MMA9555LR1 - NXP SEMICONDUCTORS

NXP Semiconductors Document Number: MMA9555L

Data Sheet: Technical Data Rev. 2.3, 8/2016

All information provided in this document is subject to legal disclaimers.

MMA9555L Intelligent Motion-

Sensing Pedometer

The MMA9555L intelligent motion-sensing pedometer is an extension of the

MMA955xL intelligent sensor platform. This device incorporates a 3-axis

MEMS accelerometer, signal conditioning, data conversion, and a 32-bit

microcontroller. This intelligent motion-sensing sensor provides sophisticated

pedometer functionality , activity level and six directional orientation monitoring.

The integrated functionality of sensor initialization, calibration, data

compensation, and computation functions off-loads CPU bandwidth from the

system application processor. Therefore, total system power consumption is

significantly reduced, because the application processor stays powered down

until absolutely needed. In addition, the device can be configured for an

autosleep/autowake capability.

MMA9555L is available in a plastic LGA package; the device is guaranteed to

operate over the extended temperature range of –40 °C to +85 °C.

Features

• High resolution 3-axis accelerometer with

16-bit ADC (0.061 mg/LSB @ 2 g)

• Selectable g range (±2/4/8 g) and output data rates (488 Hz–3.8 Hz)

• One slave SPI or I2C interface operating at up to 2 Mbps for communication

with the host processor

• 1.8 V supply voltage low power consumption

•2

µA typical current at stop mode

•117 µA for pedometer running at active and 92 µA at suspend

• 87 µA when six-direction detection mode

• Complete built-in firmware for smart sensing intelligence

• Real time and preemptive application task scheduling

• Command interpreter support command/response and streaming

mode

• Low-power pedometer with rich output information

– Step counting

– Speed, distance, calorie count estimation

– Activity level (rest, walking, jogging, running)

• Six-direction detection output

• Extensive set of power-management features and low-power

mode

• GPIO2–GPIO8 can be used for expanded configurable GPIO

functions

• Minimal external component requirements

16-pin LGA

3 mm x 3 mm x 1 mm

Case 2094- 01

MMA9555L

Top view

Pin Connections

VDD

BKGD-MS /

RGPIO9

VSS

RGPIO7 / AN1

VSSA

678

16 15 14

RGPIO8 / PDB_B

VDDA

RGPIO1 / SDA0 / SDI

RGPIO2 / SDO

RGPIO3 / SSB

RESETB

SCL0 / RGPIO0 /

SCLK

RGPIO6 / AN0

RGPIO5 /

PDB_A / INT_O

VSS

RGPIO4/INT

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

Typical Applications

This low-power, intelligent sensor is optimized for use in portable and mobile consumer products such as:

• Pedometers, wearable devices, smart watches, wristband

• Sleep monitoring

• Smart earphone

• Health mo ni to ri n g

Related Documentation

The MMA9555L device features and operations are described in reference manuals, release notes, and application notes. To

find the most-current versions of these documents:

1. Go to the NXP homepage at: nxp.com.

2. In the Keyword search box at the top of the page, enter the device number MMA9555L.

In the Refine Your Results pane on the left, click on the Documentation link.

Ordering information

Part number Firmware Temperature range Package description Shipping

MMA9555LR1 Pedometer + Six

Directions of Orientation +

GPIO Input/Output –40 °C to +85 °C LGA-16 Tape and reel

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Contents

1 Intelligent Sensing Platform Offering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5

2 General Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

2.1 Functional Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.2 Pinout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.3 Pin Function Descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.4 System Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

3 Mechanical and Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

3.1 Definitions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.2 Pin Groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.3 Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.4 Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.5 Electrostatic Discharge (ESD) and Latch-up Protection Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.6 General DC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

3.7 Supply Current Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.8 Accelerometer Transducer Mechanical Characte ristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.9 ADC Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.10 ADC Sample Rates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.11 AC Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.12 General Timing Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.13 I2C Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.14 Slave SPI Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 Communication Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

4.1 Overview of Communication Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.2 Mailbox Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.3 Mailbox Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5 Version Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

5.1 Reading the version information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6 Scheduler Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

6.1 Scheduler application elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

6.2 Interrupts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6.3 Scheduler configuration registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6.4 Scheduler status registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

7 GPIO-AppMap Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37

7.1 Overview of GPIO-AppMap application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

7.2 GPIO configuration registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

8 Mailbox Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

8.1 Overview of Mailbox application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

8.2 Mailbox configuration registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

8.3 Mailbox status registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

8.4 Reading aggregated data (Legacy mode—Quick read) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

9 Analog Front End Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48

9.1 Overview of Analog Front End application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

9.2 AFE configuration registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

9.3 AFE status registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

10 Data FIFO Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

10.1 Overview of Data FIFO application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

10.2 Modes of operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

10.3 Reading process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

10.4 Data FIFO block diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

10.5 Data FIFO configuration registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

10.6 Data FIFO status registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

11 Event Queue Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71

11.1 Overview of Event Queue application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

11.2 Event Queue configuration registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

11.3 Event Queue status registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

12 Status Register Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78

12.1 Overview of Status Register application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

12.2 Status Register configuration registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

12.3 Status Register default configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

13 Sleep/Wake Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83

13.1 Overview of Sleep/Wake application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

13.2 Sleep/Wake configuration registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

13.3 Sleep/Wake status registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

14 Reset/Suspend/Clear Control Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

14.1 Overview of Reset/Suspend/Clear Control applicatio n. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

14.2 Configuration registers for Reset/Suspend/Clear Control applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

14.3 Reset/Suspend/Clear status registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

14.4 Reboot to ROM CI from flash code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

14.5 Reboot to flash code from ROM CI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94

15 MBOX Configuration Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95

15.1 Overview of MBOX Configuration application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

15.2 Normal mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

15.3 Legacy mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

15.4 Configuring mailbox operational mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

15.5 MBOX Configuration memory map and register. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

16 Pedometer Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .99

16.1 Background and overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

16.2 Functional description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

16.3 Memory-maps and register descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103

16.4 Pedometer application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

17 GPIO Input/Output Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114

17.1 Overview of GPIO Input/Output application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

17.2 Memory maps and register descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

17.3 GPIO Input/Output configuration register descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

17.4 GPIO Inpu t/Output Status register descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

17.5 GPIO Input/Output application examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

18 Six-Direction Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119

18.1 Overview of the Six-Direction application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

18.2 Memory maps and register descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

18.3 Six Direction configuration register descriptions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120

18.4 Six Direction Status register descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

19 Sample operations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123

19.1 Read pedometer status variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.2 Read pedometer configuration variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.3 Write pedometer configuration variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.4 Read GPIO Input/output status variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.5 Read GPIO Input/output configuration variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.6 Write GPIO Input/output configuration variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.7 Read Six direction status variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.8 Read Six direction configuration variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

19.9 Write Six direction configuration variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

19.10 Reset pedometer configuration variables to their defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

19.11 Enable/disable the Pedometer appli cati on . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

19.12 Configure the AFE range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

19.13 Configure output interrupt: Activity change on GPIO6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

19.14 Configure output interrupt: Step change on GPIO7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

19.15 Configure output interrupt: Suspend change on GPIO8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

19.16 Configure output interrupt: Merged flags on GPIO6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

19.17 Configure output interrupt: Every 10 steps on GPIO7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

19.18 Configure output interrupt: Device directi on change on GPIO6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

19.19 Wake up from Deep Sleep (Stop No Clock mode) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

20 Package Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .126

20.1 Footprint and pattern information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

20.2 Marking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

20.3 Tape and reel information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

20.4 Package Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

1 Intelligent Sensing Platform Offering

NXP has a broad offering of MMA955xL devices.

The MMA9550L, MMA9551L, MMA9553L, and MMA9555L devices can function immediately as shipped. They have an internal

command interpreter and applications scheduler. These devices can interact directly with the users' host system.

The MMA9550L, MMA9551L, MMA9553L and MMA9559L devices are programmable with additional user application software.

These devices have a variety of user flash and RAM memory space available. The MMA9555L is provided with complete factory

build application specific software, no addition al us er software programming in the device is needed.

NOTE

The information and specifications provided in this data sheet are specific to the MMA9555L.

Information for the other devices can be found in the MMA955xL collateral and datasheet.

Table 1. NXP Intelligent Sensing Product Comparison

Feature - Device MMA9550L MMA9551L MMA9553L MMA9555L MMA9559L

Key elements Motion sensing Gesture sensing Pedometer

Pedometer

six-direction orientation

GPIO Input/Output

High flexibility

ADC resolution (bits) 10,12,14,16 bits 10,12, 14,16 bits 10,12,14,16 bits 10,12,14,16 bits 10,12,14,16

bits

g measurement ranges 2 g, 4 g, 8 g2 g, 4 g, 8 g2 g, 4 g, 8 g2 g, 4 g, 8 g2 g, 4 g, 8 g

Real-time and preemptive

scheduling Yes Yes Yes Yes No

Event management No No No No Yes

Slave Port Command Interpreter

• Normal mode Yes Yes Yes Yes No

• Legacy mode Yes Yes Yes Yes No

• Streaming mode Yes Yes Yes Yes No

Front-end processing

• 100 Hz BW anti-aliasing Yes Yes Yes Yes No

• 50 Hz BW anti-aliasing Yes Yes Yes Yes No

•g-mode-dependent resolution Yes Yes Yes Yes Yes

• Absolute value Yes Yes Yes Yes No

• Low-pass filter Yes Yes Yes Yes No

• High-pass filter Yes Yes Yes Yes No

• Data-ready interrupt Yes Yes Yes Yes Yes

Gesture applications

• High g/Low gNo Yes No No No

• Tilt No Yes No No No

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

• Portrait/Landscape No Yes No No No

• Programmable orientation No Yes No No No

• Tap/Double-tap No Yes No No No

• Freefall No Yes No No No

•Motion No Yes No No No

Data-storage modules

• Data FIFO Yes Yes Yes Yes No

• Event queue Yes Yes Yes Yes No

• Inter-process FIFO No No No No Yes

Power-control module

• Run and Stop on idle Yes Yes Yes Yes Yes

• Run and No stop Yes Yes Yes Yes Yes

• Stop NC Yes Yes Yes Yes Yes

• Auto-Wake / Auto-Sleep / Doze Yes Yes Yes Yes No

Data-management daemons Yes Yes Yes Yes Yes

Pedometer applications

• Step count No No Yes Yes No

•Distance No No Yes Yes No

• Adaptive distance No No Yes Yes No

• Activity monitor No No Yes Yes No

Six Directional Orientation No No No Yes No

GPIO management No No No Yes No

Table 1. NXP Intelligent Sensing Product Comparison (Continued)

Feature - Device MMA9550L MMA9551L MMA9553L MMA9555L MMA9559L

Functional Overview

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

2 General Description

2.1 Functional Overview

The MMA9555L is an intelligent motion sensing pedometer , it consists of a 3-axis, MEMS accelerometer and a mixed-signal ASIC

with an integrated, 32-bit CPU. The mixed-signal ASIC can be utilized to measure and condition the outputs of the MEMS accel-

erometer, internal temperature sensor, or a differential analog signal from an external device.

The calibrated, measured sensor outputs can be read via the slave I2C or SPI port and utilized internally within the MMA9555L

to provide advanced intelligent motion detection outputs like pedometer step count, activity le vel and six directional orientation

detections which can be accessed via the slave I2C or SPI port.

Figure 1. MMA955 5L block diagram

A block-level view is shown in Figure 1 with building blocks of devices and built-in applications summarized at a high level. The

analog/mixed-mode subsystem associated with a digital engine is composed of:

• The analog subsystem is composed of:

• A 3-axis transducer that is an entirely passive block including the MEMS structures.

• An Analog Front End (AFE) with the following:

– A capacitance-to-voltage converter

– An analog-to-digital converter

– A temperature sensor

• The digital subsystem is composed of:

• A 32-bit CPU

• Memory: RAM, ROM, and flash

• Rapid GPIO (RGPIO) port-control logic

Analog Front End (AFE)

BDM

INTC

DBG

Flash

ROM

RAM

C Master

axis

C to V

ADC

Temp

Sensor

C slave

SPI slave

Control

and

mailbox

CLKGEN

Two-channel, 16-bit

Timer / PWM module

16-bit

Modulo timer module

Programmable

delay block

INT_O

axis

RESET

DDA

SSA

RGPIO

SCL0/RGPIC0/SCLK

SDA0/RGPIO1/SDI

RGPIO2/SCL1/SDO

RGPIO3/SDA1/SSB

RGPIO4/INT

RGPIO5/PDB_A/INT_O

RGPIO6/AN0/TPMCH0

RGPIO7/AN1/TPMCH1

RGPIO8/PDB_B

BKGD/MS/RPGPIO9

AN0

AN1

TPMCH0

TPMCH1

SCL1

SDA1

PDB_A

PDB_B

SCLK

SDI

SDO

SSB

SCL0

SDA0

SIM

BKGD

INT

32 bit CPU

Pinout

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

–I

2C or SPI slave interface

– System Integration Module (SIM)

– Clock-Generation Module

The slave interfaces (either SPI or I2C) operate independently of the CPU subsystem. They can be accessed at any time,

including while the device is in low-power, deep-sleep mode.

2.2 Pinout

The package pinout definition for this device is designed as a superset of functions on NXP's other MMA955xL offerings. All pins

on the device are utilized a nd many are multiplexed.

Figure 2. Device pinout (top view)

2.2.1 Pin Functions

The following table summarizes functional options for each pin on this device.

Table 2. Pin functions

Pin # Pin Name Description

1VDD Digital power supply

2BKGD / MS / RGPIO9 Background-debug / Mode select / RGPIO9

3RESETB Active-low reset. RESETB is an open-drain, bidirectional pin. By default, the output function is not on. Must

be pulled to VDD via resistor at startup. After startup, Reset may be asserted low to reset the device.

4SCL0 / RGPIO0 / SCLK Serial clock for slave I2C / RGPIO0 / Serial clock for slave SPI

5VSS Digital ground

6SDA0 / RGPIO1 / SDI Serial data for slave I2C / RGPIO1 / SPI serial data input

7RGPIO2 / SDO RGPIO2 / SPI serial data output

8RGPIO3 / SBB RGPIO3 / SPI slave select. RGPIO3 / SSB = Low at startup selects SPI. High at startup selects I2C.

BKGD-MS / RGPIO9

RGPIO7 / AN1

SSA

678

16 15 14

RGPIO8 / PDB_B

DDA

RGPIO1 / SDA0 / SDI

RGPIO2 / SDO

RGPIO3 / SSB

RESETB

SCL0 / RGPIO0 / SCLK

RGPIO6 / AN0

RGPIO5 / PDB_A / INT_O

RGPIO4/INT

Pin Functio n Descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

2.3 Pin Function Descriptions

This section provides a brief description of the various pin functi ons available on the MMA9555L pedometer sensor. Ten of the

device pins are multiplexed with Rapid GPIO (RGPIO) functions.

VDD and VSS: Digital power and ground. VDD is nominally 1.8 V.

VDDA and VSSA: Analog power and ground. VDDA is nominally 1.8 V. To optimize performance, the VDDA line can be filtered to

remove any digital noise that might be present on the 1.8 V supply. (See Figure 3 and Figure 4.)

RESETB: The RESETB pin is an open-drain, bidirectional pin with an internal, weak, pullup resistor. At start-up, it is configured

as an input pin, but also can be programmed to become bidirectional. By default, the output function is not on. Using this feature,

the MMA9555L device can reset external devices for any purpose other than power-on reset. Reset must be pulled high at power

up to boot to Application code space. If low, it will boot to ROM code. After startup, Reset may be asserted to reset the device.

The total external capa citance to ground has to be limited when using RESETB-pin, output-drive capability . For more det ails, see

the “System Integration Modu le” chapter of the MMA955xL Intelligent, Motion-Sensing Platform Hardware Reference Manual

(MMA955xLHWRM), listed in “Related Documentation” on page 2.

Slave I2C port: SDA0 and SCL0: These are the slave-I2C data and clock signals, respectively. The MMA9555L device can be

controlled via the serial port or via the slave SPI interface.

Analog-to-Digit al Conversion: AN0, AN1: The on-chip ADC can be used to perform a differential, analog-to-digital conversion

based on the voltage present across pins AN0(–) and AN1(+). Conversions for these pins are at the same Output Data Rate

(ODR) as the MEMS transducer signals. Input levels are limited to 1.8 V differential.

Rapid General Purpose I/O: RGPIO[9:0]: The Intelligent Pedometer has a feature called Rapid GPIO (RGPIO). This is a 16-bit,

input/output port with single-cycle write, set, clear, and toggle functions available to the CPU. The MMA9555L device brings out

the lower 10 bits of that port as pins of the device. At reset, all of the RGPIO pins are configured as input pins, although pin muxing

does reassign some pins to non-RGPIO function blocks. Pullups are disabled.

RGPIO[9:6] can be set as interrupt pins for most interrupt sources. INT_O can only output interrupts from the COCO bit. For

setting sensor data output interrupts, use RGPIO6–RGPIO9.

RGPIO3 / SBB = Low at startup selects SPI. High at startup selects I2C.

RGPIO[5] or INT_O can only output interrupts from the COCO bit. For setting sensor data output interrupts, use RGPIO6–

RGPIO9.

RGPIO[9] is connected to BKGD/MS.

RGPIO[1:0] SDA0 and SCL0 are connected at reset.

Interrupt s: INT: This input pin can be used to wake the CPU from a deep-sleep mode. It can be programmed to trigger on either

rising or falling edge, or high or low level. This pin operates as a Level-7 (high-priority) interrupt.

Debug/Mode Control: BKGD/MS: At start-up, this pin operates as mode select. If this pin is pulled high during start up, the CPU

will boot normally and run code. If this pin is pulled low during start-up, the CPU will boot into active Background-Debug Mode

(BDM). In BDM, this pin operates as a bidirectional, single-wire, background-debug port. It can be used by development tools for

downloading code into on-chip RAM and flash and to debug that code. There is an internal pullup resistor on this pin, therefore,

It may be left floating.

9RGPIO4/INT RGPIO4 / Interrupt input

10 RESERVED Must be connected to VSS ground externally

11 RGPIO5 / INT_O RGPIO5 or INT_O slave-port interrupt output. INT_O can only output interrupts from the COCO bit. For

setting sensor data output interrupts, use RGPIO6–R GPIO9.

12 RGPIO6 / AN0 RGPIO6 / ADC Input 0

13 RGPIO7 / AN1 RGPIO7 / ADC Input 1

14 VDDA Analog power

15 RGPIO8 RGPIO8

16 VSSA Analog ground

Table 2. Pin functions (Continued)

Pin # Pin Name Description

System Connections

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Slave SPI Interface: SCLK, SDI, SDO and SBB: These pins control the slave SPI clock, data in, data out, and slave-select

signals, respectively. The MMA9555L platform can be controlled via this serial port or via the slave-I2C interface. SBB has a

special function at startup that selects the Slave interface mode. Low at startup selects SPI and high selects I2C.

INT_O: The slave-port output interrupt pin can be used to flag the host when a response to a command is available to read on

the slave port. INT_O can only output interrupts from the COCO bit. For sensor data output interrupts, use RGPI06–RGPIO9.

2.4 System Connections

2.4.1 Power Sequencing

An internal cir c ui t po w e re d by VDDA provides the device with a power-on-reset signal. In order for this signal to be properly rec-

ognized, it is important that VDD is powered up before or simultaneously with VDDA. The voltage potential between VDD and VDDA

must not be allowed to exceed the value specified in Table 6 on page 14.

2.4.2 Layout Recommendations

• Provide a low-impedance path from the board power supply to each power pin (VDD and VDDA) on the device and from the

board ground to each ground pin (VSS and VSSA).

• Place 0.01 to 0.1 µF capacitors as close as possible to the package supply pins to meet the minimum bypass requirement.

The recommended bypass configuration is to place one bypass capacitor on each of the VDD/VSS pairs. VDDA/VSSA ceramic

and tantalum capacitors tend to provide better tolerances .

• Capacitor leads and associated printed-circuit traces that connect to the chip VDD and VSS (GND) pins must be as short as

possible.

• Bypass the power and ground with a capacitor of approximately 1 µF and a number of 0.1-µF ceramic capacitors.

• Minimize PCB trace lengths for high-frequency signals. This is especially critical in systems with higher capacitive loads that

could create higher transient currents in the VDD and VSS circuits.

• Take special care to minimize noise levels on the VDDA and VSSA pins.

• Use separate power planes for VDD and VDDA and separate ground planes for VSS and VSSA. Connect the separate analog

and digital power and ground planes as close as possible to powe r supply outputs. If both analog circuit and digital circuits

are powered by the same power supply , it is advisable to connect a small inductor or ferrit e bead in series with both the VDDA

and VSSA traces.

• Physically separate the analog components from noisy digital components by ground planes. Do not place an analog trace

in parallel with digital traces. It is also desirable to place an analog ground trace around an analog signal trace to isolate it

from digital traces.

• Provide an interface to the BKGD/MS pin if in-circuit debug capability is desired.

• Ensure that resistors RP1 and RP2, in the following figure, match the requirements stated in the I2C standard. For the shown

configuration, the value of 4.7 kΩ would be appropriate.

2.4.3 MMA9555L Pedometer Sensor as an Intelligent Slave

I2C pullup resistors, and a few bypass capacitors are all that are required to attach this device to a host platform. The basic con-

figurations are shown in the following two figures. In addition, the RGPIO pins can be programmed to generate interrupts to a

host platform in response to the occurrence of real-time application events. In this case, the pins should be routed to the external

interrupt pins of the CPU.

NOTE

Immediately after a device reset, the state of pin number 8 (RGPIO3 / SDA1 / SSB functions) is used to select the slave port

interface mode. This implies important rules in the way the host controller or, more generally, the complete system should be

handling this pin.

First of all, whenever a reset occurs on the MMA9555L, the RGPIO3 pin level shall be consistent with the interface mode of op-

eration. This is particularly important if this pin is driven from external devices. If the RGPIO3 level does not match the current

mode of operation, an alternate mode is selected and communication with the ho st is lost.

If I2C mode is used, a good practice is to tie RGPIO3 to a pull-up resistor so that it defaults to high level. When using I2C mode

for the slave interface, the RGPIO3 pin plays two roles: RGPIO3 and mode selection. When the MMA9555L is powered on and

the mode selection is I2C, the RGPIO3 pin is released as a GPIO pin. The default setting of RGPIO3 is as an output pin and

System Connections

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

output low. In order to reduce the leakage current on the pull-up resistor, a large resistor value can be used or RGPIO3 can be

set as an input pin.

When using SPI mode for the slave interface, the situation is more complex as the same pin plays two roles: SSB and mode

selection. Moreover, after a SPI read or write operation, the SSB line returns to high level. Consequently, if the host is sending a

command to the MMA9555L that induces a subsequent reset, immediately after the write transaction, the host shall force the

SSB line to low level so that SPI mode is still selected af ter reset. The duration for the SSB line to be kept low typically depends

on the latency between the write transaction and the execution of the reset command. Such latency can be significant for the

MMA9555L pedometer firmware as the Command Interpreter and Scheduler Application are running at 30 Hz which gives a

33 ms typical latency.

The rule obviously applies also when a hardware reset is issued by the host through MMA9555L pin number 3 (RESETB active

low). Again the host has to drive the SSB line low prior to release of the hardware reset line to high level, which triggers immediate

MMA9555L reset and boot sequence. Keeping the SSB line low for a 1 ms duration (after RESETB is released) is enough for the

MMA9555L slave device to re-boot into SPI mode.

Figure 3. MMA9555L Pedo meter Sensor as an I2C slave

1.8 V

Quiet VDDA for

best performance

C1*

1 F

0.1 F

INT_OUT

I2C_DATA

I2C_CLK

4.7 K

1.8 V

0.1 F

1.8 V

MMA955X

VDD

BKGD / MS / IO9

RESETB

SCL0 / IO0 / SCLK

VSS

IO7 / AN1

IO6 / AN0

* IO5 / PDB_A / INT_O

VSS

IO4 / INT

SDA0 / IO1 / SDI

IO2 / SDO

IO3 / SSB

VSSA

IO8 / PDB_B

VDDA

4.7 K

1.8 V

4.7 K

1.8 V

4.7 K

* IO5 can only be

configured as

COCO bit interrupt

For most interrupt

sources, use

IO6-IO9.

* C1 is not necessary for

all implementations, but is

recommended as good

design practice for achieving

low noise operation.

*See the NOTE in this section.

System Connections

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Figure 4. MMA9555L Pedometer Sen sor as an SPI slave

2.4.4 Sensing Direction and Output Response

Figure 5 shows the device’s default sensing direction when measuring gravity in a static manner from the six standard orientation

modes: portrait up/down, landscape left/right and back/front.

Figure 5. Sensing direction and output response

INT_COCO

SPI_DO (MISO)

SPI_DI (MOSI)

SPI_CLK

4.7 K

1.8 V

0.1 F

1.8 V

VDD

BKGD / MS / IO9

RESETB

SCL0 / IO0 / SCLK

VSS

IO7 / AN1

IO6 / AN0

* IO5 / PDB_A / INT_O

VSS

IO4 / INT

SDA0 / IO1 / SDI

IO2 / SDO

IO3 / SSB

4.7 K

1.8 V

Quiet VDDA for

best performance

C1*

1 F

0.1 F

VSSA

IO8 / PDB_B

VDDA 14

INT_OUT

1.8 V

MMA955X

* IO5 can only be configured as

COCO bit interrupt. For most

interrupt sources, use IO6-IO9.

* C1 is not necessary for

all implementations, but is

recommended as good

design practice for achieving

low noise operation.

* See the NOTE in this section.

Pin 1

Top view Side view

Landscape Right

Gravity

Landscape Left

Portrait Up

Portrait Down

Back

Front

Xout @ 0 g

Yout @ -1 g

Zout @ 0 g

Xout @ 1 g

Yout @ 0 g

Zout @ 0 g

Xout @ 0 g

Yout @ 1 g

Xout @ -1 g

Yout @ 0 g

Zout @ 0 g

Xout @ 0 g

Yout @ 0 g

Zout @ -1 g

Xout @ 0 g

Yout @ 0 g

Zout @ 1 g

Definitions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

3 Mechanical and Electrical Specifications

This section contains electrical specification tables and reference timing diagrams for the MMA9555L device, including detailed

information on power considerations, DC/AC electrical characteristics, and AC timing specifications.

3.1 Definitions

Cross-axis sensitivity The proportionality constant that relates a variation of accelerometer output to cross acceleration. This

sensitivity varies with the direction of cross acceleration and is primarily due to mi salignment.

Full range The algebraic difference between the upper and lower values of the input range. Refer to the input/

output characteristics.

Hardware compensated Sensor modules on this device include hardware-correction factors for gain and offset errors that are

calibrated during factory test using a least-squares fit of the raw sensor data.

Linearity error The deviation of the sensor output from a least-squares linear fit of the input/output data.

Nonlinearity The systematic deviation from the straight lin e that defines the nominal input/ou tput relationship.

Pin group The clustering of device pins into a number of logical pi n gr oupings to simplify and standardize elec-

trical data sheet parameters. Pin groups are defined in Section 3.2, “Pin Groups”.

Software compensated NXP’s advanced nonlinear calibration functions that—with the first-order hardware gain and offset cal-

ibration features—improve sensor performance.

W arm-up time The time from the initial application of power for a sensor to reach its specified performance under the

documented operating conditions.

3.2 Pin Groups

The following pin gr oups are used throughout the remainder of this section.

Group 1 RESETB

Group 2 RESERVED

Group 3 RGPIO[9:0]

3.3 Absolute Maximum Ratings

Absolute maximum ratings are the limits the device can be exposed to without permanently damaging it. Absolute maximum rat-

ings are stress ratings only; functional operation at these ratings is not guaranteed. Exposure to absolute maximum ratings con-

ditions for extended periods may affect reliability.

This device contains circuitry to protect against damage due to high static voltage or electrical fields. It is advised, however , that

normal precautions be taken to avoid application of any voltages higher than maximum-rated voltages to this high-impedance

circuit. Reliability of operation is enhanced if unused inputs are tied to an appropriate logic voltage level (for instance, either VSS

or VDD).

Table 3. Absolute maximum ratings

Rating Symbol Minimum Maximum Unit

Digital supply voltage VDD –0.3 2.0 V

Analog supply voltage VDDA –0.3 2.0 V

Voltage difference, V DD to VDDA VDD – VDDA –0.1 0.1 V

Voltage difference, V SS to VSSA VSS – VSSA –0.1 0.1 V

Input voltage VIn –0.3 VDD + 0.3 V

Input/Output pin-clamp current IC–20 20 mA

Output voltage range (Open-Drain Mode) VOUTOD –0.3 VDD + 0.3 V

Storage temperature Tstg –40 125 °C

Mechanical sh ock SH — 5k g

Operating Co nditions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

3.4 Operating Conditions

3.5 Electrostatic Discharge (ESD) and Latch-up Protection

Characteristics

3.6 General DC Characteristics

Table 4. Nominal operating conditions

Rating Symbol Min Typ Max Unit

Digital supply voltage VDD 1.71 1.8 1.89 V

Analog supply voltage VDDA 1.71 1.8 1.89 V

Vo ltage difference, VDD to VDDA VDD – VDDA –0.1 —0.1 V

Vo ltage difference, VSS to VSSA VSS – VSSA –0.1 —0.1 V

Input voltage high VIH 0.7 * VDD — VDD+0.1 V

Input voltage low VIL VSS – 0.3 —0.3*VDD V

Operating temperature TA–40 25 85 °C

Table 5. ESD and latch-up protection characteristics

Rating Symbol Value Unit

Human Body Model (HBM) VHBM ±2000 V

Machine Model (MM) VMM ±200 V

Charge Device Model (CDM) VCDM ±500 V

Latch-up current at 85 °C ILAT ±100 mA

Table 6. DC characteristics(1)

1. All conditions at nominal supply: VDD = VDDA = 1.8 V.

Characteristic Symbol Condition(s)(2)

2. Pin groups are defined in “Pin Groups” on page 13.

Min Typ Max Unit

Output voltage high

• Low-drive strength

• High-drive strength VOH

Pin Groups 1 and 3

ILOAD = –2 mA

ILOAD = –3 mA VDD – 0.5 — — V

Output voltage low

• Low-drive strength

• High-drive strength VOL

Pin Groups 1 and 3

ILOAD = 2 mA

ILOAD = 3 mA ——0.5V

Output-low current

Max total IOL for all ports IOLT ———24mA

Output-high current

Max total IOH for all ports IOHT ———24mA

Input-leakage current |IIN|Pin Group 2

Vin = VDD or VSS —0.1 1 µA

Hi-Z (off-state) leakage current |IOZ|Pin Group 3 input

resistors disabled

Vin = VDD or VSS

—0.1 1 µA

Pullup resistor RPU when enabled 17.5 — 52.5 kΩ

Power-on-reset voltage VPOR — — 1.50 — V

Power-on-reset hysteresis VPOR–hys ——100—mV

Input-pin capacitance CIN ——7—pF

Output-pin capacitance COUT ——7—pF

Supply Current Characteristics

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

3.7 Supply Current Characteristics

3.8 Accelerometer Transducer Mechanical Characteristics

3.9 ADC Characteristics

Table 7. Supply current characteristics(1)

1. All conditions at nominal supply: VDD = VDDA = 1.8 V.

Characteristic Symbol Condition(s) Min Typ Max Unit

Supply current in STOPNC mode IDD–SNC Internal clocks disabled — 2 — µA

Supply current in STOPSC mode I DD–SSC Internal clock in

slow-speed mode —15—µA

Supply current in RUN mode(2)

2. Total current with the analog section active, 16 bits ADC resolution selected, MAC unit used and all peripheral clocks enabled.

IDD–R Internal clock in

fast mode —3.1—mA

Table 8. Accelerometer characteristics

Characteristic Symbol Condition(s) Min Typ Max Unit

Full range AFR

2 g±1.8 ±2 ±2.2 g4 g±3.6 ±4 ±4.4

8 g±7.2 ±8 ±8.8

Sensitivity/resolution ASENS

2 g— 0.061 — mg/LSB4 g— 0.122 —

8 g— 0.244 —

Zero-g level offset accuracy

(Pre-board mount) OFFPBM

2 g–100 — +100 mg4 g

8 g

Nonlinearity

Best fit straight line ANL

2 g—±0.25— % AFR

4 g—±0.5—

8 g—±1—

Sensitivity change vs.temperature TCSA 2 g—±0.17— %/°C

Zero-g level change vs. temperature(1)

1. Relative to 25 °C.

TCOff ——±1.9—mg/°C

Zero-g Level offset accuracy

(Post-board mount) OFFBM

2 g–100 — +100 mg4 g

8 g

Output data bandwidth BW — — ODR/2 — Hz

Output noise Noise 2 g, ODR = 488 Hz — 100 — µg/sqrt(Hz)

8 g, ODR = 488 Hz — 120 — µg/sqrt(Hz)

Cross-axis sensitivity — — –5 — 5 %

Table 9. ADC characteristics(1)

Characteristic Symbol Condition(s) Min Typ Max Unit

Input voltage VAI Voltage at AN0 or AN1 0.2 — 1.1 V

Differential input voltage VADI AN1 – AN0 –0.9 — 0.9 V

Full-scale range VFS ——1.8—V

Programmable resolution RES —101416Bits

ADC Sample Rates

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

3.10 ADC Sample Rates

The MMA9555L internal ADC supports the following sample output rates, while the pedometer application uses 30.52 fps as

default:

• 488.28 frames per second (fps)

• 244.14 fps

• 122.07 fps

• 61.04 fps

• 30.52 fps

• 15.26 fps

• 7.63 fps

• 3.81 fps

3.11 AC Electrical Characteristics

Tests are conducted using the input levels specified in Tab le 4 on page 14. Unless otherwise specified, propagation delays are

measured from the 50-percent to 50-percent point. Rise and fall times are measured between the 10-percent and 90-percent

points, as shown in the following figure.

Figure 6. Input signal measurement references

The subsequent figure shows the definitions of the followi ng signal states:

• Active state, when a bus or signal is driven and enters a low-impedance state

• Three-stated, when a bus or signal is placed in a high-impedance state

• Data Valid state, when a signal level has reached VOL or VOH

• Data Invalid state, when a signal level is in transition between VOL and VOH

Figure 7. Signal states

Conversion time @ 14-bits resolution

(Three-sample frame) tc——207—µs

Integral nonlinearity INL Full scale — ±15 — LSB

Differential nonlinearity DNL — — ±2 — LSB

Input leakage IIA ———±2µA

1. All conditions at nominal supply: VDD = VDDA = 1.8 V and RES = 14, unless otherwise noted.

Table 9. ADC characteristics(1) (Continued)

Characteristic Symbol Condition(s) Min Typ Max Unit

VIH

VIL

Fall Time

Input Signal

Note: The midpoint is VIL + (VIH – VIL)/2.

Midpoint1

Low High 90%

50%

10%

Rise Time

Data Invalid State

Data1

Data

3-stated

Data3 Valid

Data2 Data3

Data1 Valid

Data Active Data Active

Data1 Valid

General Timing Control

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

3.12 General Timing Control

3.13 I2C Ti ming

This device includes a slave I2C module that can be used to control the sensor and can be active 100 percent of the time.

Figure 8. I2C standard and fast-mode timin g

3.13.1 Slave I2C

Table 10. General timing characteristics(1)

1. All conditions at nominal supply: VDD = VDDA = 1.8 V

Characteristic Symbol Condition(s) Min Typ Max Unit

VDD rise time Trvdd 10% to 90% — — 1 ms

POR release delay(2)

2. This is the time measured from VDD = VPOR until the internal reset signal is released.

TPOR Power-up 0.35 1.5 ms

Warm-up time TWU From STOPNC —7—

sample

periods

Frequency of operation FOPH Full Speed Clock — 8 — MHz

FOPL Slow Clock — 62.5 — KHz

System clock period tCYCH Full Speed Clock — 125 — ns

tCYCL Slow Clock — 16 — μs

Full/Slow clock ratio — — — 128 —

Oscillator frequency absolute ac curacy @

25 °C — Full Speed Clock –5 — +5 %

Oscillator frequency variation over

temperature

(–40 °C to 85 °C vs. ambient) — Slow Clock –6 — +6 %

Minimum RESET assertion duration tRA —4T(3)

3. In the formulas, T = 1 system clock cycle. In full speed mode, T is nominally 125 ns. In slow speed mode, T i s nominally 16 μs.

—— —

Table 11. I2C Speed Ranges

Mode Max Baud

Rate (fSCL)Min

Bit Time Min SCL Low

(tLOW)Min SCL High

(tHIGH)Min Data setup Time

(tSU; DAT)Min/Max Data Hold Time

(tHD; DAT)

Standard 100 kHz 10 μs4.7 μs4 μs 250 ns 0 μs/3.45 μs(1)

1. The maximum tHD; DAT must be at least a transmission time less than tVD;DAT or tVD;ACK. For details, see the I2C standard.

Fast 40 0 kHz 2.5 μs1.3 μs0.6 μs 100 ns 0 μs/0.9 μs(1)

Fast + 1 MHz 1 μs 500 ns 260 ns 50 ns 0 μs/0.45 μs(1)

High-speed

supported 2.0 MHz 0.5 μs 200 ns 200 ns 10 ns(2)

2. Timing met with IFE = 0, DS = 1, and SE = 1. Refer to the chapter titled Port Controls in the MMA955xL Intelligent, Motion-Sensing Platform Hardware

Reference Manual (MMA955xLHWRM), listed in “Rela ted Documentation” on page 2.

0 ns/70 ns (100 pf)(1)

SDA

SCL

tHD; STA tHD; DAT

tLOW tSU; DAT

tHIGH tSU; STA SR PS

tHD; STA tSP

tSU; STO

tBUF

tftrtftr

Slave SPI Timing

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

3.14 Slave SPI Timing

Figure 9. SPI slave timing

Table 12. Slave SPI timing

Time

Period

(1)

1. Time period from Figure 9.

Function Symbol Min Max Unit

— Operating frequency fop 0F

OPH/4 Hz

1 SCLK period tSCLK 4—t

CYCH

2 Enable lead time tLead 0.5 — tCYCH

3 Enable lag time t Lag 0.5 — tCYCH

4 Clock (SCLK) high or low time tWSCLK 200 — ns

5 Data-setup time (inputs) tSU 15 — ns

6 Data-hold time (inputs) tHI 25 — ns

7 Access time ta—25ns

8 SDO-disable time tdis —25ns

9 Data valid (after SCLK edge) tv—25ns

10 Data-hold time (outputs) tHO 0—ns

11 Rise time

Input

Output tRI

tRO

—

—25

25 ns

12 Fall time

Input

Output tFI

tFO

—

—25

25 ns

SCLK

(INPUT)

SDI

(INPUT)

SDO

(OUTPUT)

(INPUT)

MSB IN

BIT 6 . . . 1

LSB IN

MSB OUT SLAVE LSB OUT

BIT 6 . . . 1

NOTE:

SLAVE SEE

NOTE

1. Not defined but normally MSB of character just received.

121

11 3

424

Overview of Communication Interface

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

4 Communication Interface

4.1 Overview of Communication Interface

All access to the MMA9555L is made via the slave, serial Communication Interface that is part of the hardware and firmware

infrastructure of the platform. The communication occurs in Command/Response (Normal) or Quick Read (Legacy) mode.

Commands are sent from the host and through the slave communications port (either SPI or I2C). The Communication Interface

interprets the command and sends the data to the correct application. The appl ication executes the command and returns with

data, if requested with the command response. It also responds with error codes when appropriate.

The Communications Interface works with the Ma ilbox application to implement the command and response. The mailboxes’

functionality is configured with two applications: the MBOX Configuration application (APP_ID = 0x18) and the MBOX application

(APP_ID = 0x04).

4.2 Mailbox Interface

Commands are received through a set of 32 mailboxes that are 32 registers arranged consecutively to provide addressable

memory regions. Each mailbox can hold one byte of data.

After a command has completed, the Communication Interface writes the results to the mailboxes and the results (response out)

are retrieved by the host via the SPI or the I2C slave interface.

The following figure shows the structure of the data packet when writing one byte into a specific mailbox.

If the transaction contains more than one data byte, the internal-destination mailbox address is automatically incremented so that

the incoming byte is placed in the next mailbox. For mailbox addresses greater than 31 bytes or for transactions where the

mailbox address auto-increments past mailbox 31, the destination address wraps back to the start of the mailbox addresses.

S10011000AA7 A6 A5 A4 A3 A2 A1 A0 A D7 D6 D5 D4 D3 D2 D1 D0 A P

Figure 10. I2C interface writing one byte of information to a mailbox

StopDestination Mailbox Address Data Byte

R/WDevice Address = 0x4C

Start Acknowledge

Acknowledge Acknowledge

Mailbox Usage

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

4.2.1 Mailbox Timing

Figure 11. I2C timing diagram

Figure 12. SPI timing diagram

4.3 Mailbox Usage

Commands to the MMA9555L consist of a write followed by one or more reads. It may ta ke some time to complete the command

and a flag can be checked to determine if the command has completed. That flag is the Command Complete (COCO) bit, the

seventh bit of the read data in the second mailbox. (See Table 16 on page 23.)

On a read operation, the COCO bit indicates if the command has been processed. The host processor can determine the status

of the command’s processing by repeatedly reading or polling the second mailbox until the COCO bit is set. Altern atively, the

Clock

Data

values

SA A A A P

98 00 00 00

Start

Acknowledge

Stop

Enable

Clock

MOSI

MISO

MOSI v alues

MISO v alues FF

MISO: SPI Master In, Slave Out

MOSI: SPI Master Out, Slave In

SPI: Serial, Peripheral Interface

Mailbox Usage

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

MMA9555L can be configured to assert an inte rrupt signal at the completion of a command. If configured, the INT_O interru pt

will be set immediately after the COCO bit has been set.

For more information, see “Configuring mailbox operational mode” on page 96.

4.3.1 Mailbox Command Format for a Write

Commands written to the MMA9555L are sent in the format shown in the following table. Mailboxes are filled with data, depending

on the target application. All commands start with the APP_ID, the command, the destination offset, and the number of data bytes

to writ e.

All commands must be written in a single, I2C/SPI transaction starting at Mailbox 0, but the response can be read from any subset

of the mailbox registers.

For a write-request command, the first four mailboxes must be written with enough bytes to hold the requested number of bytes.

The format of the data bytes is specific to the targeted application. (Applications are described in Table 15.)

The following table gives the details of the different parts of the data packet for a Write command.

Table 13. Mailbox commands formats

Offset76543210

0x00 Application ID (APP_ID)

0x01 0 Command Byte offset (upper 4 bits)

0x02 Byte offset (lower 8 bits)

0x03 Requested number of bytes to read/write

0x04 Write data 0

0x05 Write data 1

0x06 Write data 2

…. Write data n

Table 14. Mailbox command format details

Block Description

Application ID Application targeted for the issued command, see Table 15.

Command

Command to be performed:

• 0: Read application fixed bytes (version information)

• 1: Read application configuration bytes

• 2: Write application configuration bytes

• 3: Read application status or output

Byte offset Sets the of fset of the first byte to be accessed, counting from the start of the register space. This enables

a subset of the registers to be accessed by setting the start location to something other than zero.

Requested number

of bytes Number of bytes requested to be read or written.

Write data The data being written.

Mailbox Usage

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

4.3.2 Application IDs, names, and descriptions

The following table gives the names and IDs of the NXP applications associated with MMA9555L.

Table 15. Application descriptions

Application ID Application Name Description

0x00 Version Returns a 12-byte pack with the device identifier number and the version

numbers of the ROM, firmware, and hardware.

(For more details, see Chapter 5, “Version Application”.)

0x01 Scheduler Configures the system, applications, and the MMA9555L infrastructure to run

at specific sample rates. Additionally, the identifier reads the number of times

each task has been executed.

0x02 Reserved

0x03 GPIO-AppMap Configures the GPIO application to map a specific applica tion output bit to

specific GPIO pins. (For more details, see Chapter 7, “GPIO-AppMap

Application”) The GPIO pins are limited to GPIO6 through 9.

0x04 Mailbox

Configures an internal mailbox table to map which output bytes from specific

application identifiers will be accessible in the Normal mode and the Legacy

mode’s Quick-Read registers mailboxes. The application identifier can perform

a table reset to reinstall the default values when the MMA9555L resets.

0x05 Reserved

0x06 Analog Front End Configures different parameters of the AFE and reads XYZ data from the

accelerometer. For further details, see Chapter 9, “Analog Front End

Application”.

0x0C–0x0D Reserved

0x0F Data FIFO Configures parameters of the Data-FIFO application and reads the output

bytes from its output structure and the contents of the FIFO buffer.

0x10 Event queue Configures parameters of the Event-queue application and reads the output

bytes from its output structure and the contents of the Event-queue buffer.

0x11 Status register Provides access to the MMA9555L system-status information.

0x12 Wake/Sleep Configures the power-control modes of the accelerometer. The application has

three modes of operation: Run, Doze, and Sleep.

0x13–0x14 Reserved

0x15 Pedometer Application that can detect the step count.

0x16 Reserved

0x17 Reset/suspend/clear Controls the Reset/Suspend/Clear functions of the MMA9555L.

0x18 Mailbox mode config Configures different operation modes of the mailbox and provides the status

value of the mailbox when Stream mode is running.

0x19 GPIO Input/Output Controls GPIO2–GPIO8 as input or output pins.

0x1B–0x1F Reserved

0x20–0xFF Reserved Indicates an invalid application index.

Mailbox Usage

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

4.3.3 Mailbox command format for a read

Though all commands must be written in a single I2C/SPI transaction starting at Mailbox 0, the response can be read from any

subset of the mailbox registers. When the MMA9555L is configured to stream data (as in FIFO mode), the read commands must

be constructed as multiples of 32 bytes in order to trigger the internal transfer of the next set of data to the mailboxes.

A read-request command requires a write to the first four mailboxes.

The format of the information returned from the MMA9555L is shown in Table 16. Similar to the command format, the response

format follows the specific application’s format.

Mailboxes are filled with data depending on the target application.

All responses start with the responding APP_ID, the COCO the ERROR ST ATUS, the actual data count, and the requested data

count.

The format of the remaining data bytes is specific to the respond ing application.

Table 17 describes the details of the different parts and fields of a response message.

Table 16. Mailbox response formats

Mailbox76543210

0x00 Application ID (APP_ID)

0x01 COCO Error code

0x02 Actual number of bytes read/written

0x03 Requested number of bytes to read/write

0x04 Read data 0

0x05 Read data 1

0x06 Read data 2

…. Read data n

Table 17. Mailbox response format details

Block Description

Application ID

(APP_ID) The ID of the application that is responding. (Se e Table 16 on page 23.)

COCO Command complete.

This bit must be set to 0b when a command is written and is set to 1b by the MMA9555L platform, when

the command has been processed. The other registers do not contain valid results until this bit is set.

Error code The seven bytes that store the error code of the command. A zero indicates there was no error. (For more

information, see Table 18.)

Actual number of

bytes

Actual number of bytes read or written.

This block reports back the actual number of bytes that were read or written. It is normally the same as

the requested number of bytes, but it will be reduced if the requested number of bytes plus the Byte Offset

exceeds the number of bytes in the requested block’s data structure.

Requested number

of bytes Number of bytes requested to be read or written.

Read data Th e data that was read.

Mailbox Usage

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Table 18 describes the status or error-code results returned in Mailbox 0x01.

Table 18. Error-St atus codes returned in Mailbox 0x01

Error Code Name Description

0x00 MCI _ERROR_NONE Comma nd completed with no errors.

0x04 MCI _ERROR_PARAM Incorrect input parameter.

Error may be due to an incorrect application ID, an incomplete command,

or an incorrect offset.

0x19 MCI _INVALID_COUNT Returned when the command COUNT is greater than the output structure

size.

0x1C MCI_ERROR_COMMAND Returned any time that the command interpreter does not recognize a

command code.

0x21 MCI_ERROR_INVALID_LENGTH Returned when the host sends a number of bytes with a wrong payload.

MMA9555L checks any mismatches between the amount of bytes

received and the actual payload sent by the host.

0x22 MCI_ERROR_FIFO_BUSY FIFO is busy performing a push operation and it is not possible to execute

any other function.

0x23 MCI_ERROR_FIFO_ALLOCATED

Returned when the host tries to reconfigure the FIFO module. The FIFO

application configuration can only be written once. In order to reconfigure

the FIFO, the whole device must be reset. This is because the FIFO

application requests RAM and RAM can only be allocated once.

0x24 MCI_ERROR_FIFO_OVERSIZE Returned when the host wants to set a FIFO buffer size out of the memory

boundaries within the MMA9555L device.

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

5 Version Application

The MMA9555L device's system-version information is stored in a 12-byte packet and

contains system-identity information including device-hardware ID; the versions of the ROM

bootloader, primary firmware, and hardware; and the system-bui ld information.

Table 19 describes the system-version packet and its corresponding mailbox alignment.

Table 20 describes the Build Major and Build Minor version-number fields.

Table 19. Version command descript io n by t es

Mailbox

number Description Byte

4 Device identifier 31:24

5 Device identifier 24:16

6 Device identifier 15:8

7 Device identifier 7:0

8 ROM major version number 7:0

9 ROM minor version number 7:0

10 Firmware major version number 7:0

11 Firmware minor version number 7:0

12 Hardware major version number 7:0

13 Hardware minor version number 7:0

14 Build major version number 7:0

15 Build minor version number 7:0

Table 20. Version application, Build major and minor bytes

Byte Address Description Bit fields

3 0x1FD Build major version number

• 7–3 Build’s day of the month

Range, 1 to 31

• 2–0 Year of build, from 2010

Range, 0 to 7.

4 0x1FC Build minor version number

• 7 — Release

– 1 Engineering version

– 0 Production release

• 6–4 Build number

• 3–0 Month of build

Range, 1 to 12

Application

ID 0x00

Default speed Always

available.

Configuration

registers None.

Status

registers None.

Reading the version information

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

5.1 Reading the version information

To read the MMA9555L's version information, send the following command packets to the mailboxes:

1. MB0: Set APP_ID to 0x00.

2. MB1: Command to 0x00.

Reads version information.

3. MB2: Set offset to zero 0x00.

Starts reading at offset 0.

4. MB3: Set count field to 0x0C.

Reads12 bytes of data.

Bytes to Send: 0x00, 0x00 , 0x00, 0x0C.

The expected response to these commands is given in the following example.

NOTE

The current Firmware Build information reflects the framework build and not the pedometer

or directional features of the MMA9555L.

Example 1.

00 80 0C 0C 2F 33 48 B8 01 01 02 02 01 06 03 41

MB0: APP_ID = 0x00

MB1: STATUS = 0x80 Command Complete, no errors

MB2: RequestedData count= 0xC

MB3: Actual Data Count= 0xC

MB4-7: Device ID = 0x2F3348B8

MB8-9: ROM Version = 01.01

MB10-11: Firmware Version = 02.02

MB12-13: Hardware Version = 01.06

MB14-15: Firmware Build = 03.41 (Production #3, 4 Mar 2011)

Scheduler application eleme nts

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

6 Scheduler Application

A simple task scheduler manages execution of the applications of the MMA9555L. Based

on a run-to-completion scheme, the scheduler features very low cycle and memory

overhead.

The scheduler is tightly coupled with the Analog Front End's sampling rate and is triggered

at the start of every sample interval. The system is designed such that all applications must

complete their processing within the sample interval. The scheduler is used in the defined

applications.

A priority scheme allows short-duration, high-priority tasks, such as data sam pling and

filtering, to preempt long-duration, low-priority tasks.

The scheduler scans serially throug h the list of applications, looking for applications that

have the same priority as the scheduler's current priority. When there is a priority match, an

activity level is checked to determine if the application should be run in the current

scheduler's interval.

An application’s activity mask can be set to High, Low , Both, or None. This feature allows an application to run during high activity,

low activity, both, or not at al l. The Sleep/Wake application defines the thresholds of activity between Sleep and Wake, or High

and Low activity.

Priorities from 16 to 23 are linked directly to the frame execution rate, see Table 21. The lower-priority levels provide a range of

values for managing applications in the user system.

The scheduler automatically executes all the applications with a priority corresponding to the scheduler's current running priority

level.

Once the scheduler has identified an application to run, it does a context switch to that application. When the application

completes, context is returned to the scheduler and it looks for more applications with the same priority.

For additional information, contact NXP Sensors Applications Engineering.

6.1 Scheduler application elements

Each MMA9555L application is assigned an application code, a priority and an activity leve l. The priority and activity level

parameters determine when the scheduler runs the application.

6.1.1 Priority levels

A priority scheme allows short-duration, high-priority applications—suc h as da ta sampli n g an d fil te r i n g—to preempt long -

duration, low-priority applications.

The scheduler suppo rts 24 unique pri orities, from 0x00 to 0x17 (0 to 23, in decimal). The larger the number, the higher the

priority—higher-numbered applications run before lower-numbered applications. Multiple applications can be assigned the same

priority level.

The priority level for each application is encoded by the lower six bits in the scheduler_parameters registers. See “Scheduler

parameters register” on page 33.

Priorities from 0 to 15 (0x00 to 0x0F) can trigger an application when an interrupt occurs. Priorities 16 to 23 (0x10 to 0x17) are

linked to the Analog Front End (AFE) execution rate. All applications with a priority of 16 to 23 are automatically software-triggered

by the Scheduler.

Application

ID 0x01

Default speed (Runs all the

time.)

Configuration

registers Start on page

29.

Status

registers Start on page

36.

Scheduler appl ication elements

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

6.1.2 Activity levels

The MMA9555L uses an activity level attribute to indicate how physically active the device is. The measured physical acceleration

and motion actions of the device are classified into two ranges: high activity and low activity.

The activity level is used with the priority level to determine which applications run first. Applications can be set to run during

these conditions:

• Always run

• Run during high activity

• Run during low activity

• Never run

Table 21. Priorities descriptions

Priority Level Description

0x17 Appli cations with this priority run at 488 Hz

0x16 Appli cations with this priority run at 244 Hz

0x15 Appli cations with this priority run at 122 Hz

0x14 Appli cations with this priority run at 61 Hz

0x13 Appli cations with this priority run at 30 Hz

0x12 Appli cations with this priority run at 15 Hz

0x11 Applications with this priority run at 7 Hz

0x10 Appli cations with this priority run at 3 Hz

0x0F Highest user assignable priority level (lower than 3 Hz)

0x0E

User-assignable priority levels

0x0D

0x0C

0x0B

0x0A

0x09

0x08

0x07

0x06

0x05

0x04

0x03

0x02

0x01

0x00 Lowes t user assignable priority level

Interrupts

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

The activity level for each application is encoded in the upper two bits of the schedu ler_parameters registers. See “Scheduler

parameters register” on page 33.

The Sleep/W ake application alone determines the activity level, therefore high/low activity is entirely a function of the sleep/wake

threshold parameters. When in run mode, the scheduler only executes applications with the high activity parameter bit set.

Similarly, when in doze mode, the scheduler only executes applic ations with the low activity parameter bit set. Since these bits

are separate, an application has the optio n to set both to run regardless of the activity level.

The low activity level parameter is like a filter that skips applications normally run after each AFE sample interval. The idea is that

when the sensor is not moving, such as s itting on your desk, you can save power by not running applications, for example portrait

landscape.

6.2 Interrupts

Interrupts immediately divert execution from any application or the idle state into dedicated interrupt handlers. The scheduler is

not invoked, so the interrupt returns without redirection.

All interrupt handlers disable interrupts, so application ready, communication, and pin interrupts divert execution only from

applications or the idle state.

Interrupts are never nested.

The MMA9555L supports the interrupts listed in the Table 22. Each supported interrupt can be associated with ze ro or more

priorities. When the interrupt occurs, the scheduler triggers all the applications associated with th e priorities configured for that

interrupt.

The priorities for each interrupt are configured in the scheduler configuration parameter structure.

Interrupts are assigned to an application in the Interrupt Assignment registers. See “Interrupt assignment registers” on page 32.

6.3 Scheduler configuration registers

The scheduler has the following three groups of configuration registers:

• request_to_start register

• interrupt assignment registers

• scheduler parameters registers

Table 22. Supported interrupts (1)

1. For more information, see the MMA955xL Intelligent, Motion-Sensing Platform Hardware Reference Manual (MMA955xLHWRM), listed in “Related

Documentation” on page 2.

Name Description

SFD Start of Digital Frame interrupt.

This interrupt occurs when the start of frame signal is asserted.

COCO Conversion-complete interrupt.

This interrupt occurs when the AFE cycle has completed and all ADC conversions are complete and

ready to be used.

IRQ IRQ pin interrupt.

This interrupt occurs when the selected input pin detects the configured condition (ri s ing edge/high

level or falling edge/low level).

Scheduler configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

The configuration and status registers are listed in the following table.

The request_to_start register is a way to run the applications under scheduler control. The interrupt assignment registers connect

applications to interrupt events. The scheduler parameter registers assign activity levels and priorities to the applications.

In the event that an application does not comple te before it is triggered again, the first instance of the application runs to

completion before the second instance starts. If a third trigger occurs before the first instance of the application completes, the

application misses an instance and is marked in the timeout register.

By checking the ti meout_st atus register, the user can determi ne which priority application was missed. The corresponding bit of

the timeout is set in the timeout_status register.

6.3.1 request_to_start register

An application can be scheduled to run by settin g the bit corresponding to the application's APP_ID in the request_to_start

When an application finishes an d returns, the scheduler clears the corresponding bit in th e request_to_start register.

The request_to_start register enables a user to trigger one or more app lications via the slave-port command. When modifying

this register, the user must logically OR the current value with the new value (with a read/modify/write access) to prevent the

erasure of the task waiting to be started.

Table 23. Scheduler configuration and status registers

Configuration

0x00–0x03 32 Request_to_start

0x04–0x07 32 SFD Interrupt_AppIDs

0x08–0x0B 32 AFE COCO Interrupt_AppIDs

0x0C–0x0F 32 IRQ Interrupt_AppIDs

0x10–0x13 32 Reserved

0x14–0x17 32 Reserved

0x18–0x1B 32 Reserved

0x1C–0x1F 32 Reserved

0x20–0x23 32 Reserved

0x24–0x27 32 Reserved

0x28–0x2B 32 Reserved

0x2C 8 sched_parms_APP_ID_0x00

0x2D–0x4A 8 each sched_parms_APP_ID_0x01 through 0x1E(1)

1. Shaded rows indicate the compressed registers.

0x4B 8 sched_parms_APP_ID_0x1F

Status Address Width (bits) Register Name

0x00–0x03 32 Timeout Status

Scheduler configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

The host controller may issue a command through the slave communications port to trigger the running of an application. To do

this, the host controller does a read/modify/write to the request_to_start configuration register and sets the appropriate bit

associated with the application that the host wants to start.

Regardless of which mechanism triggers the Scheduler application to start—a hardware interrupt, a slave port command, or an

internal trap interrupt—it always executes the highest-priority a pplications first. As a result, a slave-port command could trigger

a low-priority application, but some time may occur before that application actually executes.

6.3.2 request_to_start register configuration example

To configure the request_to_start register, send this command, read the register an d modify it, and write it back.

Example 2.

1. MB0: Set the Scheduler application identifier (0x01).

2. MB1: Set the Command: Read Config application iden tifier (0x10).

3. MB2: Set the Offset to Zero field (0x00) to point to the request_to_start configuration register.

4. MB3: Set the Count field (0x04) to request four bytes.

Bytes to send: 0x01, 0x10, 0x00, 0x04.

5. Read ba ck th e ma il b oxes.

The current value of the request_to_start register is stored in MB4–MB7.

6. Modify the value as needed:

7. MB0: Set the Scheduler application identifier (0x01).

8. MB1: Set the Command: Write Config application identifier (0x20).

9. MB2: Set the Offset to Zero field (0x00) to point to the request_to_start configuration register.

10. MB3: Set the Count field (0x04) to writing four bytes.

11. MB4: Set the DATA value to 0xAA.

12. MB4: Set the DATA value to 0xBB.

13. MB4: Set the DATA value to 0xCC.

14. MB4: Set the DATA value to 0xDD.

Table 24. request_to_start register

Offset 0x00(MSB) 0x01

Bit 7654321076543210

Field request_to_start [31:24] request_to_start [23:16]

Reset 0x00 0x00

Offset 0x02 0x03(LSB)

Bit 7654321076543210

Field request_to_start [15:8] request_to_start [7:0]

Reset 0x00 0x00

Table 25. request_to_start description

Field Description

31:0

request_to_start

Indicates which APP_IDs are marked for starting at the beginning of the next scheduler interval. Each bit

corresponds to an APP_ID. It is important that the user do a read/modify/write type of access to ensure that

the contents of the resister are logically ORed with the new value to avoid erasing the request_to_start bit of

the other APP_IDs that are waiting to start. Setting the bit will mark the APP_ID for starting in the next

scheduler loop.

Units: None.

Range of valid values: 0 to 0xFFFFFFF.

Scheduler configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

Bytes to send: 0x01, 0x20, 0x00, 0x04, 0xAA, 0xBB, 0xCC, 0xDD.

6.3.3 Interrupt assignment registers

There are 10 possible interrupts in the MMA955xL platform, among these interrupts three are accessible in MMA9555L from the

host system. Each interrupt is assigned to an application through the user _interrupt parameter registers. When an interrupt

happens, the schedul er handler logically ORs the contents of the user_interrupt register with the request_to_start parameter

The scheduler runs the appropriate application the next time the application ’s priority is runable.

The scheduler uses the interrupt vector to determine which application-ready interrupt occurred and sets a bit in the

request_to_start register. In the bit vector, each bit corresponds to a task and the bit position indicates the priority of the

application.

The appropriate interrupt is acknowledged to the hardware, usually by clearing a flag bit in th e peripheral’s memory-mapped

status register. In the special case that an AFE, results-ready interrupt occurred, supervisor-only AFE registers are copied into

user-mode shadow registers.

Table 26. user_interrupt registers

Offset 0x04(MSB) 0x05

Bit 7654321076543210

Field SFD Interrupt_AppIDs [31:24] SFD Interrupt_AppIDs [23:16]

Reset 0x00 0x00

Offset 0x06 0x07(LSB)

Bit 7654321076543210

Field SFD Interrupt_AppIDs [15:8] SFD Interrupt_AppIDs [7:0]

Reset 0x00 0x00

Offset 0x08(MSB) 0x09

Bit 7654321076543210

Field AFE_COCO Interrupt_AppIDs [31:24 AFE_COCO Interrupt_AppIDs [23:16]

Reset 0x00 0x00

Offset 0x0A 0x0B(LSB)

Bit 7654321076543210

Field AFE_COCO Interrupt_AppIDs [15:8] AFE_COCO Interrupt_AppIDs [7:0]

Reset 0x00 0x00

Scheduler configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

6.3.3.1 Interrupt_App_IDs register configuration example

In this example, the user has an external interrupt source that wants to run application APP_ID = 0x19. This requires setting the

0x19 bit position in the IRQ_interrupt_APP_IDs register at offset 0x0C–0x0F.

Example 3.

1. MB0: Set the Scheduler application identifier (0x01).

2. MB1: Set the “Command: Write Config” application identifier (0x20).

3. MB2: Set the Offset to Zero field (0x0C) to point to the IRQ_interrupt_APP_IDs register.

4. MB3: Set the Count field (0x04) to write four bytes.

5. MB4: Set the DATA value to 0x20.

This bit is the 0x19th bit in this 32 bit register.

6. MB4: Set the DATA value to 0x00.

7. MB4: Set the DATA value to 0x00.

8. MB4: Set the DATA value to 0x00.

Command to send for write: 0x01, 0x20, 0x0C, 0x04, 0x20, 0x00, 0x00, 0x00.

6.3.4 Scheduler parameters register

The sched_parms registers structure is shown in Table 28. For more information on the (Activity) and (Priority) bits, see Table 29

on page 34.

Offset 0x0C(MSB) 0x0D

Bit 7654321076543210

Field IRQ Interrupt_AppIDs [31:24] IRQ Interrupt_AppIDs [23:16]

Reset 0x00 0x00

Offset 0x0E 0x0F(LSB)

Bit 7654321076543210

Field IRQ Interrupt_AppIDs [15:8] IRQ Interrupt_AppIDs [7:0]

Reset 0x00 0x00

Table 27. user_interrupt bit descriptions

Field Description

31:0

Interrupt_AppIDs

Bit vector indicating the tasks that st art after the interrupt. Each bit corresponds to a task and the bit position

indicates the task’s priority. This 32-bit parameter should match the priority of the task that is executing when

the interrupt occurs.

Units: None.

Range of valid values: 0 to 0xFFFFFF.

Table 28. sched_parms register struc ture

Bit 76543210

Field (Activity) (Priority)

Table 26. user_interrupt registers (Continued)

Scheduler configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

The variable data for the sched_parms registers include the register name, offset, and reset. Each of the possible application IDs

(0x00–0x1F) is associated with a scheduler parameter register. The following table shows the APP_IDs and their associated

Table 29. sched_parms_APP_ID bit descriptio ns

Field Description

7:6

(Activity)

Scheduler parameters for each task, this value allows accelerometer activity (motion) to determine whether

a task should run.

High and low activity thresholds are defined with the Sleep/Wake application. (See Chapter 13, “Sleep/W ake

Application”.)

Units: None.

Range of valid values:

• 0x03: ALWAYS // execute application during high and low activity

• 0x02: ACTIVE // execute application only during high activity

• 0x01: INACTIVE // execute application only during low activity

• 0x00: NEVER // never execute application

5:0

(Priority)

Scheduler parameters for each task, this value determine the priority of the application.

Units: None.

Range of valid values:

• 0x17: TASK488HZ // task running at 488 Hz

• 0x16:TASK244HZ // task running at 244 Hz

• 0x15: TASK122HZ // task running at 122 Hz

• 0x14: TASK61HZ // task running at 61 Hz

• 0x13: TASK30HZ // task running at 30 Hz

• 0x12: TASK15HZ // task running at 15 Hz

• 0x11: TASK7HZ // task running at 7 Hz

• 0x10: TASK3HZ // task running at 3 Hz

• 0x0F: PRIORITY15

• 0x0E: PRIORITY14

• 0x0D: PRIORITY13

• 0x0C: PRIORITY12

• 0x0B: PRIORITY11

• 0x0A: PRIORITY10

• 9: PRIORITY9

• 8: PRIORITY8

• 7: PRIORITY7

• 6: PRIORITY6

• 5: PRIORITY5

• 4: PRIORITY4

• 3: PRIORITY3

• 2: PRIORITY2

• 1: PRIORITY1

• 0: PRIORITY0

Table 30. sched_pa rms registers’ differentiating values

Offset N ame Application Bits 7:6 Bits 5:0

0x2C sched_parms_APP_ID_0x00 Version 0x00 0x00

0x2D sched_parms_APP_ID_0x01 Scheduler 0x00 0x17

0x2E sched_parms_APP_ID_0x02 Communications 0x03 0xD7

Scheduler configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

0x2F sched_parms_APP_ID_0x03 GPIO-AppMap 0x03 0xD7

0x30 sched_parms_APP_ID_0x04 Mailbox 0x03 0x17

0x31 sched_parms_APP_ID_0x05 Reserved — —

0x32 sched_parms_APP_ID_0x06 AFE 0x03 0xD7

0x33 sched_parms_APP_ID_0x07 Reserved 0x00 0x00

0x34 sched_parms_APP_ID_0x08 Reserved 0x00 0x00

0x35 sched_parms_APP_ID_0x09 Reserved 0x00 0x00

0x36 sched_parms_APP_ID_0x0A Reserved 0x00 0x00

0x37 sched_parms_APP_ID_0x0B Reserved 0x00 0x00

0x38 sched_parms_APP_ID_0x0C Reserved 0x00 0x00

0x39 sched_parms_APP_ID_0x0D Reserved 0x00 0x00

0x3A sched_parms_APP_ID_0x0E Reserved 0x00 0x00

0x3B sched_parms_APP_ID_0x0F Data FIFO 0x03 0xD7

0x3C sched_parms_APP_ID_0x10 Event Queue 0x03 0xD7

0x3D sched_parms_APP_ID_0x11 Status Register 0x03 0xD7

0x3E sched_parms_APP_ID_0x12 Wake/Sleep 0x03 0xD7

0x3F sched_parms_APP_ID_0x13 Reserved 0x00 0x00

0x40 sched_parms_APP_ID_0x14 Reserved 0x00 0x00

0x41 sched_parms_APP_ID_0x15 Reserved 0x00 0x00

0x42 sched_parms_APP_ID_0x16 Reserved 0x00 0x00

0x43 sched_parms_APP_ID_0x17 Reset/Suspend/Clear 0x03 0xD7

0x44 sched_parms_APP_ID_0x18 Mailbox Configuration 0x00 0x00

0x45 sched_parms_APP_ID_0x19 GPIO Input/Output 0x00 0x00

0x46 sched_parms_APP_ID _0x1A 6 Directions Detection 0x00 0x00

0x47 sched_parms_APP_ID_0x1B Reserved 0x00 0x00

0x48 sched_parms_APP_ID_0x1C Reserved 0x00 0x00

0x49 sched_parms_APP_ID_0x1D Reserved 0x00 0x00

0x4A sched_parms_APP_ID_0x1E Reserved 0x00 0x00

0x4B sched_parms_APP_ID_0x1F Reserved 0x00 0x00

Table 30. sched_parms registers’ differentiating values (Continued)

Offset N ame Application Bits 7:6 Bits 5:0

Scheduler status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.3

6.4 Scheduler status registers

The scheduler applications contain a set of output or status registers. Status registers can be read by a host processor , through

the I2C/SPI slave-port read-data commands, or by internal applications, through dire ct reads.

The scheduler status is a 32-bit register that gives the priority levels for applications that have timed out. Applications time out

when their priority level is the one that is currently running and they have been marked with request_to_start. Such an application

has not finished running before it nee ds to start again.

6.4.1 Timeouts

A timeout condition indicates that the scheduler has been compromised by an application.

Table 31. Scheduler status register

Offset 0x00(MSB) 0x01

Bit 7654321076543210

Field timeout_status[31:24] timeout_status[23:16]

Reset 0x00 0x00

Offset 0x02 0x03(LSB)

Bit 7654321076543210

Field timeout_status[16:8] timeout_status[7:0]

Reset 0x00 0x00

Table 32. sched_parms_APP_ID bit descriptio ns

Field Description

31:0

timeout_status

Indicates the priority level of the task that has timed out, one or more times.

The register sets the corresponding priority-level bit when a task is timed out (currently running and being

marked request_to_start). This bit must be monitored to verify that no user task is compromising the

scheduler execution.

Units: None.

Range of valid values: 0 to 0xFFFFFFFF.

Overview of GPIO-App Ma p application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

7 GPIO-AppMap Application

7.1 Overview of GPIO-AppMap application

The GPIO-AppMap application assigns a bit from an applicatio n’s status register to a

specific GPIO pin. The configuration registers contain the application ID and the bit number

of the output byte for each GPIO pin.

The GPIO-AppMap application connects the MMA955xL platform’s GPIO pins to st atus bits

in an application’s status registers. The GPIO-AppMap application can control four physical

GPIO pins. Each of the four GPIO pins (GPIO6, 7, 8, and 9) has an associated APP_ID

The GPIO-AppMap application also has a general polarity register where the GPIO pins can

be set to be active high or active low. The default or start-up condition of the GPIO pins are

unassigned.

The GPIO pins that can be mapped are described in Table 33.

7.2 GPIO configuration registers

The GPIO-AppMap application’s configurations registers consist of 10 eight-bit registers. This includes two registers for each of

the four GPIO pins and two registers for setting the polarity of the GPIO pin. Each GPIO pin is assigned to an APP_ID and as an

output bit from the assigned application.

The following table gives the bit descriptions for the GPIO-AppMap application’s registers. The application’s registers are shown

in Table 35 th rough Table 43.

The bit descriptions are given in Table 45 on page 40.

7.2.1 GPIO register tables

Table 33. GPIO pin names, numbers and functions

Name Pin number

GPIO6 12

GPIO7 13

GPIO8 15

GPIO9 2

Table 34. APP_ID GPIO6 register

Offset 0x00

Bit 76543210

Field APP_ID GPIO6

Reset 0xFF

Application

ID 0x03

Default speed 30 Hz.

Configuration

registers Start on page

37.

Status

registers None.

GPIO configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Table 35. SR_bitnum GPIO6 register

Offset 0x01

Bit 76543210

Field SR_bitnum GPIO6

Reset 0x00

Table 36. APP_ID GPIO7 register

Offset 0x02

Bit 76543210

Field APP_ID GPIO7

Reset 0xFF

Table 37. SR_bitnum GPIO7 register

Offset 0x03

Bit 76543210

Field SR_bitnum GPIO7

Reset 0x00

Table 38. APP_ID GPIO8 register

Offset 0x04

Bit 76543210

Field APP_ID GPIO8

Reset 0xFF

Table 39. SR_bitnum GPIO8 register

Offset 0x05

Bit 76543210

Field SR_bitnum GPIO8

Reset 0x00

Table 40. APP_ID GPIO9 register

Offset 0x06

Bit 76543210

Field APP_ID GPIO9

Reset 0xFF

GPIO configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

7.2.2 GPIO polarity configuration

Table 41. SR_bitnum GPIO9 register

Offset 0x07

Bit 76543210

Field SR_bitnum GPIO9

Reset 0x00

Table 42. GPIO_pol MSB register

Offset 0x08(MSB)

Bit 76543210

Field Reserved GPIO9 GPIO8

Reset 0x00 0 0

Table 43. GPIO_pol LSB register

Offset 0x09(LSB)

Bit 76543210

Field GPIO7 GPIO6 Reserved

Reset 0 0 0x00

Table 44. GPIO output, depending on polarity configuration and bit value

Input Bits Output Bit

GPIO_POLARITY SR_bit x VAL GP IO x

000

011

101

110

GPIO configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

7.2.3 GPIO application bit descriptions

Table 45. GPIO application bit descriptions

Field Description

7:0

APP_ID GPIOx

The application identifier (APP_ID) of the application assigned to the GPIO pin. A value of 0xFF indicates

there is no application assigned.

After a reset, no application output bits are mapped to a GPIO.

Units: None.

Range of valid values: [0:31] and 0xFF.

7:0

SR_bitnum GPIOx

The bit number of the application status registers being assigned to the GPIO pin.

The bit number depends of the amount of ou tput bytes and the position of the bit in the register .

Units: None.

Range of valid values: [0:2 55]

GPIO_polx

Defines the output polarity of the GPIO pin designated by the n variable in the fi eld name.

This register uses negative logic 0 to configure active high and 1 for active low. Table 34 on page 37

indicates which pin of the register corresponds to each GPIO.

Units: None.

Range of valid values:

0: Output is active high (output bit = high → high on GPIO pin).

1: Output is active low (output bit = high → low on GPIO pin).

Reserved Indicates that the bit is reserved.

Overview of Mailbox application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

8 Mailbox Application

8.1 Overview of Mailbox application

The Mailbox (MBOX) application gathers output data from other applications and puts that

data into the mailbox registers. This enables users to customize and group up to 28

applications’ specific data bytes for quick reads.

Normally , the host may need to read the status and output data from many applications. This

requires multiple, serial-slave-port transactions. Using the mailbox application enables the

host to read all necessary data in one serial, I2C or SPI transaction.

The MBOX application provides a shortcut for the user to read different pieces of data from

different applications by combining th e data for reading in one I2C or SPI read transaction.

The MBOX application is different than the hardware mailboxes used by the Communication Interface application. The MBOX

application combines selected data bytes from specific applications and loads them into the Communications Interface

mailboxes.

In order to properly configure the system Communications Interface, the MBOX Configuration and Mailbox applications also must

be properly configured. The MBOX Configuration application controls how the mailboxes behave and the Mailbox application

controls what is placed in the mailboxes.

8.2 Mailbox configuration registers

The Mailbox application’s registers are described in the following table. The registers’ bit descriptions are given in “MBOX bit

description s” on page 45.

Each response mailbox (MB4 to MB31) has two associated configuration registers: APP_ID register and Byte_ID register . When

the Mailbox application runs, it copies the data at the Byte_ID from the specified APP_ID and put s that value in the associated

mailbox.

Users can configure mailboxes 4 through 31. Mailboxes 20 through 31 have a special function in Legacy mode. They are updated

automatically in the Legacy/Quick-Read mode.

Table 46. MBOX registers

Offset 0x00 0x01

Bit 7654321076543210

Field APP_ID MBOX_4 Byte_ID MBOX_4

Reset 0x00 0x00

Offset 0x02 0x03

Bit 7654321076543210

Field APP_ID MBOX_5 Byte_ID MBOX_5

Reset 0x00 0x00

Offset 0x04 0x05

Bit 7654321076543210

Field APP_ID MBOX_6 Byte_ID MBOX_6

Reset 0x00 0x00

Application

ID 0x04

Default speed 30 Hz.

Configuration

registers Start on page

41.

Status

registers None.

Mailbox configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Offset 0x06 0x07

Bit 7654321076543210

Field APP_ID MBOX_7 Byte_ID MBOX_7

Reset 0x00 0x00

Offset 0x08 0x09

Bit 7654321076543210

Field APP_ID MBOX_8 Byte_ID MBOX_8

Reset 0x00 0x00

Offset 0x0A 0x0B

Bit 7654321076543210

Field APP_ID MBOX_9 Byte_ID MBOX_9

Reset 0x00 0x00

Offset 0x0C 0x0D

Bit 7654321076543210

Field APP_ID MBOX_10 Byte_ID MBOX_10

Reset 0x00 0x00

Offset 0x0E 0x0F

Bit 7654321076543210

Field APP_ID MBOX_11 Byte_ID MBOX_11

Reset 0x00 0x00

Offset 0x10 0x11

Bit 7654321076543210

Field APP_ID MBOX_12 Byte_ID MBOX_12

Reset 0x00 0x00

Offset 0x12 0x13

Bit 7654321076543210

Field APP_ID MBOX_13 Byte_ID MBOX_13

Reset 0x00 0x00

Offset 0x14 0x15

Bit 7654321076543210

Field APP_ID MBOX_14 Byte_ID MBOX_14

Reset 0x00 0x00

Table 46. MBOX registers (Continued)

Mailbox configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Offset 0x16 0x17

Bit 7654321076543210

Field APP_ID MBOX_15 Byte_ID MBOX_15

Reset 0x00 0x00

Offset 0x18 0x19

Bit 7654321076543210

Field APP_ID MBOX_16 Byte_ID MBOX_16

Reset 0x00 0x00

Offset 0x1A 0x1B

Bit 7654321076543210

Field APP_ID MBOX_17 Byte_ID MBOX_17

Reset 0x00 0x00

Offset 0x1C 0x1D

Bit 7654321076543210

Field APP_ID MBOX_18 Byte_ID MBOX_18

Reset 0x00 0x00

Offset 0x1E 0x1F

Bit 7654321076543210

Field APP_ID MBOX_19 Byte_ID MBOX_19

Reset 0x00 0x00

Offset 0x20 0x21

Bit 7654321076543210

Field APP_ID MBOX_20 Byte_ID MBOX_20

Reset 0x11 (Defaults to Status Register application) 0x00 (Status application - MSB)

Offset 0x22 0x23

Bit 7654321076543210

Field APP_ID MBOX_21 Byte_ID MBOX_21

Reset 0x11 (Defaults to Status Register application) 0x01 (Status application - LSB)

Offset 0x24 0x25

Bit 7654321076543210

Field APP_ID MBOX_22 Byte_ID MBOX_22

Reset 0x10 (Defaults to Event Queue application ) 0x03 (Event Queue Status)

Table 46. MBOX registers (Continued)

Mailbox configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Offset 0x26 0x27

Bit 7654321076543210

Field APP_ID MBOX_23 Byte_ID MBOX_23

Reset 0x0F (Defaults to Data FIFO application) 0x03 (FIFO status)

Offset 0x28 0x29

Bit 7654321076543210

Field APP_ID MBOX_24 Byte_ID MBOX_24

Reset 0x06 (Defaults to Analog Front End application) 0x28 (Analog Front End Frame Counter - MSB)

Offset 0x2A 0x2B

Bit 7654321076543210

Field APP_ID MBOX_25 Byte_ID MBOX_25

Reset 0x06 (Defaults to Analog Front End application) 0x29 (Analog Front End Frame Counter - LSB)

Offset 0x2C 0x2D

Bit 7654321076543210

Field APP_ID MBOX_26 Byte_ID MBOX_26

Reset 0x06 (Defaults to Analog Front End application) 0x00 Analog Front End Stage 0 - X MSB

Offset 0x2E 0x2F

Bit 7654321076543210

Field APP_ID MBOX_27 Byte_ID MBOX_27

Reset 0x06 (Defaults to Analog Front End application) 0x01 (Analog Front End Stage 0 - X LSB)

Offset 0x30 0x31

Bit 7654321076543210

Field APP_ID MBOX_28 Byte_ID MBOX_28

Reset 0x06 (Defaults to Analog Front End application) 0x02 (Analog Front End Stage 0 - Y MSB)

Offset 0x32 0x33

Bit 7654321076543210

Field APP_ID MBOX_29 Byte_ID MBOX_29

Reset 0x04 (Analog Front End Stage 0 - Z MSB) 0x03 (Analog Front End Stage 0 - Y LSB)

Offset 0x34 0x35

Bit 7654321076543210

Field APP_ID MBOX_30 Byte_ID MBOX_30

Reset 0x06 (Defaults to Analog Front End application) 0x04 (Analog Front End Stage 0 - Z MSB)

Table 46. MBOX registers (Continued)

Mailbox configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

8.2.1 MBOX bit descriptio ns

8.2.2 Configuring XYZ data

The MBOX application aggrega tes application data and presents it in the mailboxes.

The AFE application (APP_ID 0x06) provides the XYZ accelerometer data with output register s 0 through 5 co ntaining the

FRONTEND_Stage_0 XYZ data. The following example shows what a host would send to the MMA9555L device to create the

configuration to set up quick-read mailboxes 4–9 to contain the following, FRONTEND_Stage_0_XYZ data:

• Data X to mailboxes 4 and 5

• Data Y to mailboxes 6 and 7

• Data Z to mailboxes 8 and 9

Example 4.

MBOX0 = 0x04 /* Host communicating to MBOX Application */

MBOX1 = 0x20 /* CONFIG_W command */

MBOX2 = 0x00 /* Starting at Offset 0 which is the config for MB4 */

MBOX3 = 0x0C /* Number of bytes to write 12 bytes */

MBOX4 = 0x06 /* APP_ID_MBOX4 0x06 - AFE APP_ID = 0x06 */

MBOX5 = 0x00 /* Byte_ID_MBOX4 Data - X MSB */

MBOX6 = 0x06 /* APP_ID_MBOX5 */

MBOX7 = 0x01 /* Byte_ID_MBOX5 Data - X LSB */

MBOX8 = 0x06 /* APP_ID_MBOX6 */

MBOX9 = 0x02 /* Byte_ID_MBOX6 Data - Y MSB */

MBOX10 = 0x06 /* APP_ID_MBOX7 */

MBOX11 = 0x03 /* Byte_ID_MBOX7 Data - Y LSB */

MBOX12 = 0x06 /* APP_ID_MBOX8 */

MBOX13 = 0x04 /* Byte_ID_MBOX8 Data - Z MSB */

MBOX14 = 0x06 /* APP_ID_MBOX9 */

MBOX15 = 0x05 /* Byte_ID_MBOX9 Data Z - LSB */

Offset 0x36 0x37

Bit 7654321076543210

Field APP_ID MBOX_31 Byte_ID MBOX_31

Reset 0x06 (Defaults to Analog Front End application) 0x05 (Analog Front End Stage 0 - Z LSB)

Table 47. MBOX bit descriptions

Field Description

7:0

APP_ID MBOX_x

Specifies the application to provide the outp ut byte, using the application identifier.

Units: None.

Range of valid values: 1 to 31. V alues outside this range or values for a nonexistent application may cause

unexpected system behavior.

7:0

Byte_ID MBOX_x

Indicates the byte number of the application’s status or output registers that are being sent to this mailbox.

The most-significant byte for a specific application’s output is identified as Byte 0 and the least-significant

byte is Byte x.

Units: Nondimensional.

Range of valid values: 0 to 255.

Table 46. MBOX registers (Continued)

Mailbox status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

8.3 Mailbox status registers

There are no status registers for this application.

8.4 Reading aggregated data (Legacy mode—Quick read)

Once the MBOX application is configured and the device is set to Legacy communication mode, the aggregated data can be read.

Assuming that the MBOX application was set up as shown in Section 8.2.2, “Configuring XYZ data”, the X, Y, and Z ac celeration

data output will be available in mailbo x es 4 through 9, through the normal command/response Communications Interface.

If the host needs to just read the data without the finer control of the command/response model, the MMA9555L can be put into

Legacy mode. This assigns the desired data to registers in the Quick-Read section of the Mailbox registers (MB20–MB31).

In Legacy mode, the lower mailbox registers continue to operate in the command/response mode and the upper registers operate

in the Quick-Read mode. The data in the Quick-Read registers is automatically updated, so a read-request command is not

required before reading the data form the upper mailboxes.

The following examples show how to wake up the device, configure it for quick-reading the low-passed-filtered XYZ data, enable

the Legacy mode, and read the data.

The MMA9555L platform comes out of reset in the Low-Power or Sleep mode. In order to start the AFE application and start

collecting samples, the MMA95 55L must be brought out of Sleep mode and into Run mode

This example shows how to disable Sleep mode and enable W a ke mode.

Example 5.

MBOX0 = 0x12 /* Host communicating to Sleep/Wake Application */

MBOX1 = 0x20 /* CONFIG_Write command */

MBOX2 = 0x06 /* Starting at Offset 0x6 */

MBOX3 = 0x01 /* Number of bytes to write 1 byte */

MBOX4 = 0x00 /* Write 0x00 which wakes up the device */

Bytes to Send: 0x12, 0x20 , 0x06, 0x01, 0x00

The AFE application (APP_ID 0x06) provides the XYZ accelerometer data with output register s 0 through 5 co ntaining the

FRONTEND_Stage_0 XYZ data. By default, the Quick-Read registers (MB26–MB31) are assigned 0x00 Analog Front End S tage

0 - X MSB.

The AFE application, however, provides XYZ, low-pass-filtered data in registers 0x18 through 0x1D

(FRONTEND_488_100_L PF). To quickly read this data, the Quick-Read mailbox registers would have to be configured so that

they are populated with the low-passed-filtered, XYZ dat a.

The following example shows how a host would direct the MMA9555L device to set up quick-read mailboxes to contain the

following, FRONTEND_488_1 00_LPG XYZ data:

• Data X to mailboxes 26 and 27

• Data Y to mailboxes 28 and 29

• Data Z to mailboxes 30 and 31

Example 6.

MBOX0 = 0x04 /* Host communicating to MBOX Application */

MBOX1 = 0x20 /* CONFIG_W command */

MBOX2 = 0x2C /* Starting at Offset 0x2C, the configuration starting point for MB26 */

MBOX3 = 0x0C /* Number of bytes to write 12 bytes */

MBOX4 = 0x06 /* APP_ID_MBOX26 = 0x06 - AFE APP_ID = 0x06 */

MBOX5 = 0x18 /* Byte_ID_MBOX26 = 0x18 - LPF Data starts at register 0x18 - X MSB */

MBOX6 = 0x06 /* APP_ID_MBOX27 */

MBOX7 = 0x19 /* Byte_ID_MBOX27 Data - X LSB */

MBOX8 = 0x06 /* APP_ID_MBOX28 */

MBOX9 = 0x1A /* Byte_ID_MBOX28 Data - Y MSB */

MBOX10 = 0x06 /* APP_ID_MBOX29 */

Reading aggregated data (Legacy mode—Quick read)

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

MBOX11 = 0x1B /* Byte_ID_MBOX29 Data - Y LSB */

MBOX12 = 0x06 /* APP_ID_MBOX30 */

MBOX13 = 0x1C /* Byte_ID_MBOX30 Data - Z MSB */

MBOX14 = 0x06 /* APP_ID_MBOX31 */

MBOX15 = 0x1D /* Byte_ID_MBOX31 Data Z - LSB */

Bytes to send: 0x04, 0x20, 0x2C, 0x0C, 0x06, 0x18, 0x06, 0x19, 0x06, 0x1A, 0x06, 0x1B, 0x06, 0x1C, 0x06, 0x1D.

The host then must configure the Mailbox application to operate in Le gacy mode, as shown in the following example.

Example 7.

1. MB0 = 0x18.

Sets the “APP_ID: Mailbox Mode Config” application identifier (0x18).

2. MB1 = 0x20.

Sets the “Command: Write Config” (0x20).

3. MB2 = 0x00.

Sets the Offset to Zero field (0x00) to point to the configuration register.

4. MB3 = 0x01.

Sets the Count field to 0x01 because only one data byte nee ds to be sent.

5. MB4 = 0x10.

Sets the DATA value to 0x10, which sets the LEGACY field to 1b or Legacy mode.

Bytes to send: 0x18, 0x20, 0x00, 0x01, 0x10.

The MMA9555L platform now is set to Legacy mode and the Quick-Read registers are being constantly updated with the low-

pass-filtered, AFE data.

All that remains is the issuing of a command to read the six bytes starting at MB26, which cont ains the XYZ data i n constant-read

mode.

In the following example, “0x__ ” represents the data that is sent back to the host.

Example 8.

MBOX0 = 0x04 /* Host communicating to MBOX Application */

MBOX1 = 0x30 /* Read Output Data command */

MBOX2 = 0x1A /* Starting at Offset 0x1A, the hexadecimal offset for mailbox 26 */

MBOX3 = 0x06 /* Number of bytes to read 6 bytes two bytes each for X, Y, andZ*/

MBOX4 = 0x__ /* MSB - X */

MBOX5 = 0x__ /* LSB - X */

MBOX6 = 0x__ /* MSB - Y */

MBOX7 = 0x__ /* LSB - Y */

MBOX8 = 0x__ /* MSB - Z */

MBOX9 = 0x__ /* LSB - Z*/

Bytes to send: 0x04, 0x30, 0x1A, 0x06, 0x__ , 0x__ , 0x__ , 0x__ , 0x__ , 0x__ .

Overview of Analog Front End application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9 Analog Front End Application

9.1 Overview of Analog Front End application

The Analog Front End application (AFE) samples raw accelerometer data from the analog-

to-digital converter (ADC) at the execution rate of the application, applies factory and user

trim-correction terms, and filters data to several configurable bandwidths.

For the proper operation of the Pedometer , it is recommended that any change to any of the

configuration registers of the AFE Application be avoided unless the outcome is well

understood.

Figure 13. Front-end signal processing

9.1.1 Sample rate

The rate at which the ADC samples the accelerometer data is defined by the sfd_rate register, which is offset 0x0C in the

configuration registers of this applic ation. The sample rate can be changed from 488 Hz to 3. 81 Hz by setting the appropriate

value in the sfd_rate register. For more details, see Table 59 and Table 60 on page 55.

NOTE

Although the sample rate can be changed in the hardware, it is recommended that the 30 Hz

sample rate not be changed, because the Pedometer applica tion requires 30 Hz and the

MMA9555L runs at 30 Hz after MMA9555L startup.

Application

ID 0x06

Default speed 30 Hz.

Configuration

registers Start on page

52.

Status

registers Start on page

56.

Analog Front End

ADC data

Sample rate

Offset

correction

Scale

correction

Anti-aliasing

filter Normalize

Configurable, low-pass

filter

Temperature output

External input

conversion

1:2

Outputs

Raw

488/100 Hz

Configurable,

low-pass filter

ABS

Anti-aliasing

Configurable,

high-pass filter

Normalized

488/100 Hz

Normalized

244/50 Hz

Absolute value

488/100 Hz

Normalized

488 Hz/Low-pass filter

Temperature

External

Normalized

488 Hz/High-pass filter

Overview of Analog Front End application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.1.2 Offset and scale correction

The AFE’s offset and scale correction stages of the signal chain applies trim offset and scaling correction factors which were

measured at factory calibration and stored inside each device. Since user offset s are defined at 8-g resolution, those offsets are

shifted according to the g mode.

User offsets are used to calibrate and compensate for the physical mounting of the part inside the final product. After board mount

and assembly, the final test process may include a test to fine tune and compensate the accelerometer orientation.

9.1.3 Anti-aliasing filter

After trim correction, the front end uses a sixth-order Chebyshev filter, ru nning up to 488 Hz, to limit the signal bandwidth to

100 Hz.

Figure 14. Frequency response of Analog Front End anti-aliasing filter

The bandwidth of the anti-aliasing filter depends on the sample rate at which the front end application is running. The following

table shows the variation of the filter bandwidth according to the sample rate.

Table 48. Anti-aliasing filter bandwidth for different sample rates

Sample rate Stage-0 anti-aliasing Filter Stage-1 anti-aliasing Filter

Bandwidth (Hz) Bandwidth (Hz)

488.28 100 50

244.17 50 25

122.07 25 12.5

61.04 12.5 6.25

31.52 6.25 3.125

15.26 3.125 1.562

7.63 1.562 0.781

3.81 0.781 0.390

Overview of Analog Front End application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.1.4 Raw data

The output of the sensor is a 16-bit, signed value. The sensor always uses all the bits for high accuracy . Depending on the range

setting (2-, 4-, or 8-g mode), the output value per g changes.

The following table shows the full scale value at the different g ranges, as well as the value of a measured 1-g acceleration at the

different g ranges.

9.1.5 Normalization

The filt ere d d ata is sh ifted according to th e g mode to normalize the reso l u ti on to the 8-g range. The normalized data allows for

common handling of the data in the other applications. Data is normalized so that 1-g force acceleration shows output of 0x1000

counts or 4096 decimal counts.

9.1.6 Down-sampling and stage-1, anti-aliasing filter

The output of the normalizer is down-sampled by two to generate data sampled at half of the original sample rate. At 488 Hz, the

previous, sixth-order Chebyshev filter is applied to down-sampled (244 Hz) data, to create a 50-Hz bandwidth data stream.

Table 6 0 on page 55 provides more details about the varying of the bandwidth, depending of the sample rate of the front-end

application.

9.1.7 Absolute value

The absolute value of the sensor output is computed.

9.1.8 Configurable, low-pass and high-pass filters

First-order, low-pass and high-pass filters—with separate configurable cutoff frequencies at –3 dB—are provided.

Eqn. 1

Eqn. 2

Table 49.Raw accelerometer output, according to g mode

Range Full scale One-g acceleration

+ 2 g+ 32 K 16 K

+ 4 g+ 32 K 8 K

+ 8 g+ 32 K 4 K

Overview of Analog Front End application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Figure 15. Frequency response of co nfi gu ra b le , high- and low-pass filter s

The two following tables contain the cutoff frequency of the filters, varying with the value of K and the sample rate at which the

front-end application is executed.

Table 50. Cut-off frequency as a function of K and the sample rat e for low-pass filter

LPF cut-off frequenc y (Hz)

Sample rate

= 488.28 Sample rate

= 244.14 Sample rate

= 122.07 Sample rate

= 61.04 Sample rate

= 30.52 Sample rate

= 15.26 Sample rate

= 7.63 Sample rate

= 3.81

1 56.13 28.07 14.03 7.02 3.51 1.75 0.88 0.4385

2 22.50 11.25 5.62 2.81 1.40 0.70 0.3516 0.1758

3 10.39 5.19 2.60 1.30 0.65 0.32 0.1623 0.0811

4 5.014 2.51 1.25 0.63 0.31 0.16 0.0783 0.0392

5 2.47 1.23 0.62 0.31 0.15 0.08 0.0385 0.0193

6 1.22 0.6116 0.31 0.15 0.08 0.04 0.0191 0.0096

7 0.61 0.30 0.15 0.08 0.04 0.02 0.0095 0.0048

8 0.30 0.15 0.08 0.04 0.02 0.01 0.0048 0.0024

9 0.15 0.076 0.04 0.02 0.01 0.0047 0.0024 0.0012

10 0.0759 0.038 0.019 0.0095 0.0047 0.0024 0.0012 0.0006

11 0.0379 0.019 0.0095 0.0047 0.0024 0.0012 0.0006 0.0003

12 0.019 0.0095 0.0048 0.0024 0.0012 0.0006 0.0003 0.0001

13 0.0095 0.0048 0.0024 0.0012 0.0006 0.0003 0.0001 0.00007

14 0.0047 0.0024 0.0012 0.0006 0.0003 0.0001 0.0007 0.00004

15 0.0024 0.0012 0.0006 0.0003 0.0002 0.00008 0.00004 0.00002

AFE configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.2 AFE configuration registers

9.2.1 afe_csr

Table 51. Cut-off frequency as a function of K and the sample rate for high-pass filter

HPF cut-off frequency (Hz)

Sample rate =

488.28 Sample rate =

244.14 Sample rate =

122.07 Sample rate

= 61.04 Sample rate

= 30.52 Sample rate

= 15.26 Sample rate

= 7.63 Sample rate =

3.81

1 31.932 15.966 7.9831 3.9915 1.9958 0.9979 0.4989 0.2495

2 17.405 8.7023 4.3511 2.1756 1.0878 0.5439 0.2719 0.136

3 9.1573 4.5787 2.2893 1.1447 0.5723 0.2862 0.1431 0.0715

4 4.7092 2.3546 1.1773 0.5887 0.2943 0.1472 0.0736 0.0368

5 2.3912 1.1956 0.5978 0.2989 0.1495 0.0747 0.0374 0.0187

6 1.2054 0.6027 0.3014 0.1507 0.0753 0.0377 0.0188 0.0094

7 0.6051 0.3026 0.1513 0.0756 0.0378 0.0189 0.0095 0.0047

8 0.3026 0.1513 0.0757 0.0378 0.0189 0.0095 0.0047 0.0024

9 0.1513 0.0757 0.0378 0.0189 0.0095 0.0047 0.0024 0.0012

10 0.0756 0.0378 0.0189 0.0095 0.0047 0.0024 0.0012 0.0006

11 0.039 0.0195 0.0098 0.0049 0.0024 0.0012 0.0006 0.0003

12 0.0195 0.0098 0.0049 0.0024 0.0012 0.0006 0.0003 0.0002

13 0.0098 0.0049 0.0025 0.0012 0.0006 0.0003 0.0002 8E–05

14 0.0049 0.0025 0.0012 0.0006 0.0003 0.0002 8E–05 4E–05

15 0.0024 0.0012 0.0006 0.0003 0.0002 8E–05 4E–05 2E–05

Table 52. afe_csr registers

Offset 0x00(MSB) 0x01(LSB)

Bit 765 4 321076543210

Field FS Ext

ADC Temp CM Reserved Reserved

Reset 0x00 0 0 0x00 0x00 0x00

AFE configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.2.2 user_offset [XYZ]

Often, during the mounting process, the accelerometer sensor is not mounted perfectly flat to the board and might also be rotated

slightly. This register enables a user to make an after-manufacturing calibration correction.

Table 53. afe_csr bit descriptions

Field Description

7:6

Full-scale selection. AFE_CSR[FS] and AFE_BIAS[SC_AAF_EN] are combined to control AFE gain and

trim mode.

Units: None.

Range of values:

Full-scale data range XYZ acceleration scaling (mg/LSB)

00: ±8 g 0.244

01: ±2 g 0.061

10: ±4 g 0.122

11: ±8 g 0.244

Ext ADC

Specifies whether an external input will or will not be measured during the next analog acquisition phase.

Note: The ExtADC and Temp bits must not be set at the same time.

Units: None.

• 0: No external input is measured during the next analog acquisition phase.

• 1: Enables the four AFE channels to measure the external analog input during the next analog acquisition phase.

Temp

Specifies whether the temperature sensor output will or will not be measured during the next analog

acquisition phase.

Note: The ExtADC and Temp bits must not be set at the same time.

Units: None.

Temperature will change slowly so it can be measured with a very low sample rate (1 Hz or less) by

occasionally replac ing an external ADC measurement with the Temperature ADC meas ure me nt.

Range of valid values: For valid values for FS and CM parameters, see the Intelligent, Motion-Sensing

Platform Hardware Reference Manual (MMA955xLHWRM), listed in “Related Documentation” on page 2

Accelerometer Reference Manual (MMA955xLRM).

• 0: No temperature sensor output will be measured during the next analog acquisition phase.

• 1: The temperature sensor output will be measured during the next analog acquisition phase.

3:2

Conversion Mode. Controls the ADC resolution/accuracy versus power and conversion time trade-offs.

Units: None

• 00: Conversion complete in 32 cycles

• 01: Conversion complete in 16 cycle

• 10: Conversion complete in eight cycles

• 11: Conversion complete in four cycles

Reserved Bit field reserved.

Table 54. user_offset [XYZ] registers

Offset 0x02(MSB) 0x03(LSB)

Bit 7654321076543210

Field user_offset[X] user_offset[X][

Reset 0xFF 0xFF

Offset 0x04(MSB) 0x05(LSB)

Bit 7654321076543210

Field user_offset[Y] user_offset[Y]

AFE configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.2.3 config_k

This register’s bits are shown in the following table.

Reset 0xFF 0xFF

Offset 0x06(MSB) 0x07(LSB)

Bit 7654321076543210

Field user_offset[Z] user_offset[Z]

Reset 0xFF 0xFF

Table 55. user_offset [XYZ] bit descriptions

Field Description

7:0

user_offset[XYZ]

Sets user offset s in the X, Y, and Z axes for the accelerometer , depending on the position on the device in

the user board. These values are considered as post-mount offsets.

Units: 0.244 mg/LSB.

Range of valid values: –32,768 to 32,767.

Reset value: 0xFF which is interpreted as –1.

Table 56. config_k registers

Offset 0x08 0x09

Bit 7654321076543210

Field config_k[HIGHPASS] config_k[LOWPASS]

Reset 0x00 0x00

Offset 0x0A 0x0B

Bit 7654321076543210

Field config_k[TEMP_LPF] config_k[EIC_LPF]

Reset 0x00 0x00

Table 57. config_k bit descriptions

Field Description

7:0

config_k[HIGHPASS]

High-pass filter configurable cutoff.

Units: None.

Range of valid values: 0 to 15.

7:0

config_k[LOWPASS]

Low-pass filter configurable cutoff.

Units: None.

Range of valid values: 0 to 15.

Table 54. user_offset [XYZ] registers (Continued)

AFE configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.2.4 sfd_rate

This register’s bits are shown in the following table. The system defaults to 30 Hz; therefore, this document assumes that 30 Hz

is the rate being run. If the user slows down the rate by changing the sfd_rate register, all references to the system frame rate

scale accordingly.

7:0

config_k[TEMP_LPF]

Low-pass filter, configurable cutoff for temperature sensor output.

Units: None.

Range of valid values: 0 to 15.

7:0

config_k[EIC_LPF]

Low-pass filter, configurable cutoff for external input conversion output.

Units: None.

Range of valid values: 0 to 15.

Table 58. sfd_rate register

Offset 0x0C

Bit 76543210

Field sfd_rate

Reset 00000111

Table 59. sfd_rate bit description

Field Description

7:0

sfd_rate

Defines the system frame interval, the time period for each sample or the system sample rate in Hz.

Units: None.

Range of valid values: 7 to 14. Table 60 shows the relation between the register value and the interval

between each frame.

Table 60. Frame interval, ac cording to the sfd_rate value

sfd_rate value Time frame (s) Max frames per second

7 2.05E–3 488.28

8 4.10E–3 244.17

9 8.19E–3 122.07

10 1.64E–2 61.04

11 3.28E–2 30.52

12 6.55E–2 15.26

13 1.31E–1 7.63

14 2.62E–1 3.81

Table 57. config_k bit descriptions

Field Description

AFE status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.3 AFE status registers

9.3.1 output[FRONTEND_Stage_0][XYZ]

These registers’ bits are shown in the following table.

9.3.2 output[FRONTEND_Stage_1][XYZ]

These registers’ bits are shown in the following table.

Table 61. output[FRONTEND_Stage_0][XYZ] registers

Offset 0x00(MSB) 0x01(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0][X] output[FRONTEND_Stage_0][X]

Reset 0x00 0x00

Offset 0x02(MSB) 0x03(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0][Y] output[FRONTEND_Stage_0][Y]

Reset 0x00 0x00

Offset 0x04(MSB) 0x05(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0][Z] output[FRONTEND_Stage_0][Z]

Reset 0x00 0x00

Table 62. output[FRONTEND_Stage_0][XYZ] bit description

Field Description

7:0

output[FRONTEND_Stage_0][XYZ]

Normalized accelerometer data sampled at the default rate with complete bandwidth.

Units: 0.244 mg/LSB.

Range of valid values: –32,768 to 32,767.

Table 63. output[FRONTEND_Stage_1][XYZ] registers

Offset 0x06(MSB) 0x07(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_1][X] output[FRONTEND_Stage_1][X]

Reset 0x00 0x00

Offset 0x08(MSB) 0x09(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_1][Y] output[FRONTEND_Stage_1][Y]

Reset 0x00 0x00

AFE status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.3.3 output[FRONTEND_Stage_0_ABS][XYZ]

These registers’ bits are shown in the following table.

Offset 0x0A(MSB) 0x0B(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_1][Z] output[FRONTEND_Stage_1][Z]

Reset 0x00 0x00

Table 64. output[FRONTEND_Stage_1][XYZ] bit description

Field Description

7:0

output[FRONTEND_Stage_1][XYZ]

Normalized accelerometer data sampled at the default rate of half bandwidth.

Units: 0.244 mg/LSB.

Range of valid values: –32,768 to 32,767.

Table 65. output[FRONTEND_Stage_0_ABS][XYZ] registers

Offset 0x0C(MSB) 0x0D(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_ABS][X] output[FRONTEND_Stage_0_ABS][X]

Reset 0x00 0x00

Offset 0x0E(MSB) 0x0F(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_ABS][Y] output[FRONTEND_Stage_0_ABS][Y]

Reset 0x00 0x00

Offset 0x10(MSB) 0x11(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_ABS][Z] output[FRONTEND_Stage_0_ABS][Z]

Reset 0x00 0x00

Table 66. output[FRONTEND_Stage_0_ABS][XYZ] bit description

Field Description

7:0

output[FRONTEND_Stage_0_ABS][XYZ]

Absolute value normalized accelerometer data sampled at the default rate of

complete bandwidth.

Units: 0.244 mg/LSB.

Range of valid values: 0 to 32,767.

Table 63. output[FRONTEND_Stage_1][XYZ] registers (Continued)

AFE status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.3.4 output[FRONTEND_Stage_0_GM][XYZ]

These registers’ bits are shown in the following table.

9.3.5 output[FRONTEND_Stage_0_LPF][XYZ]

These registers’ bits are shown in the following table.

Table 67. output[FRONTEND_Stage_0_GM][XYZ] registers

Offset 0x12(MSB) 0x13(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_GM][X] output[FRONTEND_Stage_0_GM][X]

Reset 0x00 0x00

Offset 0x14(MSB) 0x15(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_GM][Y] output[FRONTEND_Stage_0_GM][Y]

Reset 0x00 0x00

Offset 0x16(MSB) 0x17(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_GM][Z] output[FRONTEND_Stage_0_GM][Z]

Reset 0x00 0x00

Table 68. output[FRONTEND_Stage_0_GM][XYZ] bit description

Field Description

7:0

output[FRONTEND_Stage_0_GM][XYZ]

Raw accelerometer data sampled at the default rate with complete bandwidth. The

resolution depends on the g-mode setting configured by afe_csr[fs].

Units:

•±2 g mode: 0.061 mg/LSB

•±4 g mode: –0.122 mg/LSB

•±8 g mode: 0.244 mg/LSB

Range of valid values:

•±2 g mode: 0.061 mg/LSB = –32768 to 32767

•±4 g mode: 0.122 mg/LSB = –8192 to 8192

•±8 g mode: 0.244 mg/LSB = –4096 to 4096

Table 69. output[FRONTEND_Stage_0_LPF][XYZ] registers

Offset 0x18(MSB) 0x19(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_LPF][X] output[FRONTEND_Stage_0_LPF][X]

Reset 0x00 0x00

Offset 0x1A(MSB) 0x1B(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_LPF][Y] output[FRONTEND_Stage_0_LPF][Y]

Reset 0x00 0x00

AFE status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.3.6 output[FRONTEND_Stage_0_HPF][XYZ]

These registers’ bits are shown in the following table.

Offset 0x1C(MSB) 0x1D(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_LPF][Z] output[FRONTEND_Stage_0_LPF][Z]

Reset 0x00 0x00

Table 70. output[FRONTEND_Stage_0_LPF][XYZ] bit description

Field Description

7:0

output[FRONTEND_Stage_0_LPF][XYZ]

Normalized accelerometer data sampled at the default rate, with configurable,

low-pass filter cutoff.

Units: 0.244 mg/LSB.

Range of valid values: –32,768 to 32,767.

Table 71. output[FRONTEND_Stage_0_HPF][XYZ] registers

Offset 0x1E(MSB) 0x1F(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_HPF][X] output[FRONTEND_Stage_0_HPF][X]

Reset 0x00 0x00

Offset 0x20(MSB) 0x21LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_HPF][Y] output[FRONTEND_Stage_0_HPF][Y]

Reset 0x00 0x00

Offset 0x22(MSB) 0x23(LSB)

Bit 7654321076543210

Field output[FRONTEND_Stage_0_HPF][Z] output[FRONTEND_Stage_0_HPF][Z]

Reset 0x00 0x00

Table 72. output[FRONTEND_Stage_0_HPF][XYZ] bit description

Field Description

7:0

output[FRONTEND_Stage_0_HPF][XYZ]

Normalized accelerometer data sampled at the default rate, with configurable,

high-pass filter cutoff.

Units: 0.244 mg/LSB.

Range of valid values: –32,768 to 32,767.

Table 69. output[FRONTEND_Stage_0_LPF][XYZ] registers (Continued)

AFE status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.3.7 output_temp

This register’s bits are shown in the following table.

9.3.8 output_EIC

This register’s bits are shown in the following table.

Table 73. output_temp registers

Offset 0x24(MSB) 0x25(LSB)

Bit 7654321076543210

Field output_temp output_temp

Reset 0x00 0x00

Table 74. output_temp bit descript ion

Field Description

7:0

output_temp

Temperature sensor output measurement.

Units: ADC counts.

output_temp(in count) = –51.4T + 1146, where T is temperature in °C

Note that this is only a typical characteristic example. User shall perform minimal calibration to adjust

at least the offset.

Range of valid values: –32,768 to 32,767.

Table 75. output_EIC registers

Offset 0x26(MSB) 0x27(LSB)

Bit 7654321076543210

Field output_EIC output_EIC

Reset 0x00 0x00

Table 76. output_EIC bit description

Field Description

7:0

output_EIC

Output of the external, analog-input conversion value.

Units: ADC counts.

output_EIC(in count) = 29570 (AN0–AN1) – 122, where AN0–AN1 is in V.

Note that this equation is only a typical example, with ADC conversion in 16-bit mode.

Range of valid values: –32,768 to 32,767.

AFE status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

9.3.9 frame_counter

This register’s bits are shown in the following table.

Table 77. frame_counter registers

Offset 0x28(MSB) 0x29(LSB)

Bit 7654321076543210

Field frame_counter frame_counter

Reset 0x00 0x00

Table 78. output_EIC bit description

Field Description

7:0

frame_counter

Provides the number of frames processed at the configured sample rate. It is not a real-time

representation because the time that the device remains in the stop mode is not taken into account.

The frame counter will restart at zero when it reaches 65,535.

Units: Nondimensional.

Range of valid values: 0 to 65,535.

Overview of Data FIFO application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

10 Data FIFO Application

10.1 Overview of Data FIFO application

The Data FIFO (First In First Out) application is a buffer intended to store the output data

from an application. Every scheduler interval, the Data FIFO application gathers the output

data from an application and stores it until the host processor reads the data.

The FIFO application uses the mailboxes differently than other applications—operating in

the streaming mode. In streaming mode, the host continues reading data until a maximum

of up to 255 bytes is read per host request. The host must read all the data that it requested.

The FIFO can be connected to one application and can collect packets of data in different

sizes (one, two, four, or six bytes).

The Data FIFO has two different modes of operation: S t op on Overflow and Free Run.

The application’s status register displays current status values such as overflow condition, watermark reached, and buffer empty.

These conditions have a flag that is asserted indi vidually each time one of these conditions occurs.

The user can configure the FIFO buffer size by writing to the fifo_size word within the configuration registers. The buffer size can

be configured only once and is limite d by the amount of RAM available. The amount of available RAM can be impacted by the

Event Queue Application which also can be confi gured to use large amounts of RAM.

NOTE

Before configuring the Data FIFO application, it is recommended that the Data FIFO

Application be suspended. After the parameter is configured, remove the application from

suspend. A suspend is done with the Reset/Suspend/Clear Applicati on (APP_ID 0x17).

10.2 Modes of operation

This section examines the modes of operation of the FIFO buffer.

10.2.1 Stop-on-overflow

The FIFO stores data from an application, every single frame (a scheduler interval), as long as the FIFO is enabled. In this mode,

the FIFO stores data until an overflow condition is reached. At an overflow condition, the overflow flag is set.

The host asynchronously reads payload packets from the Data FIFO application. Reading payload packets frees up slot s for new

entries into the FIFO. If the host reads data faster than the applications put data into the FIFO, the overflow condition will never

happen.

The overflow condition occurs when the available buffer memory is full and there is no space available for another packet.

10.2.2 Free-run

The FIFO behaves as a circular buffer that stores data from the configured channel, every single frame, as long as the FIFO is

enabled. In this mode, the FIFO never stops storing data, even though the overflow condition is reached and the overflow flag is

set.

When the FIFO becomes full, the oldest data in the buffer will be overwritten first.

10.3 Reading process

To read the data FIFO, the host sends a read-data command to the MMA9555L device that calls the Data FIFO application, stores

the requested data within the FIFO into a buffer, and returns the number of bytes read. The data FIFO does not tag each entry

with a timestamp, only storing a timestamp for the last entry.

When the reading process is performed, the Data FIFO application calculates the timestamp for the first group of requested data

and appends the timestamp to the data. If the host requests N bytes and that is bigger than the entry size, the pop routine will

Application

ID 0x0F

Default speed 30 Hz.

Configuration

registers Start on page

67.

Status

registers Start on page

69.

Reading process

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

append the timestamp only for the first entry that fits in the N bytes requested. The host must calculate the timestamps for the

extra entries requested within the N bytes.

The host can request to read up to 255 bytes at a time. Assuming the AFE is providing data, this is exactly 36 packets of AFE data.

Each host, FIFO-read transaction includes a status byte and a timestamp word. These three bytes are prefixed to the payload

data.

Payload data is prefixed with the APP_ID of the application that has provi ded the data. In the AFE case, the APP_ID is 0x06.

(255 – 3 (status and timestamp) ) / 7 (APP_ID + 6 byte XYZ data) = 36

Reading the FIFO example

The device powers up in Sleep mode, but it may become necessary to wake the MMA9555L device.

Waking the device uses the following mailboxes:

MB0: 0x12, App_ID = 0x12; Power Controller modes

MB1: 0x20, Command 0x20 = Write configuration; Offset = 0

MB2: 0x06, Offset = 0x06

MB3: 0x01, Count of data to write

MB4: 0x00, Actual Data Value; Clears sleep bit

Bytes to Send: 0x12, 0x20 , 0x06, 0x01, 0x00 .

Example 9.

To configure for FIFO operation, write the following transaction to the Data-FIFO application:

1. MB0: Set APP_ID to (0x0F).

Selects the Data-FIFO application.

2. MB1: Comman d to (0 x2 0) .

Command is a W rite Configuration space.

3. MB2: Set offset to zero (0x00).

Start writing configuration values at register 0.

4. MB3: Set count field to (0x0A).

Sends nine bytes.

5. MB4: Send Data (0x0C).

Sends six bytes, free-run mode.

6. MB5: Send Data (0x00).

7. MB6: Send Data (0x00).

8. MB7: Send Data (0x00).

9. MB8: Send Data (0x00).

10. MB6: Send Data (0x3C).

Reserves 60 bytes—10 packets of six bytes each.

11. MB7: Send Data (0x06).

Associates APP ID = AFE – .

12. MB5: Send Data (0x00).

13. MB6: Send Data (0x00).

14. MB7: Send Data (0x00).

Bytes to Send: 0x0F, 0x20, 0x00, 0x0A, 0x0C, 0x00, 0x00, 0x00, 0x00, 0x3C, 0x06, 0x00, 0x00, 0x00.

The configuration registers can only be written once. To reconfigure the FIFO, the device first must be reset.

Read the FIFO applications status register to get the data.

Reading process

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Send the following command to set up for reading the status register.

Example 10.

1. MB0: Set APP_ID to (0x0F).

Selects the Data-FIFO application.

2. MB1: Comman d to (0 x3 0) .

Sends a Read Status spa ce command.

3. MB2: Set offset to zero (0x03).

Starts reading the configuration values from register 0x03.

4. MB3: Set count field to (0x0A).

Reads 10 bytes (three status bytes, one APP_ID, and six bytes of data).

Bytes to Send: 0x0F, 0x30, 0x03, 0x0A.

This results in the following response.

0F 80 0A 0A 05 83 13 06 00 81 FF EA 11 0C

The last six bytes are the AFE data: X, Y, and Z.

This response was with the device flat, in the Face-Up orientation. The X and Y data are close to 0x0000, or 0 g, and the Z data

is close to 0x1000, or 1 g.

MB0: APP_ID = 0x0F; FIFO application

MB1: STATUS = 0x80; Command Comp lete, no errors

MB2: RequestedData count = 0x0A; 10 bytes of data

MB3: Actual Data Count = 0x0A; 10 bytes of data

MB4: 0x05 = FIFO Status; Watermark and Overflow flag is set

MB5–MB6: = 0x8313; Timestamp

MB7: APP ID of the application providing the actual data = 0x06; AFE application

MB8–MB9: AFE X data; 0x0081

MB10–MB11: AFE Y data; 0xFFEA

MB12–MB13: AFE Z Data; 0x110C

The read size for one (1+6 byte) payload is 10 bytes. The size for two payloads is 17 bytes, 3 = 24 bytes.

Reading three payloads

Send the following command to set up for reading the status register.

Example 11.

1. MB0: Set APP_ID to (0x0F).

Selects the Low-g application.

2. MB1: Comman d to (0 x3 0)

Sends a Write Configuration space command.

3. MB2: Set offset to zero (0x03).

Starts writing configuration values at register 0.

4. MB3: Set count field to (0x18)

Reads 24 bytes (3 status byes + 3x(APP_ID+6 data)).

Bytes to Send: 0x0F, 0x30, 0x03, 0x18.

The response is below:

0F 80 18 18 05 33 53 06 00 93 00 7F 11 06 06 00 A2 00 7D 11 08 06 00 9C 00 79 11 07

Reading process

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

The last six bytes are the AFE data, X, Y, and Z.

This response was with the device flat, in the Face -Up orientation. The X and Y data are close to 0x0000—or 0-g—and the Z

data is close to 0x1000—or 1-g.

MB0: APP_ID = 0x0F; FIFO application

MB1: STATUS = 0x80; Command Comp lete, no errors

MB2: Requested data count = 0x18; 24 bytes of data

MB3: Actual Data Count = 0x18; 24 bytes of data

MB4: 0x05 = FIFO Status; Watermark and Overflow flag is set

MB5-6: = 0x3353; Timestamp

MB7: APP ID of the application providing the actual data = 0x06; The AFE application

MB8-9: AFE X data; 0x0093

MB10-11: AFE Y data; 0x007F

MB12-13: AFE Z Data; 0x1106

MB14: APP ID of the application providing the actual data = 0x06; the AFE application

MB15-16: AFE X data; 0x00A1

MB17-18: AFE Y data; 0x007D

MB19-20: AFE Z Data; 0x1108

MB21: APP ID of the application providing the actual data = 0x06; the AFE application

MB22-23: AFE X data; 0x009C

MB24-25: AFE Y data; 0x0079

MB26-27: AFE Z Data; 0x1107

To read data stored by the data FIFO application, the host must send a Read Data command along with a specific offset value.

This process has three conditions:

• The offset must be fixed to three

• Th e number of bytes to read must be larger than one and a multiple of the entry size

• The host must add three bytes to de-count the total bytes to read

Failure to adhere to the three conditions above could cause the data FIFO to enter into an error state and be unable to pop

coherent data. To recover the data FIFO, reset the flag in the Reset_control byte (APP_ID 0x17).

When the command is sent, the first four bytes that the MMA9555L device returns correspond to the response of the command.

The next byte gives the status of the data FIFO application module and the following two bytes represent the timestamp; thus the

three-byte offset.

These bytes are part of those requested by the host, so it is very important that the user add three bytes to the number of bytes

to read. The data stored in the data FIFO comes after these seven bytes.

If the module is storing data at the exact moment that a read is issued by the host, the MMA9555L device will return an error

condition (A2). When this occurs, the host must retry reading the data. If any other error is returned, the host must take the proper

action.

Data FIFO block diagram

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

10.4 Data FIFO block diagram

Figure 16. Data FIFO model

Figure 16 shows the block-level model of the data FIFO. The application is driven by the watermark and mode inputs that

configure the functional ity.

The watermark le ve l he lps the host prevent dat a lo ss by ra ising a warning just before the overflow condition occurs. When the

number of bytes in the buffer approaches its capacity, the data FIFO asserts the watermark flag in the status register. The

watermark level is user-configurable. If the level of 0 is configured, the watermark is disabled.

The channel has its own data format code (DFC) bit field that configures th e payload to be store d (one, two, four, or six bytes).

A NULL or zero value in the APP_ID Channel register means the channel is disabled. Any valid APP_ID value means the channel

is enabled.

The data FIFO has a status register in its output structure that contains status flags such as watermark, overflow, and buffer

empty. These flags can be mapped to th e GPIO pins to generate an interrupt to the host.

The output also has an Entry Size re gister that shows the size, in bytes, of each entry that the data FIFO calculated, according

to its payload configuration. A Records Number register records the numb er of en tries stored in the data FIFO. Both registers

help the host to calculate how many bytes to request, so that it can dump the entire FIFO buffer. A simple multiplication of those

two registers’ value gives the total number of bytes stored in the FIFO.

T im eS tamp r egis ter

FIFO bu f fer

( Hos t dec ides the siz e

in bytes)

Entry

size Records

number

GP IO mapping logic

Frame

counter

APP_ID =

nn Watermark

level

Mode

FIFO size

•S t o p on ov er f l ow

•Free run

Interrupt

WM OvF Empty

flag flag flag

Data FIFO configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

10.4.1 Entries format

Channel enabled

Figure 17. FIFO-entry formats, when channel enabled

10.5 Data FIFO configuration registers

This section contains the FIFO configuration registers. These registers can only be written once. To reconfigure the FIFO, the

device must be reset. This is because the FIFO application requests RAM and RAM can only be allocated once.

10.5.1 FIFO configuration byte

Table 79. FIFO Config Byte register

Offset 0x00

Bit 76543210

Field Reserved DFC1 Mode

Reset 0x00 0x00 0x00

Table 80. FIFO Config Byte bit descriptions

Field Description

Reserved Bit field reserved.

3:2

DFC1

(Data Format Code)

Configures the payload size of the channel.

Units: None.

Range of valid values: 0 to 3.

• 00: One byte.

• 01: Two bytes.

• 10: Four bytes

• 11: Six bytes.

1:0

Mode

Configures the FIFO mode.

Units: None.

Range of valid values:

• 00: Free Run.

• 01: Stop On Overflow.

APP_ID (1 byte) Payload (Nbytes)

En try 1

En try 2

•

Entry M

Size de fined by DFC1

(1, 2, 4, or 6 bytes)

Data FIFO configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

10.5.2 FIFO size word

10.5.3 FIFO APP_ID

10.5.4 Watermark

Table 81. FIFO-size word registers

Offset 0x04(MSB) 0x05(LSB)

Bit 7654321076543210

Field FIFO Size Word 1 FIFO Size Word 2

Reset 0x00 0x00

Table 82. FIFO-size word bit description

Field Description

7:0

FIFO Size Word

Reserves the maximum size (in bytes) that the FIFO can use. This is limited by the available RAM.

Units: Bytes.

Range of valid values: 0 to available RAM.

0x1C8 (decimal, 456) is the maximum amount of RAM that can be requested from the MMA9555L device.

The RAM is shared by multiple applications, so be careful not to set the FIFO to use more memory than

is physically available. That will cause unknown and undesirable results.

Table 83. FIFO Channel APP_ID register

Offset 0x06

Bit 76543210

Field FIFO Ch APP_ID

Reset 0x00

Table 84. FIFO Channel APP_ID bit description

Field Description

7:0

FIFO Ch APP_ID The APP_ID of the application that supplied data to be buffered by the FIFO.

Range of valid values: 0 to 0xFF.

Table 85. Watermark registers

Offset 0x08(MSB) 0x09(LSB)

Bit 7654321076543210

Field Watermark Watermark

Reset 0x00 0x00

Data FIFO status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

10.6 Data FIFO status registers

10.6.1 Records number

10.6.2 Entry size

Table 86. Watermark bit description

Field Description

7:0

Watermark

Sets the count, in bytes, for the FIFO to set or clear the watermark flag.

Units: Bytes.

Range of valid values: 0–available RAM.

Table 87. Records-number register

Offset 0x00(MSB) 0x01(LSB)

Bit 7654321076543210

Field Records Number Records Number

Reset 0x00 0x00

Table 88. Records-number bit description

Field Description

7:0

Records Number

This word stores the current number of records in the FIFO buffer.

A record is the payload packet of dat a comprised of an APP_ID and the actual data—which could be one,

two, four, or six bytes long. A record can be two, three, four, or seven bytes long.

Units: Number of entries in the Data FIFO (entry size in bytes = Ch APP_ID+ DFC1).

Range of valid values: 0 to available oxF FFF.

Table 89. Entry-size register

Offset 0x02

Bit 76543210

Field Entry Size

Reset 0x00

Table 90. FIFO config-byte/bit description

Field Description

7:0

Entry Size

This byte shows the size in bytes of each entry that the data FIFO has stored, that calculation based on

its configuration.

Units: Bytes.

Range of valid values: 0 to 6.

Data FIFO status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

10.6.3 FIFO_Status

Table 91. FIFO_Status register

Offset 0x03

Bit 76543210

Field on_going_push on_going_pop Reserved ovf_flag empty_ flag wmrk_ flag

Reset 0x00 0x00 0x00 0 0 0

Table 92. FIFO_Status bit descriptions

Field Description

fifo_on_going_push

Indicates that a push operation is being executed—the is FIFO receivi ng data from the application.

Units: Nondimensional.

Range of valid values: 0 to 1.

• 0: A push is not being executed.

• 1: A push is being executed.

fifo_on_going_pop

Indicates that a pop operation is being executed. The FIFO is sending out data and it is bei n g read.

Units: Nondimensional.

Range of valid values: 0 to 1.

• 0: A pop operation is not being executed.

• 1: A pop operation is being executed.

5:3

Reserved Bit field reserved.

fifo_ovf_flag

Indicates that FIFO buffer has reached the maximum number of entries allowed. This meaning can vary

depending of the mode of operation.

Units: Nondimensional.

Range of valid values:

• 0: Not overflow condition.

• 1: Overflow condition.

fifo_empty_flag

Indicates whether the FIFO buffer is empty.

Units: Nondimensional.

Range of valid values:

• 0: FIFO buffer is not empty.

• 1: FIFO buffer is empty.

fifo_wmrk_flag

Indicates when the entries in the FIFO buffer have reached the watermark count.

Units: Nondimensional..

Range of valid values:

• 0: Watermark not reached.

• 1: Watermark reached.

Overview of Event Queue application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

11 Event Queue Application

11.1 Overview of Event Queue application

This application manages a queue of asynchronous events. The size of the queue is flexible

and can be configured by writing to the queue_size word within the configuration registers

of the Event Queue Application.

The size of the Event Queue is limited by the available RAM. The am ount of RAM may be

reduced by the Data FIFO Application which also can be configured to use the RAM.

Some applications inside the MMA9555L platform have an eight-bit event-mask register

within configuration-registers structure that selects the specific event to be stored into the

Event Queue. The user can set an application’s event-mask bit to enable or prevent that

application’s events from being added to the Event Queue.

When the selected event happens, Event Queue Application calls a routine with the following prototype to push the application’s

event into the Event Queue:

void eventQueue_push(void *data, uint8_t size)

With these variables:

• Data: Pointer to the first element of the data to be stored into the queue. The data must have the order: APP_ID + Payload

bytes.

• S ize: Amount of data (in bytes) to be stored into the queue.

Each entry into the Event Queue is of fixed size and has the following format:

Figure 18. Entry format for the Event Queue

If an application’s payload is less than three bytes, the Event Queue will store the data and complete the entry padding with zeros.

If the application has a payload more than three bytes, the Event Queue will calculate the number of entries that this payload

needs to be successfully stored, split in the format shown in Figure 18.

If an application tries to push data into the Event Queue and there is not enough space to store it, the Event Queue will ignore

the attempt. This will be transparent for the application since there is no comm u ni c a ti o n between the application and the Event

Queue.

11.1.1 Modes of operation

The Event Queue works only in one mode. It stores data and stops when the end of the queue is reached and asserts an overflow

flag. The queue is not circular.

The application has a configurable watermark that asserts a flag when entries have reached the configured point.

11.1.2 Reading process

To read the Event Queue, the host sends a read-status command to the MMA9555L device, calling the Event Queue application

that stores the data within the queue into a buffer and returns the number of bytes read. If the number of requested bytes is not

a multiple of the entry size, the pop routine ignores the extra bytes and tells the host how many effective bytes were popped.

To read data stored by the Event Queue application, the host must send a Read Data command along with a specific offset value.

The following examples show the command for reading the data stored by the Event Queue Application.

Application

ID 0x10

Default speed 30 Hz.

Configuration

registers Start on page

74.

Status

registers Start on page

76.

Frame Counter APP ID Payload

Six bytes per entry

Overview of Event Queue application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Reading Event Queue example

The following example shows how to configure the Event Queue application.

Example 12.

1. MB0: Set APP_ID to (0x10).

Selects the Data-FIFO application.

2. MB1: Command to (0x20).

Sends a Write Configuration space command.

3. MB2: Set offset to zero (0x00).

Starts writing configuration values at register 0.

4. MB3: Set count field to (0x06).

Sends nine bytes.

5. MB4: Send Data (0x00).

Sets Queue size.

6. MB5: Send Data (0x50).

7. MB6: Send Data (0x00).

Watermark

8. MB7: Send Data (0x05).

9. MB8: Send Data (0x00).

Timeout.

10. MB6: Send Data (0x00).

Bytes to Send: 0x10, 0x20, 0x00, 0x06, 0x00, 0x50, 0x00, 0x05, 0x00, 0x00.

The configuration registers can only be written once. If the Event Queue must be reconfigured, the device must be reset and the

configuration rewritten.

Some data now must be sent to the event queue. In this example, the Low-g application is configured to send an event.

Example 13.

1. MB0: Set APP_ID to (0x09).

Specifies the Low-g application.

2. MB1: Command to (0x20).

Sends a Write Configuration space command.

3. MB2: Set offset to zero (0x09).

4. Start writing configuration values at Register 9.

5. MB3: Set count field to (0x01).

Sends nine bytes.

6. MB4: Send Data (0x08) – Event Mask Register.

Enables Low-g events.

Bytes to Send: 0x09, 0x20 , 0x09, 0x01, 0x08 .

In this example, all other Low-g configuration register values are at the reset default values.

The device powers up in Sleep mode, but it may become necessary to wake the part. That process is done in the following

example.

Example 14.

1. MB0: Set App_ID to (0x12).

Selects the Power Controller modes.

2. MB1: Command to (0x20).

Sends a write configuration , with offset = 0.

3. MB2: Set offset to (0x06).

4. MB3: Set count field to (0x01).

Overview of Event Queue application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

5. MB4: Send the da ta value (0x00).

Bytes to Send: 0x12, 0x20 , 0x06, 0x01, 0x00 .

The device is enabled and configured to have an event Queue and send Low-g events to the Event Queue.

To cause a Low-g event that can be measured on the X, Y, and Z axes, toss the board into the air. Read the Event Queue

applications status register to get the data.

To set up for reading the status register, send the command in the following example.

Example 15.

1. MB0: Set APP_ID to (0x10).

Selects the Event Queue application.

2. MB1: Command to (0x30).

Sends a Read Status space command.

3. MB2: Set offset to zero (0x03).

Start reading status values at register 0.

4. MB3: Set count field to (0x20).

Reads 10 bytes (3 status + APP_ID+6 data)

Bytes to Send: 0x10, 0x30 , 0x03, 0x20.

The following response is returned:

10 80 13 20 09 95 AC 09 0F 00 00 95 BE 09 0F 00 00 95 D0 09 0F 00 00

MB0: APP_ID = 0x10; Event Queue application

MB1: STATUS = 0x80; Command Comp lete, no errors

MB3: Actual Data Count = 0x13; 10 bytes of data

MB2: Requested Data count = 0x20; 10 bytes of data

MB4: 0x09 = Event Queue Status; Watermark and Overflow flags are set

MB5–MB6: = 0x95AC; Timestam p

MB7: APP ID of the application providing the actual data = 0x09; the AFE application

MB8–MB10: 0x0F0000 = 0x0F is the status register from the Low-g applications; 0x0F indicate s a Low-g even t on all axes.

MB5–MB6: = 0x95BE; Timestamp

MB7: APP ID of the application providing the actual data = 0x09; the AFE application

MB8–MB10: 0x0F0000

MB5–MB6: = 0x95D0; Timestamp

MB7: APP ID of the application providing the actual data = 0x09; the AFE applications

MB8–MB10: 0x0F0000

The offset is fixed to three bytes.

Event Queue configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

When the command is sent, the first four bytes that the MMA9555L device returns correspond to the response of the command.

The fifth byte is the status from the Event Queue application. Th is byte is part of the bytes requested by the host, therefore it is

very important that the user adds one byte to the number of bytes to be read.

Due to the application’s read functionality, if the application is storing data at the exact moment a read is issued by the host, the

MMA9555L device will return an error condition. When this occurs, the host must retry reading the data. If any other error is

returned, the host must take the proper action.

11.1.3 Event Queue block diagram

The following figure shows the Event Queue Data Flow Model that receives the Application ID and the N size of the payload from

a specific application. The Event Queue logic appends the frame counter with this data and pushes the entry (six bytes in size)

into the queue. If the queue is full, the logic will ignore the push request.

Figure 19. Event Queue data flow

11.2 Event Queue configuration registers

The Event Queue application’s configuration can only be written once. In order to reconfigure the Event Queue, the whole device

must be reset. This is because the Eve nt Queue application requests RAM and RAM can only be allocated once.

AP P ( AP _ID)

Q ueu e pr oc es s ing

Data Array

Host decide s

the size

(in by tes)

Frame

Counter G P IO m a pping

logic

Event_Queue_Flag Regis ter

AP_ID – Payload N

Event_Queue_Mask Regis ter

Event_Queue_Flag Register

Var i ous elem ents in the application

can s et or clear b its in this r egis ter.

Logical AND

Payload N

Config command c an

Modify this register.

Config command can

modify this table.

Command calls a

pop r outine t o dum p

t he memory.

Fu ll WM First entry (after re set)

Interrupt

Push

subroutine

16-bit fram e count AP_ID Pay load

Event Queue configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

11.2.1 queue_size

11.2.2 queue_wmrk

11.2.3 queue_timeout

Table 93. queue_size registers

Offset 0x00(MSB) 0x01(LSB)

Bit 7654321076543210

Field queue_size

Reset

Table 94. queue_size bit description

Field Description

7:0

queue_size

Defines the size in bytes that the Event Queue will reserve, in order to store the data sent by any

application.

Units: Bytes

Range of valid values: 0–available RAM.

0x1C8 (decimal 456) is the maximum amount of RAM that can be requested from the MMA9555L device.

The RAM is shared by multiple applications, so be careful not to set the FIFO to use more memory than

is physically available. That will cause unknown and undesirable results.

Table 95. queue_wmrk registers

Offset 0x02(MSB) 0x03(LSB)

Bit 7654321076543210

Field queue_wmrk

Reset

Table 96. queue_wmrk bit description

Field Description

7:0

queue_wmrk

Sets the count, in bytes, for the Event Queue to set or clear the watermark flag.

Units: Bytes.

Range of valid values: 0 to available bytes in th e buffer.

Table 97. queue_timeout registers

Offset 0x04(MSB) 0x05(LSB)

Bit 7654321076543210

Field queue_timeout

Reset

Event Queue status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

11.3 Event Queue status registers

11.3.1 records_number

11.3.2 entry_size

Table 98. queue_timeout bit description

Field Description

7:0

queue_timeout

Sets the count, in cycles, for the Event Queue to set or clear the time-out flag.

Units: Time; [queue_timeout] * [1/SRqueue] ).

Range of valid values: 0 to 65,5 35.

SR_queue is the sample rate of the Event Queue application, which defaults to 30 Hz.

Table 99. records_number registers

Offset 0x00(MSB) 0x01(LSB)

Bit 7654321076543210

Field records_number

Reset

Table 100. records_number bit description

Field Description

7:0

records_number

Shows the current number of entries or records stored in the queue.

Units: Entries (Entry = six bytes).

Range of valid values: 0 to 65,535. Typically, this number should not be more than the available RAM

divided by the payload size.

Table 101. entry_size registers

Offset 0x02

Bit 76543210

Set-bit values 00000110

Field entry_size

Reset 00000110

Table 102. entry_size bit description

Field Description

7:0

entry_size

Shows the size in bytes of each entry or record in the queue. This value is six bytes fixed and is not user-

configurable.

Units: Bytes.

Range of valid values: Fixed to six.

Event Queue status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

11.3.3 queue_status

Table 103. queue_status registers

Offset 0x03

Bit 76543210

Field on_going_push on_going_pop Reserved to_flag ovf_flag empty_flag wmrk_flag

Reset

Table 104. queue_status bit descriptions

Field Description

on_going_push

Indicates that a push operation is being executed.

Units: Nondimensional.

Range of valid values: 0 to 1.

on_going_pop

Indicates that a pop operation is being executed.

Units: Nondimensional..

Range of valid values: 0 to 1.

5:4

Reserved Bit field reserved.

to_flag

Indicates when the Event Queue has not be en read for the time configured by the queue_TimeOut

parameter once the overflow marker has been reached.

Units: Nondimensional.

Range of valid values: 0 to 1.

ovf_flag

Indicates when the Event Queue is full and no more entries can be stored.

Units: Nondimensional.

Range of valid values: 0 to 1.

empty_flag

Indicates when the Event Queue is empty, no records or entries having been stored.

Units: Nondimensional.

Range of valid values: 0 to 1.

wmrk_flag

Indicates when the number of bytes within the Event Queue has reached the watermark.

Units: Nondimensional.

Range of valid values: 0 to 1.

Overview of Status Register application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

12 Status Register Application

12.1 Overview of Status Register application

The Status Register Application provides a simple way for users to combine specific status

information bits from multiple applications and read that combined information from one

place.

The Status Register Application configures the output of its status register by mapping a

specific status register bit to a specific output bit of a specific application. This enable s the

Status Register Application to provide a combined status from the selected bits of user-

specified applications.

There are eight, user-configurable bits in the Status Register. Each bit mirrors an output bit

in the related application.

12.2 Status Register configuration registers

The following tables show the configuration registers for the Status Register Application. The bit descriptions are given in

Table 1 22 on page 82.

12.2.1 APP_ID SR_00

12.2.2 Output_Bit_ID SR_00

12.2.3 APP_ID SR_01

Table 105. APP_ID SR_00 register

Offset 0x00

Bit 76543210

Field APP_ID SR_00

Reset 0x07

Table 106. Output_Bit_ID SR_00 register

Offset 0x01

Bit 76543210

Field Output_Bit_ID SR_00

Reset 0x00

Table 107. APP_ID SR_01 register

Offset 0x02

Bit 76543210

Field APP_ID SR_01

Reset 0x07

Application

ID 0x11

Default speed 30 Hz.

Configuration

registers Start on page

78.

Status

registers Start on page

82.

Status Register configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

12.2.4 Output_Bit_ID SR_01

12.2.5 APP_ID SR_02

12.2.6 Output_Bit_ID SR_02

12.2.7 APP_ID SR_03

Table 108. Output_Bit_ID SR_01 register

Offset 0x03

Bit 76543210

Field Output_Bit_ID SR_01

Reset 0x01

Table 109. APP_ID SR_02 register

Offset 0x04

Bit 76543210

Field APP_ID SR_02

Reset 0x07

Table 110. Output_Bit_ID SR_02 register

Offset 0x05

Bit 76543210

Field Output_Bit_ID SR_02

Reset 0x02

Table 111. APP_ID SR_03 register

Offset 0x06

Bit 76543210

Field APP_ID SR_03

Reset 0x07

Status Register configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

12.2.8 Output_Bit_ID SR_03

12.2.9 APP_ID SR_04

12.2.10 Output_Bit_ID SR_04

12.2.11 APP_ID SR_05

Table 112. Output_Bit_ID SR_03 register

Offset 0x07

Bit 76543210

Field Output_Bit_ID SR_03

Reset 0x03

Table 113. APP_ID SR_04 register

Offset 0x08

Bit 76543210

Field APP_ID SR_04

Reset 0x07

Table 114. Output_Bit_ID SR_04 register

Offset 0x09

Bit 76543210

Field Output_Bit_ID SR_04

Reset 0x04

Table 115. APP_ID SR_05 register

Offset 0x0A

Bit 76543210

Field APP_ID SR_05

Reset 0x00

Status Register configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

12.2.12 Output_Bit_ID SR_05

12.2.13 APP_ID SR_06

12.2.14 Output_Bit_ID SR_06

12.2.15 APP_ID SR_07

Table 116. Output_Bit_ID SR_05 register

Offset 0x0B

Bit 76543210

Field Output_Bit_ID SR_05

Reset 0x00

Table 117. APP_ID SR_06 register

Offset 0x0C

Bit 76543210

Field APP_ID SR_06

Reset 0x07

Table 118. Output_Bit_ID SR_06 register

Offset 0x0D

Bit 76543210

Field Output_Bit_ID SR_06

Reset 0x06

Table 119. APP_ID SR_07 register

Offset 0x0E

Bit 76543210

Field APP_ID SR_07

Reset 0x00

Table 120. APP_ID SR_07 register description

Field Description

7:0

APP_ID (APP_ID SR_n)

The application identifier. Zero value and 0xFF are reserved.

Units: None.

Range of valid values: [0 to 31] and 0xFF, realistically up to 0x1F, refer to the App-ID table

Status Register default configuration

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

12.2.16 Output_Bit_ID SR_07

12.3 Status Register default configuration

After reset, the status register configuration registers contain the Data Ready and Command Complete bits.

NOTE

The upper two bits in the upper byte are fixed, but the lower eight bits in the lower byte can

be remapped by the user to any application and bits.

Table 121. Output_Bit_ID SR_07 register

Offset 0x0F

Bit 76543210

Field Output_Bit_ID SR_07

Reset 0x00

Table 122. Output_Bit_ID SR_07 register description

Field Description

7:0

Bit_ID (Output_Bit_ID SR_n)

The bit number to be mapped on the Status Register bit n.

Units: None.

Range of valid values: [0 to 255], refer to the register memory map of each application

Table 123. Status Re gister MSB

Offset 0x00

Bit 15 14 13 12 11 10 9 8

Field Command

Complete Data

Ready N/A N/A N/A N/A N/A N/A

Reset

Table 124. Status Register LSB

Offset 0x01

Bit 76543210

Field Unassigned Reserved Unassigned Reserved

Reset

Overview of Sleep/Wake application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

13 Sleep/Wake Application

13.1 Overview of Sleep/Wake application

This application configures and controls the power-control modes of the accelerometer

provides configuration fl exibility for minimizing power consumption.

The application has three modes of operation: Run, Doze , and Sleep. The Sleep/Wake

module puts the accelerometer into Doze mode automatically when no movement is

detected. When a change in orientation or movement above the threshold is detected for the

specified time period, the application returns to the Run mode.

To save a significant amount of power , only run the calculation-intensive applications when

the accelerometer is in motion.

Using the activity level settings, some tasks may easily be bypassed when the accelerometer is sleeping. For example, it may

not be necessary to run the Pedometer ap plication while the device is sitting undisturb ed flat on a desktop.

13.1.1 Run mode

In Run mode, all applications are scheduled to run at their maximum established frame rate. An application enters Run mode if

the following conditions are met:

• The GPIO interrupt is asserted (RGPIO4/INT)

• A write command is issued from the host to the MMA9555L

• M ovement above the threshold is detected and the previous state was Doze mode

Figure 20. MMA9 555L’s power modes state diagram

Application

ID 0x12

Default speed 30 Hz.

Configuration

registers Start on page

84.

Status

registers Start on page

87.

Sleep mode,

nothing done

Run mode,

application

executing

Doze mode,

short time between

AFE samples

Doze mode,

long time between

AFE samples

Sleep = 1

Sleep = 0

Sleep = 1

Some movement

detected

No movement or

host command

for the short

configured time

Movement

above threshold

detected

No movement or host

command for the short

configured time

Average sample rate

0 Hz SR 1/(long time) Hz SR 30 Hz SR

Pedometer

1/(short time) Hz SR

Sleep/Wake configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

13.1.2 Doze mode

In Doze mode, the application only executes four AFE samples at a sample rate defined by the user . The user can configure two

sample rate values: long time and short time. These paramete rs ar e configured in the long_time_off and short_time_off

registers, respectively.

The short-time sample rate is used when the sensor detects some movement, but not enough to change to Run mode.

The long-time sample rate is used when the Sleep/Wake module detects no movement in the accelerometer.

The application enters Doze mode when the Sleep/Wake module detects no movement in the accelerometer for a specified

period of time. The amount of time is configured in the doze_thresh re gister.

13.1.3 Sleep mode

In Sleep mode, the MMA9555L device does nothing and remains in the lowest power mode. The device can enter this mode only

when the user sets the SNCEN bit from the cfg configuration register or when the application starts. Since the SNCEN bit is set

by default, the application starts in Sleep mode.

To exit the Sleep mode, the user must clear the SNCEN bit from the cfg configuration register. This is done by issuing the

corresponding write configuration command through the slave communications interface.

13.2 Sleep/Wake configuration registers

The following sections give the configuration registers for the Sleep/Wake application.

13.2.1 sensitivity_thresh

13.2.2 doze_time_thresh

Table 125. sensitivity_thresh registers

Offset 0x00(MSB) 0x01(LSB)

Bit 7654321076543210

Field sensitivity_thresh sensitivity_thresh

Reset 0x00 10100000

Table 126. sensitivity_thresh bit description

Field Description

7:0

sensitivity_thresh

Configures the movement threshold of the application to change from Doze to Run mode.

Units: None.

Range of valid values: 120 to 300.

Table 127. doze_time_thresh registers

Offset 0x02 (MSB) 0x03 (LSB)

Bit 7654321076543210

Field doze_thresh doze_thresh

Reset 0000111110100000

Sleep/Wake configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

13.2.3 long_time_off

13.2.4 short_time_off

Table 128. doze_time_thresh bit description

Field Description

7:0

doze_thresh

Configures the time that the device must be still before entering Doze mode.

For example, if the system sample rate if 488 Hz, then to set a time of 1 second, write 488 (0x1EB) to this

Units: Algorithm cycles (Time = [Algorithm cycles] * [1/SRPWRCTRL]).

Range of valid values: 1 to 65,535

Table 129. long_time_off registers

Offset 0x04

Bit 76543210

Field Reserved long_time_off [3:0]

Reset 0x00 0 1 1 1

Table 130. long_time_off bit description

Field Description

7:4

Reserved Bit field reserved.

3:0

long_time_off

Configures the long-time interval between AFE samples when the application is in Doze mode.

Units: Time.

Range of valid values: from 0 to 10.

Long-time values Time (seconds)

• 0........................................ 4.1 ms

• 1...................................... 8.19 ms

• 2...................................... 16.4 ms

• 3......................................... 32 ms

• 4...................................... 65.5 ms

• 5....................................... 131 ms

• 6....................................... 162 ms

• 7....................................... 524 ms

• 8......................................... 1.05 s

• 9........................................... 2.1 s

• 10....................................... 4.19 s

Table 131. short_time_off register

Offset 0x05

Bit 76543210

Field Reserved short_time_off [3:0]

Reset 0x00 0 1 1 0

Sleep/Wake configuration registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

13.2.5 cfg

Table 132. short_time_off bit description

Field Description

7:4

Reserved Bit field reserved.

3:0

short_time_off

Configures the short-time interval between AFE samples when the applica ti on is in Doze mode.

Units: Time.

Range of valid values: 0 to 10.

Long-time values Time (seconds)

• 0........................................ 4.1 ms

• 1...................................... 8.19 ms

• 2...................................... 16.4 ms

• 3......................................... 32 ms

• 4...................................... 65.5 ms

• 5....................................... 131 ms

• 6....................................... 162 ms

• 7....................................... 524 ms

• 8......................................... 1.05 s

• 9........................................... 2.1 s

• 10....................................... 4.19 s

Table 133. cfg register

Offset 0x06

Bit 76543210

Field Reserved Stop_DIS IRQ_EN SCHEN FLEEN SNCEN

Reset 0x00 00001

Table 134. cfg bit descriptions

Field Description

7:5

Reserved Bit field reserved.

Stop_DIS

Disables or enables the low-power mode. If this bit is set, the device doesn’t execute the STOP assembler

instruction even if the SNCEN, FLEEN, or SCHEN bits are set as 1b.

• 0: Enables STOP mode.

• 1: Disables STOP mode.

IRQ_EN

Enables or disables the IRQ interruption in the GPIO4.

• 0: Disables IRQ interruption.

• 1: Enables IRQ interruption.

SCHEN

Enables or disables the Doze mode.

• 0: Disables the Doze mode.

• 1: Enables the Doze mode.

Sleep/Wake status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

13.3 Sleep/Wake status registers

13.3.1 scheduler_mode

FLEEN

Controls the use of long and short time between AFE samples when in Doze mode. If this bit is cleared,

the application does not use the long- and short-time values to determine the time between AFE samples.

Instead, the time is fixed as 2.05 ms.

• 0: Time between AFE samples fixed at 2.05 ms.

• 1: Long- and short-time values determine the time between AFE samples.

SNCEN

Enables or disables the Sleep mode.

Note: When this bit is set, the device will enter Sleep mode. The device can only exit this mode is by

clearing this bit via a configuration-write command.

• 0: Disables the Sleep mode.

• 1: Enables the Sleep mode.

Table 135. scheduler_mode register

Offset 0x00

Bit 76543210

Field ——————scheduler_mode

Reset 00000000

Table 136. scheduler_mode bit description

Field Description

1:0

scheduler_mode

Shows the scheduler mode when the SCHED and FLEEN bits are set in the cfg register . If those bits are

not set, the value of this register may not reflect the actual scheduler mode.

Units: None.

Range of valid values: 0 to 0x02.

• 00: Doze mode. Frame rate determined by the long_time_off configuration register.

• 01: Doze mode. Frame rate determined by the short_time_off configuration register.

• 10: Run mode.

Table 134. cfg bit descriptions (Continued)

Field Description

Overview of Reset/Suspend/Clear Control application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

14 Reset/Suspend/Clear Control Application

14.1 Overview of Reset/Suspend/Clear Control

application

This application provides a way to reset, suspend, and clear the outputs of the applications

in the MMA9555L. The reset and clear functions are implemented in each application as

callback functions. The suspend function is handled in the Scheduler Application.

One of the requirements of an application on the MMA9555L dev ice is that it has a reset

and clear function that can be called by the scheduler or another application. This chapter

describes how an application’s reset and clear callback functions can be called or

triggered.

There are three groups of configuration register s for the Reset/Suspend/Clear Control

application.

14.1.1 Reset

The reset bit, when set, schedules a res et for an application. At the next system cycle, the reset process is handled. The reset

bit is automatically cleared by the Scheduler Application.

When the reset bit for an application is set, the following actions occur:

• Th e application’s reset callback function is executed. The reset function is part of an application and it typically resets the

application’s outputs and internal variables.

• The reset bit is cleared.

• The scheduled applica tio n is ex ecuted.

14.1.2 Suspend

The suspend bit, when set, prevents an application from executing while the suspend bit is set. Setting or clearing the suspend

flag is managed by the host through a command.

To preserve data coherency in an application, the suspend flag must be set before attempting to modify an application’s

configuration. The bit then must be cleared after the configuration ha s been changed.

14.1.3 Clear

The clear bit clears an applicatio n’s outputs. The clear flag is automatically cleared by the scheduler.

When an application’s clear bit is set, it causes the following actions:

• Th e application’s clear callback is executed. This typically resets the application’s outputs.

• The clear flag is cleared.

• Th e application is executed.

Application

ID 0x17

Default speed 30 Hz.

Configuration

registers Start on page

89.

Status

registers None.

Configuration registers for Reset/Suspend/Clear Control applications

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

14.2 Configuration registers for Reset/Suspend/Clear Control

applications

14.2.1 Reset configuration register

Table 137. Reset registers

Offset (MSB) 0x00 = reset_bits[31:24]

Bit 31 30 29 28 27 26 25 24

Field Reserved Six-Direction GPIO Input/

Output Reserved

Reset 11111 1 1 1

Offset 0x01 = reset_bits[23:16]

Bit 23 22 21 20 19 18 17 16

Field Rst/Susp/

Clr Reserved Pedometer Reserved Reserved Auto-Wake/

Sleep St atus Event FIFO

Reset 01111 1 1 1

Offset 0x02 = reset_bits[15:8]

Bit 15 14 13 12 11 10 9 8

Field Data FIFO Reserved

Reset 11111 1 1 1

Offset (LSB) 0x03 = reset_bits[7:0]

Bit 76543 2 1 0

Field Reserved AFE Reserved MBOX GPIO_AP

PMAP CI Scheduler General Rst

Reset 11111 1 1 1

Table 138 . Rese t bi t de s crip t io ns

Field Description

31:27

Reserved Not used.

Six Direction • 0: Normal operation.

• 1: Initiates the reset sequence of the Six Directio n application.

GPIO Input/Output • 0: Normal Operation.

• 1: Initiates the reset sequence of the GPIO Input/Output application.

Reserved Not used.

Reset/Suspend/Clear • 0: Normal operation.

• 1: Initiates the reset sequence of the Reset/Susp end/Clear application.

Reserved Not used.

Configuration registers for Reset/Suspend/Clear Control applications

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

14.2.2 Suspend configuration register

Pedometer • 0: Normal operation.

• 1: Initiates the reset sequence of the Pedometer application.

20:19

Reserved Not used.

Auto-Wake/Sleep • 0: Normal operation.

• 1: Initiates the reset sequence of the Auto-Wake/Sleep application.

Reserved Not used.

Event-FIFO • 0: Normal operation.

• 1: Initiates the reset sequence of the Event-Queue application.

Data FIFO • 0: Normal operation.

• 1: Initiates the reset sequence of the Data FIFO application.

14:8

Reserved Reserved

AFE • 0: Normal operation.

• 1: Initiate the reset sequence of the front-end application.

Reserved Reserved

Mailbox • 0: Normal operation.

• 1: Initiates the reset sequence of the mailbox application.

GPIO_AppMap • 0: Normal operation.

• 1: Initiates the reset sequence of the GPIO AppMap application.

Command Interpreter • 0: Normal operation.

• 1: Initiates the reset sequence of the comma nd-interpreter application.

Scheduler • 0: Normal operation.

• 1: Initiates the reset sequence of the scheduler-application.

General Reset • 0: Normal operation.

• 1: Initiates a system-wide reset sequence of all MMA9555Lapplications.

Table 139. Suspend registers

Offset (MSB) 0x04 = reset_bits[31:24]

Bit 31 30 29 28 27 26 25 24

Field Reserved Six

Direction GPIO Input/

Output Reserved

Reset 11111111

Table 138. Reset bit descriptions (Continued)

Field Description

Configuration registers for Reset/Suspend/Clear Control applications

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Offset 0x05 = reset_bits[23:16]

Bit 23 22 21 20 19 18 17 16

Field Rst/Susp/Clr Reserved Pedometer Reserved Auto-Wake/

Sleep Status Event FIFO

Reset 01111111

Offset 0x06 = reset_bits[15:8]

Bit 15 14 13 12 11 10 9 8

Field Data FIFO Frame

Counter Reserved

Reset 11111111

Offset (LSB) 0x07 = reset_bits[7:0]

Bit 76543210

Field Reserved AFE Reserved MBOX GPIO CI Scheduler General

Susp

Reset 11111111

Table 140 . Susp e nd bit descriptio ns

Field Description

31:27

Reserved Not used.

Six Direction • 0: Normal Operation

• 1: Suspend the Six Direction application.

GPIO Input/Output • 0: Normal Operation

• 1: Suspend the GPIO Input/output application.

Reserved Not used.

Reset/Suspend/Clear • 0: Normal operation.

• 1: Initiates the suspend sequence of the Reset/Suspend/Clear application.

Reserved Not used.

Pedometer • 0: Normal operation.

• 1: Suspend the Pedometer application.

20:19

Reserved Not used.

Auto-Wake/Sleep • 0: Normal Operation

• 1: Initiates the suspend sequence of the Auto-Wake/Sleep application.

Reserved Not used.

Event-FIFO • 0: Normal Operation

• 1: Initiates the suspend sequence of the Event-Queue application.

Table 139. Suspend registers (Continued)

Configuration registers for Reset/Suspend/Clear Control applications

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

14.2.3 Clear configuration register

Data FIFO • 0: Normal operation.

• 1: Initiates the suspend sequence of the Data FIFO application.

14:8

Reserved • Reserved

AFE • 0: Normal Operation

• 1: Initiate the suspend sequence of the front-end application.

Reserved Reserved.

Mailbox • 0: Normal Operation

• 1: Initiates the suspend sequence of the mailbox application.

GPIO AppMap • 0: Normal Operation

• 1: Initiates the suspend sequence of the GPIO AppMap application.

Command Interpreter • 0: Normal Operation

• 1: Initiates the suspend sequence of the command-interpreter application.

Scheduler • 0: Normal Operation

• 1: Initiates the suspend sequence of the scheduler-application.

General Suspend • 0: Normal Operation

• 1: Initiates a system-wide suspend sequence of all MMA9555Lapplications.

Table 141. Clear registers

Offset (MSB) 0x08 = reset_bits[31:24]

Bit 31 30 29 28 27 26 25 24

Field Reserved Six

Direction GPIO Input/

Output Reserved

Reset 1111111 1

Offset 0x09 = reset_bits[23:16]

Bit 23 22 21 20 19 18 17 16

Field Rst/Susp/Clr Reserved Pedometer Reserved Auto-

Wake/

Sleep Status Event FIFO

Reset 0111111 1

Offset 0x10 = reset_bits[15:8]

Bit 15 14 13 12 11 10 9 8

Field Data FIFO Frame

Counter Reserved

Reset 1111111 1

Table 140. Suspend bit descriptions (Continued)

Field Description

Configuration registers for Reset/Suspend/Clear Control applications

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Offset (LSB) 0x11 = re set_bits[7 :0]

Bit 7654321 0

Field Reserved AFE Reserved MBOX GPIO CI Scheduler General Clear

Reset 1111111 1

Table 142. Clear bit de scriptions

Field Description

31:27

Reserved Not used.

Six Direction • 0: Normal Operation

• 1: Clear the Six Direction application

GPIO Input/Output • 0: Normal Operation

• 1: Clear the GPIO Input/output application

Reserved Not used.

Reset/Suspend/Clear • 0: Normal operation.

• 1: Clear the Reset/Suspend/Clear application.

Reserved Not used.

Pedometer • 0: Normal operation.

• 1: Clear sequence of the Pedometer application.

20:19

Reserved Not used.

Auto-Wake/Sleep • 0: Normal Operation

• 1: Clear the Auto-Wake/Sleep application.

Reserved Not used.

Event-FIFO • 0: Normal Operation

• 1: Clear the Event-Queue application.

Data FIFO • 0: Normal operation.

• 1: Clear the Data FIFO application.

14:8

Reserved Reserved.

AFE Reserved.

AFE • 0: Normal Operation

• 1: Clear the front-end application.

Reserved Reserved.

Mailbox • 0: Normal Operation

• 1: Clear the mailbox application.

Table 141. Clear registers (Continued)

Reset/Suspend/Cle ar status registers

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Once an application has set a flag, it can be reset by one of the following mechanisms:

• E xecute a power-on reset.

• Wake the device after a low-power mode.

• Direct the host to write to general, reset/suspend/clear configur ation bit.

• Direct the host to write to an application reset/suspend/clear configuration bit.

14.3 Reset/Suspend/Clear status registers

There are no status registers.

14.4 Reboot to ROM CI from flash code

In order to reboot to ROM Command Interpreter , it is necessary to execute the reset callback function of the reset/suspend/clear

application by setting the respective reset flag. The complete command for this operatio n is :

Example 16.

MBOX0 = 0x17 /*Application ID*/

MBOX1 = 0x20 /*CONFIG_W command*/

MBOX2 = 0x01 /*Offset*/

MBOX3 = 0x01 /*Number of bytes to write*/

MBOX4 = 0x80 /*Data*/

14.5 Reboot to flash code from ROM CI

The operation to reboot into flash code when the ROM Command Interpreter is running can be perfor med by sending a

CI_RESET command, the mailbox settings for this command is:

Example 17.

MBOX0 = 0x29 /*ROM Command for boot to flash*/

MBOX1 = 0x00 /*Reserved*/

MBOX2 = 0xFF /*CI_PWR*/

MBOX3 = 0xFF /*CI_PWR*/

MBOX4 = 0xFF /*CI_PWR*/

MBOX5 = 0xFF /*CI_PWR*/

For details about the ROM CI commands, see the MMA955xL Intelligent, Motion-Sensing Platform Hardware Reference Manual

(MMA955xLHWRM), listed in “Related Documentation” on page 2 .

GPIO AppMap • 0: Normal Operation

• 1: Clear the GPIO AppMap application.

Command Interpreter • 0: Normal Operation

• 1: Clear the command-interpreter application.

Scheduler • 0: Normal Operation

• 1: Clear the scheduler-application.

General Clear • 0: Normal Operation

• 1: Clear all MMA9555L applications.

Table 142. Clear bit descriptions (Continued)

Field Description

Overview of MBOX Configuration application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

15 MBOX Configuration Application

15.1 Overview of MBOX Configuration

application

The MBOX Configuration applicatio n works with the Mailbox application (Chapter 8,

“Mailbox Application”) and the Communications application (Chapter 4, “Communication

Interface”) to provide data back to the host in a way that the host can best use the data.

The MBOX Configuration applicatio n configures how the mailboxes behave. The Mailbox

application configures what data is stored in the mailboxes.

By default, the MMA9555L operates in the Command/Response mode, where a host must

issue a write command followed by one or more reads to get data. The MMA9555L can also

be put into a Legacy mode, where the host just issues a read command to get data.

The mailboxes can be accessed in either of two modes: Normal or Legacy . The mailboxes’ default mode is Normal, but the mode

can be changed through this the mailbo x configuration application (APP_ID = 0x18).

The following figure shows the differences between the Normal and Legacy modes.

15.2 Normal mode

In Normal mode, only the command/response communications model is supported. In order to read valid data from the

MMA9555L, the host must send a command through the mailboxes and wait for the command to be processed. Then, the host

must read back the mailboxes that now have the data. The host can wait for the command to be proce s sed by polling the

Command Complete (COCO) bit or the host can wait for the INT_O interrupt.

The Normal mode fully supports streaming-read transactions when the response to a command may be more than 32 bytes long.

The following procedure give s the sequence for setting up the interrupt pin to go active after a COCO:

Example 18.

1. MB0: Set the “APP_ID: Communication application” (0x18) application identifier.

2. MB1: Set the “Command: Write Config” (0x20) application identifier.

3. MB2: Set the Offset to Zero field (0x00) to point to the configuration register.

4. MB3: Set the Count field to (0x01).

This is done because only one data byte needs to be sent.

5. MB4: Set the DATA (0x80) bit 7.

This enables the interrupt pin.

Address Normal Mode Legacy Mode

Command

Response

mailboxes

Command

Response

mailboxes

...

20 Quick-Read

mailboxes

...

Figure 21 . Difference between Normal and Legacy modes

Application

ID 0x18

Default speed Always

available.

Configuration

registers See page 97.

Status

registers None.

Legacy mode

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Bytes to Send: 0x18, 0x20 , 0x00, 0x01, 0x80 .

15.3 Legacy mode

In Legacy mode, the lower-a ddress mailboxes operate as described in the Normal mode—in the command/response

communications model. MB20 through MB31, however, are used as Quick-Read registers. These registers are automa ti ca l l y

updated at the end of each sample frame with the latest results from the chosen applications.

The Mailbox appli ca tion determines what data will appear in the mailboxes.

The quick-read output data is selected with the configurati on of the Mailbox application. (For more detail, see “Mailbox

Application” on page 41.)

Quick-Read registers enable the host to quickly and directly read a limited set of data directly from the MMA9555L without first

having to issue a comma nd and wait for the completion of the command processing. This makes support easier for legacy

systems that expect to read sensor data. (In Legacy mode, MB20 to MB31 are reserved for mapping the Quick-Read registers.)

By default, the Quick-Read registers (MB20–MB31) contain the following data:

MB20–MB21 = S tatus 0,1

MB22 = Event Queue status

MB23 = FIFO status

MB24–MB25 = AFE Frame Counter

MB26–MB27 = AFE, Stage 0; X-axis data

MB28–MB29 = AFE, Stage 0; Y-axis data

MB30–MB31 = AFE, Stage 0; Z-axis data

This data—in the Quick-Read registe rs in Legacy mode—can be changed with the Mailbox application.

15.4 Configuring mailbox operational mode

The operational mode of the slave communications interface mailbox is configured via the Mailbox Configuration application. This

application allows the host system to configure the slave communications interface functions including the mailbox transaction

interrupt pin mode, mailbox Normal/Legacy modes, and transaction-streaming mode s.

The following example shows how to configu r e the mailbox operating mode from Normal to Legacy

Example 19.

1. MB0: Set the “APP_ID: Mailbox Mode Config” application identifier (0x18).

2. MB1: Set the “Command: Write Config” application identifier (0x20).

3. MB2: Set the Offset to Zero field (0x00) to point to the configuration register.

4. MB3: Set the Count field to 0x01 because only one data byte needs to be sent.

5. MB4: Set the DATA value to 0x10.

This sets the Legacy field to 1b which selects the Legacy mode.

Bytes to send: 0x18, 0x20, 0x00, 0x01, 0x10.

MBOX Configuration memory map and register

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

15.5 MBOX Configuration memory map and register

15.5.1 MBOX Configuration memory map

15.5.2 MBOX Configuration register

Table 143. memory map

Offset

address Register Access Reset Details

0x00 MBOX Configuration register Read/Write 0x00 Section 15.5.2

Table 144. MBOX Configuration register

Offset 0x00

Bit 76543210

Field INT_O_EN INT_O_POL INT_O_

FRAME_EN LEGACY UPDMODES — —

Reset 0000 00 00

Table 145. Communications configura tion register field descriptions

Field Description

INT_O_EN

Enables or disables the assertion of the INT_O signal every time a mailbox command is bee n

processed.

Range of valid values:

0 Disables the assertion of the INT_O signal.

1 Enables the assertion of the INT_O signal.

INT_O_POL

Configures the polarity of the INT_O signal when it is asserted.

Range of valid values:

0 Active high.

1 Active low.

INT_O_FRAME_EN

If enabled, generates the INT_O interrupt on completion of the AFE sample—once each frame. If not

enabled, the INT_O signal is generated on a command-complete basis.

This bit was added to support synchronization between the host and the MMA9555L device. Data will

be ready on a frame basis.

Range of valid values:

0: Interrupt not generated.

1: Interrupt generated on completion of AFE samp le.

MBOX Configuration memory map an d re g is ter

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

LEGACY

Selects between Normal and Legacy mode.

Range of valid values:

0: Normal mode.

1: Legacy mode.

UPDMODES

When in Legacy mode, configures how and when the Quick-Read registers are updated.

This field is valid only if the Mailbox is operating in Legacy mode. See Bit 4.

Range of valid values:

00 Mode 0: Updates the Quick–Read registers (QR) whether the slave port is active or inactive.

01 Mode 1: Updates the QR register s only if the slave port is inactive. If the slave port is active, the

update takes no action and waits until the slave port is inactive.

10 Mode 2: Updates the QR registers if the sl ave port is inactive. If the slave port is active (I2C

transactions are running), this mode will enable a receive interrupt in the slave port to be triggered

immediately after the transaction ends. After this, the QR register is immediately updated and the

receive interrupt disabled.

1:0

Reserved Reserved.

Table 145. Communications configuration register field descriptions (Continued)

Field Description

Background and overview

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16 Pedometer Application

16.1 Background and overview

The MMA9555L’s major application is the ped ometer.The pedometer has calculations for

step-counting, speed, distance, activity-monitoring, and calorie-co unting, as well as

autonomous sleep functionality to mi nimize current consumption.

The following figure illustrates the hardware and software components and interactions in

the MMA9555L.

Figure 22. Pedometer Data Flow Diagra m

16.2 Functional description

16.2.1 Step detection

Step detection is based solely on detecting step impact, without taking into consideration the consumer’s height, weight, or

gender.

The algorithm operates by keepin g track of momentary acceleration, defined as:

where X, Y, and Z represent a single accelerometer reading, normalized by dividing by 1 g.

The values of A are accumulated over a fixed period of time (0.19 seconds). At every reading, the average A for that period is

calculated and saved. The algorithm detects steps by analyzing the spread of the accumulated average A values. The spread is

the difference between minimum and maximum of the calculated values.

For a step to be reported, the spread in the buffer of average values of A has to exceed a fixed threshold (0.13 g) and stay above

that threshold for at least the fixed value of 0.07 seconds. If the spread falls below the threshold sooner than 0.07 seconds, the

motion is ignored.

The STEPCNT variable contains the number of steps detecte d since the last reset. That count is updated every time a step is

detected.

Application ID 0x15

Default speed 30 Hz.

Configuration

registers Start on

page 104.

Status registers St art on

page 108.

Host

processor

Platform

Device MMA9555L firmware Pedometer firmware

Analog Front End

Slave port

RGPIO

Analog Front End

application

Command

Interpreter

RGPIO

application

2Y2Z2

++=

Functiona l description

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.2.2 Distance estimation

The distance estimation begins with the Base Stride Length (BSL), the estimated stride length for this consumer. The BSL is

calculated as follows:

where Height is the consumer’s height and GenderFactor is 0.415 for males or 0.413 for females. For more information about

Height, see “Height/Weight register” on page 106. For more information on GenderFactor, see “Filter register” on page 106.

If no consumer information is provided, BSL is set to 0, and the resulting distance values are 0. If there is a need to update the

BSL without consumer information, the configuration structure can be used to set a fixed stride length.

The estimated stride length is calculated by adjusti ng the BSL for step rate (steps/second). Stride length for a particular step is

calculated as follows:

The StepRateFactor values are shown in the following table:

The overall distance is calculated as the sum of estimated stride lengths for all steps detected since the last reset.

The DISTANCE variable contains the value of overall distance and is updated every time a step is detected.

16.2.3 Speed calculation

Speed is calculated over a sliding time window as:

where Distance is the total distance covered by all steps detected within the time window. Time is the length of the window and

can be configured by the SPDPRD variable.

For more information, see:

• Speed: “Speed register” on page 110

• Distance: “Distance register” on page 110

•Time: “Filter register” on page 106

• SPDPRD variable: “Speed Period/Step Threshold register” on page 107

The SPEED variable contains the current speed value and is updated every time a step is detected or once per second if there

are no steps. If there are no steps, the speed may not necessarily fall to zero even if the activity level, which is described in the

following section, falls to Rest. The activity level is reset to Rest if there are no steps for a certain amount of time. The speed

calculation does not include a similar reset when there are no steps. Therefore, it may conflict with the activity level. In this

scenario, the user should disregard the speed if the activity level is Rest.

Table 146. St epRateFactor calculation

Step rate, S

(steps/sec) StepRateFactor

S < 1.6 (very slow) 0.88

1.6 ≤ S < 1.8 (slow) 0 .95

1.8 ≤ S < 2.35 (normal) 1.00

2.35 ≤ S < 2.8 (fast) 1.30

S ≥ 2.8 (very fast) 2.30

BSL Height centimeters()GenderFactor 1.1××=

Stride BSL StepRateFactor×=

Speed Distance (meters)

Time

--------------------------------------------

Functio nal description

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.2.4 Activity-level calculation

The activity-level calculation is based on the speed value. The activity-level value is assigned according to the following table.

The ACTIVITY variable contains the current activity level and is updated every time a step is detected or once per second if there

are no steps. Additionally, if no steps are detected for the previous 2.5 seconds, the activity level is reset to Rest.

16.2.5 Calorie-expenditure calculation

The estimated amount of calories burned by a single step is calc ulated as:

where S tepRate is calculated as described in “Distance estimation” on p age 100, Weight is the consumer’s weight in kilograms,

and MetabolicFactor is calculated according to the following table:

For more information, see:

— StepRate: “Filter register” on page 106

— Weight: “Height/Weight register” on page 10 6

The CALS variable contains the total amount of calories burned since the la st reset. The value is updated every time a step is

detected.

16.2.6 Debounce count

The debounce_count() function implements a debounce counter as defined in application note Moti on and Free fall Detection

Using the MMA8450Q (AN3917), listed in “Related Documentation” on page 2.

If the input condition is satisfied, th e count is incremented by one up to the threshold. Otherwise, the count is decremented or

cleared depending on the debounce counter mode.

The debounce counter’s behavior is shown in Figure 23.

Table 147. Activity-level calculation

Latest speed, S

(Km/h) Activity level

S ≥ 10.5 Running

6.5 ≤ S < 10.5 Jogging

1.0 ≤ S < 6.5 Walking

S < 1.0 Res t

Table 148. MetabolicFact or calculation

Step Rate, S

(steps/sec) MetabolicFactor

S < 1.6 (very slow) 2.0

1.6 ≤ S < 1.8 (slow) 2.5

1.8 ≤ S < 2.35 (normal) 3.8

2.35 ≤ S < 2.8 (fast) 8.0

S ≥ 2.8 (very fast) 12.5

Calories MetabolicFactor 0.00029×

StepRate

----------------------------------------------------------------------Weight×=

Functiona l description

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Figure 23 . Debounce counter behavior

16.2.7 Autonomous susp end

The pedometer uses the acceleration vector magnitude squared, (X2 + Y2 + Z2), to determine if the device is stationary. It is

designed to suspend the pedomete r conservatively and wake the pedometer aggressively to avoid missing any steps.

The autonomous-suspend function compares the acceleration vector magnitude to the configurable minimum and maximum

thresholds (SLEEPMIN and SLEEPMAX) and passes the boolean result to a debounce counter . If the thresholds are satisfied for

at least SLEEPTHD samples, the pedometer autonomously suspends. The thresholds are satisfied if the output of the debounce

counter is asserted.

If the thresholds are not satisfied for at least SLEEPTHD samples, the pedometer executes normally.

The parameters SLEEPMIN, SLEEPMAX, SLEEPTHD, and SLP_DBCNTM configure the behavior. The SLEEPMAX

parameter’s reset value disables the autonomous suspend function by default.

For more information, see:

• SLEEPMIN: “Sleep Minimum register” on page 104

• SLEEPMAX: “Sleep Maximum register” on page 104

• SLEEPTHD: “Sleep Count Threshold register” on page 105

• SLP_DBCNTM: “Configuration/Step Length register” on page 105

If custom sleep functionality is desired, a user may disable the pedometer’s autonomous-suspend functionality and instead use

the MMA9555L’s Reset/Suspend/Clear application to enable or disable the pedometer . For an example, see “Enable/disable the

Pedometer application” on page 124.

Low- g ev ent

on all three ax es

(Freefall)

Count threshold

FF_MT

c ounter v alue

EA F F

Low- g ev ent

on all three ax es

(Freefall)

(a)

EA F F

DBCNTM = 1

(b)

EA F F

DBCNTM = 0

(c)

Count threshold

FF_MT

c ounter v alue

Low- g ev ent

on all three ax es

(Freefall)

Count threshold

FF_MT

c ounter v alue

Memory-ma ps and register descrip t io ns

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3 Memory-maps and register descriptions

The Pedometer Application running in the MMA9553L device has eigh t configuration registers and six status or data registers.

The configuration registers all ow the user to customize and control the behavior of the pedometer application. The status

registers report back the measured and calculate d data.

All status registers are shown as 16-bits wide. They are byte-accessible, but should be read 16 bits (two bytes) or more at a time

with a single command, if the user wishes to read them atomically.

Similarly, configur ation registers are shown as 16-bits wide but are also byte-accessible . Most fields define d within the

configuration registers are 8-bits or less and are byte-aligned, so they can be written one byte at a time if desired. All bytes should

be written using a single command if the user wishes to modify them atomically.

16.3.1 Pedometer memory maps

Table 149. Configuration registers

Offset

address Register Access Reset Details

0x0 Sleep Minimum register R/W 0x0000 “Sleep Minimum register” on page 104

0x2 Sleep Maximum register R/W 0x0000 “Sleep Maximum register” on page 104

0x4 Sleep Count Threshold register R/W 0x0001 “Sleep Count Threshold register” on page 105

0x6 Config/Step Length register R/W 0x0000 “Configuration/Step Length register” on page 105

0x8 Height/Weight register R/W 0xAF50 “Height/Weight register” on page 106

0xA Filter register R/W 0x0403 “Filter register” on page 106

0xC Speed Period register R/W 0x0582 “Speed Period/Step Threshold register” on page 107

0xE Activity Count Threshold

0x10 Step Coalesce register R/W 0x01 “Step Coalesce register” on page 107

Table 150. Status registers

Offset

address Register Access Reset Details

0x0 Status register R 0x0002 “Status register” on page 108

0x2 Step count register R 0x0000 “S tep Count register” on page 109

0x4 Distance register R 0x0000 “Distance register” on page 110

0x6 Speed register R 0x0000 “Speed register” on page 110

0x8 Calories register R 0x0000 “Calories register” on page 110

0xA Sleep Count register R 0x0000 “Sleep Count register” on page 111

Memory-maps and register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.2 Pedometer configuration-register descriptions

16.3.2.1 Sleep Minimum register

16.3.2.2 Sleep Maximum register

Table 151. Sleep Minimum register

Bit 1514131211109876543210

Read SLEEPMIN

Write

Reset 0x0000

Table 152. Sleep Minimum register field descriptions

Field Description

15:0

SLEEPMIN

Minimum acceleration vector magnitude for autonomous suspend.

The acceleration vector magnitude must be greater than SLEEPMIN and less than SLEEPMAX to satisfy the

autonomous suspend condition(1). At rest, the acceleration vector magnitude measures approximately 1 g.

Therefore, SLEEPMIN and SLEEPMAX are expected to be set to values near 1 g (4096 at 0.244 mg/LSB

resolution).

Valid range: 0x0000:0xFFFF (uint16). Units: 0.244 mg/LSB

1. This condition must be satisfied for SLEEPTHD samples for the pedometer to autonomously suspend. See Table 156 on page 105.

Table 153. Sleep Maximum register

Bit 1514131211109876543210

Read SLEEPMAX

Write

Reset 0x0000

Table 154. Sleep Maximum register field descriptions

Field Description

15:0

SLEEPMAX

Maximum acceleration vector magnitude for autonomous suspend.

The acceleration vector magnitude must be greater than SLEEPMIN and less than SLEEPMAX to satisfy the

autonomous suspend condition(1). At rest, the acceleration vector magnitude measures approximately 1 g.

Therefore, SLEEPMIN and SLEEPMAX are expected to be set to values near 1 g (4096 at 0.244 mg/LSB

resolution).

Set to SLEEPMAX 0 to disable autonomous suspend.

Valid range: 0x0000:0xFFFF (uin t16).

Units: 0.244 mg/LSB

1. This condition must be satisfied for SLEEPTHD samples for the pedometer to autonomously suspend. See Tab l e 156 on page 105 .

Memory-ma ps and register descrip t io ns

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.2.3 Sleep Count Threshold register

16.3.2.4 Configuration/Step Length register

Table 155. Sleep Count Threshold reg ister

Bit 1514131211109876543210

Read SLEEPTHD

Write

Reset 0x0001

Table 156. Sleep Count Threshold register field descriptions

Field Description

15:0

SLEEPTHD

Autonomous suspend debounce count threshold.

The autonomous suspend condition(1) must be satisfied for SLEEPTHD samples for the pedometer to

autonomously suspend.

Valid range: 0x0000:0xFFFF (uint16).

1. The acceleration vector magnitude must be greater than SLEEPMIN and less than SLEEPMAX to satisfy this condition. For more information on

SLEEPMIN and SLEEPMAX, see “Sleep Minimum register” and “Sleep Maximum register”.

Table 157. Configuration/S tep Length register

Bit 1514131211109876543210

Read

CONFIG

ACT_DBCNTM

SLP_DBCNTM

— STEPLEN

Write

Reset 000 00000 0x00

= Unimplemented or reserved

Table 158. Configuration/Step Length register field descriptions

Field Description

CONFIG

(Re)initializes the pedometer with current configuration values.

Modifications to other pedometer configurati on registers will not take effect until this bit is set. It is

automatically cleared after the (re)initialization completes.

0: Do not (re)initialize the pedometer

1: (Re)initialize the pedometer with current configuration values

ACT_DBCNTM

Activity debounce counter mode.

0: Decrement the count when the activity level changes

1: Clear the count when the activity level changes

SLP_DBCNTM

Autonomous suspend debounce counter mode.

0: Decrement the count when the device is in motion

1: Clear the count when the device is in motion

12:8

—Reserved.

Set to 0.

7:0

STEPLEN

Step length in centimeters.

Set to 0 to automatically estimate the consumer’s step length based on gender and height.

Valid range: 0x00:0xFF (uint8)

Memory-maps and register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.2.5 Height/Weight register

16.3.2.6 Filter register

Table 159. Height/Weight register

Bit 1514131211109876543210

Read HEIGHT WEIGHT

Write

Reset 0xAF 0x50

Table 160. Height/Weight register field descriptions

Field Description

15:8

HEIGHT

Height in centimeters.

Used to estimate step length, if STEPLEN = 0.

Valid range: 0x00:0xFF (uint8)

Default = 0xAF (175 centimeters).

7:0

WEIGHT

Weight in kilograms.

Used to estimate step length, if STEPLEN = 0.

Valid range: 0x00:0xFF (uint8)

Default = 0x50 (80 kilograms).

Table 161. Filter register

Bit 1514131211109876543210

Read FILTSTEP MALE FILTTIME

Write

Reset 0x04 0 0x03

Table 162. Filter register field descriptions

Field Description

15:8

FILTSTEP

Number of steps that must occur within FIL TTIME for the pedometer to decide the consumer is making steps.

Set to 0 to disable step filtering. If the value specified is greater than 6, then 6 will be used.

Valid range: 0x00:0x06 (ui nt8).

Default = 0x04.

MALE

Gender

0: Female

1: Male

6:0

FILTTIME

Number of seconds in which filter steps must occur.

Set to 0 to disable step filtering.

Valid range: 0x00:0x7F (uint8)

Default = 0x03.

Memory-ma ps and register descrip t io ns

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.2.7 Speed Period/Step Threshold register

16.3.2.8 Activity Count Threshold register

16.3.2.9 Step Coalesce register

Table 163. Speed Period register

Bit 1514131211109876543210

Read SPDPRD STEPTHRESHOLD

Write

Reset 0x05 0x82

Table 164. Speed Period/Step Threshold regist er field descriptions

Field Description

15:8

SPDPRD

Number of seconds in which to compute speed.

If set to a value greater than 5, then 5 will be used.

Valid range: 0x02:0x05.

Warning: Do not set SPDPRD to 0 or 1 as this may cause undesirable behavior.

7:0

STEPTHRESHOLD

Magnitude acceleration threshold to detect a step. Large values make the pedometer less sensitive;

small values make the pedometer more sensitive an d may lead to false positives.

Units: 1 mg/LSB

Valid range: 0x00:0xFF (uint8)

Default: 0x82 (0.13 g)

Table 165. Activity Count Threshold register

Bit 1514131211109876543210

Read ACTTHD

Write

Reset 0x0000

Table 166. Activity Count Threshold register field descriptions

Field Description

15:0

ACTTHD

Activity debounce count threshold.

The internal activity level must be stable for ACTTHD samples before ACTIVITY is updated.

Valid range: 0x0000:0xFFFF (uint16)

0: The activity debouncer is effectively bypassed.(1)

1: The current internal activity level must equal the previous internal activity level in order to update ACTIVITY.

1. For more information on the activity debouncer, see Table 158 on page 105.

Table 167. Step Coalesce register

Bit 76543210

Read STEPCOALESCE

Write

Reset 0X01

Memory-maps and register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.3 Pedometer status-register descriptions

16.3.3.1 Status regi ster

Table 168. Activity Count Threshold register field descriptions

Field Description

7:0

STEPCOALESCE

Number of steps to coalesce before asserting STEPCHG.

0: Disables STEPCHG.

1: Asserts STEPCHG after every step. The default.

Valid range: 0x0 0:0xFF (uint8).

Table 169. Status register

Bit 1514131211109876543210

Read

MRGFL

SUSPCHG

STEPCHG

ACTCHG

SUSP

ACTIVITY

VERSION

Write

Reset 00000 000 0x02

= Unimplemented or reserved

Table 170. Status regist er field descriptions

Field Description

MRGFL

Merged status change flags.

This bit is the logical OR of the SUSPCHG, STEPCHG, and ACTCHG flags. It can be routed to a pin to

enable a single, merged-output interrupt using the MMA955xL GPIO application(1).

The host can trigger an interrupt on rising edges to receive notification when at least one of the status

change flags is asserted. The host is responsible for resolving the source if desired. That can be done by

comparing the STEPCNT to a previous value to determine that a STEPCNT change caused the MRGFL

assertion.

0: None of the status change flags are asserted

1: At least one of the status change flags (SUSPCHG, STEPCHG, ACTCHG) is asserted

SUSPCHG

Indicates a change in the SUSP bit.

This bit is transient and only asserts during frames in which the SUSP bit changes from the previous frame.

A frame is one 30-Hz period. This bit can be routed to a pin to enable output interrupts using the

MMA9555L GPIO AppMap application(1). The host can trigger an interrupt on rising edges to receive

notification when the pedometer suspends or resumes.

0: No change in the SUSP bit since the last pedometer call.

1: The SUSP bit changed since the last pedometer call.

STEPCHG

Indicates a change in STEPCNT by STEPCOALSCE steps.

This bit is transient and only asserts during frames in which STEPCNT changed from the previous frame.

A frame is one 30-Hz period. This bit can be routed to a pin to enable output interrupts using the

MMA9555L GPIO AppMap application(1). The host can trigger an interrupt on rising edges to receive

notification after every step.

0: The step count has not been incremented by STEPCOALESCE steps since the last STEPCHG

assertion or the pedometer was last initialized.

1: The step count has been incremented by STEPCOALESCE steps since the last STEPCHG assertion

or the pedometer was last ini tialized.

Memory-ma ps and register descrip t io ns

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.3.2 Step Count register

ACTCHG

Indicates a change in activity level.

This bit is transient and only asserts during frames in which ACTIVITY changed from the previous frame.

A frame is one 30-Hz period. This bit can be routed to a pin to enable output interrupts using the

MMA9555L GPIO AppMap application(1). The host can trigger an interrupt on rising edges to receive

notification when the activity level is changed.

0: No change in activity level since last pedometer call

1: New activity level since last pedometer call

SUSP

Indicates whether the pedometer is active or has been autonomously suspended.

This bit can be routed to a pin to enable output interrupts using the MMA9555L GPIO AppMap

application(1). The host can trigger an interrupt on rising edges to receive notification when the pedometer

is autonomously suspended and trig ger an interrupt on falling edges to receive notification when the

pedometer resumes.

0: Pedometer is active

1: Pedometer is suspended

10:8

ACTIVITY

Activity level:

000: Unknown

001: Rest

010: Walking

011: Jogging

100: Running

101–111: Reserved

7:0

VERSION

Version number of the pedometer application, incremented by one for each new release.

0: R1.32

1: R1.33

2: R1.34

1. For more information on the GPIO AppMap application, see Chapter 7, “GPIO-AppMap Application” .

Table 171. Step Count register

Bit 1514131211109876543210

Read STEPCNT

Write

Reset 0x0000

= Unimplemented or reserved

Table 172. Step Count register field descriptions

Field Description

15:0

STEPCNT The total step count since the pedometer was last reset.

Valid range: 0x00 00:0xFFFF (uint16)

Table 170. Status regist er field descriptions

Field Description

Memory-maps and register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.3.3 Distance register

16.3.3.4 Speed register

If there are no steps, the speed may not necessarily fall to zero even if the activity level falls to rest . See 16.2.3, “Speed

calculation” on page 100 for more information.

16.3.3.5 Calories register

Table 173. Distance register

Bit 1514131211109876543210

Read DIST

Write

Reset 0x0000

= Unimplemented or reserved

Table 174. Distance register field descriptions

Field Description

15:0

DIST The total distance in meters since the pedometer was last reset.

Valid range: 0x0 000:0xFFFF (uint16).

Table 175. Speed register

Bit 1514131211109876543210

Read SPEED

Write

Reset 0x0000

= Unimplemented or reserved

Table 176. Speed reg ister field descriptions

Field Description

15:0

SPEED Average speed in meters per hour over SPDPRD(1).

Valid range: 0x0 000:0xFFFF (uint16)

1. For information on SPDPRD, see Table 164 on page 107.

Table 177. Calories register

Bit 1514131211109876543210

Read CALS

Write

Reset 0x0000

= Unimplemented or reserved

Pedometer application examples

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.3.3.6 Sleep Count register

16.4 Pedometer application examples

16.4.1 Pedometer application configuration example

To write all the pedometer configuration registers, the following command packet shall be sent from the host to the device

mailboxes. The most significant byte of a register (MSB) is written in the lowest-numbered mailbox.

NOTE

The question marks represent placeholders for the application specific values. Please

replace the question marks with values for the application .

MB0 = 0x15: Set the Pedometer Application Identifier (0x15)

MB1 = 0x20: Set the Command: Write Config command, with zero offset (0x20)

MB2 = 0x00: Set the Offset to point to the first configuration register

MB3 = 0x11: Set the Count field to declare writing 17 bytes

MB4–MB5 = 0x????: Value for Sleep Min Register

MB6–MB7 = 0x????: Value for Sleep Max Register

MB8–MB9 = 0x????: Value for Sleep Count Thresh old

MB10–MB11 = 0x????: Value for Config / Step Length Register

MB12–MB13 = 0x????: Value for Height / Weight

MB14–MB15 = 0x????: Set the Filter Register

MB16–17 = 0x????: Set the Speed Period / Ste p Threshold Register

MB18–19 = 0x????: Set the Activity Count

MB20 = 0x??: Set the Step Coalesce

Bytes to send: 0x15, 0x20, 0x00, 0x11, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??,

0x??, 0x??, 0x??

Table 178. Calories register field descriptions

Field Description

15:0

CALS Total calorie count since the pedometer was last rese t.

Valid range: 0x0 000:0xFFFF (uint16)

Table 179. Sleep Count register

Bit 1514131211109876543210

Read SLEEPCNT

Write

Reset 0x0000

= Unimplemented or reserved

Table 180. Sleep Count register field descriptions

Field Description

15:0

SLEEPCNT Current value of the autonomous suspend debounce counter.

Valid range: 0x0 000:0xFFFF (uint16)

Pedometer application examples

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

To read all the pedometer configuration registers, send the following command packet from the host to the device mailboxes.

This can be used as a device identificatio n command, allowing a host to differentiate the MMA9555L from the MMA955xL.

MB0: 0x15 = pedometer application ID

MB1: 0x10 = opcode to read configura tion

MB2: 0x00 = offset into pedometer configuration register map

MB3: 0x11 = number of bytes to read

The MMA9555L response will be:

MB0: 0x15 = pedometer application ID

MB1: 0x80 = COCO=1, error code=0

MB2: 0x11 = actual number of bytes read

MB3: 0x11 = requested number of bytes to read

MB4: sleep minimum MSB

MB5: sleep minimum LSB

MB6: sleep maximum MSB

MB7: sleep maximum LSB

MB8: sleep count threshold MSB

MB9: sleep count threshold LSB

MB10: config

MB11: step length MB12: height

MB13: weight

MB14: filter step

MB15: male, filter time

MB16: speed period

MB17: step threshold

MB18: activity count threshold MSB

MB19: activity count threshold LSB

MB20: step coalesce

Pedometer application examples

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

16.4.2 Pedometer application read example

To read all the pedometer status registers, send the following command packet from the host to the device mailboxes:

MB0 = 0x15: Set the Pedometer Application Identifier (0x15)

MB1 = 0x30: Set the Command: Read Status command, with zero offset (0x30)

MB2 = 0x00: Set the Offset (0x00) to point to the first status register

MB3 = 0x0C: Set the Count field to (12) to declare reading 12 bytes

Read back the mailboxes, when the COCO (Command Complete) bit is set the status data will be in the mailbox registers.

Bytes to send: 0x15, 0x30, 0x00, 0x0C

The response to this command will be:

MB0: 0x15 = pedometer application ID

MB1: 0x80 = COCO=1, error code=0

MB2: 0x0C = actual number of bytes read

MB3: 0x0C = requested number of bytes to read

MB4: pedometer status register MSB

MB5: pedometer status register LSB

MB6: step count MSB

MB7: step count LSB

MB8: distance MSB

MB9: distance LSB

MB10: speed MSB

MB11: speed LSB

MB12: calories MSB

MB13: calories LSB

MB14: sleep count MSB

MB15: sleep count LSB

Overview of GPIO Input/Output application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

17 GPIO Input/Output Application

17.1 Overview of GPIO Input/Output application

The GPIO input/output application provides a function that can control seven physical GPIO

pins of MMA9555L. It can set the direction GPIOs as input or output, control the pin level

when the pin is set as an output pin and read the pin level through its status register. It also

has a mask register, called the Enable Configuration Register, to avoid conflict with the GPIO

AppMap application APP-ID 0x03.

The GPIO pins that are available to this application are described in Table 181.

17.2 Memory maps and register descriptions

The GPIO Input/Output Application has three confi guration registers and one status register. The configuration registers allow

the user to customize and control the behavior of the GPIO Input/Output application. The status registers report back the level of

the GPIO2–GPIO9. The status register is 8 bits wide.

Similarly, configur ation registers are 8 bits wide. They can be written one byte at a time if desired. All bytes should be written

using a single command if the user wishes to modify them atomically.

17.2.1 GPIO Input/Output memory maps

Table 181. GPIO pin names, numbers and functions

Name Pin number

GPIO2 7

GPIO3 8

GPIO4 9

GPIO5 11

GPIO6 12

GPIO7 13

GPIO8 15

GPIO9 2

Table 182. Configuration Registers

Offset

address Register Access Reset Details

0x00 GPIO input/output direction register R/W 0x0F “GPIO input/output direction register” on page 115

0x01 GPIO input/output enable register R/W 0x0F “GPIO input/output enable register” on page 115

0x02 GPIO input/output data register R/W 0x05 “GPIO input/output data register” on page 116

Table 183. Status register

Offset

address Register Access Reset Details

0x00 GPIO input/output Status register R 0x05 “GPIO Input/Output S tatus register” on page 116

Application

ID 0x19

Default speed 30 Hz.

Configuration

registers Start on page

115.

Status

registers Start on page

116.

GPIO Input/Output configuration register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

17.3 GPIO Input/Output configuration register descriptions

17.3.1 GPIO input/output direction register

17.3.2 GPIO input/output enable register

Table 184. GPIO input/output direct ion register

Bit 76543210

Read DIR8 DIR7 DIR6 DIR5 DIR4 DIR3 DIR2

Write

Reset 0x0F

= Unimplemented or reserve d

Table 185. GPIO input/output direction register field description

Field Description

6:0

DIR8–DIR2

GPIO data direction. The value of this register is shifted and then copied to the hardware register RGPIO_DIR.

0: Configured as an input

1: Configured as an output

Table 186. GPIO input/output enable register

Bit 76543210

Read EN8 EN7 EN6 EN5 EN4 EN3 EN2

Write

Reset 0x0F

= Unimplemented or reserve d

Table 187. GPIO input/output enable register description

Field Description

6:0

EN8–EN2

GPIO enable. The value of this register is shifted and then copied to the hardware register RGPIO_EN.

0: Disable the pin in this application

1: Enable the pin in this applicati on

GPIO Input/Output Status register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

17.3.3 GPIO input/output data register

17.4 GPIO Input/Output Status register descriptions

17.4.1 GPIO Input/Output Status register

NOTE

Though GPIO9 cannot be set in the configuration registers, the pin level can be detected in

the status register when GPIO9 is set as interrupt pin in APP-ID 0x03.

Table 188. GPIO input/output data register

Bit 76543210

Read DATA8 DATA7 DATA6 DATA5 DATA4 DATA3 DATA2

Write

Reset 0x05

= Unimplemented or reserve d

Table 189. GPIO input/output data register description

Field Description

6:0

EN8–EN2

GPIO data output. The value of this register is shifted and then copied to the hardware register RGPIO_DATA.

0: Output low on the pin

1: Output high on the pin

Table 190. GPIO input/output status register

Bit 76543210

Read DATA9 DATA8 DATA7 DATA6 DATA5 DATA4 DATA3 DATA2

Write

Reset 0x05

= Unimplemented or reserve d

Table 191. GPIO input/output status register description

Field Description

7:0

DATA9–DATA2

GPIO data output. The value of this register is read from hardware register RGPIO_DATA.

0: A properly enabled RGPIO output pin is driven with a logic 0, or a properly enabled RGPIO input pin was read

as a logic 0

1: A properly enabled RGPIO output pin is driven with a logic 1, or a properly enabled RGPIO input pin was read

as a logic 1

GPIO Input/Output application examples

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

17.5 GPIO Input/Output application examples

17.5.1 GPIO Input/Output application configuration example

To write all the GPIO Input/Output configuration registers, the following command packet should be sent from the host to the

device mailboxes. The most significant byte of a regist er (MSB) is written in the lowest-numbered mailbox.

NOTE

The question marks represent placeholders for the application specific values. Please

replace the question marks with the values for the application.

MB0 : 0x19= Set the GPIO Input/Output Application Identifier (0x19)

MB1 : 0x20= Set the Command: Write Config command, with zero offset (0x20)

MB2 : 0x00= Set the Offset to point to the first configuration register

MB3 : 0x03= Set the Count field to declare writing 3 bytes

MB4 : 0x??= Value for GPIO input/output direction register

MB5 : 0x??= Value for GPIO input/output enable register

MB6 : 0x??= Value for GPIO input/output data register

Bytes to send: 0x19, 0x20, 0x00, 0x03, 0x??, 0x??, 0x??

To read all the GPIO Input/Output configuration registers, the following command packet should be sent from the host to the

device mailboxes.

MB0: 0x19= GPIO Input/Output application ID

MB1: 0x10= opcode to read configuration

MB2: 0x00= offset into GPIO Input/Output configuration regi ster map

MB3: 0x03= number of bytes to read

The MMA9555L response will be:

MB0: 0x19 = GPIO Input/Output application ID

MB1: 0x80 = COCO=1, error code=0

MB2: 0x03 = actual number of bytes read

MB3: 0x03 = requested number of by tes to read

MB4: Value of GPIO input/output di rection register

MB5: Value of GPIO input/output enable register

MB6: Value of GPIO input/output da ta register

17.5.2 GPIO Input/Output application read example

To read the GPIO Input/Output status register, the following command packet is sent from the host to the device mailb oxes:

MB0 : 0x19 = Set the GPIO Input/Output Application Identifier (0x19)

MB1 : 0x30 = Set the Command: Read Status command, with zero offset (0x30)

MB2 : 0x00 = Set the Offset (0x00) to point to the first status register

MB3 : 0x01= Set the Count field to (1) to declare reading 1 byte

Bytes to send: 0x19, 0x30, 0x00, 0x01

To read the mailboxes, when the COCO (Command Complete) bi t is set, the status data are in the mailbox registers.

The response to this command is:

MB0: 0x19 = GPIO Input/Output application ID

GPIO Input/Output application examples

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

MB1: 0x80 = COCO=1, error code=0

MB2: 0x01 = actual number of bytes read

MB3: 0x01 = requested number of by tes to read

MB4: GPIO input/output Status register

Overview of the Six-Direction application

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

18 Six-Direction Application

18.1 Overview of the Six-Direction application

The Six-Direc tion application detects six major di rectional orientations of the device in three-

dimensional space. It determines the primary axis that the device is oriented: +X, –X, +Y,

–Y, +Z or –Z, with reference opposite to the direction of gravity . It uses the coordinate system

as defined in Figure 5 on page 12.

When the absolute g value of the current direction is less than half g, the application detects

which axis has the largest ab so l ut e g value. If this axis is kept as the largest and the

debounce count meets the count threshold, it updates the status of the direction. When the

absolute g value of the current direction is larger than half g, it keeps current direction.

18.2 Memory maps and register descriptions

The Six-Direction Application running in the MMA9555L device has tw o configuration registers and two status registers. Th e

configuration registers allow the user to customize and control the behavior of the Six-Direction application. The status registers

report current direction status, status change flag and debounce count status.

The status registers are 8 bits wide. They are byte-accessible, but should be read two bytes at a time with a single command, if

the user wishes to read them atomically.

Similarly, configur ation registers are 8 bits wide. They can be written one byte at a time if desired. All bytes should be written

using a single command if the user wishes to modify them atomically.

18.2.1 Six Direction register memory maps

Table 192. Configuration registers

Offset

address Register Access Reset Details

0x00 SixDir Count Threshold register R/W 0x1E “SixDir Count Threshold register” on page 120

0x01 SixDir Debounce mode register R/W 0x01 “SixDir Debounce mode register” on page 120

Table 193. Status register

Offset

address Register Access Reset Details

0x00 SixDir Current Status register R/W 0x06 “SixDir Current Status register” on page 121

0x01 SixDir Debounce count register R/W 0x00 “SixDir Debounce count register” on page 121

Application

ID 0x1A

Default speed 30 Hz.

Configuration

registers Start on page

120.

Status

registers Start on page

121.

Six Direction configuration register descriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

18.3 Six Direction configuration register descriptions

18.3.1 SixDir Count Threshold register

Table 195. SixDir Count Threshold register description

18.3.2 SixDir Debounce mode register

Table 197. SixDir Debounce mode register description

Table 194. SixDir Count Threshold register

Bit 76543210

Read

Write SDTHD

Reset 0x30

= Unimplemented or reserve d

Field Description

7:0

SDTHD

SixDir debounce count threshold.

The status of the direction is not changed until the debounce count meets this threshold.

Valid range: 0x00:0xFF (uint8).

Table 196. SixDir Debounce mode register

Bit 76543210

Read

Write SDM

Reset 0x01

= Unimplemented or reserve d

Field Description

SDM

SixDir debounce counter mode.

0: Decrement the count when the device changes direction

1: Clear the count when the device changes direction

Six Direction Status register de scriptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

18.4 Six Direction Status register descriptions

18.4.1 SixDir Current Status register

Table 199. SixDir Current Status register description

18.4.2 SixDir Debounce count register

Table 201. SixDir Debounce count register description

18.4.3 Six Direction application configuration example

To write all the Six-Direction configuration registers, the host should send the following command packet to the mailboxes. The

most significant byte of a register (MSB) is written in the lower numbered mailbox.

Table 198. SixDir Current Status register

Bit 76543210

Read

Write SC_FLG AXIS_POS AXIS

Reset 0x06

= Unimplemented or reserve d

Field Description

SC_FLG

Direction Status change flag.

0: Direction has not changed

1: Direction changed. The bit is cleared when the register is read.

AXIS_POS

Sign of the direction of the axis detected

0 : Negative Direction

1: Positive direction

1:0

AXIS

Direction is on which axis.

00: X axis

01: Y axis

10: Z axis

Table 200. SixDir Debounce count register

Bit 76543210

Read

Write SDCNT

Reset 0x00

= Unimplemented or reserve d

Field Description

7:0

SDCNT The total debounce count since the direction status was last reset.

Valid range: 0x00:0xFF (uint8)

Six Direction Status register descr iptions

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

NOTE

The question marks represent placeholders for the application-specific values. Please

replace the question marks with the desired values for the application.

MB0 : 0x1A= Set the Six-Direction Application Identifier (0 x1A)

MB1 : 0x20= Set the Command: Write Config command, with zero offset (0x20)

MB2 : 0x00= Set the Offset to point to the first configuration register

MB3 : 0x02= Set the Count field to declare writing 2 bytes

MB4 : 0x??= Value for SixDir Count Threshol d register

MB5 : 0x??= Value for SixDir Debounce mode register

Bytes to send: 0x1A, 0x20, 0x00, 0x02, 0x?? , 0x? ?

To read all the Six-Direction configuration registers, the following command packet is sent from the host to the device mailboxes.

MB0: 0x1A= Six-Direction applica tion ID

MB1: 0x10= opcode to read configuration

MB2: 0x00= offset into Six-Direction configuration register map

MB3: 0x02= number of bytes to read

The MMA9555L response will be:

MB0: 0x1A = Six-Direction application ID

MB1: 0x80 = COCO=1, error code=0

MB2: 0x02 = actual number of bytes read

MB3: 0x02 = requested number of by tes to read

MB4: Value of SixDir Count Threshold register

MB5: Value of SixDir Debounce mode register

18.4.4 Six Direction application read example

To read the Six-Direction status register, the following command packet is sent from the host to the device mailboxes:

MB0 : 0x1A = Set the Six-Direction Application Identifie r (0x1A)

MB1 : 0x30 = Set the Command: Read Status command, with zero offset (0x30)

MB2 : 0x00 = Set the Offset (0x00) to point to the first status register

MB3 : 0x02= Set the Count field to (2) to declare reading 2 bytes

Bytes to send: 0x1A, 0x30, 0x00, 0x02

To read the mailboxes, when the COCO (Command Complete) bi t is set, the status data is in the mailbox register s.

The response to this command is:

MB0: 0x1A= Six-Direction applica tion ID

MB1: 0x80 = COCO=1, error code=0

MB2: 0x02 = actual number of bytes read

MB3: 0x02 = requested number of by tes to read

MB4: Value of SixDir Curren t Status registe r

MB5: Value of SixDir Debounce count register

Read pedometer status variables

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

19 Sample operations

This section provides sample slave-port commands to read and modify application variables.

19.1 Read pedometer status variables

This command reads all 12 bytes of the status variables from the Pedometer application (APP_ID=0x15), starting at byte of fset 0.

15 30 00 0C

19.2 Read pedometer configuration variables

This command reads all 16 bytes of the configuration variables from the Pedometer application (APP_ID=0x15), st arting at byte

offset 0.

15 10 00 10

19.3 Write pedometer configuration variables

This command writes all 16 bytes of the configuration variables to the Pedometer application (APP_ID=0x15), starting at byte

offset 0.

15 20 00 10 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF

19.4 Read GPIO Input/output status variables

This command reads the status variable from the GPIO input/output application (APP_ID=0x19), starting at byte offset 0.

19 30 00 01

19.5 Read GPIO Input/output configuration variables

This command reads all 3 bytes of the configuration variables from the GPIO input/output application (APP_ID=0x19), starting

at byte offset 0.

19 10 00 03

19.6 Write GPIO Input/output configuration variables

This command writes all 3 bytes of the configuration variables to the GPIO input/output application (APP_ID=0x19), starting at

byte offset 0.

19 20 00 03 xx xx xx

19.7 Read Six direction status variables

This command reads the two status variables from the Six Direction application (APP_ID=0x1A), starting at byte offset 0.

1A 30 00 02

19.8 Read Six direction configuration variables

This command reads all 2 bytes of the configuration variables from the Six Direction application (APP_ID=0x1A), starting at byte

offset 0.

1A 10 00 02

Write Six direction configuration variables

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

19.9 Write Six direction configuration variables

This command writes all 3 bytes of the configuration variables to the Six Direction application (APP_ID=0x19), starting at byte

offset 0.

1A 20 00 02 xx xx

19.10 Reset pedometer configuration variables to their defaults

This command writes one byte of configuration variable to the Reset/Suspend/Clear application (APP_ID=0x17) starting at byte

offset 1.

This causes the scheduler to invoke the pedometer's reset function, pedometer_reset().

17 20 01 01 20

19.11 Enable/disable the Pedometer application

This command writes one byte of configuration variable to the Reset/Suspend/Clear application (APP_ID=0x17) starting at byte

offset 5.

This causes the scheduler to suspend the Pedome ter application, even if the device is not stationary.

17 20 05 01 20 (disable)

17 20 05 01 00 (enable)

19.12 Configure the AFE range

This command writes one byte of the configuration variable to the AFE application (APP_ID=0x06), starting at byte offset 0. Since

the pedometer uses a normalized acceleration output provided by th e AFE application, the g mode only affects the saturation

level and noise.

Regardless of what g mode the AFE is configured to, for or by other applications, the resolution seen by the Pedometer

application is always 8 g.

06 20 00 01 40 (2 g mode)

06 20 00 01 80 (4 g mode)

06 20 00 10 00 (8 g mode)

For more information on configuring the AFE rang e, see the "AFE configuration registers" section.

19.13 Configure output interrupt: Activity change on GPIO6

This command writes two bytes of the configuration variable to the GPIO application (APP_ID=0x03), starting at byte offset 0.

This causes the GPIO application to copy the pedometer's ACTCHG status bit to GPIO6 after every new accelerometer sample.

The host processor can trigger an interrupt on rising edges of this pin to receive notification when the activity level chang es.

03 20 00 02 15 04

19 20 01 01 (AB & 6F)

19.14 Configure output interrupt: Step change on GPIO7

This command writes two bytes of the configuration variable to the GPIO application (APP_ID=0x03), starting at byte offset 2.

This causes the GPIO application to copy the pedometer's STEPCHG status bit to GPIO7 after every new accelerometer sample.

The host processor can trigger an inte rrupt on rising edges of this pin to receive notification when the step count changes.

03 20 02 02 15 05

19 20 01 01 (AB & 5F)

Configure outpu t inte rru pt: Sus p end change on GPIO8

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

19.15 Configure output interrupt: Suspend change on GPIO8

This command writes two bytes of the configuration variable to the GPIO application (APP_ID=0x03) starting at byte offset 4.

This causes the GPIO application to copy the pedometer's SUSPCHG status bit to GPIO8 after every new accelerometer sample.

The host processor can trigger an interrupt on rising edges of this pin to receive notification when the pedometer autonomously

suspends or resumes.

03 20 04 02 15 06

19 20 01 01 (AB & 3F)

19.16 Configure output interrupt: Merged flags on GPIO6

This command writes two bytes of the configuration variable to the GPIO application (APP_ID=0x03) starting at byte offset 0.

This causes the GPIO application to copy the pedometer's MRGFL status bit to GPIO6 after every new accelerometer sample.

The host processor can trigger an interrupt on rising edges of this pin to receive notification the activity-level, ste p-count, or

suspend-state changes.

03 20 00 02 15 07

19 20 01 01 (AB & 6F)

19.17 Configure output interrupt: Every 10 steps on GPIO7

The first command writes one byte of configuration variable to the Pedometer application (APP_ID = 0x15), starting at byte offset

13. This causes the pedometer to coalesce steps and assert STEPCHG once every 10 steps.

The second command writes two bytes of configuration variables to the GPIO application (APP_ID = 0x03), st arting at byte offset

2. This causes the GPIO application to copy the pedo meter's STEPCHG status bit to GPIO7 after every new accelerometer

sample.

15 20 0D 01 0A

03 20 02 02 15 05

19 20 01 01 (AB & 5F)

19.18 Configure output interrupt: Device direction change on GPIO6

This command writes two bytes of the configuration variable to the GPIO application (APP_ID=0x03), starting at byte offset 0.

This causes the GPIO application to copy the Six-Direction's SC_FLG status bit to GPIO6 after every new accelerometer sample.

The host processor can trigger an interrupt on rising edges of this pin to receive notification when the activity level chang es.

03 20 00 02 1A 07

19 20 01 01 (AB & 6F)

19.19 Wake up from Deep Sleep (Stop No Clock mode)

By default, the MMA955xL initializes all applications after a hardware reset and then falls into Deep Sleep mode where all system

clocks are stopped. A slave-port command can be used to wake up the clocks, enable the accelerometer, and execute the

pedometer.

This command writes one byte of configuration variable to the sleep/wake application (APP_ID=0x12) starting at byte offset 6.

12 20 06 01 00

Footprint and pattern information

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

20 Package Information

The MMA9555L uses a 16-lead LGA package, case number 2094. Use the following link for the latest diagram of the package:

www.nxp.com/files/shared/doc/package_info/98ASA00287D.pdf

20.1 Footprint and pattern information

Figure 24. Package bottom view

Figure 25. Pac kage overlaid on PCB footprint di agram (top view)

Package pad size

0.24 mm x 0.35 mm

Pin 16

Pin 1 ID

Pin 1

Package size (Measurements in mm)

PCB land extension

From the edge of the package

PCB land pad

PCB pad distance

to package edge

Marking

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Figure 26. Recommended PC B footprint

20.2 Marking

Solder mask opening

0.777 mm x 1.377 mm

(PCB land + 0.0637 mm larger all around.

Remove slivers between pa ds.)

PCB land pad size

0.65 mm x 0.25 mm

Solder stencil opening

0.62 mm x 0.22 mm

(PCB land – 0.015 mm smaller all around)

Top View

263

9555

ALYW

Traceability date code

Assembly site

Lot code

Work week

Part number

NXP code

Tape and reel information

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

20.3 Tape and reel information

Figure 27. Tape dimensions

The devices are oriented on the tape as shown in Figure 28. The dot marked on each devi ce indicates pin 1.

Figure 28. Tape and reel orientation

Barcode label

side of reel

Pin 1

Direction

to unreel

Package Description

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

20.4 Package Description

Use the following link for the latest diagra m of th e package:

www.nxp.com/files/shared/doc/package_info/98ASA00287D.pdf

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

Revision History

Revision

number Revision

date Description of chang es

1.0 10/2014 Initial release of document.

2.0 3/2015

Features, 117 µA for pedometer... was 190 µA for pedometer

Figure 2, Device pinout

Changed pin 6 from RGPIO/SDA0/SDI to RGPIO1/SDA0/SDI

Changed pin 8 from RGPIO3/SBB to RGPIO3/SSB

Figures 3 and 4

Changed pin 7 from IO2/SCL1/SDO to IO2/SDO

Changed pin 8 from IO3/SDA1/SSB to IO3/SSB

Added Sections 4–10.

Section 16.3.2.7, added Step Threshold

Table 167, Version Reset changed from 0x01 to 0x02

Table 168, 7:0, VERSION, added 2: R1.34

Section 16.4.1, To write all the pedometer configuration registers,...

MB3 = 0x11: Set the Count field to declare writing 17 bytes

was

MB3 = 0x10: Set the Count field to declare writing 16 bytes

MB16-17 = 0x????: Set the Speed Period / Step Threshold Register

was

MB16–MB17 = 0x????: Set the Speed Period

Added MB20 = 0x??: Set the Step Coalesce

Bytes to send: 0x15, 0x20, 0x00, 0x11, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??,

0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??

was

Bytes to send: 0x15, 0x20, 0x00, 0x10, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??,

0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??, 0x??

Section 16.4.1, To read all the pedometer configuration registers,...

MB3: 0x11=number of bytes to read

was

MB3: 0x10=number of bytes to read

MB2: 0x11 = actual number of bytes read

was

MB2: 0x10 = actual number of bytes read

MB3: 0x11 = requested number of bytes to read

was

MB3: 0x10 = requested number of bytes to read

MB15: male, filter time

was

MB15: male, filter time MB16: step period

Added MB16: speed period

MB17: step threshold

was

MB17: step coalesce

Added MB20: step coalesce

Deleted

Added Section 19.3.2.9, Step Coalesce register

Section 19.6, Write GPIO Input/output configuration variables was Write pedometer configuration variables

Section 19.13, 19 20 01 01 (AB & 6F) was 19 20 01 01

Section 19.14, added 19 20 01 01 (AB & 5F)

Section 19.15, 19 20 01 01 (AB & 3F) was 19 20 01 01

Section 19.16, 19 20 01 01 (AB & 6F) was 19 20 01 01

Section 19.17, 19 20 01 01 (AB & 5F) was 19 20 01 01

Section 19.18, 19 20 01 01 (AB & 6F) was 19 20 01 01

2.1 5/2015

Section 2.4.3, Note, deleted “Note that such a connection exists when the Master I2C interface is used (SDA1

function for pin 8).”

Figure 3, changed resistor from R2 to R4

Table 150, Status register, changed Reset from 0x0001 to 0x0002

MMA9555L Intelligent Pedometer Data Sheet, Rev. 2.2

2.2 6/2015 •Table 146 StepRateFactor value changed to 1.30

•Section 16.2.5, “Calorie-expenditure calculation,” on page 101 corrected Calorie-expenditure equation to

match the calculation.

2.3 8/2016 • Section 16.3.1, “ Pedometer memory maps,” on page 103, changed Step Coalesce register offset address

from 0xF to 0x10

Revision

number Revision

date Description of chang es

Document Number: MMA9555L

Rev. 2.3

8/2016

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