mma9555l with nrf51422 using i2c

[abhinavnagaraj]

I am using the MMA9555L with the nrf 51422 as master using i2c communication protocol. I have read the datasheet and sent the respective commands as mentioned there for each respective function but i am not getting the specified response from MMA9555L . An uint8_t pedo_read12[21]={0x15, 0x20, 0x00, 0x11, 0x00, 0x00, 0xff, 0xff, 0x01, 0x00, 0x00, 0x00, 0x50, 0xaf, 0x03, 0x04, 0x82, 0x05,0x00, 0x00} .This is the array sent by me as mentioned in article "pedometer configuration example" in  datasheet. Have attached screenshot of response. Any help will be appreciated.

regards 

Abhinav

[JackITB]

Hello Abhinav,

To start with, I recommend you simply awaken the device and read the pedometer results:

1/ IIC WRITE TRANSACTION :: Starting MB = 00
   Write : 12 20 06 01 00 // disable sleep mode (STOPNC) in Sleep-Wake Application

Move the DUT during a few sec to simulate motion

2/ IIC WRITE TRANSACTION :: Starting MB = 00
   Write : 15 30 00 0C // query pedometer data-status (12 bytes total)

3/ IIC READ TRANSACTION :: Starting MB = 00, No. bytes to read = 16
   Read : 15 80 0C 0C 01 02 00 1F 00 2E 00 00 00 02 00 00

   -->Step count is 0x1F = 31d

Then you can periodically loop to step 2/ to get updated pedometer data

Also, I suggest you take a look at this thread: Reading Aggregated Data Legacy Mode on MMA9555L ,

as well as the attached draft document. You will find useful information about the "command / response" communication protocol.

At last, if you still struggle, please provide log of the slave interface traffic to trace back potential errors in the communication with MMA9555L.

Regards,   Jacques.