Using LIS25BA with STM32L4 Nucleo Board

[Arka]

I am using STM32L452RE Nucleo Board and LIS25BA module.

I2C works fine. I wish to get accelerometer data through TDM now. I am unable to do so. For now, I am using polling mode. The code I am using is given below and the SAI configuration I am using is also attached.

/* USER CODE BEGIN 2 */
  int16_t rdat[8];
  uint8_t chipid=0;
  uint8_t cmax=0x7f;
  uint8_t ctrlreg=0;
  uint8_t tdmctrlreg=0x64;
  uint8_t axesctrlreg=0xe0;
  uint8_t rcmax;
 uint8_t rctrlreg;
 uint8_t rtdmctrlreg;
 uint8_t raxesctrlreg;
  HAL_I2C_Mem_Read (&hi2c2, 0x33, 0x0f, 1, &chipid, 1, 100);
  HAL_I2C_Mem_Write(&hi2c2, 0x32, 0x25, 1, &cmax, 1, 100);
  HAL_I2C_Mem_Write(&hi2c2, 0x32, 0x26, 1, &ctrlreg, 1, 100);
  HAL_I2C_Mem_Write(&hi2c2, 0x32, 0x2e, 1, &tdmctrlreg, 1, 100);
  HAL_I2C_Mem_Write(&hi2c2, 0x32, 0x2f, 1, &axesctrlreg, 1, 100);
  HAL_I2C_Mem_Read (&hi2c2, 0x33, 0x25, 1, &rcmax, 1, 100);//read data back
  HAL_I2C_Mem_Read (&hi2c2, 0x33, 0x26, 1, &rctrlreg, 1, 100);//read data back
  HAL_I2C_Mem_Read (&hi2c2, 0x33, 0x2e, 1, &rtdmctrlreg, 1, 100);//read data back
  HAL_I2C_Mem_Read (&hi2c2, 0x33, 0x2f, 1, &raxesctrlreg, 1, 100);//read data back
  /* USER CODE END 2 */
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
   HAL_SAI_Receive(&hsai_BlockA1, (uint8_t*)rdat, 8, 100);
    /* USER CODE END WHILE */
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */

 Please let me know if it is possible to get data using SAI or I2S or any other method using this nucleo board or any other board. Thanks.

[Foued_KH]

Hello @Arka , 

Could you please check these threads : 
https://community.st.com/t5/mems-sensors/tdm-interface-with-sai-for-lis25ba/m-p/110640
https://community.st.com/t5/mems-sensors/lis25ba-tdm-interface-restrictions/m-p/267008

Hope it helps!
Foued

[Arka]

It doesnt work for some reason. I have tried all possible configurations, 8kHz, 16kHz and 24kHz. The first 2 seems to give some random values which do not change based on acceleration. 24kHz mode gives some rapidly changing values but I think the clock is not synchronized properly. I should get three 16 bit values corresponding to x-y-z axes in 3 slots. But the rdat variable is filled up with 4 slots. So probably the 48 bits do not get synced with 16 bit slots of my array.

RM0394 page 1349 says "In the SAI, the single ratio MCLK/FS = 256 is considered." But for LIS25BA this is impossible as it needs MCLK=12.288MHz and does not support FS at 48kHz. So I tried using PWM to emulate SAI_MCLK as given here STM32 Drive LIS25BA - MEMS Sensors - Electronic Engineering World - Forum (eeworld.com.cn)

But even this does not work.