LIS2DTW12 - SPI

[DivyaJayan]

Hi, 

I am attempting to obtain readings from the LIS2DTW12 accelerometer on board, utilizing the SPI interface and an STM32F098RCT6 microcontroller.

I’m accessing the ‘who_am_i’ register along with the high and low registers for the x, y, and z axes. Upon debugging, I’ve found that the high and low values for the x, y, and z axes are consistently 0xff, resulting in raw x, y, and z values of 0xffff.

Notably, these values remain unchanged even when the board is in motion.

Please help me.

Here is the code:

#define LIS2DTW12_WHO_IAM_I_ADDR    0x0F
#define LIS2DTW12_OUT_X_L_ADDR      0x28
#define LIS2DTW12_OUT_X_H_ADDR      0x29
#define LIS2DTW12_OUT_Y_L_ADDR      0x2A
#define LIS2DTW12_OUT_Y_H_ADDR      0x2B
#define LIS2DTW12_OUT_Z_L_ADDR      0x2C
#define LIS2DTW12_OUT_Z_H_ADDR      0x2D

uint8_t LIS2DTW12_ReadReg(uint8_t reg){

	uint8_t Received_data = 0;
	uint8_t address = reg | 0x80;

	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_RESET);
	HAL_SPI_Transmit(&hspi1, &address,1,50);
	HAL_SPI_Receive(&hspi1, &Received_data, 1, 50);
	HAL_GPIO_WritePin(GPIOA, GPIO_PIN_4, GPIO_PIN_SET);
	return Received_data;
}
int main(void){
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_SPI1_Init();

  uint8_t who_am_i = LIS2DTW12_ReadReg(LIS2DTW12_WHO_IAM_I_ADDR);
  if(who_am_i != 0x44){}

  uint8_t x_low  = LIS2DTW12_ReadReg(LIS2DTW12_OUT_X_L_ADDR);
  uint8_t x_high = LIS2DTW12_ReadReg(LIS2DTW12_OUT_X_H_ADDR);
  uint8_t y_low  = LIS2DTW12_ReadReg(LIS2DTW12_OUT_Y_L_ADDR);
  uint8_t y_high = LIS2DTW12_ReadReg(LIS2DTW12_OUT_Y_H_ADDR);
  uint8_t z_low  = LIS2DTW12_ReadReg(LIS2DTW12_OUT_Z_L_ADDR);
  uint8_t z_high = LIS2DTW12_ReadReg(LIS2DTW12_OUT_Z_H_ADDR);

  uint16_t  x_raw = ((x_high << 8)|x_low);
  uint16_t  y_raw = ((y_high << 8)|y_low);
  uint16_t  z_raw = ((z_high << 8)|z_low);

  while (1)
  {
  }
}
static void MX_SPI1_Init(void){ 
  hspi1.Instance = SPI1;
  hspi1.Init.Mode = SPI_MODE_MASTER;
  hspi1.Init.Direction = SPI_DIRECTION_2LINES;
  hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
  hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
  hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
  hspi1.Init.NSS = SPI_NSS_SOFT;
  hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_2;
  hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
  hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
  hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
  hspi1.Init.CRCPolynomial = 7;
  hspi1.Init.CRCLength = SPI_CRC_LENGTH_DATASIZE;
  hspi1.Init.NSSPMode = SPI_NSS_PULSE_ENABLE;
  if (HAL_SPI_Init(&hspi1) != HAL_OK)
  {
    Error_Handler();
  }
}

After debugging, values are obtaining as follows:

[Sarra.S]

Hello @DivyaJayan,

Try reading other registers to see if they return valid data, if the who_am_i register returns the expected value (0x44), there might be an issue with the sensor itself 

[Andrew Neil]

---

@DivyaJayan wrote:

I’m accessing the ‘who_am_i’ register :

---

So, as @Sarra.S asked,  does that return the correct value?

Are there any other devices on the same SPI bus? If so, are they working OK?

Have you used a logic analyser or oscilloscope to verify what's happening on the wires?

Please post your schematic showing the connections between the STM32 and the LIS2DTW12