
-
UNUSED
30
wr
ITPH
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 54 Revision 1.1, 2012-04-03
Interval Timer Precounter Register (Low Byte)
ITPL Offset Wakeup Value Reset Value
Interval Timer Precounter Register (Low
Byte)
BAHUUHE8H
Field Bits Type Description
ITPL 7:0 wr Interval Timer Precounter Register (Low Byte);
Reset: E8H
7 07 0
wr
ITPL
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 55 Revision 1.1, 2012-04-03
3.7 Clock Controller
The Clock Controller for internal clock management is part of the system controller.
In SP37T the microcontroller (CPU) clock source is always based on the 12 MHz RC HF Oscillator (system clock).
to provide minimum current consumption. The internal clock divider (SFR DIVIC) may be used to slow down the
speed of the microcontroller and to reduce the current consumption further. The crystal is used as clock source
for the RF Transmitter and for the Timer Unit (e.g. for oscillator calibrations). The start up of the crystal (e.g. for
RF Transmission) can be performed automatically by a ROM library function (see [1]). Figure 10 shows the
clocking scheme for the different SP37T blocks.
Figure 10 SP37T Clock Concept
2kHz RC LP Oscillator (Low Power)
The 2 kHz RC LP Oscillator stays active throughout all operating states except THERMAL SHUTDOWN state.
The typical oscillator frequency is 2kHz. Characteristics can be found in Table 44 “2 kHz RC LP Oscillator” on
Page 161.
12MHz RC HF Oscillator (High Frequency)
The 12 MHz RC HF Oscillator runs at typical 12 MHz and is used as system clock for the SP37T in RUN state.
Characteristics can be found in Table 43 “12 MHz RC HF Oscillator” on Page 161.
12 MHz RC HF
Oscillator
(Systemclock)
Crystal
Oscillator
19,6875 MHz
18,0800 MHz
2 kHz RC LP
Oscillator
RC LF
Oscillator
:64 / :16 / :4 / :1
8051 CPU and
Peripherals
:8
Interval Timer
LF On/Off Timer
LF Baseband
Receiver
Timer Unit
RF Transmitter
:4
PP2
DIVIC
TMOD
*2
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 56 Revision 1.1, 2012-04-03
Crystal Oscillator
The crystal oscillator is a Negative Impedance Converter (NIC) oscillator with a crystal operating in series
resonance. Characteristics can be found in Table 42 “Crystal Oscillator, fCrystal = 18 MHz...20 MHz” on
Page 160.
RC LF Oscillator
The RC LF Oscillator is part of the LF Receiver and only used as clock for the LF Receiver Baseband.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 57 Revision 1.1, 2012-04-03
Internal Clock Divider
DIVIC Offset Wakeup Value Reset Value
Internal Clock Divider B9H000000UUB00H
Field Bits Type Description
UNUSED 7:2 - UNUSED
Reset: 00H
DIVIC 1:0 wr SystemClock Divider
00B Duvide by 1
01B Divide by 4
10B Divide by 16
11B Divide by 64
Reset: 0H
7 072
-
UNUSED
10
wr
DIVIC
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 58 Revision 1.1, 2012-04-03
3.8 Crystal Pulling
To achieve FSK transmission, the reference frequency of the NIC crystal oscillator is detuned by switching
between two different capacitances (one for the low and one for the high FSK frequency). These capacitance
values are achieved with embedded switchable capacitors and/or with external capacitors, mounted in series to
the crystal. For ASK transmission, the capacitance can be used to tune the center frequency.
The SP37T offers the possibility to use either internal capacitors and/or external capacitors for pulling the crystal
frequency. This is determined by the SFR bit RFTX.FSKSWITCH.
Note: Cparasitic used in Figure 11, Figure 13 and Figure 14 is the overall parasitic capacitance between the pins
XGND an XCAP (switch, bond wires, pad parasitics,...). The formulas for calculating the resulting
capacitance for ASK/FSK (CASK, CFSKHIGH, CFSKLOW) only take into account the dominating factor of
CSwitch, OFF.. Specification for the parasitic capacitance can be found in Table 42 “Crystal Oscillator,
fCrystal = 18 MHz...20 MHz” on Page 160.
The following pages show the configurations for ASK/FSK using internal or external capacitors.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 59 Revision 1.1, 2012-04-03
FSK with internal capacitors
• In the configuration shown in Figure 11 the internal capacitors are used. The desired capacitor values must
be selected by using SFR XTAL1 and SFR XTAL0. The exact values used should be verified by module level
testing.
• During FSK transmission the output of the Manchester/Biphase Encoder determines which capacitor value is
used. The capacitor value in SFR XTAL0 is applied when the output of the Manchester/Bi-phase Encoder is 0;
SFR XTAL1 is applied when the output is 1.
Note: SFR bit RFTX.FSKSWITCH must be set to 0 for this configuration
(3)
(4)
Figure 11 FSK using the internal capacitors
OFFSwitchXTALFSKHIGH
CCC
,1
+≅
OFFSwitchXTALFSKLOW
CCC
,0
+≅
Internal Cap Array (8 capacitors)
SFR XTAL1
SFR XTAL0
Cswitch,OFF
XTALCAP
XGND
FSK Switch
RFTX.FSKSWITCH
(‘0’ for Internal Cap Bank )
RFTX.ASKFSK
(‘1’ for ASK )
Mod
Bit Encoder
Buffer
Shift Reg
SFR RFD
RFS.RFSE Shift Reg Empty
RF Manchester/Bi-Phase Encoder (simplified view )
RFENC.RFMODE
Raw Data
PA
Control
Logic
RFC.ENPA
RF PA
Enable
RFS.RFBF
RFENC.RFDLEN
Timer1 Bitrate Strobe
RFENC.TXDD
Encoder Output
(PP 2 when CFG 1. RFTXPEN set )
CFG1.RFTXPEN
18 - 20 MHz
XTAL Crystal
Oscillator
C
pa ra si ti c
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 60 Revision 1.1, 2012-04-03
ASK with internal capacitor
• In the configuration shown in Figure 12 the internal capacitor array is used. The desired capacitor value must
be selected by using SFR XTAL1 to establish the RF carrier frequency. The exact value used should be
verified by module level testing.
• During ASK transmission the output of the Manchester/Biphase Encoder controls the RF Power Amplifier. The
PA is enabled when the output of the Manchester/Bi-phase Encoder is 1; disabled when the output is 0.
(5)
Figure 12 ASK using the internal capacitor
OFFSwitchXTALASK
CCC
,1
+≅
Internal Cap Array (8 capacitors)
Cswitch,OFF
XTALCAP
XGND
FSK Switch
RFTX.ASKFSK
(‘1’ for ASK )
Mod
Bit Encoder
Buffer
Shift Reg
SFR RFD
RFS.RFSE Shift Reg Empty
RF Manchester/Bi-Phase Encoder (simplified view )
RFENC.RFMODE
Raw Data
RFC.ENPA
RF PA
Enable
Encoder Output
(PP 2 when CFG 1. RFTXPEN set )
RFS.RFBF
RFENC.RFDLEN
Timer1 Bitrate Strobe
RFENC.TXDD
SFR XTAL1
SFR XTAL0
RFTX.FSKSWITCH
(normally 0 in ASK mode )
18 - 20 MHz
XTAL Crystal
Oscillator
C
pa ra si ti c
PA
Control
Logic
CFG1.RFTXPEN
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 61 Revision 1.1, 2012-04-03
FSK with external capacitors
• In the configuration shown in Figure 13 the FSK switch is used in conjunction with external capacitors.
Guidelines for determining the external capacitor values are Equation (6) and Equation (7). The exact values
used should be verified by module level testing.
• During FSK transmission the output of the Manchester/Biphase Encoder opens and closes the FSK switch.
The FSK switch is closed when the output of the Manchester/Bi-phase Encoder is 0; opened when the output
is 1.
Note: SFR bit RFTX.FSKSWITCH must be set to 1 for this configuration
(6)
(7)
Figure 13 FSK using only external capacitors
6d
(
)
()
OFFSwitch
OFFSwitch
FSKHI GH
CCC
CCC
C
,21
,21
++
+⋅
≅
1
CCFSKLOW
≅
Internal Cap Array (8 capacitors)
SFR XTAL1
SFR XTAL0
XTALCAP
XGND
FSK Switch
18 - 20 MHz
XTAL
Crystal
Oscillator
C1
C2
RFTX.FSKSWITCH
(‘1’ for External Caps )
Note: XT AL 0 should
be set to ‘ 0 x00 ’ w hen
using exter nal caps !
RFTX.ASKFSK
(‘0’ for FSK )
Mod
Bit Encoder
Buffer
Shift Reg
SFR RFD
RFS.RFSE Shift Reg Empty
RF Manchester/Bi-Phase Encoder (simplified view )
RFENC.RFMODE
Raw Data
RFC.ENPA
RF PA
Enable
RFS.RFBF
RFENC.RFDLEN
Timer1 Bitrate Strobe
RFENC.TXDD
Encoder Output
(PP 2 when CFG 1. RFTXPEN set )
Cswitch,OFF
C
para sitic
PA
Control
Logic
CFG1.RFTXPEN
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 62 Revision 1.1, 2012-04-03
ASK with external capacitor
• In the configuration shown in Figure 14 an external capacitor is used to establish the RF carrier frequency. A
guideline for determining the external capacitor value is Equation (8). The exact value used should be verified
by module level testing.
• During ASK transmission the output of the Manchester/Biphase Encoder controls the RF Power Amplifier. The
PA is enabled when the output of the Manchester/Bi-phase Encoder is 1; disabled when the output is 0.
Note: SFR XTAL1 is typically set to 00H for this configuration.
(8)
Figure 14 ASK using only an external capacitor
1,1
CCCC
OFFSwitchXTALASK
++≅
Internal Cap Array (8 capacitors)
XTALCAP
XGND
FSK Switch
C1
SFR XTAL1
SFR XTAL0
RFTX.ASKFSK
(‘1’ for ASK )
Mod
Bit Encoder
Buffer
Shift Reg
SFR RFD
RFS.RFSE Shift Reg Empty
RF Manchester/Bi-Phase Encoder (simplified view )
RFENC.RFMODE
Raw Data
RFC.ENPA
RF PA
Enable
RFS.RFBF
RFENC.RFDLEN
Timer1 Bitrate Strobe
RFENC.TXDD
Encoder Output
(PP 2 when CFG 1. RFTXPEN set )
RFTX.FSKSWITCH
(normally 0 in ASK mode )
Cswit ch,OFF
18 - 20 MHz
XTAL Crystal
Oscillator
C
pa ra si ti c
PA
Control
Logic
CFG1.RFTXPEN
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 63 Revision 1.1, 2012-04-03
XTAL Frequency Register (FSKLOW)
XTAL Frequency Register (FSKHIGH/ASK)
XTAL0 Offset Wakeup Value Reset Value
XTAL Frequency Register (FSKLOW) C4HUUHFFH
Field Bits Type Description
FSKLOW 7:0 w FSK Low Frequency
Pulling/Trimming capacitor select for lower FSK modulation frequency.
The capacitor array is binary weighted from
00000001B: 156fF
00000010B: 312fF
...
11111111B: 40pF
Reset: FFH
XTAL1 Offset Wakeup Value Reset Value
XTAL Frequency Register (FSKHIGH/ASK) C3HUUHFFH
Field Bits Type Description
FSKHASK 7:0 w FSK High Frequency / ASK Center Frequency
Pulling/Trimming capacitor select for upper FSK modulation frequency
and ASK center frequency. The capacitor array is binary weighted from
00000001B: 156fF
00000010B: 312fF
...
11111111B: 40pF
Reset: FFH
7 07 0
w
FSKLOW
7 07 0
w
FSKHASK
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 64 Revision 1.1, 2012-04-03
3.9 RF 315/434 MHz FSK/ASK Transmitter
Figure 15 RF Transmitter Block Diagram
The RF-Transmitter can be configured for the 315/434 MHz ISM-Band frequencies by setting SFR bits RFTX.3-
2[ISMB1-0] and choosing the proper crystal according to Table 9 below.
Table 9 Crystal Selection
Center Frequency [MHz] PLL Divider Factor Required XTAL Frequency [MHz]
433.92 24 18.0800
315.00 16 19.6875
PLL
VCO
PA
Charge
Pump
Phase
Detector
Crystal
frequency
315 MHz
434 MHz
1736MHz
1890MHz
Divider
÷ 2
Divider
÷2/÷3
Divider
÷4
Divider
÷3/÷2
Divider
÷2
Divider
PLL Lock Detector
(used by ROM Library
function )
RFTX.ISMB1-0
RFTX.PAOP1-0
RFC.EnPA
FSK-
Modulator
FSK-
Transmit data
ASK-
Transmit data
Manchester/
BiPhase
Encoder
RFS
RFENC
RFD
RFTX
L
O
G
I
C
RFC.ENFSYN
Loop-
Filter
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 65 Revision 1.1, 2012-04-03
Voltage Controlled Oscillator (VCO)
The VCO uses on-chip inductors and varactors for tuning. The tuning range VCO is split up into 16 frequency
ranges.
A ROM library function (see [1]) is available which selects the tuning curve automatically dependent on
environmental conditions (Tambient, Vbat).
Note: Re-calibration of the tuning curve is necessary when Vbat changes by more than 800mV or Tambient changes
by more than 70°C.
Power Amplifier PA
In a typical application, the highly efficient power amplifier is automatically turned on by the Manchester/BiPhase
encoder as soon as data is written to the SFR RFD. After the last bit is transmitted and the shift register is empty
the PA is turned off again. If, however, the automatic control of the PA is not desired, then manual control is
possible when SFR bit RFC.0[ENPA] is set.
The nominal output power levels are specified in Table 36 “RF Transmitter” on Page 153. The output power is
determined by SFR bits RFTX.1-0[PAOP1-0] and the matching network (see also “Test Board” on Page 142 for
details on the matching network).
Note: For test purpose the PLL synthesizer and the power amplifier can be enabled separately by using the
SFR RFC control register. The power amplifier should be switched on with a delay of at least 100µs after
enabling the frequency synthesizer. This delay is needed for the PLL to lock.
PLL Monitoring
In order to avoid unwanted out-of-band emissions in case the PLL goes out-of-lock, the SP37T includes a PLL
Monitoring feature . This feature can be enabled via SFR bit RFC.7[ENPLLMON]. If PLL Monitoring is enabled
and the PLL becomes unlocked, the RF Power Amplifier is automatically disabled and SFR bit RFS.7[PADIS] bit
is set. The application program can verify that a transmission was successful by checking PADIS - if PADIS is
clear, the PLL remained locked throughout the transmission.
Note: The Manchester/BiPhase Encoder state machine continues executing transmission even though PA is off.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 66 Revision 1.1, 2012-04-03
RF-Transmitter Control Register
RFC Offset Wakeup Value Reset Value
RF-Transmitter Control Register C8H00H00H
Field Bits Type Description
ENPLLMON 7 wr Enables PLL Monitoring
PLL Monitoring will automatically disable the PA during RF transmission
if the PLL goes out of lock.
0B Disable
1B Enable
Reset: 0H
UNUSED 6:2 - UNUSED
Reset: 00H
ENPLL 1 wr Enable RF Frequency Synthesizer (PLL)
The ROM Library Function VCO-Tuning should be used to enable the
PLL. After RF transmission is complete this bit may be used to disable the
PLL.
0B Disable
1B Enable
Reset: 0H
ENPA 0 wr Enable RF Power Amplifier (PA)
This bit is normally cleared to allow the Manchester/Bi-Phase Encoder to
control the RF PA during transmission. (see SFR CFG1 RFTXPEN for
exceptional case)
0B PA controlled automatically by Manchester/Bi-Phase Encoder
1B PA controlled manually
Reset: 0H
7 077
wr
ENPLLMO
N
62
-
UNUSED
11
wr
ENPLL
00
wr
ENPA
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 67 Revision 1.1, 2012-04-03
RF-Transmitter Configuration Register
RFTX Offset Wakeup Value Reset Value
RF-Transmitter Configuration Register AEHUUU0UUUUB87H
Field Bits Type Description
FSKSWITCH 7 wr FSK modulation switch
0B Switch is always open (disabled) - to be used with internal pulling
capacitors
1B Switch is controlled by RF Encoder when ASKFSK = 0B to be used
with external capacitors
The FSK Switch is open when the RF Encoder output is 1. The FSK
Switch is closed when the RF Encoder output is 0. Switch is closed
when ASKFSK = 1B.
Reset: 1H
ITXD 6 wr Invert Transmit Data
0B Data not inverted
1B Data inverted
Reset: 0H
ASKFSK 5 wr ASK/FSK Modulation Select
0B FSK modulation (Frequency Shift Keying)
1B ASK modulation (Amplitude Shift Keying)
Reset: 0H
UNUSED 4 - UNUSED
Reset: 0H
ISMB 3:2 wr RF Frequency Band Select
00B 300MHz - 320MHz
01B 433MHz - 450MHz
10B Reserved
11B Reserved
Reset: 1H
PAOP 1:0 wr RF Power Amplifier Output Stage Select
00B 1 PA output stage enabled
01B 2 PA output stages enabled
10B 2 PA output stages enabled
11B 3 PA output stages enabled
Reset: 3H
7 077
wr
FSKSWIT
CH
66
wr
ITXD
55
wr
ASKFSK
44
-
UNUSED
32
wr
ISMB
10
wr
PAOP
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 68 Revision 1.1, 2012-04-03
3.10 Manchester/BiPhase Encoder
The SP37T offers a Hardware Manchester/BiPhase encoder which uses Timer 1 (see “Timer Unit” on Page 105)
to configure the bitrate for the encoder. The application software needs to configure the timer and can
subsequently send the raw uncoded data to the Manchester/BiPhase Encoder which takes care about encoding
and the RF transmission itself (controlling the Power Amplifier). Using the Hardware encoder allows that the CPU
to be operated at a reduced clock rate thereby reducing the peak current consumption during RF transmission.
The reduced CPU clock rate also reduces the possibility of clock noise artifacts in the RF signal (see “Internal
Clock Divider” on Page 57). Furthermore, the encoder creates a resume event after sending each byte so that
the application can enter IDLE state while sending each databyte (see “Resume Event Flag Register” on
Page 50). It is recommended to use both reduced clock rate and IDLE mode for best performance during RF
transmission.
Figure 16 Manchester/BiPhase Encoder
The encoder mode, transmit buffer length, and RF carrier idle state are all controlled by SFR RFENC. The RFENC
settings for encoder mode and transmit buffer length take effect upon transfer of the data from SFR RFD to the
internal shift register, not at the time of writing to SFR RFENC.
The RF Power Amplifier (RF PA) is controlled by the PA Control Logic. In most cases the control logic enables
and disables the RF PA according to the table in Figure 17. Cases in which the behavior differs from this table
include usage of SFR bit RFTXPEN and the PLL Monitoring features.
By enabling the RF Encoder Data Output alternate port functionality of PP2 via the SFR bit RFTXPEN in CFG1,
the SFR bit ENPA in SFR RFC must be set in order to allow the RF Encoder output to properly modulate the RF
PA. It is recommended that the RF Encoder Data Output functionality of PP2 is used only during software
development debugging or device testing. Another exception to the behavior in Figure 17 is when the PLL
Monitoring feature is enabled. See “PLL Monitoring” on Page 65 for more details."
Mod
Bit Encoder
Buffer
Shift Reg
SFR RFD
RFENC.TXDD
RFS.RFSE Shift Reg Empty
RF Manchester/Bi-Phase Encoder (simplified view )
RFENC.RFMODE
Raw Data
RFTX.ASKFSK
PA
Control
Logic
RFC.ENPA
RF PA
Enable
Encoder
Output
RFS.RFBF
RFENC.RFDLEN
Timer1 Bitrate Strobe
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 69 Revision 1.1, 2012-04-03
Figure 17 RF PA Control Logic
By default the transmission takes place byte-aligned (SFR bits RFENC.7-5[RFDLEN2-0]= 111b. If less than 8 Bits
should be transmitted, SFR bits RFENC.7-5[RFDLEN2-0] can be set to any value between 110b...000b to transmit
only 7...1 MSBs of the transmit buffer SFR RFD. In this case the unused LSBs are disregarded.
In addition to Manchester/BiPhase encoding, it is also possible to send data with a user-defined encoding scheme,
e.g. for sending a preamble. This can be achieved by the chipmode (SFR bits RFENC.2-0[RFMOD2-0] = 101b).
In chipmode the encoder sends each bit in SFR RFD without any encoding.
The following figure shows the timing diagrams for the different encoding schemes:
Figure 18 Diagram of the Different RF Encoder Modes
Encoder
Output
RF PA
Enable
X
1
X
00Mod
X0 Mod
10TXDD
110TXDD
ON
Mod
OFF
ON
11 1 TXDD TXDD
RFC.ENPA RFS.RFSE RFTX.ASKFSK
Data
Clock
Manchester
Inverted Manchester
Differential Manchester
Biphase-0
Biphase-1
10100110
SFR RFD
Clock
Chip
10100110
Encoder- Mode
(Manchester/BiPhase)
Chip- Mode
time
Start of
data transmission
Transmission finished
in
Chip-Mode
Transmission
finished
in
Encoder-Mode
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 70 Revision 1.1, 2012-04-03
As shown in Figure 16 “Manchester/BiPhase Encoder” on Page 68 Timer 1 (see “Timer Unit” on Page 105)
is used as bitrate generator and has to be configured according to the desired bitrate. The required timer clock
source is the crystal oscillator. The required timer value can be calculated with the following formula:
(9)
This timer value has to be written to the timer registers (see “Timer 1 Register High Byte” on Page 115 and
“Timer 1 Register Low Byte” on Page 115).
RF Encoder Status
SFR RFS represents the status of the RF Encoder.
After writing a databyte to SFR RFD, the SFR bit RFS.0[RFBF] is set by the encoder hardware. It is cleared
automatically when the databyte in SFR RFD is transferred to the shift register and the buffer is ready to be filled
with the next databyte.
Since the encoder creates a resume event (see “Resume Event Flag Register” on Page 50) when the
SFR bit RFS.0[RFBF] is cleared, the application can enter IDLE state between sending two consecutive
databytes.
Note: It is necessary to provide the RF encoder with a continuous data stream to prevent the RF receiver from
losing synchronization.
SFR bit RFS.1[RFSE] is cleared as long as the shift register still contains data that has to be transmitted and is
set if there is no more data available in the shift register (this indicates the end of a data transmission) and
automatically turns off the RF Power Amplifier.
If PLL Monitoring is enabled and the PLL becomes unlocked, the RF Power Amplifier is automatically disabled and
SFR bit RFS.7[PADIS] bit is set. The application program can verify that a transmission was successful by
checking PADIS - if PADIS is clear, the PLL remained locked throughout the transmission.
Note: The Manchester/BiPhase Encoder state machine continues executing transmission even though PA is off.
[]
1
1
8
−
⎟
⎟
⎟
⎟
⎠
⎞
⎜
⎜
⎜
⎜
⎝
⎛
⎥
⎦
⎤
⎢
⎣
⎡
⋅
=
s
Baudrate
Hzf
timervalue sourcetimerclock
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 71 Revision 1.1, 2012-04-03
RF-Encoder Tx Control Register
RFENC Offset Wakeup Value Reset Value
RF-Encoder Tx Control Register CAHE0HE0H
Field Bits Type Description
RFDLEN 7:5 wr RF Data Length
Number of bits to be transmitted from SFR RFD.
000B Transmit RFD MSB only
001B Transmit RFD two MSBs
010B
011B
100B
101B
110B
111B Transmit all bits of RFD
Reset: 7H
UNUSED 4 - UNUSED
Reset: 0H
TXDD 3 wr RF Encoder Idle state
Determines the state of the RF Transmitter when the RF Shift Register is
empty and the SFR bit RFC.0[ENPA] is set.
0B FSK Carrier low / ASK Carrier off
1B FSK Carrier high / ASK Carrier on
Reset: 0H
RFMODE 2:0 wr RF Encoder Mode
Refer to Diagram of different RF Encoder modes figure.
000B Manchester
001B Inverted Manchester
010B Differential Manchester
011B Biphase 0
100B Biphase 1
101B Chip Mode (NRZ)
110B Reserved
111B Reserved
Reset: 0H
7 075
wr
RFDLEN
44
-
UNUSED
33
wr
TXDD
20
wr
RFMODE
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 72 Revision 1.1, 2012-04-03
RF-Encoder Tx Data Register
RFD Offset Wakeup Value Reset Value
RF-Encoder Tx Data Register C9H00H00H
Field Bits Type Description
RFD 7:0 w RF Data Transmit Byte
Reset: 00H
7 07 0
w
RFD
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 73 Revision 1.1, 2012-04-03
RF-Encoder Tx Status Register
RFS Offset Wakeup Value Reset Value
RF-Encoder Tx Status Register CBH02H02H
Field Bits Type Description
PADIS 7 wr PLL Monitoring PA Status
If the PLL Monitoring is enabled (RFC.ENPLLMON is set) and during RF
transmission the PLL goes out of lock, this bit is set and the PA is
automatically disabled. The PA remains disabled until this bit is cleared
by CPU. This bit can be cleared only when the content of the RF shift
register is cleared. Writing a logical '1' to this bit has no effect.
0B PA is enabled
1B PLL Monitoring has disabled the PA
Reset: 0H
UNUSED 6:2 - UNUSED
Reset: 00H
RFSE 1 r RF Encoder Shift Register Empty Flag
Automatically set by hardware if no further bits are available in RF Shift
Register. When RF Shift Register becomes empty, the state of the RF
Transmitter is determined by SFR RFENC.3 [TXDD].
0B Data transmission in progress
1B Data transmission complete
Reset: 1H
RFBF 0 r RF Encoder Buffer Full
Automatically set by hardware on write to SFR RFD and cleared when
data in SFR RFD is transferred to RF Shift Register.
0B Buffer empty, SFR RFD ready for new data
1B Buffer full, do not write to SFR RFD
Reset: 0H
7 077
wr
PADIS
62
-
UNUSED
11
r
RFSE
00
r
RFBF
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 74 Revision 1.1, 2012-04-03
3.11 LF Receiver
Figure 19 LF Receiver Block Diagram
The LF Receiver is used for wireless data transmission towards the SP37T and for waking up the device from
POWERDOWNstate.
It can generate a wakeup directly by the carrier detector if the carrier amplitude is above a predefined threshold,
or it can decode the received data and wake up the microcontroller only if a sync match pattern or
sync match pattern/wakeup pattern is detected in the data stream.
Data recovery using a synchronizer and a decoder is available for Manchester coded data. The synchronizer can
also handle Manchester code violations. Other coding scheme can be handled by the microcontroller at the chip
level, thus no limitations on data coding schemes apply.
An LF On/Off Timer is implemented to generate periodical On/Off switching (polling) of the LF Receiver in
POWER DOWN state to minimize the current consumption.
Low Noise
Amplifier
LF Receiver
Voltage Divider
Carrier Detector
Data
Slicer
LF RX Analog Front End AFE
Attenuator AGC
RSSI
Generator
Data
Filter
LF
xLF
LF-Antenna
LF RX On/Off Timer
RC LF Oscillator
LF RX Baseband Processor
LF Data Recovery
LF Carrier
Detector Filter
Bit Rate Generator
ENLFRX
LFBBM.1-0
ENOOTIM
LFONIND
Sync/Pattern Match
Wakeup
Carrier Detect
Wakeup
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 75 Revision 1.1, 2012-04-03
LF Receiver Control Register
LFRXC Offset Wakeup Value Reset Value
LF Receiver Control Register 98H0UUUUU00B00H
Field Bits Type Description
CDRECAL 7 wc Restart Carrier Detect Recalibration
Calibration is automatically performed each time the LFRx is powered on.
This bit forces manual Recalibration when set. This bit is automatically
cleared after Recalibration has started
0B Cleared automatically after Recalibration has started
1B Start Carrier Detect Recalibration
Reset: 0H
DISAGC 6 wr Disable Automatic Gain Control (AGC)
0B Enable
1B Disable
Reset: 0H
LFBBM 5:4 wr LF Baseband Processor Mode
It is recommended to first disable the LF Receiver (ENLFRX = 0) prior to
changing the LF Baseband Processor Mode.
00B Disabled, only Carrier Detect function remains
Note: Carrier Detector Filter may be enabled separately
01B Mode 1: LF baseband is enabled while LF Receiver is on
10B Mode 2: LF baseband is enabled only after carrier detection
11B Not used
Reset: 0H
ENOOTIM 3 wr Enable On/Off Timer
This bit controls the LF On/Off Timer. This bit has to be stable for at least
1 LP RC clock (2 kHz) period in order to take effect. When the LF On/Off
Timer is disabled the LF Receiver is controlled by ENLFRX. This bit is
automatically cleared if sync or pattern match wakeup occurs.
0B Disable On/Off Timer
1B Enable On/Off Timer
Reset: 0H
ENLFRX 2 wr Enable LF Receiver
This bit controls power to LF Receiver and has priority over ENOOTIM.
0B LF Receiver disabled
1B LF Receiver state is determined by On/Off Timer
Reset: 0H
7 077
wc
CDRECAL
66
wr
DISAGC
54
wr
LFBBM
33
wr
ENOOTIM
22
wr
ENLFRX
11
r
SYNCIND
00
r
LFONIND
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 76 Revision 1.1, 2012-04-03
SYNCIND 1 r Synchronization Indicator
This bit is set upon Sync Match and remains set as long as valid
Manchester data is detected. When invalid Manchester bit is detected
this bit is cleared and SFR bit LFRXS.DECERR is set.(e.g. Figure 29)
0B No Synchronization
1B Synchronization achieved
Reset: 0H
LFONIND 0 r LF ON/OFF Indicator
Indicates if the LF Analog Frontend is turned on or off. This bit may be
used to observe the LF On/Off Timer period and duty cycle.
0B LF Analog Frontend power is off
1B LF Analog Frontend power is on
Reset: 0H
Field Bits Type Description
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 77 Revision 1.1, 2012-04-03
3.12 LF Receiver Analog Front End
Figure 20 LF Receiver AFE Block Diagram
The LF Receiver Analog Frontend has two input pins LF and xLF. An antenna coil in parallel resonance to a
capacitor and resistor are externally connected to them in the application. The LF input pins are protected against
overvoltage with antiparallel ESD-Diodes. The “Differential Input Capacitance” on Page 155 needs to be
considered for the calculation of the parallel resonance frequency of the antenna.
A Voltage Divider with three divider factors is available to attenuate the LF input signal. The attenuation is
determined by the SFR bits LFRX0.1-0[SELIN1-0].
The LF input signal is amplified with a Low Noise Limiter Amplifier and the signal strength is indicated by the RSSI
Generator. The internal RSSI signal is used as input for the Carrier detector and the ASK demodulator.
The Carrier Detector has an adjustable threshold which is determined by SFR bits LFRX0.7-4[CDETT3-0]. An LF
input signal above the Carrier Detector threshold level may trigger a device wakeup from POWER DOWN state.
The Carrier Detector Raw (CDRAW) signal is used as input for the LF Baseband.
The ASK demodulator consists of a datafilter together with a data threshold generator and the dataslicer. The
demodulated output signal (LFRAW) is used as input for the LF Baseband.
To cover a high dynamic range of the LF input signal an input attenuator with an Automatic Gain Control (AGC) is
implemented. In the event that AGC is not desired, it can be disabled by setting SFR bit LFRXC.6[DISAGC].
HP-Filter
Protection
Diodes
Protection
Diodes
Input
Caps
Voltage
Divider
AGC (ATTN)
Antenna
damping
Low Noise
Amplifier
Data
Comp
AGC
Peak Det ect or
LFRXS.
LFRAW
LF
xLF
ATTN
TRH_ATTN
LF_DF
TRH_Data
CDETT
RSSI
ATTN Threshold
RSSI Generator
CDETT
DF[3]
ÆLFGAIN
Low Noise Limiter
Amplifier
RSSI Generator
Volt ag e D ivider
Carrier Detector
LF RX Analog FrontEnd (AFE)
LFRXS.
CDRAW
Threshold
Datafilter
Data Threshold
Generator
Carrier
Comp
DISAGC
CDETT.3-0
CDRECAL
DYNTR.1-0
ATR.1-0
SELIN.1-0
LFENFCTC
LFENCDCAL
AG CT C D . 1- 0
AG CT C A . 2- 0
ACT
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 78 Revision 1.1, 2012-04-03
LF Receiver Configuration Register 0
LFRX0 Offset Wakeup Value Reset Value
LF Receiver Configuration Register 0 B7HUUH38H
Field Bits Type Description
CDETT 7:4 wr Carrier Detector Threshold Level
0000B: Lowest threshold
...
1111B: Highest threshold
Reset: 3H
ATR 3:2 wr AGC Threshold
These bits must be set to 11B.
Reset: 2H
SELIN 1:0 wr LF-Receiver Input Select
00B Antenna voltage divider factor 1
01B Antenna voltage divider factor 6,8
10B Antenna voltage divider factor 22
11B Do not use
Reset: 0H
7 074
wr
CDETT
32
wr
ATR
10
wr
SELIN
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 79 Revision 1.1, 2012-04-03
3.13 LF Attenuator (AGC)
An input attenuator is provided to limit strong signals and interferers across the differential input. An automatic gain
control block (fast attack, slow decay) is implemented to cover a high dynamic range of the LF input signal. The
AGC threshold is determined by the SFR bits LFRX0.3-2[ATR1-0] and the carrier detector settings in
SFR bits LFRX0.7-4[CDETT3-0]. The attenuator attack time is controlled via the SFR bits LFRX2.2-0[AGCTCA2-
0]. The decay slew rate can be adjusted by SFR bits LFRX1.7-6[AGCTCD1-0]. Please refer to the register
description for the proper setting of the AGC SFR bits.
Figure 21 AGC Timing diagram
LF Receiver Configuration Register 1
LFRX1 Offset Wakeup Value Reset Value
LF Receiver Configuration Register 1 B6HUUH00H
Field Bits Type Description
AGCTCD 7:6 wr AGC Decay Time Constant
Recommended setting 00B
Reset: 0H
ACT 5:4 wr Autocalibration Time
Recommended setting for LF Telegram detection 10B
Recommended setting for carrier detection 01B
Reset: 0H
Res 3:0 Reserved
These bits must be set to 0000B.
Reset: 0H
Incoming
LF Signal
AGC Attenuation
(LF Input C onductance )
Initial AGC Attack Final AGC Decay
AGC is m aintained while signal is present or
briefl y OOK m odulated
7 076
wr
AGCTCD
54
wr
ACT
30
Res
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 80 Revision 1.1, 2012-04-03
LF Receiver Configuration Register 2
LFRX2 Offset Wakeup Value Reset Value
LF Receiver Configuration Register 2 AFHUUH77H
Field Bits Type Description
Res 7:3 Reserved
These bits must be set to 01110B.
Reset: 0EH
AGCTCA 2:0 wr AGC Attack Time Constant Selection
Recommended setting 111B
Reset: 7H
7 073
Res
20
wr
AGCTCA
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 81 Revision 1.1, 2012-04-03
3.14 LF Carrier Detector
A level detection circuit is implemented to determine if the carrier amplitude is above a predetermined level. An LF
input signal above the Carrier Detector threshold level may cause a device wakeup from POWER DOWN state.
Three different Carrier Detector thresholds can be chosen by the application. In order to achieve LF sensitivity as
specified in Table 40 “LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz” on
Page 157 an appropriate Voltage Divider setting (SFR bits LFRX0.1-0[SELIN1-0]) is used in conjunction with the
adjustable threshold level (SFR bits LFRX0.7-4[CDETT3-0]). During the testing and calibration process at the
factory, individually calibrated CDETT values are programmed into each device. The CDETT calibration
information for each device may vary, and so the application software must retrieve the calibrated CDETT values
from the appropriate Flash address and apply it in conjunction with the predefined SELIN setting. The complete
proper setting for SFR LFRX0 (CDETT[7:4], ATR[3:2], SELIN[1:0]) for the according Carrier Detector Threshold
Level must be read by the application from the following Flash addresses and be written into SFR LFRX0 :
• Carrier Detector Threshold 1: Flash address 5810H
• Carrier Detector Threshold 2: Flash address 580FH
• Carrier Detector Threshold 3: Flash address 580EH
Carrier Detector Filtering
To prevent the device from undesired carrier detect wakeups, an LF Carrier Detector Filter is implemented.
SFR LFCDFLT is used to determine the Filtering Time. The LF Carrier Detector Filter is enabled/disabled
according to LFCDFLT.CDFT[6-0]. The following figure shows the behavior of the LF Carrier Detector Filter.
Figure 22 LF Receiver Carrier Detector Filtering
Three different Carrier Detector Filter settings are predefined for the application. In order to achieve LF filter times
as specified in Table 40 “LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz” on
Page 157 an appropriate Filter Time setting (SFR LFCDFLT.CDFT[6-0]) needs to be applied. During the testing
and calibration process at the factory, individually calibrated CDFT values are programmed into each device. The
CDFT calibration information for each device may vary, and so the application software must retrieve the
calibrated CDFT values from the appropriate Flash address. The proper settings for SFR LFCDFLT are indicated
in following list:
• Carrier Detector Filter Time 1: [CDFT.6-0]: Flash address 580DH
• Carrier Detector Filter Time 2: [CDFT.6-0]: Flash address 580CH
• Carrier Detector Filter Time 3: [CDFT.6-0]: Flash address 580BH
Figure 23 summarizes the LF Carrier Detector response versus input signal duration and amplitude.
Incoming
LF Signal
Recovered
Carrier
POWERDOWN RUN
Operating
State
FTFTFT FT FT
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 82 Revision 1.1, 2012-04-03
Figure 23 LF Carrier Detector Response
Automatic Carrier Detector Threshold Calibration
To achieve high sensitive thresholds the Carrier Detector has to be calibrated. This auto-calibration is enabled by
setting SFR bit LFCDM0.3[LFENCDCAL] and is executed everytime the LF Receiver is turned on (either manually
by SFR bit LFRXC.2[ENLFRX] or automatically by the LF On/Off Timer). An auto-calibration sequence can be
manually initiated by setting SFR bit LFRXC.7[CDRECAL]. The auto-calibration duration is determined by
SFR bits LFRX1.5-4[ATC1-0] and specified in Table 40 “LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V,
fLF = 120 kHz...130 kHz” on Page 157. For the proper setting of the auto-calibration please refer to the register
description.
If set, SFR Bit LFCDM0.2[LFENFCTC] “freezes” the threshold level after the calibration is finished.
If this bit is not set, the threshold will follow the mean value of the input signal, resulting in a threshold signal that
is dependent on the LF signal strength.
Note: If SFR Bit LFCDM0[LFENFCTC] is set, a periodic recalibration is required especially at higher temperatures
since the “frozen” threshold level might drift after the Carrier Detector Freeze Hold Time (TCDCFH). The
recalibration is achieved automatically by the next Off/On transition of the LF On/Off Timer or by turning off
and on the LF Receiver manually by SFR Bit LFRXC.2[ENLFRX]. The Carrier Detector Freeze Hold Time is
specified in Table 40 “LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz” on
Page 157.
The following figure shows the timing behavior of the calibration.
Detection Possible
No Detection
LF Signal
Amplitude
LF Signal
Duration
S
max
S
det
S
nodet
t
CDnodet
t
CDdet
t
CDCFH
Always
Detection
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 83 Revision 1.1, 2012-04-03
Figure 24 Carrier Detector Threshold Calibration Timing
Incoming
LF Signal
LF RX OFF LF RX ON
LF Receiver
Operating State
Recovered Carrier
LFRXS.CDRAW
Carrier Detector
Autocalibration
t
calibr ation
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 84 Revision 1.1, 2012-04-03
LF Carrier Detect Filtering
LFCDFLT Offset Wakeup Value Reset Value
LF Carrier Detect Filtering B2HUUH00H
Field Bits Type Description
CDFM 7 wr Carrier Detector Filtering Mode
For typical applications it is recommended to set this bit to 0B.
0B Filter enabled
1B Filter enabled until Carrier detected
Reset: 0H
CDFT 6:0 wr Carrier Detector Filtering Time
01H-7FH Enables and adjusts filtering time in steps of 1 LF RC Oscillator
period (typ. 11.1 us).
00H Disables filtering.
Reset: 00H
7 077
wr
CDFM
6 0
wr
CDFT
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 85 Revision 1.1, 2012-04-03
LF Carrier Detector Mode Register 0
LFCDM0 Offset Wakeup Value Reset Value
LF Carrier Detector Mode Register 0 B5HUUUUUUU0B00H
Field Bits Type Description
Res 7:6 Reserved
These bits must be set to 00B.
Reset: 0H
DYNTR 5:4 wr Carrier Detector Dynamic Threshold
Recommended setting 01B
Reset: 0H
LFENCDCAL 3 wr Enable LF Carrier Detect Calibration
0B Disable Calibration
1B Calibration occurs each LF Rx power up
Reset: 0H
LFENFCTC 2 wr Enable LF Calibration Freeze
0B Disable Calibration Freeze
1B Hold Calibration threshold
Reset: 0H
Res 1 Reserved
This bit must be set to 0B.
Reset: 0H
UNUSED 0 - UNUSED
Reset: 0H
7 076
Res
54
wr
DYNTR
33
wr
LFENCDC
AL
22
wr
LFENFCT
C
11
Res
00
-
UNUSED
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 86 Revision 1.1, 2012-04-03
3.15 LF Receiver On/Off Timer
An On/Off Timer is implemented to reduce the LF Receiver current consumption in POWER DOWN state. It can
be enabled by SFR bit LFRXC.3[ENOOTIM]. The LF Analog Frontend will be periodically turned On and Off
corresponding to the timer settings. The current state of the LF Receiver (On or Off) can be evaluated using
SFR bit LFRXC.0[LFONIND].The LF Receiver On/Off Timer incorporates a precounter (SFR LFOOTP) as
timebase and a postcounter for independently setting the On time and the Off time (SFR LFOOT).
LF Receiver On/Off Timer Calibration
The calibration process is done automatically by a ROM Library function (see [1]) which calibrates the timebase
to 50ms.
If any other (uncalibrated) timebase is needed SFR LFOOTP can be configured manually according the following
equation:
(10)
The On time and the Off time can be configured individually using SFR LFOOT. They can be calculated using the
two following two equations:
(11)
(12)
(13)
[] []
Hzf
LFOOTP
stimebase
ilatorkHzRCLPOsc2
1
+
=
[]
()()()
[
]
(
)
()
[]
HzfLFOOTP
LFOOTPLFOOTPIntegerONTIM
sontime
ilatorkHzRCLP Osc2
1
114/1
⋅+
+
⋅
+
⋅
+
=
[]
()()()
[
]
[
]
()
1
14/1
+
⋅
+
⋅
+
=LFOOTP
stimebaseLFOOTPIntegerONTIM
sontime
[]
()()
[]
()
[]
41
411
2
⋅⋅+=
⋅
+
⋅
+
=stimebaseOFFTIM
Hzf
LFOOTPOFFTIM
sofftime
ilatork HzRCLPOsc
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 87 Revision 1.1, 2012-04-03
LF On/Off Timer Configuration Register
LF OnOff Timer Precounter
LFOOT Offset Wakeup Value Reset Value
LF On/Off Timer Configuration Register C6HUUH00H
Field Bits Type Description
OFFTIM 7:4 wr LF Polling OFF-Time
If time base is set to 50 ms (default after calibration) in SFR LFOOTP :
0000B: 200 ms
...
1111B: 3.2 s
Reset: 0H
ONTIM 3:0 wr LF Polling ON-Time
If time base is set to 50 ms (default after calibration) in SFR LFOOTP :
0000B: 12.5 ms
...
1111B: 200 ms
Reset: 0H
LFOOTP Offset Wakeup Value Reset Value
LF OnOff Timer Precounter C5HUUH64H
Field Bits Type Description
LFOOTP 7:0 wr LF ON/OFF Timer Precounter
Establishes timebase for the LF-ON/OFF-Timer.
00H: 1 RC-LP-Oscillator (2 kHz) periods
01H: 2 RC-LP-Oscillator (2 kHz) periods
...
FFH: 256 RC-LP-Oscillator (2 kHz) periods
Reset: 64H
7 074
wr
OFFTIM
30
wr
ONTIM
7 07 0
wr
LFOOTP
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 88 Revision 1.1, 2012-04-03
3.16 LF Receiver Baseband
The LF Receiver Baseband circuitry allows reception of ASK modulated LF Telegrams. As in the case of the
LF Carrier Detector, the LF Receiver Baseband may be enabled and disabled manually via
SFR LFRXC.2[ENLFRX] or automatically by the LF Receiver On/Off Timer. The LF Receiver Baseband may be
operated in one of two modes: Mode 1, in which the baseband is fully operational whenever the LF receiver is
enabled; and Mode 2, in which the baseband is only operational after the LF Carrier Detector has detected an
incoming signal. LF Baseband Mode selection is accomplished by SFR bits LFRXC5:4[LFBBM]. The specified
telegram sensitivity is only accomplished in Mode 1 and with the proper SFR register settings(see Table 68 “LF
Receiver Special Function Register Settings for Telegram Mode” on Page 156)
Figure 25 LF Receiver Baseband
WUF.LFPM0
WUF.LFPM1
WUF.LFSY
WUF.LFCD
Manchester Decoder
LF Data Recovery
LF Carrier Detector Filter
Chip Buffer
LF RX Baseband Processor
LFRXS.LFDOV
LFPCFG.SYNM
LFRXS.DECERR
LFRXS.LFBP
LFRXS.LFDATA
LFRXS.LFOV
LFRXD
LFDIV
LFPCFG.PSL
LFPCFG.PSEL
Bitrate Generator
1 Bit Serial Data Buffer
LFRXS.CDRAW
LFRXS.LFRAW
Sync Matching
LFP0L/LFP0H
LFP1L/LFP1H
LF Pattern matching 0
LF Pattern matching 1
Wakeup Pattern Detector
8 Bit Data Buffer
LFRXS.SYNCIND
RC LF Oscillator
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 89 Revision 1.1, 2012-04-03
LF Telegram Format
The LF Receiver Baseband requires that an LF Telegram contain at least two elements: a Preamble sequence
and a Synchronization Pattern. The LF Telegram may also contain a user defined "wakeup ID" field which may
be either 8-bits or 16-bits in length. The LF Receiver baseband supports matching against two different wakeup
ID patterns, allowing separate "broadcast address" and "unique address" ID patterns to be implemented, for
example. Finally, an LF Telegram will typically contain at least one data bit, so the reception of data as individual
bits or groups of 8-bit bytes is supported. The CPU must handle the unloading of buffered data bits or bytes to
prevent data overflow. The LF Receiver Baseband is configured for a specific LF Telegram format via the
SFR LFPCFG. Figure 26 illustrates typical LF Telegram formats and the relationship of the telegram elements.
Figure 26 LF Receiver Baseband Configurations
An LF Telegram must begin with a Preamble sequence, which serves to stabilize the LF Data Threshold within the
LF Analog Front End. The Preamble typically consists of several Manchester symbols, all of equal value (i.e. all
'0' or all '1' bits). A Preamble may consist of mixed value bits, but in this case the duration of the Preamble must
be longer than that required for equal value bits. There is no maximum duration for the Preamble. The "raw data"
output of the LF Data Comparator may be observed via the SFR bit LFRXS.5[LFRAW].
A Synchronization ("Sync") pattern must follow the Preamble. The Sync pattern is 9.5 bits (18 chips) in duration,
and includes non-Manchester symbols so that it is not possible to accidentally encounter the Sync pattern in any
other portion of a properly formatted LF Telegram. The Sync Matching circuit within the LF Receiver Baseband is
responsible for monitoring the raw data output of the LF Data Comparator and determining when a Sync pattern
has been received. Detection of the Sync pattern (a "Sync match") will cause the SFR bit LFRXS.1[SYNCIND] to
be set, and may be used as a CPU wakeup event. Figure 27 provides more detail relating to the Preamble
sequence and Sync pattern.
Sync pattern (18chips) Wakeup Pattern (8-16Bits) Data #1 Data #n
Sync pattern (18chips) Data #1 Data #n
0
1
SYNM
Pr eamble
Pr eamble
Decoded by the synchronizer Decoded by the Manchester DecoderRun in for adjusting the data slicer threshold
Legend:
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 90 Revision 1.1, 2012-04-03
Figure 27 LF Telegram Format
The LF Telegram data payload must follow the synchronization pattern, and may be of any arbitrary length.
Figure 28 illustrates the relationship between modulated Manchester symbols and decoded data bits. In the case
that the LF Receiver Baseband is configured to detect a Wakeup ID pattern, the first 8 or 16 bits (depending on
length of the wakeup ID) will be considered as ID bits rather than as data bits. Detection of a Wakeup ID pattern
(a "Pattern Match") may be used as a CPU wakeup event. Decoding and buffering of incoming LF Telegram bits
will continue until the Manchester Decoder within the baseband encounters a decoding error (code violation) or
until the LF Receiver Baseband is disabled. A decoding error will cause the SFR bit LFRXS.6[DECERR] to be set
and SFR bit LFRXC.1[SYNCIND] to be cleared.
Figure 28 LF Decoder
t
preamble
t
bit
1.5·t
bit
3·t
bit
t
bit
t
bit
2·t
bit
t
bit
2·t
bit
t
bit
0.5·t
bit
9 t
bit
PREAMBLE SYNC WAKEUP ID DATA
1
DATA
n-1
DATA
n
1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 1 1 0 0 0 1 0 1 1 0 0 1 1 0 0 1 0
LF Signal
Manchester
Deccoded
Data
01
Tbit
Manchester
Enccoded
Data
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 91 Revision 1.1, 2012-04-03
LF Telegram Mode Settling Time
LF Telegram reception using the LF Receiver Baseband requires some "startup time" to elapse after it is enabled.
When the LF Receiver is brought from any other mode (typically "off") into Baseband Mode 1, there is a settling
time that must be allowed to elapse before any LF telegram reception may begin.
The sequence of events that take place when Baseband Mode 1 is enabled is shown in Figure 29. When the LF
Receiver is brought from any other mode into Baseband Mode 2, the LF Carrier Detector auto-calibration time
must be allowed to elapse before any LF telegram reception may begin (in Mode 2 the auto-calibration and
telegram mode settling times are coincident. The auto-calibration time is always greater than telegram mode
settling time, so only the former needs to be considered for timing purposes). The startup sequence for LF
Baseband Mode 2 is similar to that for LF Carrier Detection as shown in Figure 24. When the LF Receiver
Baseband is used in conjunction with the LF Receiver On/Off Timer, the result is a self-polling LF data interface.
The appropriate startup time requirement (“Settling time” on Page 156 for Mode 1, “Auto-Calibration time” on
Page 157 for Mode 2) must be considered and enabled via the SFR bits LFRX1.5:4[ACT]. Furthermore, the
startup time must also be included within the LF "On time" duration when configuring the LF Receiver On/Off
Timer.
Figure 29 LF Receiver Baseband Telegram Timing
Incoming
LF Signal
OFF LF RX ON
LF Receiver
Operating State
Recovered Data
LFR XS .LFRAW
Receiver Settling
t
settling
Data Slicer
stabilization
t
preamble
Sync Indicator
LFRXC.SYNCIND
Decode Error
LFRXS.DECERR
Preamble Sync Wakeup ID Data
Cleared w hen
LFRXS is read
Set when SYNC
is decoded
Cleared upon
manchester error
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 92 Revision 1.1, 2012-04-03
LF Bitrate Generator Calibration
A ROM Library function which automatically configures the bitrate clock divider SFR LFDIV is available. It
automatically compensates drift and offset of the RC LF Oscillator.
The ROM Library function compares the current RC LF Oscillator frequency towards the highly accurate crystal
oscillator frequency and configures the SFR LFDIV according to frequency of the RC LF Oscillator.
Attention: It is mandatory to call ROM Library function “LF_BaudrateCalibration” at least once before the
LF Receiver is used. It is recommended to store the SFR LFDIV value into the FLASH and
reprogram SFR LFDIV with such a value anytime the LF Receiver is operated.
The bitrate tolerance is specified in Table 38 “LF Receiver Telegram, Vbat = 2.1 V...3.6 V, fLF =
120 kHz...130 kHz” on Page 156; it can only be achieved with the usage of this ROM Library function and under
the specified conditions.
If this calibration is performed regularly by the application, the bitrate tolerance for the transmitted data can be
increased compared to this specified value. For details on the ROM Library function see [1].
LF Bitrate Divider Factor
LFDIV Offset Wakeup Value Reset Value
LF Bitrate Divider Factor B4H00UUUUUUB17H
Field Bits Type Description
UNUSED 7:6 - UNUSED
Reset: 0H
LFDIV 5:0 wr LF Bitrate Divider
LF Bitrate generator division factor. The reset value corresponds to an LF
baudrate of 3.9 kbit/s
Reset: 17H
7 076
-
UNUSED
50
wr
LFDIV
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 93 Revision 1.1, 2012-04-03
3.17 Wakeup Pattern Detector
Two independent wakeup patterns - each with a length of 8 or 16 bits (SFR bit LFPCFG.1[PSL]) are available
(SFR LFP1L/H and SFR LFP0L/H).
SFR bit LFPCFG.0[PSEL] determines on which pattern (pattern 0 only, or either pattern 0 or pattern 1) a wakeup
can occur.
Note: The Wakeup must be enabled in addition in the SFR WUM (see Table “Wakeup Mask Register” on
Page 49) to globally enable the wakeup on LF Patterns.
LF Pattern Detection Configuration Register
LFPCFG Offset Wakeup Value Reset Value
LF Pattern Detection Configuration Register C7H00UU00UUB00H
Field Bits Type Description
UNUSED 7:6 - UNUSED
Reset: 0H
Res 5 Reserved
This bit must be set to 0B.
Reset: 0H
SYNM 4 wr LF Synchronizer Mode
0B Sync and Pattern match
1B Sync match only
Reset: 0H
UNUSED 3:2 - UNUSED
Reset: 0H
PSL 1 wr Pattern Sequence Length
0B 8 bit sequence
1B 16 bit sequence
Reset: 0H
PSEL 0 wr Pattern Select
Selects which LF Wakeup Pattern (P0 or P0 and P1) can cause an LF
Pattern Match Wakeup.
0B LFP0 Pattern Detection Enable
1B LFP0 and LFP1 Pattern Detection Enable
Reset: 0H
7 076
-
UNUSED
55
Res
44
wr
SYNM
32
-
UNUSED
11
wr
PSL
00
wr
PSEL
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 94 Revision 1.1, 2012-04-03
LF Pattern 0 Detector Sequence Data MSB
LF Pattern 0 Detector Sequence Data LSB
LFP0H Offset Wakeup Value Reset Value
LF Pattern 0 Detector Sequence Data MSB CDHUUHFFH
Field Bits Type Description
LFCODEP0 7:0 wr LF Pattern 0 Sequence Data MSB
High Byte of 16 bit pattern, ignored in case of 8 bit pattern.
Reset: FFH
LFP0L Offset Wakeup Value Reset Value
LF Pattern 0 Detector Sequence Data LSB CCHUUHFFH
Field Bits Type Description
LFCODEP0 7:0 wr LF Pattern 0 Sequence Data LSB
Low Byte of 16 bit pattern, or 8 bit pattern.
Reset: FFH
7 07 0
wr
LFCODEP0
7 07 0
wr
LFCODEP0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 95 Revision 1.1, 2012-04-03
LF Pattern 1 Detector Sequence Data MSB
Note: LFP1H and LFP1L may be used as two additional GPR registers (value maintained during powerdown, but
not in event of RESET) if only wakeup on Pattern Match 0 is required.
LF Pattern 1 Detector Sequence Data LSB
LFP1H Offset Wakeup Value Reset Value
LF Pattern 1 Detector Sequence Data MSB CFHUUHFFH
Field Bits Type Description
LFCODEP1 7:0 wr LF Pattern 1 Sequence Data MSB
High Byte of 16 bit pattern, ignored in case of 8 bit pattern.
Reset: FFH
LFP1L Offset Wakeup Value Reset Value
LF Pattern 1 Detector Sequence Data LSB CEHUUHFFH
Field Bits Type Description
LFCODEP1 7:0 wr LF Pattern 1 Sequence Data LSB
Low Byte of 16 bit pattern, or 8 bit pattern.
Reset: FFH
7 07 0
wr
LFCODEP1
7 07 0
wr
LFCODEP1
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 96 Revision 1.1, 2012-04-03
3.18 LF Receiver Data Interface
LF Receiver Data Interface
The received data can be read by the microcontroller using the following different interfaces:
• 8 bit databyte (synchronized, Manchester decoded)
• Serial bitstream data (synchronized, Manchester decoded)
• RAW data (synchronized, chip level)
• RAW Carrier Detect (un-synchronized)
8 Bit databyte
Synchronized and decoded databytes are received using SFR LFRXD.
Decoded bits are shifted into an 8 bit receive buffer, until a byte boundary is reached. The received byte is then
shifted into the SFR LFRXD, and a flag SFR bit LFRXS.3[LFDP] is set, while the following byte is shifted into the
receive buffer. If the SFR LFRXD is not read before the following byte is received, it will be overwritten, and an
overflow flag SFR bit LFRXS.4[LFDOV] is set.
Serial bitstream data
Synchronized and decoded serial data can be received by using SFR bit LFRXS.0[LFDATA].
A flag SFR bit LFRXS.1[LFBP] is set if data is pending, while the following bit is buffered. If the
SFR bit LFRXS.0[LFDATA] is not read before the following bit is received, it will be overwritten, and an overflow
flag SFR bit LFRXS.2 [LFOV] is set.
RAW data
Synchronized and undecoded serial data can be read by the microcontroller using SFR bit LFRXS.5[LFRAW].
This can be used to handle any other coding scheme than Manchester. This bit is the RAW output after the
synchronizer, thus the decoding (including identifying the beginning/end of a bit period) has to be done by the
application software.
RAW Carrier Detect
Un-synchronized and undecoded serial data can be read by the microcontroller using SFR bit LFRXS.7 [CDRAW].
This indicates if a Carrier Signal is currently present (SFR bit LFRXS.7[CDRAW]==1) or not
(SFR bit LFRXS.7[CDRAW]==0). The application software can perform the LF baseband processing; in order to
implement non-standard LF information encoding schemes, for example.
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 97 Revision 1.1, 2012-04-03
LF Receiver Data Register
LFRXD Offset Wakeup Value Reset Value
LF Receiver Data Register A5HUUH00H
Field Bits Type Description
LFRXD 7:0 r LF Receiver Data
Reset: 00H
7 07 0
r
LFRXD
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 98 Revision 1.1, 2012-04-03
LF Receiver Status Register
LFRXS Offset Wakeup Value Reset Value
LF Receiver Status Register A4HXUXUUUUUBX0X00000B
Field Bits Type Description
CDRAW 7 r Carrier Detector Raw Data
Instantaneous value of comparison of LF Carrier versus the LF Carrier
Detect Threshold.
Reset: XB
DECERR 6 rc Manchester Decode Error
0B No error detected
1B Error detected
Reset: 0H
LFRAW 5 r LF Receiver Raw Data
Instantaneous output of the LF Data slicer.
Reset: XB
LFDOV 4 rc LF Data Byte Overwritten
This bit will be set if a new LF data byte is received prior to the previous
byte being read from SFR LFRXD.
Reset: 0H
LFDP 3 r LF Data Byte Pending
This bit will be set if a new LF data byte is available in SFR LFRXD.
It will be cleared when the LFRXD register is read.
Reset: 0H
LFOV 2 rc LF Serial Decoded Data Overwritten
This bit will be set if a new LF data bit is received prior to the previous bit
being read from LFDATA.
Reset: 0H
LFBP 1 rc LF Serial Decoded Data Pending
This bit will be set if a new LF data bit is available in LFDATA.
Reset: 0H
LFDATA 0 r LF Serial Decoded Data
0B Manchester 0 decoded
1B Manchester 1 decoded
Reset: 0H
7 077
r
CDRAW
66
rc
DECERR
55
r
LFRAW
44
rc
LFDOV
33
r
LFDP
22
rc
LFOV
11
rc
LFBP
00
r
LFDATA
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 99 Revision 1.1, 2012-04-03
3.19 16 Bit CRC (Cyclic Redundancy Check) Generator/Checker
Figure 30 CRC (Cyclic Redundancy Check) Generator/Checker
CRC is a powerful method to detect errors in data packets that have been transmitted over a distorted connection.
The CRC Generator/Checker divides each byte of a data packet by a polynomial, leaving the remainder which
represents the checksum. The CRC-Generator/Checker is using the 16 Bit CCITT polynomial x16+x12+x5+1. The
16 bit start value is determined by the initial contents of SFR CRC0 and SFR CRC1.
CRC Generation and Checking
Figure 31 shows the basic usage of the CRC16.
Figure 31 Example for CRC16 usage
CRC Shiftregister/Logic
CRCC.CRCSS
CRCD
CRC1 (High Byte )
CRC0 (Low Byte )
CRCC.CRCValid
CRCC.CRCSD
Polynom ial = x
16
+x
12
+x
5
+1
0xAB 0x02 0x04 0xCC 0x00
0xB5 0x06
0xFF 0xFF
0xAB 0x02 0x04 0xCC 0x00
0x00 0x00
0xFF 0xFF
0xB5 0x06
Preload value
CRC1 CRC0
Example data
Resulting CRC16
CRC1 CRC0
Preload value
Example data incl.
Checksum
Resulting CRC16
CRC1 CRC0
CRC1 CRC0
CRC Generation (Transmitter side )
CRC Checking (Receiver side)
Append checksum to
transmitted data
0xB5 0x06
(CRCC.CRCValid = 1)
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 100 Revision 1.1, 2012-04-03
Byte aligned CRC Generation
CRC generation is done by executing the following steps:
• The CRC shift register has to be initialized by writing FFH (or if desired another start value) to both SFR CRC0
and SFR CRC1.
• The databytes which are to be used for the CRC Generation have to be shifted one after the other into the
SFR CRCD.The process of CRC Generation is automatically invoked when data bytes are written to the
SFR CRCD.
Note: Processing the data in SFR CRCD takes 3 instruction cycles, therefore the application has to assure that
there are no consecutive write instructions without one extra instruction cycle between.
• The resulting checksum is available in the CRC Result Register SFR CRC0 and SFR CRC1 after the last data
byte has been processed.
Byte aligned CRC Checking
CRC checking is done by executing the following steps:
• The CRC shift register has to be initialized by writing FFH (or if desired another start value) to both SFR CRC0
and SFR CRC1.
• The databytes which should be checked have to be shifted one after the other into the SFR CRCD. It is
important that the order (MSB-LSB) is the same as it was during the CRC Generation. In addition to the data
the CRC16 has to be shifted into SFR CRCD as well (first the high byte then the low byte - see also Figure 31).
The process of CRC Checking is automatically invoked when data bytes are written to the SFR CRCD.
Note: Processing the data in SFR CRCD takes 3 instruction cycles, therefore the application has to assure that
there are no consecutive write instructions without one extra instruction cycle between.
Note: One instruction cycle corresponds to 6 system clock cycles.
• After the last byte is processed the SFR bit CRCC.1[CRCValid] indicates the correctness of the CRC
calculation after the last data byte has been processed and both - SFR CRC0 and SFR CRC1 are 0.
Serial bitstream CRC Generation/Checking
The CRC Generator/Checker features a serial mechanism to perform CRC generation and checking of non byte-
aligned data streams. In this case SFR bit CRCC.5[CRCSS] and SFR bit CRCC.6[CRCSD] are used instead of
SFR CRCD.
The data stream is written bit by bit into SFR bit CRCC.6[CRCSD]. Each bit is processed by setting the flag
SFR bit CRCC.5[CRCSS].
The following figure shows an example for the usage of SFR bit CRCC.5[CRCSS] and SFR bit CRCC.6[CRCSD].
Note: No time limitations apply when using serial data, so the software can shift and strobe without any wait states
between processing consecutive bits.
Figure 32 Example for serial CRC generation/checking
CRCC.CRCSD
Data to be encoded
0 1 1 0 0 0 1 0 1 1 1 0 0
CRCC.CRCSS
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 101 Revision 1.1, 2012-04-03
Note: The serial and byte-aligned generation/checking mechanism is interchangeable within the same
generation/checking process.
Example: If a data packet consists of 18 bits, 16 bits can be processed byte-aligned via SFR CRCD and the
two remaining bits can be processed bit-aligned by using SFR bit CRCC.5[CRCSS] and
SFR bit CRCC.6[CRCSD].
CRC Control Register
CRCC Offset Wakeup Value Reset Value
CRC Control Register A9H02H02H
Field Bits Type Description
UNUSED 7 - UNUSED
Reset: 0H
CRCSD 6 wr CRC Serial Data
Reset: 0H
CRCSS 5 w CRC Serial Data Strobe
By setting this bit the data bit from CRCSD is strobed into CRC
generator/checker
Reset: 0H
UNUSED 4:2 - UNUSED
Reset: 0H
CRCVALID 1 r CRC Valid
This bit is set automatically when all CRC result bits are zero.
0B CRC check failed
1B CRC check successful
Reset: 1H
UNUSED 0 - UNUSED
Reset: 0H
7 077
-
UNUSED
66
wr
CRCSD
55
w
CRCSS
42
-
UNUSED
11
r
CRCVALI
D
00
-
UNUSED
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 102 Revision 1.1, 2012-04-03
CRC Data Register
CRC Shift Register 1 (high byte)
CRCD Offset Wakeup Value Reset Value
CRC Data Register AAH00H00H
Field Bits Type Description
CRCD 7:0 w CRC Data Register
Reset: 00H
CRC1 Offset Wakeup Value Reset Value
CRC Preload/Result Register 1 (high byte) ADH00H00H
Field Bits Type Description
CRC1 7:0 wr CRC Preload/Result Register 1 (high byte)
Reset: 00H
7 07 0
w
CRCD
7 07 0
wr
CRC1
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 103 Revision 1.1, 2012-04-03
CRC Shift Register 0 (low byte)
CRC0 Offset Wakeup Value Reset Value
CRC Preload/Result Register 0 (low byte) ACH00H00H
Field Bits Type Description
CRC0 7:0 wr CRC Preload/Result Register 0 (low byte)
Reset: 00H
7 07 0
wr
CRC0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 104 Revision 1.1, 2012-04-03
3.20 Pseudo Random Number Generator
The SP37T offers a Pseudo Random Number Generator. It consists of a Maximum Length Linear Feedback Shift
Register (MLFSR) as built in hardware unit which creates a new pseudo random number everytime
SFR bit CFG1.5[RNGEn] is set.
Figure 33 Shift Register Implementation
A user-defined start value (except 00H) can be written to SFR RNGD. The default value is 55H.
The generation of a new random number is initiated by setting SFR bit CFG1.5[RNGEn]. The random number
generation requires one systemclock cycle, thus the application can read the generated number in the next
instruction without any extra wait states.
Random Number Generator Data Register
RNGD Offset Wakeup Value Reset Value
Random Number Generator Data Register ABHUUH55H
Field Bits Type Description
RNGD 7:0 wr Random Number Generator Data Register
Reset: 55H
XOR
Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0
SFR RNGD
XORXOR
7 07 0
wr
RNGD
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 105 Revision 1.1, 2012-04-03
3.21 Timer Unit
The SP37T comprises two independent 16 bit timers which operate as down counters. Different timer modes are
available for extended functionality.
Basic Timer Configuration
Timer 0 and Timer 1 comprise two fully programmable 16-bit timers, which can be used for time measurements
as well as generating time delays. The clock source is selectable in order to enlarge the timer runtime.SFR TMOD
is used to select the clock source and the desired timer mode.
Setting the SFR bit TCON.0[T0Run] (respectively SFR bit TCON.4[T1Run]) starts Timer 0 (resp. Timer 1). The
Timer counts down from the start values SFR TH/L0 (resp. SFR TH/L1) using the selected counter clock (see
SFR TMOD) until the timer is elapsed. SFR bit TCON.1[T0Full] (resp. SFR bit TCON.5[T1Full]) is set.
Note: The timer full flag is set when the timer would underflow from 0000H ==> FFFFH. To count e.g. 10 events
with timer 0 SFR TL0 has to be configured to 9H instead of 0AH.
After a timer is elapsed there are two possibilities that can occur (dependant on the selected timer mode):
•Reload: If the selected timer mode uses timer reload, the timer is automatically reloaded and restarted.
•Stop: If the selected timer mode doesn’t use timer reload, the timer is stopped and SFR bit TCON.0[T0Run]
(resp. SFR bit TCON.4[T1Run]) is cleared.
Timer Modes
Timer mode 0
Comprises:
• 16 bit timer with reload
The timer unit is configured as one 16 bit reloadable timer.
SFR TL0 and SFR TH0 hold the start value.
When SFR bit TCON.0[T0Run] is set, the timer starts counting down.
SFR bit TCON.1[T0Full] is set when the timer is elapsed.
The timer value is reloaded from SFR TL1 and SFR TH1 and the timer is restarted automatically.
SFR bit TCON.1[T0Full] has to be cleared by the application software. It is not cleared automatically on a read-
access.
Figure 34 Timer Mode 0
Note: In this mode both SFR bit TCON.4[T1Run] and SFR bit TCON.5[T1Full] are not used.
T0Run
T1Run
Timer 0
Timer 0 Reload
TL0
T0Full
T1Full
Reload
TH0
TL1 TH1
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 106 Revision 1.1, 2012-04-03
Timer Mode 1
Comprises:
• 16 bit timer without reload
• 8 bit timer with reload and bitrate strobe signal for RF Transmitter
Timer 0 operates as a 16 bit timer with the start value in SFR TL0 and SFR TH0, timer run bit
SFR bit TCON.0[T0Run] and timer elapsed indicator SFR bit TCON.1[T0Full].
If the timer is elapsed, it is stopped, SFR bit TCON.1[T0Full] is set and the timer run bit SFR bit TCON.0[T0Run]
is cleared.
Timer 1 sets up a reloadable 8 bit timer holding the startup value in SFR TL1, timer reload value in SFR TH1, timer
run bit in SFR bit TCON.4[T1Run] and timer elapsed indicator in SFR bit TCON.5[T1Full].
Figure 35 Timer Mode 1
Timer Mode 2
Comprises:
• 8 bit timer with reload
• 8 bit timer with reload and bitrate strobe signal for RF Transmitter
Timer 0 sets up a reloadable 8 bit timer holding the start value SFR TL0, timer reload value SFR TH0, timer run
bit SFR bit TCON.0[T0Run] and timer elapsed indicator SFR bit TCON.1[T0Full].
Timer 1 sets up a reloadable 8 bit timer holding the start value SFR TL1, timer reload value SFR TH1, timer run
bit SFR bit TCON.4[T1Run] and timer elapsed indicator SFR bit TCON.5[T1Full].
Figure 36 Timer Mode 2
T0Run
T1Run
Timer 0
Timer 1
TL0
T0Full
T1Full
TH0
TL1 TH1
Timer 1 Reload
Reload
Bitrate strobe
T0Run
T1Run
Timer 1
TL0
T0Full
T1Full
TH0
TL1 TH1
Timer 1 Reload
Reload
Bitrate strobe
Timer 0 Timer 0 Reload
Reload
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 107 Revision 1.1, 2012-04-03
Timer Mode 3
Comprises:
• 8 bit timer without reload (1)
• 8 bit timer without reload (2)
• 8 bit timer with reload and bitrate strobe signal for RF Transmitter
Timer 0 (1) uses SFR TL0 as start value.
Setting SFR bit TCON.0[T0Run] starts the timer.
SFR bit TCON.1[T0Full] is set when the timer is elapsed.
SFR bit TCON.0[T0Run] is cleared automatically when the timer is elapsed.
Timer 0 (2) uses SFR TH0 as start value.
Setting SFR bit TCON.4[T1Run] starts the timer.
SFR bit TCON.5[T1Full] is set when the timer is elapsed.
SFR bit TCON.4[T1Run] is cleared automatically when the timer is elapsed.
Timer 1 operates as a dedicated 8 bit bitrate timer for the RF Encoder. The timer uses no Run bit or Full flag. It is
started automatically when the timer mode is activated.
Figure 37 Timer Mode 3
T0Run
T1Run
Timer 1
TL0
T0Full
T1Full
TH0
TL1 TH1
Timer 1 Reload
Reload
Bitrate strobe
Timer 0 (1) Timer 0 (2 )
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 108 Revision 1.1, 2012-04-03
Timer mode 4
Comprises:
• 16 bit timer with reload and bitrate strobe signal for RF Transmitter
The timer unit is configured as one 16 bit reloadable timer.
SFR TL1 and SFR TH1 hold the start value.
If SFR bit TCON.4[T1Run] is set, the timer starts counting.
SFR bit TCON.5[T1Full] is set when the timer is elapsed.
The timer value is reloaded from SFR TL0 and SFR TH0 and the timer is restarted automatically.
SFR bit TCON.5[T1Full] has to be cleared by the application software. It is not cleared on read-access.
Figure 38 Timer mode 4
Note: In this mode both SFR bit TCON.0[T0Run] and SFR bit TCON.1[T0Full] are not used.
T0Run
T1Run
Timer 1 Reload
Timer 1
TL0
T0Full
T1Full
Reload
TH0
TL1 TH1
Bitrate strobe
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 109 Revision 1.1, 2012-04-03
Timer Mode 5
Comprises:
• 8 bit timer with reload
• 16 bit timer without reload and bitrate strobe signal for RF Transmitter
Timer 0 sets up a reloadable 8 bit timer holding the start value in SFR TL0, timer reload value in SFR TH0, timer
run bit SFR bit TCON.0[T0Run] and timer elapsed indicator in SFR bit TCON.1[T0Full].
Timer 1 operates as a 16 bit timer with the start value in SFR TL1 and SFR TH1, timer run bit
SFR bit TCON.4[T1Run] and timer elapsed indicator SFR bit TCON.5[T1Full]. If the timer is elapsed the timer is
stopped, SFR bit TCON.5[T1Full] is set and the timer run bit SFR bit TCON.4[T1Run] is cleared.
Figure 39 Timer Mode 5
T0Run
T1Run
Timer 0
Timer 1
TL0
T0Full
T1Full
TH0
TL1 TH1
Reload
Timer 0 Reload
Bitrate strobe
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 110 Revision 1.1, 2012-04-03
Timer Mode 6
Comprises:
• 16 bit timer without reload
• 16 bit timer without reload and bitrate strobe signal for RF Transmitter
Timer 0 operates as a 16 bit timer with the start value in SFR TL0 and SFR TH0, timer run bit
SFR bit TCON.0[T0Run] and timer elapsed indicator SFR bit TCON.1[T0Full].
If the timer is elapsed the timer is stopped, SFR bit TCON.1[T0Full] is set and the timer run bit
SFR bit TCON.0[T0Run] is cleared.
Timer 1 operates as a 16 bit timer with the start value in SFR TL1 and SFR TH1, timer run bit
SFR bit TCON.4[T1Run] and timer elapsed indicator SFR bit TCON.5[T1Full].
If the timer is elapsed the timer is stopped, SFR bit TCON.5[T1Full] is set and the timer run bit
SFR bit TCON.4[T1Run] is cleared.
Figure 40 Timer Mode 6
Timer Mode 7
This timer mode is not available for application usage. It is used by the ROM library functions for calibration
purpose.
T0Run
T1Run
Timer 0
Timer 1
TL0
T0Full
T1Full
TH0
TL1 TH1
Bitrate strobe
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 111 Revision 1.1, 2012-04-03
Timer Mode Register
TMOD Offset Wakeup Value Reset Value
Timer Mode Register 89H00H00H
Field Bits Type Description
T1CLK 7:6 wr Timer 1 Clock Source Select
00B System clock
01B If TCLKM = 0: System clock divided by SFR DIVIC and 8
If TCLKM = 1: Crystal Oscillator divided by 4
10B 4kHz (2*2kHz LP RC Oscillator)
11B If TCLKM = 0: PP2 event count (rising edge)
Reset: 0H
T0CLK 5:4 wr Timer 0 Clock Source Select
00B System clock
01B If TCLKM = 0: System clock divided by SFR DIVIC and 8
If TCLKM = 1: Crystal Oscillator divided by 4
10B 4kHz (2*2kHz LP RC Oscillator)
11B If TCLKM = 0: Timer 1 underflow event count
Reset: 0H
TCLKM 3 wr Timer Unit Crystal Clock Source Enable
If TCLKM is set to 1, then Crystal Oscillator is available as T0 and T1
clock source, refer to T0CLK and T1CLK.
When TCLKM is set, the Crystal Oscillator is automatically enabled.
When TCLKM is cleared, the crystal oscillator will be disabled unless
required by other functional blocks (e.g. during RF transmission, or while
SFR CFG0.EnXOSC = 1).
Note: It is recommend to call StartXtalOsc() ROM library function prior to
setting TCLKM.
0B Crystal Oscillator is not available as Timer clock source
1B Crystal Oscillator is available as Timer clock source
Reset: 0H
7 076
wr
T1CLK
54
wr
T0CLK
33
wr
TCLKM
20
wr
TM
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 112 Revision 1.1, 2012-04-03
TM 2:0 wr Timer Mode
000B Mode 0: 16 bit timer w/ reload and no baudrate strobe
001B Mode 1: 16 bit timer w/o reload and 8 bit timer w/ reload
010B Mode 2: two 8 bit timers w/ reload
011B Mode 3: two 8 bit timers w/o reload and 8 bit timer w/ reload
100B Mode 4: 16 bit timer w/ reload
101B Mode 5: 8 bit timer w/ reload and 16 bit timer w/o reload
110B Mode 6: two 16 bit timer w/o reload
111B Mode 7: Not available for application use
Reset: 0H
Field Bits Type Description
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 113 Revision 1.1, 2012-04-03
Timer Control Register
TCON Offset Wakeup Value Reset Value
Timer Control Register 88H00H00H
Field Bits Type Description
UNUSED 7:6 - UNUSED
Reset: 0H
T1FULL 5 wr Timer 1 Full Flag
Set if a Timer 1 underflow has occurred.
Reset: 0H
T1RUN 4 wr Timer 1 Run
0B Timer 1 is stopped
1B Timer 1 counts downward
Reset: 0H
UNUSED 3:2 - UNUSED
Reset: 0H
T0FULL 1 wr Timer 0 Full Flag
Set if a Timer 0 underflow has occurred.
Reset: 0H
T0RUN 0 wr Timer 0 Run
0B Timer 0 is stopped
1B Timer 0 counts downward
Reset: 0H
7 076
-
UNUSED
55
wr
T1FULL
44
wr
T1RUN
32
-
UNUSED
11
wr
T0FULL
00
wr
T0RUN
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 114 Revision 1.1, 2012-04-03
Timer 0 Register High Byte
Timer 0 Register Low Byte
TH0 Offset Wakeup Value Reset Value
Timer 0 Register High Byte 8CH00H00H
Field Bits Type Description
TH0 7:0 wr Timer 0 High Byte
Timer 0 [15:8]
Reset: 00H
TL0 Offset Wakeup Value Reset Value
Timer 0 Register Low Byte 8AH00H00H
Field Bits Type Description
TL0 7:0 wr Timer 0 Low Byte
Timer 0 [7:0]
Reset: 00H
7 07 0
wr
TH0
7 07 0
wr
TL0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 115 Revision 1.1, 2012-04-03
Timer 1 Register High Byte
Timer 1 Register Low Byte
TH1 Offset Wakeup Value Reset Value
Timer 1 Register High Byte 8DH00H00H
Field Bits Type Description
TH1 7:0 wr Timer 1 High Byte
Timer 1 [15:8]
Reset: 00H
TL1 Offset Wakeup Value Reset Value
Timer 1 Register Low Byte 8BH00H00H
Field Bits Type Description
TL1 7:0 wr Timer 1 Low Byte
Timer 1 [7:0]
Reset: 00H
7 07 0
wr
TH1
7 07 0
wr
TL1
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 116 Revision 1.1, 2012-04-03
3.22 General Purpose Input/Output (GPIO)
The SP37T has three GPIO pins that are used for:
• General purpose by the application software
• Dedicated digital peripherals (“Alternative Port Functionality” on Page 118).
• Operating mode selection (“Resets and Operating Mode Selection” on Page 20)
• If configured for general purpose usage, the GPIO pins can be accessed directly by the CPU. All GPIO pins
have selectable pull-up and pull-down resistors.
Note: The GPIO pins are configured as input with the pull-up resistor enabled after reset. In POWER DOWN state
and THERMAL SHUTDOWN state the GPIOs keep their configuration.
Peripheral Port Configuration
The following table shows the different possible configurations for the GPIO pins.
The ’x’ in the table has to be replaced by either 0,1 or 2 (for PP0, PP1 or PP2).
Note: The GPIO pin PP2 can be configured as external wakeup. For the required register settings please refer to
“External Wakeup on PP2” on Page 118.
Spike Suppression on Input Pins
To avoid unstability when reading the GPIO pins, a synchronization stage with a two-stage spike filter is included.
Due to the synchronization stage the following conditions might occur:
• Signal duration (TSIGNAL) < 1 systemclock1) period (1 TCLK): Signal is suppressed
•1T
CLK < TSIGNAL < 2 TCLK: undefined if suppressed or passed
•T
SIGNAL > 2 TCLK: Signal appears in SFR P1IN
Figure 41 shows examples of different input signals and how they are processed by the the synchronization stage
and the spike filter.
Table 10 GPIO Port Configuration
P1DIR.x P1OUT.x P1SENS.x I/O Pull-up/
pull-down
Comment
0 0 - Output No LOW (sink)
0 1 - Output No HIGH (source)
1 0 - Input No high-Z (Tri-State)
1 1 0 Input Pull-up Weak-High
1 1 1 Input Pull-down Weak-Low
1) For PP0, PP1 and PP2 the synchronization stage uses the undivided systemclock (SFR DIVIC) as clocksource, so
SFR DIVIC has no influence.
The synchronization stage is disabled in POWER DOWN state, so it is not used for an external wakeup (see “External
Wakeup on PP2” on Page 118).
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 117 Revision 1.1, 2012-04-03
Figure 41 Synchronization Stage & Spike Suppression Examples
Systemclock
PPx @ the pin
PPxInput Register
Signal is visible wi th the 4th
rising edge of the system clock
Signal
suppressed
since it is
not stable
for 2 rising
edges of the
systemclock
Systemclock
PPx @ the pin
PPxInput Register
Spike
suppre
ssed Signal is visible with the 4 th
rising edge of the system clock
Systemclock
PPx @ the pin
PPxInput Register
Spike
suppress
ed Signal is visible with the 4th
rising edge of the system clock
Spike
suppre
ssed
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 118 Revision 1.1, 2012-04-03
External Wakeup on PP2
PP2 can be used as an external wakeup source if enabled by the Wakeup-Mask SFR bit WUM.1[EXT1] and
configured as input pin by setting SFR bit P1DIR.2[PPD2].
The internal pull-up/pull-down resistor is enabled if SFR bit P1OUT.2[PPO2] is set. SFR bit P1SENS.2[PPS2]
selects the sensitivity (high active/low active):
Alternative Port Functionality
In Table 12, the alternative port functionality which has higher priority than standard I/O port functionality is shown.
Table 11 External Wakeup Configuration
SFR Settings Description
SFR bit P1DIR.2[PPD2] = 1
SFR bit P1OUT.2[PPO2]=1
SFR bitP1SENS.2[PPS2] = 0
SFR bit WUM.1[EXT] = 0
PP2 configured as Input, pull-up enabled, Wakeup
occurs if PP2 is forced to LOW externally.
SFR bit P1DIR.2[PPD2] = 1
SFR bit P1OUT.2[PPO2] =1
SFR bitP1SENS.2[PPS2] = 1
SFR bit WUM.1[EXT] = 0
PP2 configured as Input, pull-down enabled, Wakeup
occurs if PP2 is forced to HIGH externally.
Table 12 I/O Port 1 - Alternative Functionality
Pin Function I/O Description
PP0 I2C-SCL I I2C Serial Clock Line
Configured to I2C clock pin if SFR bit CFG1.6 [I2CEN] is set.
Weak-High has to be provided by an external pull-up resistor or by the
I2C master device.
Port Pin I/O I/O Standard I/O port functionality
PP1 I2C-SDA I/O I2C Serial Data
Configured to I2C data pin if bit CFG1.6 [I2CEN] is set.
Weak-High has to be provided either by the internal pull-up resistor, by
an external pull-up resistor or by the I2C master device.
Port Pin I/O I/O Standard I/O port functionality
PP2 TX Data Out O RF Encoder Data Output
If bit CFG1.4[RFTXPEN] is set to one, the Manchester/BiPhase encoded
data is delivered serially to PP2.
Port Pin I/O I/O Standard I/O port functionality / External Wakeup
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 119 Revision 1.1, 2012-04-03
IO-Port 1 Direction Register
P1DIR Offset Wakeup Value Reset Value
IO-Port 1 Direction Register 91HUUHFFH
Field Bits Type Description
Res 7:3 Reserved
These bits must be set to 11111B.
Reset: 1FH
PPD2 2 wr PP2 I/O Port Direction
0B Output
1B Input
Reset: 1H
PPD1 1 wr PP1 I/O Port Direction
0B Output
1B Input
Reset: 1H
PPD0 0 wr PP0 I/O Port Direction
0B Output
1B Input
Reset: 1H
7 073
Res
22
wr
PPD2
11
wr
PPD1
00
wr
PPD0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 120 Revision 1.1, 2012-04-03
IO-Port 1 Data In Register
P1IN Offset Wakeup Value Reset Value
IO-Port 1 Data In Register 92H00000XXXB00000XXXB
Field Bits Type Description
UNUSED 7:3 - UNUSED
Reset: 00H
PPI2 2 r PP2 I/O-Port Input Data
0B LOW Level
1B HIGH Level
Reset: XB
PPI1 1 r PP1 I/O-Port Input Data
0B LOW Level
1B HIGH Level
Reset: XB
PPI0 0 r PP0 I/O-Port Input Data
0B LOW Level
1B HIGH Level
Reset: XB
7 073
-
UNUSED
22
r
PPI2
11
r
PPI1
00
r
PPI0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 121 Revision 1.1, 2012-04-03
IO-Port 1 Data Out Register
P1OUT Offset Wakeup Value Reset Value
IO-Port 1 Data Out Register 90HUUHFFH
Field Bits Type Description
Res 7:3 Reserved
These bits must be set to 11111B.
Reset: 1FH
PPO2 2 wr PP2 I/O-Port Output Data / Pulling Resistor
When SFR P1DIR.PPD2 is clear (output), then PPO2 defines the output
port state.
When SFR P1DIR.PPD2 is set (input), then PPO2 controls the input
pulling resistor.
0B Output low / Tristate
1B Output high / Pulling Resistor enabled
Reset: 1H
PPO1 1 wr PP1 I/O-Port Output Data / Pulling Resistor
When SFR P1DIR.PPD1 is clear (output), then PPO1 defines the output
port state.
When SFR P1DIR.PPD1 is set (input), then PPO1 controls the input
pulling resistor.
0B Output low / Tristate
1B Output high / Pulling Resistor enabled
Reset: 1H
PPO0 0 wr PP0 I/O-Port Output Data / Pulling Resistor
When SFR P1DIR.PPD0 is clear (output), then PPO0 defines the output
port state.
When SFR P1DIR.PPD0 is set (input), then PPO0 controls the input
pulling resistor.
0B Output low / Tristate
1B Output high / Pulling Resistor enabled
Reset: 1H
7 073
Res
22
wr
PPO2
11
wr
PPO1
00
wr
PPO0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 122 Revision 1.1, 2012-04-03
IO-Port 1 Sensitivity Register
P1SENS Offset Wakeup Value Reset Value
IO-Port 1 Sensitivity Register 93H00000UUUB00H
Field Bits Type Description
UNUSED 7:3 - UNUSED
Reset: 00H
PPS2 2 wr PP2 I/O-Port Sensitivity
Only applies when SFR P1DIR.PPD2 is set (input) and SFR
P1OUT.PPO2 is set (enable pulling).
0B Pull-up Resistor
1B Pull down Resistor
Reset: 0H
PPS1 1 wr PP1 I/O-Port Sensitivity
Only applies when SFR P1DIR.PPD1 is set (input) and SFR
P1OUT.PPO1 is set (enable pulling).
0B Pull-up Resistor
1B Pull down Resistor
Reset: 0H
PPS0 0 wr PP0 I/O-Port Sensitivity
Only applies when SFR P1DIR.PPD0 is set (input) and SFR
P1OUT.PPO0 is set (enable pulling).
0B Pull-up Resistor
1B Pull down Resistor
Reset: 0H
7 073
-
UNUSED
22
wr
PPS2
11
wr
PPS1
00
wr
PPS0
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 123 Revision 1.1, 2012-04-03
3.23 I2C Interface
For communication between a host and the SP37T a I2C slave interface is implemented.
• PP1 is used as serial data line (SDA)
• PP0 is used as serial clock line (SCL)
• SP37T responds to I2C Address 6CH or a general call (if enabled) by addressing slave address 00H. General
call can be enabled by setting SFR bit CFG2.6[I2CGCEN].
• The data transfer rate is specified in “I2C Interface” on Page 166.
Note: In PROGRAMMING mode and DEBUG mode the I2C Interface is handled by the mode handlers located in
the ROM automatically. Manual access to those registers is only required if the I2C Interface is utilized in
NORMAL mode
Using the slave I2C interface in NORMAL mode
To enable the I2C interface the SFR bit CFG1.6[I2CEN] has to be set. Once the I2C interface has been enabled,
the SP37T waits for a start condition to occur.
After the SP37T has received a start condition, the following received 8 bits are compared to the device address.
If the address matches, the hardware automatically generates an acknowledge, sets SFR bit I2CS.7[AM] and
configures SFR bit I2CS.3[RNW] according to the received address which determines if the I2C access is read or
write.
Dependant on SFR bit I2CS.3[RNW] the following two actions has to be performed by the application software:
(SFR bit I2CS.3[RnW] == 0) - Receive I2C-data
• If SFR bit I2CS.0[RBF] is set, one byte has been received and can be read by the application software via
SFR I2CD.
Each byte is acknowledged automatically as long as no receive buffer overflow (SFR bit I2CS.5[OV]) occurs.
• If SFR bit I2CS.4[S] is set, a stop condition has occurred; the transmission was closed by the I2C master
device.
• If SFR bit I2CS.7[AM] is set, a restart condition has been initiated. In case of a write access (SFR bit
I2CS.3[RNW] == 1) a branch to the transmit subroutine has to be performed.
(SFR bit I2CS.3[RnW] == 1) - Transmit I2C-data
• Data to be transmitted has to be written to SFR I2CD.
SFR bit I2CS.1[TBF] cleared when the data written to SFR I2CD is taken over by the shift-register. If the I2C
master device requests more data bytes it creates an acknowledge (SFR bit I2CS.2[RACK]) and subsequently
new data may be written to SFR I2CD. If no data is provided, the I2C-interface automatically sets line SCL to
low until data is written to SFR I2CD (slave device gains access over the I2C clock line).
• If SFR bit I2CS.4[S] is set, the transmission process has been terminated by the I2C master device and the
transmission subroutine can be left.
To control I2C slave interface the following registers are implemented:
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 124 Revision 1.1, 2012-04-03
I2C Data Register
I2C Status Register
I2CD Offset Wakeup Value Reset Value
I2C Data Register 9AH00H00H
Field Bits Type Description
I2CD 7:0 wr I2C Data Register
Reset: 00H
I2CS Offset Wakeup Value Reset Value
I2C Status Register 9BH00H00H
Field Bits Type Description
AM 7 rc I2C Address Match
This bit will be set when the device address or general call matches with
received address byte. It is automatically cleared by hardware after I2CS
is read.
Reset: 0H
UNUSED 6 - UNUSED
Reset: 0H
OV 5 rc I2C Overflow
This bit will be set when a received byte is not read out before a new byte
is received. In this case the old byte value is kept, the new byte is
rejected. Overflow also occurs if a new byte is written to register I2CD
prior to transmitting the previous byte. In this case the old byte value is
overwritten with the new byte. This bit is automatically cleared by
hardware after I2CS is read.
Reset: 0H
7 07 0
wr
I2CD
7 077
rc
AM
66
-
UNUSED
55
rc
OV
44
rc
S
33
r
RNW
22
r
RACK
11
r
TBF
00
r
RBF
SP37T
Tire Pressure Monitoring Sensor
Special Function Registers
Datasheet 125 Revision 1.1, 2012-04-03
S4rcI2C Stop Condition
This bit will be set when a stop condition is detected. It is automatically
cleared by hardware after I2CS is read.
Reset: 0H
RNW 3 r I2C Read/Write Information
RnW reflects the state of the Read/Write bit received within the I2C
address byte.
0B I2C Write Command
1B I2C Read Command
Reset: 0H
RACK 2 r I2C Acknowledge
0B Not acknowledged
1B Acknowledged
Reset: 0H
TBF 1 r I2C Transmit Buffer Full
Bit is automatically cleared after the data byte is transferred to the shift
register.
0B Ready to accept new byte
1B Byte transmission is pending
Reset: 0H
RBF 0 r I2C Receive Buffer Full
Bit is automatically cleared by hardware after I2CD is read.
0B No new received data
1B Received data byte is available
Reset: 0H
Field Bits Type Description
SP37T
Tire Pressure Monitoring Sensor
Datasheet 126 Revision 1.1, 2012-04-03
3.23.1 Programming mode Operation
In PROGRAMMING mode the SP37T is only accessible via the I²C Interface.
The device is operating using the internal 12 MHz RC HF Oscillator.
If started up in PROGRAMMING mode (see “Resets and Operating Mode Selection” on Page 20), the SP37T
waits until an I2C commands is received.
Figure 42 PROGRAMMING Mode State Diagram
Note: To avoid programming failures all PROGRAMMING mode commands are protected by a 16 bit CRC at the
end of each command (“16 Bit CRC (Cyclic Redundancy Check) Generator/Checker” on Page 99
shows details about the used CRC polynomial).
The checksum has to be calculated over all bytes in the command excluding the SP37T I²C device address.
PROGRAMMING Mode Commands
•“FLASH Write Line” on Page 127
•“FLASH Erase” on Page 127
•“FLASH Check Erase Status” on Page 128
•“FLASH Read Line” on Page 129
•“Read Status” on Page 130
•“FLASH Check CRC” on Page 131
•“FLASH Set User Configuration Sector Lock” on Page 131
•“Measure Pressure” on Page 132
•“Measure Acceleration” on Page 134
•“Measure Temperature” on Page 136
•“Measure Supply Voltage” on Page 137
Figure 43 shows the nomenclature for the I2C commands.
Figure 43 I2C Legend - PROGRAMMING Mode
Reset with PP0/PP1 in condition
„PROGRAMMING mode“
Wait for
incoming I2C
commands
No I2C Command received
Execute I 2C
command
Valid I2C Command received
finished
from master to slave S start condition nA not acknowledge
from slave to master P stop condition A acknowledge
SR repeated start condition, may be replaced by Stop-Start condition
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Datasheet 127 Revision 1.1, 2012-04-03
3.23.1.1 FLASH Write Line
The FLASH Write Line command writes 32 bytes to the FLASH. The start address has to be a multiple of 20H.
This command should only be used if the FLASH line is fully erased. If an already programmed FLASH line gets
overwritten (without being erased before) the resulting data is undefined.
Note: After the Stop condition (P) is received the data is programmed into the FLASH. During the programming
time incoming I²C commands are not acknowledged. This programming time is specified in Table 49.
Figure 44 FLASH Write Line I2C Command
3.23.1.2 FLASH Erase
The FLASH Erase command erases the individual sectors of the FLASH.
Note: After the Stop condition (P) is received the selected FLASH sectors are being erased. During the erase time
incoming I²C commands are not acknowledged. This erase time is specified in Table 49.
Figure 45 FLASH Erase Command
Table 13 FLASH Write Line Parameters
Parameter Description
AdrHi High Byte of FLASH start address
AdrLo Low Byte of FLASH start address Must be a multiple of 20H
Data0 - Data 31 32 Databytes that shall be written to the FLASH line indicated with AdrHi&AdrLo
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Table 14 FLASH Erase Parameters
Parameter Description
Sect Selects which sectors to erase
Note: Set individual bits to ’1’ to erase or to ’0’ to NOT erase
Bit7:2 protected FLASH area -don’t care
Bit1 FLASH User Configuration Sector
Bit0 FLASH Code Sector
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
AS 0x6C AdrHi AdrLoA AA Data0 ...AData31 ACRCH CRCLA A P
AS 0x6C 0xA2 SectA A CRCH CRCLA A P
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Tire Pressure Monitoring Sensor
Datasheet 128 Revision 1.1, 2012-04-03
3.23.1.3 FLASH Check Erase Status
This function returns the status of the selected FLASH sector(s).
Note: After the first Stop condition (P) is received the selected FLASH sectors are checked. During this time
incoming I²C commands are not acknowledged.
Figure 46 FLASH Check Erase Status Command
Table 15 FLASH Check Erase Parameters
Parameter Description
Sect Selects which sectors to erase
Note: Set individual bits to ’1’ to check or to ’0’ to NOT check.
Bit7:2 protected FLASH area -don’t care
Bit1 FLASH User Configuration Sector
Bit0 FLASH Code Sector
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Table 16 FLASH Check Erase Return values
Parameter Description
Status Returns the Status of the Check
Note: ’0’ means Sector is erased or unchecked ’1’ means that at least one bit is not erased
in the checked Sector.
Bit7:2 protected FLASH area -don’t care
Bit1 FLASH User Configuration Sector
Bit0 FLASH Code Sector
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Status
AS 0x6C 0xA3 SectA A CRCH CRCLA A P
AS 0x6D ACRCH ACRCL nA P
Pause > 35ms
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Tire Pressure Monitoring Sensor
Datasheet 129 Revision 1.1, 2012-04-03
3.23.1.4 FLASH Read Line
The contents of the FLASH memory can be read out using the following command.
Figure 47 FLASH Read Line Command
Table 17 FLASH Read Line Parameters
Parameter Description
AdrHi High Byte of FLASH start address
AdrLo Low Byte of FLASH start address Must be a multiple of 20H
Table 18 FLASH Read Line Return values
Parameter Description
Data0 - Data 31 32 Databytes Read from FLASH starting at address AdrHi&AdrLo
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Data0AS 0x6C AdrHi AdrLoA A 0x6D ASR S A ... AData31 ACRCH ACRCL nA P
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3.23.1.5 Read Status
This function is intended to read out the status of previous I2C commands. It can be called whenever desired to
verify if errors occurred since the last Read Status call.
Figure 48 FLASH Read Status Command
Table 19 FLASH Read Status Return values
Parameter Description
Status Status byte
Bit7:4 CmdCnt Counter indicating the number of executed commands since first detected
error
Note: 0000b = no error occurred since the last call
0001b = 1 command
...
1111b = 15 commands or more
Bit3:2 ErrCntInvCmdL Counter of erroneous events since last call
Note: 00b = no error
01b = one error
10b = two errors
11b = three or more errors
Bit1 InvCmdL Flag indicating if there was a invalid command or execution failure since the
last call.
Note: 0b = no failure found
1b = failure found
Bit0 CRCFail CRC Failure detected since the last call
Note: 0b = no CRC Error detected since the last call
1b = one or more CRC Error detected since last call
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Status
AS 0x6C 0xA4 A
AS 0x6D ACRCH ACRCL nA P
Pause > 9µs
0x14 A0x9E A P
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3.23.1.6 FLASH Check CRC
This function performs a CRC check on the locked FLASH Code sector. The CRC-Generator/Checker is using the
16 bit CCITT polynomial x16+x12+x5+1 with a preload value of FFFFH. The resulting CRC checksum (CRCHi,
CRCLo) is compared with value stored at the FLASH addresses 577DH and 577EH in the FLASH Code sector. For
this function to operate correctly the CRC of the entire code sector, including memory locations otherwise unused
by the application software, must be considered.
Figure 49 FLASH Check CRC
3.23.1.7 FLASH Set User Configuration Sector Lock
This command may be issued in order to lock the User Configuration Sector from any further writing or reading.
This command causes Lockbyte 3 to become set. The structure for this command is as follows:
Figure 50 FLASH Set User Configuration Sector Lock
Table 20 FLASH Check CRC Return values
Parameter Description
Status Status Byte
Returns the pass/fail information of the FLASH Check CRC
Note: 00H = CRC Check passed, no ECC error detected
FFH = CRC Check failed
FEH = CRC Check passed, but ECC error detected (correctable error)
CRCHi High Byte of calculated CRC16 (not the CRCH Byte stored in the FLASH address 577DH)
CRCLo Low Byte of calculated CRC16 (not the CRCL Byte stored in the FLASH address 577EH)
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
StatusAS 0x6D ACRCHi ACRCLo ACRCH ACRCL nA P
AS 0x6C 0xA6 A0x34 A0xDC A P
Pause > 21.5ms
AS 0x6C 0xA1 0x44A A 0x3B A P
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3.23.1.8 Measure Pressure
This function performs a pressure sensor measurement.
The result can either:
• Compensated for sensitivity, offset and temperature
• Output as raw value without performing the compensation
The function can measure up to 64 samples with a specified sample rate and can average them in order to
compensate for noise.
Figure 51 Measure Pressure
Note: 1) When the sample rate is > 0, this time increases
Table 21 Measure Pressure Parameters
Parameter Description
ConfigH Config Parameters
Bit7:1 Reserved
Bit0 Selects source of raw temperature data for compensation
Note: 0b = Perform new raw temperature measurement
1b = Use raw temperature data from previous measurement
ConfigL Config Parameters
Bit7 Select Pressure Measurement, set to 1b
Bit6 Defines if the RAW ADC result is compensated
Note: 0b = temperature compensation is performed. Returns Compensated & RAW value
1b = no compensation is performed. Returns only RAW value
Bit5:4 Select Pressure Range
Note: 00b = Reserved
01b = Reserved
10b = Reserved
11b = 1300 kPa
Bit3 Reserved, set to 0b
Bit2:0 Number of ADC measurements that are taken and averaged
Note: 000b = 1 Samples (default)
001b = 2 Samples
010b = 4 Samples
011b = 8 Samples
100b = 16 Samples
101b = 32 Samples
110b = 64 Samples
111b = 64 Samples
AS 0x6C 0xA7 A A AS-Rate CRCH ACRCL A P
StatusAS 0x6D AData0 A... AData5 ACRCH ACRCL nA P
Pause > 984µs
1)
ConfigH AConfigL
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Datasheet 133 Revision 1.1, 2012-04-03
S-Rate Bit7:0 Number of systemclock cycles divided by 8 between two consecutive samples (only
applicable if more than one sample is taken and averaged)
Note: 00H = No delay (fastest possible samplerate)
01H..4FH = Not allowed
50H..FFH = 1/samplerate (samplerate in systemclocks divided by 8)
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Table 22 Measure Pressure Return Values
Parameter Description
Status Status Byte
Bit7 Reserved
Bit6 Reserved
Bit5 Reserved
Bit4 VMIN warming
Note: 0B= Battery Supply Voltage above VMIN threshold
1B= Battery Supply Voltage below VMIN threshold
Bit3 Reserved
Bit2 Sensor Fault Wire Bond Check
Note: 0B = Wire Bond Check successful
1B = Wire Bond Check Failed
Bit1 Overflow of ADC Result
Note: 0B= No overflow of the ADC Result
1B= Overflow of the ADC Result
Bit0 Underflow of the ADC Result
Note: 0B= No underflow of the ADC Result
1B= underflow of the ADC Result
Data0 Compensated Pressure High Byte
Data1 Compensated Pressure Low Byte
Data2 RAW Pressure High Byte
Data3 RAW Pressure Low Byte
Data4 RAW Temperature High Byte
Data5 RAW Temperature Low Byte
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Table 21 Measure Pressure Parameters (cont’d)
Parameter Description
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Datasheet 134 Revision 1.1, 2012-04-03
3.23.1.9 Measure Acceleration
This function performs an acceleration sensor measurement.
The result can either:
• Compensated for sensitivity, offset and temperature
• Output as raw value without performing the compensation
The function can measure up to 64 samples with a specified sample rate and can average them in order to
compensate for noise.
Figure 52 Measure Acceleration
Note: 1) When the sample rate is > 0, this time increases
Table 23 Measure Acceleration Parameters
Parameter Description
ConfigH Config Parameters
Bit7:1 Reserved
Bit0 Selects source of raw temperature data for compensation
Note: 0b = Perform new raw temperature measurement
1b = Use raw temperature data from previous measurement
ConfigL Config Parameters
Bit7 Select Acceleration Measurement, set to 0b
Bit6 Defines if the RAW ADC result is compensated
Note: 0b = temperature compensation is performed. Returns Compensated & RAW value
1b = no compensation is performed. Returns only RAW value
Bit5:4 Specifies the sensor gain, set to 00b
Bit3 Measure Mode:
Note: 0b = Average value
1b = Maximum value
Bit2:0 Number of ADC measurements that are taken and averaged
Note: 000b = 1 Samples (default)
001b = 2 Samples
010b = 4 Samples
011b = 8 Samples
100b = 16 Samples
101b = 32 Samples
110b = 64 Samples
111b = 64 Samples
StatusAS 0x6D AData0 A... AData5 ACRCH ACRCL nA P
Pause > 984µs
1)
AS 0x6C 0xA8 ConfigHA A AS-Rate CRCH ACRCL A PA ConfigL
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Datasheet 135 Revision 1.1, 2012-04-03
S-Rate Bit7:0 Number of systemclock cycles divided by 8 between two consecutive samples (only
applicable if more than one sample is taken and averaged)
Note: 00H = No delay (fastest possible samplerate)
01H..5EH = Not allowed
5FH..FFH = 1/samplerate (samplerate in systemclocks divided by 8)
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Table 24 Measure Acceleration Return values
Parameter Description
Status Status Byte
Bit7 Reserved
Bit6 Reserved
Bit5 Reserved
Bit4 VMIN warning
Note: 0b = Battery Supply Voltage above VMIN threshold
1b = Battery Supply Voltage below VMIN threshold
Bit3 Sensor Fault Diagnosis Resistor
Note: 0b = Diagnosis Resistor Check successful
1b = Diagnosis Resistor Check failed
Bit2 Sensor Fault Wire Bond Check
Note: 0b = Wire Bond Check successful
1b = Wire Bond Check failed
Bit1 Overflow of ADC Result
Note: 0b = No overflow of the ADC Result
1b = Overflow of the ADC Result
Bit0 Underflow of ADC Result
Note: 0b = No underflow of the ADC Result
1b = Underflow of the ADC Result
Data0 Compensated Acceleration High Byte
Data1 Compensated Acceleration Low Byte
Data2 RAW Acceleration High Byte
Data3 RAW Acceleration Low Byte
Data4 RAW Temperature High Byte
Data5 RAW Temperature Low Byte
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
Table 23 Measure Acceleration Parameters (cont’d)
Parameter Description
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Datasheet 136 Revision 1.1, 2012-04-03
3.23.1.10 Measure Temperature
This function performs a temperature measurement. The result is compensated for sensitivity and offset.
Figure 53 Measure Temperature
Table 25 Measure Temperature Return values
Parameter Description
Status Status Byte
Bit7 Reserved
Bit6 Reserved
Bit5 Reserved
Bit4 VMIN warning
Note: 0b = Battery Supply Voltage above VMIN threshold
1b = Battery Supply Voltage below VMIN threshold
Bit3 Reserved
Bit2 Reserved
Bit1 Overflow of ADC Result
Note: 0b = No overflow of the ADC Result
1b = Overflow of the ADC Result
Bit0 Underflow of ADC Result
Note: 0b = No underflow of the ADC Result
1b = Underflow of the ADC Result
Data0 Compensated Temperature High Byte
Data1 Compensated Temperature Low Byte
Data2 RAW Temperature High Byte
Data3 RAW Temperature Low Byte
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
AS 0x6C 0xA9 A0xC5 A0x33 A P
StatusAS 0x6D AData0 A... AData3 ACRCH ACRCL nA P
Pause > 534µs
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Datasheet 137 Revision 1.1, 2012-04-03
3.23.1.11 Measure Supply Voltage
This function performs a battery voltage measurement. The result is compensated for offset.
Figure 54 Measure Supply Voltage
Table 26 Measure Supply Voltage Return values
Parameter Description
Status Status Byte
Bit7 Reserved
Bit6 Reserved
Bit5 Reserved
Bit4 Reserved
Bit3 Reserved
Bit2 Reserved
Bit1 Overflow of ADC Result
Note: 0b = No overflow of the ADC Result
1b = Overflow of the ADC Result
Bit0 Underflow of ADC Result
Note: 0b = No underflow of the ADC Result
1b = Underflow of the ADC Result
Data0 Compensated Battery Voltage High Byte
Data1 Compensated Battery Voltage Low Byte
Data2 RAW Battery Voltage High Byte
Data3 RAW Battery Voltage Low Byte
CRCH High Byte of CRC16
CRCL Low Byte of CRC16
AS 0x6C 0xAA A0xF5 A0x50 A P
StatusAS 0x6D AData0 A... AData3 ACRCH ACRCL nA P
Pause > 385µs
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Tire Pressure Monitoring Sensor
Datasheet 138 Revision 1.1, 2012-04-03
3.23.2 DEBUG Mode Operation
Note: DEBUG mode operation is automatically handled by the development environment provided by Infineon.
Manual changes of the SFRs (see Table 27) and/or usage of the Debugger Commands (see “Debugger
Commands” on Page 139) by other tools may result in undefined operation.
3.23.2.1 Debug Special Function Register
The SP37T incorporates 8 debug registers that are cleared after Wakeup and Reset.
CPU Debug Compare Register 0 (high)
DBCH0 Offset Wakeup Value Reset Value
CPU Debug Compare Register 0 (high) 95H00H00H
Field Bits Type Description
DBCH0 7:0 wr CPU Debug Compare Register 0 (high)
Reset: 00H
Table 27 DEBUG mode SFRs
Register Short Name Register Long Name Offset Address Wakeup Value Reset Value
DBCH0 Debug Compare Register 0 (highbyte) 95H00H00H
DBCL0 Debug Compare Register 0 (lowbyte) 94H00H00H
DBCH1 Debug Compare Register 1 (highbyte) 9DH00H00H
DBCL1 Debug Compare Register 1(lowbyte) 9CH00H00H
DBTH0 Debug Target Register 0 (highbyte) 97H00H00H
DBTL0 Debug Target Register 0 (lowbyte) 96H00H00H
DBTH1 Debug Target Register 1 (highbyte) 9FH00H00H
DBTL1 Debug Target Register 1 (lowbyte) 9EH00H00H
7 07 0
wr
DBCH0
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Datasheet 139 Revision 1.1, 2012-04-03
3.23.2.2 Debugging Functionality
During program execution the Program Counter (PC) of the microcontroller is continuously compared with the
contents of the DBCHx + DBCLx registers.
In case of a match the PC is automatically set to the address given in DBTHx + DBTLx to handle exceptions (e.g.
breakpoints).
The debugger consists of a debug handler and a single stepper. The debug handler processes the I2C
communication and debug command interpretation. The debug commands SetSFR, ReadSFR, SetMemory,
ReadMemory and SetPC, ReadPC are executed directly by the debug handler. The debug commands Single
Step, Run Interruptible and Run to next Breakpoint are executed by the single stepper.
3.23.2.3 Debugger Commands
The following figure shows the I2C nomenclature for the commands.
Figure 55 I2C Legend - DEBUG Mode
3.23.2.3.1 SetSFR - Set an SFR to a User-defined Value
Figure 56 DEBUG SetSFR Command
Addr: represents the address of the SFR to be set.
Data: this value has to be put into the SFR address specified by Addr.
3.23.2.3.2 ReadSFR - Read the Value of One SFR
Figure 57 DEBUG ReadSFR Command
Addr: represents the address of the SFR to be read.
Data: this value was read on the SFR address specified by Addr.
from master to slave S start condition nA not acknowledge
from slave to master P stop condition A acknowledge
SR repeated start condition, may be replaced by Stop-Start condition
AS 0x6C 0x00 AdrA A AData P
Pause > 9µs Data nAAS 0x6C 0x03 AdrA A P AS 0x6D P
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Datasheet 140 Revision 1.1, 2012-04-03
3.23.2.3.3 SetMemory - Set one Byte in RAM to a User-defined Value
Figure 58 DEBUG SetMemory Command
Addr: represents the address of the internal data memory to be set.
Data: this value that has to be written into the internal data memory byte specified by Addr.
3.23.2.3.4 ReadMemory - Read One Byte of the RAM
Figure 59 DEBUG ReadMemory Command
Addr: represents the address of the Internal data memory location to be read.
Data: this value was read from the internal data memory address specified by Addr.
3.23.2.3.5 SetPC - Set the Program Counter to a user-defined value
Figure 60 DEBUG SetPC Command
AdrHi: MSB of the new Program Counter.
AdrLo: LSB of the new Program Counter.
3.23.2.3.6 ReadPC - Read the Program Counter
Figure 61 DEBUG ReadPC Command
PCHi: MSB of the Program Counter.
PCLo: LSB of the Program Counter.
3.23.2.3.7 SingleStep
Execute one Opcode Instruction and return to the debug handler.
Figure 62 DEBUG SingleStep Command
AS 0x6C 0x06 AdrA A AData P
Pause > 9µs Data nAAS 0x6C 0x09 AdrA A P AS 0x6D P
AS 0x6C 0x0C AdrHiA A AAdrLo P
Pause > 9µs PCHi nAAS 0x6C 0x0F A P AS 0x6D PPCLoA
AS 0x6C 0x12 A P
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Datasheet 141 Revision 1.1, 2012-04-03
3.23.2.3.8 Run Interruptible
The function executes consecutive single steps until any I²C command is received on the bus. Compared to
running the program in real-time this function has a slower execution speed by a factor of roughly 1/50, thus it
cannot be used for debugging time critical application code.
Figure 63 DEBUG Run Interruptible Command
3.23.2.3.9 Run to Next Breakpoint
The debugged program is executed without single steps in real-time. This enables debugging of runtime critical
functions like RF transmission or LF data receiving. The execution is stopped when the PC matches one of the
two hardware breakpoints. The second Breakpoint (Register 1) can be set if required using the SetSFR command.
Note: If none of these breakpoints is hit the communication to the debugger is lost.
Figure 64 DEBUG Run to Next Breakpoint Command
BPHi: MSByte of the Breakpoint Register 0.
BPLo: LSByte of the Breakpoint Register 0.
AS 0x6C 0x15 A P
AS 0x6C 0x18 BPHiAAABPLo P
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Tire Pressure Monitoring Sensor
Specification
Datasheet 142 Revision 1.1, 2012-04-03
4 Specification
4.1 Test Board
The parameters described in Table 35 “Supply Currents” on Page 151 and Table 36 “RF Transmitter” on
Page 153 were obtained using the SP37T Testboard described in this chapter. The environment of the customer
application have not been taken into account.
4.1.1 SP37T Test Board Schematics
Figure 65 SP37T Test Circuit / Schematic
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 143 Revision 1.1, 2012-04-03
4.1.2 SP37T Test Board Layout
Figure 66 SP37T Test Board Layout
4.1.3 SP37T Test Board Placement
Figure 67 SP37T Test Board Placement
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 144 Revision 1.1, 2012-04-03
4.1.4 SP37T Test Board Bill of Material
Table 28 SP37T Test Board Bill of Material
Part Value
C41 100 nF
C42 100 nF, ESR max. 15 Ohm
IC1 SP37T
R11, R50, R51, R52, 0R Jumper
X11 2pin Header (male)
X51 5pin Header (male)
X01 SMA Connector (female)
315 MHz 434 MHz
PLow PMed/High PLow PMed/High
C01 5.6 pF 4.7 pF 2.7 pF 2.7 pF
C02 n.p. n.p. n.p. n.p.
C03 51 nH1)
1) Coilcraft 0603CS
39 pF 0 Ohm 0 Ohm
C04 12pF 8.2pF 2.2nH
1) 2.2 nH1)
C05 2.7 pF 1.5 pF n.p. n.p.
C15 100 pF 100 pF 100 pF 47 pF
L01 43 nH1) 47 nH1) 22 nH1) 30 nH1)
L02 27 pF 47 nH1) 30 nH1) 18 nH1)
L03 0Ohm 0Ohm 33pF 27pF
L04 18 nH1) 18 nH1) 12 nH1) 18 nH1)
L05 0 Ohm 0 Ohm 5.6 pF 5.6 pF
L06 n.p. n.p. n.p. n.p.
Q21 NDK NX5032SD
19.6875 MHz
EXS00A-02825
NDK NX5032SD
18.0800 MHz
EXS00A-03552
C21 15pF 15pF
C22 4.7 pF 7.5 pF
L21 82nH 82nH
BAT11 Battery Clip 2032
C31, C32, C33, C50, C51, C52,
L31, R12, R31, R32
Not placed
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Specification
Datasheet 145 Revision 1.1, 2012-04-03
4.2 Absolute Maximum Ratings
Table 29 Absolute Maximum Ratings
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Max. Supply Voltage Vbatmax -0.3 – +4.0 V ■1.1
Operating
Temperature
Tj-40 – +150 °C Max 24 hrs
accumulated over
lifetime between 125°C
and 150°C. Device
powered Vbat=3.6 V
■1.2
-55 -40 °C Temperature
measurement,
operation of interval
timer
■1.3
Operating
temperature
(transient)
Ttrans +150 – +175 °C Max 3 min., 10 times
over lifetime device
powered Vbat=3.6 V
■1.4
Storage temperature Tstorage -40°C – +150 °C Max 1000 hours
accumulated over
lifetime between 125°C
and 150°C. Device not
powered
■1.5
ESD robustness HBM VESD,HBM – 5000 V All pins According to
EIA/JESD22-A114-B
■1.6
ESD robustness CDM VESD,CDM – 500 V All pins (According to
ESDA STM 5.3.1)
■1.7
– 750 V Corner pins (According
to ESDA STM 5.3.1)
■1.8
Latch up ILU -100 – +100 mA AEC-Q100 (transient
current)
■1.9
Input voltage VIn,Digital -0,3 – Vbat +
0,3
V Pin PP0, PP1, PP2 ■1.10
VIn,LF -0,3 – +0,3 V Pin LF, XLF ■1.11
XTAL Input Voltage VIn,XTAL -0,3 – Vreg +
0,3
V Pin XTAL ■1.12
Input and Output
current (digital I/O
pins)
IIO,Digital ––4mAPin PP0, PP1, PP2■1.13
Input current (LF pins) IIn,LF ––4mAPin LF, XLF ■1.14
Input Pressure range pIn 0–2000kPa– ■1.15
2000 – 2500 kPa Max. 2 sec.
5 times over lifetime
■1.16
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Tire Pressure Monitoring Sensor
Specification
Datasheet 146 Revision 1.1, 2012-04-03
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Attention: Stresses above the max. values listed here may cause permanent damage to the device.
Exposure to absolute maximum rating conditions for extended periods may affect device
reliability. Maximum ratings are absolute ratings; exceeding only one of these values may
cause irreversible damage to the integrated circuit.
Static acceleration astatic – 3000 g – ■1.17
Mechanical shock ashock – 4000 g Level: 4000 g peak
Pulse duration: 0.3ms
Waveform: Half sine
Power: 3.0 V
5 shocks each dir. +/-
x,y,z-axis
(MIL-STD 883E)
■1.18
Table 29 Absolute Maximum Ratings
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
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Tire Pressure Monitoring Sensor
Specification
Datasheet 147 Revision 1.1, 2012-04-03
4.3 Operating Range
The following operating conditions must not be exceeded in order to ensure correct operation of the SP37T.
All parameters specified in the following sections refer to these operating conditions unless otherwise mentioned.
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 30 Operating Range
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Supply Voltage Vbat1 2.1 – 3.6 V Measurement of
pressure, acceleration
or temperature.
Operation of
LF receiver
■2.1
Vbat2 1.9 – 3.6 V Battery measurements,
microcontroller,
RF transmitter,
FLASH reading
■2.2
Vbat3 2.5– 3.6V FLASH
programming/erasing
■2.5
Ambient Temperature TOperating -40 – 125 °C Normal Operation ■2.11
TFlash 0–60°CFLASH
programming/erasing
■2.12
z-axis acceleration aOperating – 1600 g Exceeding this value
will result in a higher
pressure error than
specified in Table 31
■2.13
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Tire Pressure Monitoring Sensor
Specification
Datasheet 148 Revision 1.1, 2012-04-03
4.4 Characteristics
Product characteristics involve the spread of values within the specified voltage and ambient temperature range.
Supply voltage: Vbat = 1.9 V ... 3.6 V, unless otherwise specified
Ambient temperature: Tamb = -40°C ... +125°C, unless otherwise specified
4.4.1 Pressure Sensor (1300kPa variant)
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 31 Pressure Sensor (1300 kPa variant)1) , Vbat = 2.1 V...3.3 V
1) This table is based on the average of 2 ADC samples
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Minimum Input
Pressure
pin, min – – 100 kPa T= -40...125°C 4.1
Maximum Input
Pressure2)
2) The maximum input pressure is equal or greater than 1300 kPa for +40°C< T < 125°C. For -40°C < T < + 40°C, the
maximum input pressure is allowed to decrease below 1300 kPa but shall respect the following law:
Pin max >= 1300kPa + 4.15 * (T - 40°C)
pin, max 1300 – – kPa T= -40...125°C 4.2
Input Pressure Range pin,100-500 100 – 500 kPa T= -40...125°C 4.3
Measurement Error pError,100-500 -35 – +35 kPa T= -40...0°C 4.4
-23 – +23 kPa T= 0...80°C 4.5
-50 – +50 kPa T= 80...125°C 4.6
Input Pressure Range pin,500-1050 500 – 1050 kPa T= -40...125°C 4.8
Measurement Error pError,500-1050 -30 – +30 kPa T= -40...0°C 4.9
-23 – +23 kPa T= 0...40°C 4.10
-30 – +30 kPa T= 40...80°C 4.11
-40 – +40 kPa T= 80...125°C 4.12
Input Pressure Range pin,1050-1300 1050 – 1300 kPa T= -40...125°C 4.14
Measurement Error pError,1050-
1300
-35 – +35 kPa T= -40...0°C 4.15
-25 – +25 kPa T= 0...40°C 4.16
-30 – +30 kPa T= 40...80°C 4.17
-50 – +50 kPa T= 80...125°C 4.18
RAW LSB resolution pLSB,RAW 0.9– 2.0kPaT=-40°C ■4.19
1.12 – 2.3 kPa T= 25°C ■4.20
1.3 – 2.75 kPa T= 125°C ■4.21
Pressure
Measurement Stability
Range
psta -4.7 4.7 kPa Minimum 95% of the
measurements
■4.22
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 149 Revision 1.1, 2012-04-03
4.4.2 z-axis Acceleration Sensor
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 32 z-axis Acceleration Sensor1), Vbat = 2.1 V...3.3 V
1) This table is based on the average of 2 ADC samples
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Input Acceleration
Range
ain -115 – 115 g T= -40...125°C ■5.1
Sensitivity Error aSensitivity -18.75 – +18.75 % T= -40...90°C 5.2
-24 – +24 % T= 90...125°C 5.3
Offset Error aOffset -6 – +6 g T= -20...70°C 5.4
-8.5 – +8.5 g T= -40...-20°C
T= 70...90°C
5.5
-12 – +12 g T= 90...125°C 5.6
RAW LSB resolution aLSB,RAW 0.46 – 0.82 g T= -40°C ■5.9
0.53 – 0.93 g T= 25°C ■5.10
0.62 – 1.14 g T= 125°C ■5.11
Acceleration
Measurement Stability
Range
arandom -1.6 – +1.6 g Minimum 95% of the
measurements
■5.12
Accelerometer Quality
Factor
Qacc ––600– ■5.13
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 150 Revision 1.1, 2012-04-03
4.4.3 Temperature Sensor
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
4.4.4 Battery Sensor
Table 33 Temperature Sensor1), Vbat = 2.1 V...3.6 V
1) This table is based on the average of 2 ADC samples
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Measurement Error TError -3 – +3 °C T= -20...70°C 6.1
-5 – +5 °C T= -40..-20°C
T= 70..125°C
6.2
Temperature
Measurement Stability
Range
Tsta -1 +1 °C Minimum 95% of the
measurements
■6.3
Table 34 Battery Sensor1), Vbat = 2.1 V...3.6 V
1) This table is based on the average of 2 ADC samples
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Measurement Error VError -100 – +100 mV – 7.1
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 151 Revision 1.1, 2012-04-03
4.4.5 Supply Currents
Table 35 Supply Currents
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Supply Current RF
Transmission1)
Modulation: FSK
SFR DIVIC[1:0]: 11B
IP Low,1.9V,-40 ––8mAV
bat=1.9V, T=-40°C
SFR RFTX.PAOP = 00b
Pout ~1 dBm
Zload,434MHz ~ 500 Ohm
Zload,315MHz ~ 650 Ohm
■8.1
IP Low,3.0V,-40 ––9mAV
bat=3.0V, T=-40°C
SFR RFTX.PAOP = 00b
Pout ~5 dBm
Zload,434MHz ~ 500 Ohm
Zload,315MHz ~ 650 Ohm
■8.3
IP Low,3.0V,25 ––10mAV
bat=3.0V, T= 25°C
SFR RFTX.PAOP = 00b
Pout ~5 dBm
Zload,434MHz ~ 500 Ohm
Zload,315MHz ~ 650 Ohm
8.4
IP Low,3.0V,125 ––12mAV
bat= 3.0 V, T= 125°C
SFR RFTX.PAOP = 00b
Pout ~5 dBm
Zload,434MHz ~ 500 Ohm
Zload,315MHz ~ 650 Ohm
■8.5
IP Med,1.9V,-40 ––10mAV
bat=1.9V, T=-40°C
SFR RFTX.PAOP = 01b
Pout ~4 dBm
Zload,434MHz ~ 300 Ohm
Zload,315MHz ~ 450 Ohm
■8.6
IP Med,3.0V,-40 ––12mAV
bat=3.0V, T=-40°C
SFR RFTX.PAOP = 01b
Pout ~8 dBm
Zload,434MHz ~ 300 Ohm
Zload,315MHz ~ 450 Ohm
■8.8
IP Med,3.0V,25 ––14mAV
bat=3.0V, T= 25°C
SFR RFTX.PAOP = 01b
Pout ~8 dBm
Zload,434MHz ~ 300 Ohm
Zload,315MHz ~ 450 Ohm
8.9
IP
Med,3.0V,125
––15mAV
bat= 3.0 V, T= 125°C
SFR RFTX.PAOP = 01b
Pout ~8 dBm
Zload,434MHz ~ 300 Ohm
Zload,315MHz ~ 450 Ohm
■8.10
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 152 Revision 1.1, 2012-04-03
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
POWER DOWN
current
RAM lower memory
block powered down
SFR CFG2.PDLMB:1b
IPD,3.0V,25°C – – 700 nA Vbat= 3.0 V, T= 25°C 8.13
IPD,3.0V,90°C ––3.5µAV
bat=3.0V, T=90°C ■8.14
IPD,3.0V,125°C ––19.5µAV
bat= 3.0 V, T= 125°C 8.15
POWER DOWN
current
RAM lower memory
block kept powered
SFR CFG2.PDLMB:0b
IPD_RAMen,3.0
V,25°C
– – 750 nA Vbat=3.0V, T=25°C ■8.16
IPD_RAMen,3.0
V,90°C
––3.9µAV
bat=3.0V, T=90°C ■8.17
IPD_RAMen,3.0
V,125°C
––21µAV
bat= 3.0 V, T= 125°C ■8.18
THERMAL
SHUTDOWN current
RAM lower memory
block powered down
SFR CFG2.PDLMB:1b
ITS,3.0V,125°C ––170µAV
bat= 3.0 V, T= 125°C 8.19
THERMAL
SHUTDOWN current
RAM lower memory
block powered down
SFR CFG2.PDLMB:1B
ITS_RAMen,
3.0V, 125°C
––175µAV
bat= 3.0 V, T= 125°C ■8.20
IDLE current
SFR DIVIC: 00B
Timer0 active
IIdle,3.0V,25°C ––1mAV
bat= 3.0 V, T= 25°C 8.21
IIdle,3.0V,125°C ––1.1mAV
bat= 3.0 V, T= 125°C ■8.22
RUN current
(Peripheral units in
active state)
SFR DIVIC: 00B
IRun,3.0V,25°C ––2.1mAV
bat= 3.0 V, T= 25°C 8.23
IRun,3.0V,125°
C
––2.4mAV
bat= 3.0 V, T= 125°C ■8.24
RUN current (PLL
enabled)
SFR DIVIC: 11B
IPLL,3.0V,25°C ––8mAV
bat=3.0V, T=25°C ■8.25
IPLL,3.0V,125°
C
––9mAV
bat= 3.0 V, T= 125°C ■8.26
LF Receiver current
SFR bits LFBBM: 00B
ILF_Add,AFE 4µA ■8.27
LF Receiver current2)
SFR bits LFBBM: 01B
ILF_Add,l 6.1 µA Vbat=3.0V,
T= -40...90°C
■8.28
ILF_Add,f, 7.8 µA Vbat=3.0V,
T=-40...125°C
■8.29
1) These parameters were obtained using the SP37T Test Board. Tolerances of the passive elements (matching network) not
taken into account. The environment of the customer application have not been taken into account
2) This additional LF current is valid for all LF baseband conditions. The difference in current consumption between decoding
and not decoding is negligible.
Table 35 Supply Currents (cont’d)
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 153 Revision 1.1, 2012-04-03
4.4.6 RF Transmitter
Table 36 RF Transmitter1)
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Transmit Frequency fTx,315MHz 300 320 MHz – ■9.1
fTx,433.92MHz 433 450 MHz – ■9.2
Output Power
transformed into
50 Ohm
Plow,
433.92 MHz
456dBmV
bat=3.0V, T=25°C
SFR RFTX.PAOP = 00b
Zload~ 500 Ohm
9.5
Pmed,
433.92 MHz
789dBmV
bat=3.0V, T=25°C
SFR RFTX.PAOP = 01b
Zload~ 300 Ohm
9.6
Plow, 315 MHz 456dBmV
bat=3.0V, T=25°C
SFR RFTX.PAOP = 00b
Zload~ 650 Ohm
9.9
Pmed, 315 MHz 789dBmV
bat=3.0V, T=25°C
SFR RFTX.PAOP = 01b
Zload~ 450 Ohm
9.10
Output Power change
over temperature
dP-40°C 0–+1dBV
bat=3.0V, T=-40°C ■9.13
Output Power change
over temperature
dP125°C 0–-1.5dBV
bat= 3.0 V, T= 125°C ■9.14
Output Power change
over supply voltage
dP1.9V 0–-8dBV
bat=1.9V, T=25°C ■9.15
Output Power change
over supply voltage
dP2.5V 0–-2.8dBV
bat=2.5V, T=25°C ■9.17
Output Power change
over supply voltage
dP3.6V 0–+2.8dBV
bat=3.6V, T=25°C ■9.18
Datarate DRRF – – 10 kBit/s Equivalent to
20 kchips/s
■9.19
Datarate accuracy dDRRF ––+/-1%f
crystal =
18.080/19.6875MHz
DRRF = 9600Bit/s
SFR TMOD.T1CLK =
01b
SFR TMOD.TCLKM =
1b
■9.20
Spurious emissions
(incl. harmonics)
@ fTx = 315 MHz
Pspurii,FCC – – -28 dBc FCC 15.231a/e
2nd - 10th harmonic
other spurious <1GHz
■9.21
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 154 Revision 1.1, 2012-04-03
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Spurious emissions
(incl. harmonics)
@ fTx = 433.92 MHz
Pspurii,ETSI,RB – – -54 dBm ETSI EN300220
BW = 10 kHz, 47-
74 MHz, 87.5 MHz-
118 MHz, 174-
230 MHz, 470-
862 MHz
■9.22
Spurious emissions
(incl. harmonics)
@ fTx = 433.92 MHz
Pspurii,ETSI,<1
G
– – -36 dBm ETSI EN300220
BW = 10 kHz
other <1 GHz
■9.23
Spurious emissions
(incl. harmonics)
@ fTx = 433.92 MHz
Pspurii,ETSI,>1
G
– – -30 dBm ETSI EN300220
BW = 10 kHz >1 GHz
■9.24
Phase Noise PPN, 10kHz – – -80 dBc/H
z
fCarrier +/- 10 kHz ■9.25
PPN, 100kHz – – -80 dBc/H
z
fCarrier +/- 100 kHz ■9.26
PPN, 1 MHz – – -90 dBc/H
z
fCarrier +/- 1 MHz ■9.27
PPN, 10 MHz ––-120dBc/H
z
fCarrier +/- 10 MHz ■9.28
1) The parameter in this table were obtained using the SP37T Test Board. Tolerances of the passive elements (matching
network) not taken into account. The environment of the customer application have not been taken into account.
Table 36 RF Transmitter1) (cont’d)
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 155 Revision 1.1, 2012-04-03
4.4.7 LF Receiver
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 37 LF Receiver, Vbat = 2.1 V...3.6 V
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Differential Input
Capacitance
CInput,LF 8–12pF@ 125kHz ■10.1
Differential Input
Resistance DC
RInput,LF 1M Ohm AGC disabled 10.2
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 156 Revision 1.1, 2012-04-03
LF Receiver Telegram
Figure 68 LF Receiver Special Function Register Settings for Telegram Mode
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 38 LF Receiver Telegram, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Datarate DRLF –3.9–kBit/s– 10.6
Datarate error DRerror,c -2.5 2.5 % Using
“LFBaudrateCalibration
” ROM Library function
once for initial
calibration in production
@ Vbat= 2.5 V, T= 25°C
■10.8
Preamble length tpreamble 24–msDRLF = 3.9 kbit/s,tbit =
1/DRLF
■10.9
Settling time tsettling 2.4 3.5 5.8 ms LFRX enabled by
LFOOT1)
Min/Max tolerances
from 2 kHz RC
Oscillator applied
SFR LFRX1.ACT = 10b
SFR bit ENOOTIM = 1b
1) If LF Receiver (LFRX) is enabled by CPU via SFR LFRXC.ENLFRX or autocalibration cycle is started by
SFR LFRXC.CDRECAL then up to one additional 2 kHz RC oscillator period must be added to the given times
■10.10
LF Telegram
Sensitivity
LFtele,det,f 2.5 mVpp Refer to test case T-1.2 ■10.13
Table 39 LF Receiver Telegram, Vbat = 2.1 V...3.6 V, T = -20 °C...90 °C, fLF = 120 kHz...130 kHz
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
LF Telegram
Sensitivity
LFtele,det,l 1.3 mVpp Refer to test case T-1.2 10.19
// Basic LF Telegram Configuration
LFRX0 = 0x8C; // AGC Threshold, LF Antenna Voltage Divider Factor
LFRX1 = 0x20; // AGC Decay Time Constant, Autocalibration Time
LFRX2 = 0x77; // AGC Attack Time Constant
LFCDM0 = 0x1C; // Enable Autocalibration
LFRXC = 0x14; // Enable AGC, LF Baseband on while LFRx enabled, Enable LFRx
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 157 Revision 1.1, 2012-04-03
LF Receiver Carrier Detector
Figure 69 LF Receiver Special Function Register Settings for Carrier Detection
Table 40 LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Auto-Calibration time tcalibration,1 3.8 5.5 9.1 ms LFRX enabled by
LFOOT1)
Min/Max tolerances
from 2 kHz RC
Oscillator applied
SFR LFRX1.ACT = 01b
SFR bit ENOOTIM = 1b
■10.20
Maximum Amplitude
for Carrier Detector
Filter
Smax,f 30 mVpp Refer to test case T-1.1 ■10.22
LF Carrier Detect
Threshold 12)
Snodet,1,f 0.33 mVpp Refer to test case T-1.2 ■10.23
Sdet,1,f 3.35 mVpp ■10.24
LF Carrier Detect
Threshold 22)
Snodet,2,f 2 mVpp Carrier Detector Filter
Time 1
Refer to test case T-1.2
■10.25
Sdet,2,f 11 mVpp ■10.26
LF Carrier Detect
Threshold 32)
Snodet,3,f 10 mVpp Refer to test case T-1.2 ■10.27
Sdet,3,f 50 mVpp ■10.28
Carrier Detector Filter
Time 1
tCDnodet,1 62 µs Refer to test case T-1.1 10.29
tCDdet,1 240 µs 10.30
Carrier Detector Filter
Time 2
tCDnodet,2 500 µs Refer to test case T-1.1 ■10.31
tCDdet,2 800 µs ■10.32
Carrier Detector Filter
Time 3
tCDnodet,3 800 µs Refer to test case T-1.1 ■10.33
tCDdet,3 1150 µs ■10.34
// Defines
#define CDETT_Levels_Base_Address 0x580E
#define CDETT_Level 1// Configure Carrier Detector Threshold Level (values 1, 2 or 3)
#define CDFLT_Times_Base_Address 0x580B
#define CDFLT_Time 1// Configure Carrier Detector Filter Time (values 1, 2 or 3)
// Basic LF Carrier Detection Configuration, Sensitivity Settings, Filter Settings
LFCDM0 = 0x1C; // Carrier Detector Dynamic Treshold, Enable Autocalibration & Freeze Hold
// Load Carrier Detector Filter Time from Flash
LFCDFLT = CBYTE[CDFLT_Times_Base_Address-(CDFLT_Time-3)];
// Load Carrier Detector Threshold from Flash
LFRX0 = CBYTE[CDETT_Levels_Base_Address-(CDETT_Level-3)];
LFRX1 = 0x10; // AGC Decay Time Constant, Autocalibration Time
LFRX2 = 0x77; // AGC Attack Time Constant
LFRXC = 0x04; // Enable AGC, LF Baseband off, Enable LFRx
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 158 Revision 1.1, 2012-04-03
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Carrier Detection
Freeze Hold Time
tCDCFH,125 2 s T=125°C ■10.35
tCDCFH,25 300 s T=25°C ■10.36
1) If LF Receiver (LFRX) is enabled by CPU via SFR LFRXC.ENLFRX or autocalibration cycle is started by
SFR LFRXC.CDRECAL then up to one additional 2 kHz RC oscillator period must be added to the given times
2) For reliable carrier detection a minimum pulse length of 240µs is required
Table 41 LF Receiver Carrier Detection, Vbat = 2.3 V...3.3 V, T = -20 °C...90 °C, fLF = 120 kHz...130 kHz
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Maximum Amplitude
for Carrier Detector
Filter
Smax,l 100 mVpp Refer to test case T-1.1 ■10.37
LF Carrier Detect
Threshold 21)2)
1) For reliable carrier detection a minimum pulse length of 240µs is required
2) Tested with LF Carrier Detector Filter Time 1 - verified by characterization/design for LF Carrier Detector Filter Times 2, 3
Snodet,2,l 3 mVpp Carrier Detector Filter
Time 1
Refer to test case T-1.2
10.38
Sdet,2,l 10 mVpp 10.39
Table 40 LF Receiver Carrier Detection, Vbat = 2.1 V...3.6 V, fLF = 120 kHz...130 kHz (cont’d)
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 159 Revision 1.1, 2012-04-03
4.4.8 LF Test Cases
T-1.1, Test Case for large LF signal measurements
Setup
Figure 70 Test Circuit for large LF signal measurements
T-1.2, Test Case for small LF signal measurements
Setup
Figure 71 Test Circuit for small LF signal measurements
Test Circuit
50
ASIC
Vp=1/2*Q*50 mV/µT
Q = 2 .5
50
Vp=1/2*Q*50 mV/µT
Q = 2 .5
Note: Vppdiff = 4*Vp
50
16 .5k
50
16. 5k
LF
XLF
vLF
Alternate Test Circuit
100
16 .5k
100
16 .5k
Epcos
B1032
ASIC
LF
XLF
50
vLF
Test Circuit
50
ASIC
V
p
=1/2*Q*50 mV/µT
Q = 2 .5
50
V
p
=1/2*Q*50 mV/µT
Q = 2 .5
Note: V
ppdiff
= 4*V
p
50
50
LF
XLF
vLF
Alternate Test Circuit
100
100
Epcos
B1032
ASIC
LF
XLF
50
vLF
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 160 Revision 1.1, 2012-04-03
4.4.9 Crystal Oscillator
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 42 Crystal Oscillator, fCrystal = 18 MHz...20 MHz
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Crystal startup time tXTAL,Startup – 700 1250 µs Measured on SP37T
Test Board (see “Test
Board” on Page 142)
with Crystal NX5032SD
EXS00A-03552
CL=12 pF, fCrystal =
18,08 MHz
■12.1
Parasitic capacitance
from XTAL pin to GND
(PCB tracks, XTAL
shield, etc.)
Cparasitic ––4pF– ■12.2
Serial resistance of
the crystal
RRmax ––60Ohm– 12.3
Input inductance LOSC,3.0V,25°
C
2.02.93.8µHV
bat= 3.0 V, T= 25°C 12.4
LOSC 1.82.94.3µH– ■12.5
Internal cap bank
maximum capacitance
Cbank 36 40 44 pF Between pin XTALCAP
and pin XGND
SFR XTAL1 = FFH
SFR RFENC.TXDD = 1
■12.6
FSK Switch ON
resistance
RSwitch,ON 60 Ohm Between pin XTALCAP
and pin XGND
SFR bit FSKSWITCH =
1B
SFR RFENC.TXDD = 1
12.7
FSK Switch OFF
resistance
RSwitch,OFF 100 kOhm Between pin XTALCAP
and pin XGND
SFR bit FSKSWITCH =
0B
SFR RFENC.TXDD = 1
12.8
FSK Switch OFF
capacitance
CSwitch,OFF 3.2 3.5 3.8 pF Between pin XTALCAP
and pin XGND
SFR XTAL1 = 0x00B
SFR bit FSKSWITCH =
0B
SFR RFENC.TXDD = 1
■12.9
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 161 Revision 1.1, 2012-04-03
4.4.10 12 MHz RC HF Oscillator
4.4.11 2 kHz RC LP Oscillator
Table 43 12 MHz RC HF Oscillator
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Operating frequency fRC,HF 11.04 12.00 12.96 MHz 13.1
Table 44 2 kHz RC LP Oscillator
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Operating frequency fRC,LP 1.32 2.7kHzV
bat= 3.0 V, T= 25°C 14.1
Frequency drift dfRC,LP -7 – +7 % – 14.2
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 162 Revision 1.1, 2012-04-03
4.4.12 Interval Timer & LF On/Off Timer
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 45 Interval Timer / LF On/Off Timer
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Interval Timer
Precounter calibration
error
dfITP -0.083 – 0 %/Hz Error is dependent
upon Interval Timer
timebase specified to
“Interval Timer
Calibration” ROM
Library function.
This error does not
include reference clock
(XTAL or 12 MHz RC
oscillator) and
2 kHz RC LP oscillator
drift errors.
■15.1
LF On/Off Timer
calibration error
“On” Time
dfLFON -1.64 – 4.92 % Error is assumes usage
of “Interval Timer
Calibration” ROM
Library function.
This error does not
include reference clock
(XTAL or 12 MHz RC
oscillator) and
2 kHz RC LP oscillator
drift errors.
■15.2
LF On/Off Timer
calibration error
“Off” Time
dfLFOFF -1.64 – 0 % Error is assumes usage
of “Interval Timer
Calibration” ROM
Library function.
This error does not
include reference clock
(XTAL or 12 MHz RC
oscillator) and
2 kHz RC LP oscillator
drift errors.
■15.3
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 163 Revision 1.1, 2012-04-03
4.4.13 Voltage Regulator
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 46 Voltage Regulator1)2)
1) The voltage regulator is designed to supply only the internal blocks of the SP37T and not designed to drive any external
circuitry, thus only the decoupling cap is allowed to be connected to pin Vreg. A 100nF decoupling cap with an maximum
ESR of 15 Ohm is recommended for proper operation.
2) The voltage regulator is designed to supply only the internal blocks of the SP37T. It is not designed to drive any external
circuitry, including the embedded PA. A 100nF decoupling cap with an maximum ESR of 15 Ohm is recommended for
proper operation. It is not prohibited to connect the PA to pin Vreg as long as the customer verifies that the behavior of the
different SP37T devices is always correct and within the specification.
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Regulated output
voltage in RUN state
VREG 1.92.12.4V V
bat=2.1V - 3.6V, 17.1
Regulated output
voltage at low battery
in RUN state
VREG,Low 1.8– 2.1V V
bat= 1.9 V - 2.1 V 17.2
Regulated output
voltage in
Programming mode
VREG 2.3 2.5 2.75 V Vbat= 2.5 V - 3.6 V 17.4
Regulated output
voltage in
POWERDOWN and
THERMAL
SHUTDOWN
VREG,PD 1.7– 2.5V – 17.5
External Capacitance
at Vreg Pin
CVREG 60 100 – nF Maximum ESR 15 Ohm ■17.6
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 164 Revision 1.1, 2012-04-03
4.4.14 Power On Reset / Brown Out Reset
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
4.4.15 VMIN Detector
Table 47 Power On Reset / Brown Out Reset
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Power On Reset level VPOR 0.2 0.4 1.7 V Min. supply voltage
level measured at Pin
VREG for a valid logic
LOW at Power On
Reset circuit
■16.1
Power On Reset
release level
VTHR 1.7 – 1.8 V Measured at Pin VREG 16.3
Power On reset time tPOR 0.25 – 10 ms – 16.4
Brown Out detect level
in RUN state
VRUN,BRD 1.7 – 1.8 V Measured at Pin VREG 16.5
Brown Out detect level
in POWERDOWN and
THERMAL
SHUTDOWN
VPD,BRD 0.7 – 1.7 V Measured at Pin VREG 16.8
Mode selection time tmode ––2.5ms– ■16.10
Minimum detectable
Brown Out glitch in
RUN state
tBrownout,RUM ––1µs– ■16.11
Minimum detectable
Brown Out glitch in
POWERDOWN and
THERMAL
SHUTDOWN state
tBrownout,PD ––100µs– ■16.12
Table 48 VMIN Detector
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Low battery threshold
warning level
THLBAT 2.0 2.1 2.2 V Used by ROM Library
functions only
18.1
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 165 Revision 1.1, 2012-04-03
4.4.16 FLASH Memory
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
4.4.17 TMAX Detector
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 49 FLASH Memory
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Erase/Program
temperature
TFL 0–+60°C– ■19.1
Erase/Program supply
voltage
Vbat3 2.5– 3.6V – ■19.2
Endurance EnFlash 100 – – cycles Programming/erase
cycles per wordline
■19.3
Erase time tErase – 102 – ms Min/max can be derived
by adding the tolerance
and drift of the
12 MHz RC HF Osc.
(see Table 43)
■19.4
Write time per FLASH
line
tProgram – 2.2 – ms FLASH line = 32 Byte
min/max can be derived
by adding the tolerance
and drift of the
12 MHz RC HF Osc.
(see Table 43)
■19.5
Table 50 TMAX Detector
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
THERMAL
SHUTDOWN release
temperature
TTMAX,Release 115.5 – – °C Used by
“ThermalShutdown”
ROM Library function
only. The TMAX enable
temperature is verified
to be above the release
temperature.
■20.1
THERMAL
SHUTDOWN enable
temperature
TTMAX, Enable 117 – 125 °C 20.2
SP37T
Tire Pressure Monitoring Sensor
Specification
Datasheet 166 Revision 1.1, 2012-04-03
4.4.18 Watchdog Timer
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
4.4.19 Digital I/O pins
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
4.4.20 I2C Interface
Attention: Test ■ means that the parameter is not subject to production test.
It was verified by design/characterization.
Table 51 Watchdog Timer
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Watchdog timeout tWatchdog 0.6 1 1.7 s Min/max is derived by
considering the
tolerance and drift of
the 2 kHz RC LP Osc.
(see Table 44)
■21.1
Table 52 Digital I/O pins
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
Input LOW voltage VIL -0.2 – 0.4 V – 22.1
Input HIGH voltage VIH VBat -
0.4
– VBat +
0.2
V– 22.2
Output LOW voltage VOL – – 0.5 V IOL= 1.6 mA 22.3
Output HIGH voltage VOH VBat -
0.5
– – V IOH= -1.6 mA 22.4
Output transition time tHL, LH – – 30 ns 20 pF load, 10% ... 90% ■22.5
Parasitic capacitance Cpad ––5pF– ■22.6
Internal pullup /
pulldown resistor
Rup/down 35 50 70 kOhm Pin PP0, PP1 22.7
Rup/down 175 250 335 kOhm Pin PP2 22.8
Table 53 I2C Interface
Parameter Symbol Values Unit Note / Test Condition Test Number
Min. Typ. Max.
I2C bitrate DRI2C – – 400 kbit/s SFR DIVIC[1:0]: 00B■23.1
SP37T
Tire Pressure Monitoring Sensor
Package Information
Datasheet 167 Revision 1.1, 2012-04-03
5 Package Information
5.1 Package Outline
Figure 72 PG-DSOSP-14-6 Package Dimensions
Dimensions in [mm]1)2)
1) Dimension does not include mold flash, protrusions or gate burrs. Mold flash, protrusions and gate burrs do not exceed
0.15mm (0.006 inch) per side.
2) Dimension does not include inter-lead flash or protrusions. Inter-lead flash and protrusions do not exceed 0.25mm (0.010
inch) per side.
SP37T
Tire Pressure Monitoring Sensor
Package Information
Datasheet 168 Revision 1.1, 2012-04-03
5.2 Identification Code
Figure 73 PG-DSOSP-14-6 marking
The marking for the SP37T is on the topside of the package.
5.2.1 Identification Code Definition
KKJWWNNNSXX: Infineon Lot Number
ZZZZZ: Product Identification (SP370)
O: Pin 1 Marking
NNNNN: Manufacturer Version (NN = 23 Villach Sensor) and Sensor Information Code (NN = 15)
G: Green Package Indicator1)
YYWW: Date Code (YY = Year, WW = week)
1) The Green Package fulfils the solder condition for Pb-Free Assembly according to IPC/JEDEC J-STD-020C.
SP37T
Tire Pressure Monitoring Sensor
References
Datasheet 169 Revision 1.1, 2012-04-03
References
This section contains documents used for cross-reference throughout this document.
[1] SP37T ROM Library function guide
Published by Infineon Technologies AG
www.infineon.com