Reading data from L3GD20 (SPI)

[Ala1980]

Hi,

did anyone try to connect to the gyro (L3GD20) on F303Discovery board over SPI?

I have a problem even with reading the WHO_AM_I register:

My code is generated with Cube and I added the following lines:

𝐮𝐢𝐧𝐭𝟖_𝐭 𝐝𝐚𝐭𝐚_𝐰𝐡𝐨𝐚𝐦𝐢, 𝐚𝐝𝐝𝐫𝐞𝐬𝐬_𝐰𝐡𝐨𝐚𝐦𝐢;

𝐚𝐝𝐝𝐫𝐞𝐬𝐬_𝐰𝐡𝐨𝐚𝐦𝐢 = 𝟎𝐱𝟎𝐟 | 𝟎𝐱𝟖𝟎; -- set RW

𝐇𝐀𝐋_𝐆𝐏𝐈𝐎_𝐖𝐫𝐢𝐭𝐞𝐏𝐢𝐧(𝐆𝐏𝐈𝐎𝐄,𝐆𝐏𝐈𝐎_𝐏𝐈𝐍_𝟑, 𝐆𝐏𝐈𝐎_𝐏𝐈𝐍_𝐑𝐄𝐒𝐄𝐓);--reset CS on SPI

𝐇𝐀𝐋_𝐒𝐏𝐈_𝐓𝐫𝐚𝐧𝐬𝐦𝐢𝐭𝐑𝐞𝐜𝐞𝐢𝐯𝐞(&𝐡𝐬𝐩𝐢𝟏, &𝐚𝐝𝐝𝐫𝐞𝐬𝐬_𝐰𝐡𝐨𝐚𝐦𝐢,&𝐝𝐚𝐭𝐚_𝐰𝐡𝐨𝐚𝐦𝐢,𝟐,𝟓𝟎);

𝐇𝐀𝐋_𝐆𝐏𝐈𝐎_𝐖𝐫𝐢𝐭𝐞𝐏𝐢𝐧(𝐆𝐏𝐈𝐎𝐄,𝐆𝐏𝐈𝐎_𝐏𝐈𝐍_𝟑, 𝐆𝐏𝐈𝐎_𝐏𝐈𝐍_𝐒𝐄𝐓);--set CS on SPI

Having that the 𝐌𝐗_𝐒𝐏𝐈𝟏_𝐈𝐧𝐢𝐭() is called before so that the SPI should be initialized correctly, but the problem I can't read the expected WHO_AM_I value (D4)

[Eleon BORLINI]

Hi @Ala1980​ ,

I suggest you to check the STM32CubeF3 package, especially the L3GD20-related functions you can find in the driver folder at Drivers\BSP\STM32F3-Discovery.

To have a more complete overview of an entire project including the gyroscope SPI communication and data acquisition, you may start from the Demo available in the projects folder at \Projects\STM32F3-Discovery\Demonstrations\SW4STM32\STM32F3-Discovery_Demo.

You may insert these lines in your code, or at least check if you are doing well in your code (both for the low-level SPI configuration and for the mid-level gyro read/write register functions):

/********************************* LINK GYROSCOPE *****************************/
/**
  * @brief  Configures the GYROSCOPE SPI interface.
  * @retval None
  */
void GYRO_IO_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
  
  /* Configure the Gyroscope Control pins ------------------------------------------*/
  /* Enable CS GPIO clock and  Configure GPIO PIN for Gyroscope Chip select */  
  GYRO_CS_GPIO_CLK_ENABLE();  
  GPIO_InitStructure.Pin = GYRO_CS_PIN;
  GPIO_InitStructure.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStructure.Pull  = GPIO_NOPULL;
  GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_HIGH;
  HAL_GPIO_Init(GYRO_CS_GPIO_PORT, &GPIO_InitStructure);
 
  /* Deselect : Chip Select high */
  GYRO_CS_HIGH();
 
  /* Enable INT1, INT2 GPIO clock and Configure GPIO PINs to detect Interrupts */
  GYRO_INT_GPIO_CLK_ENABLE();
  GPIO_InitStructure.Pin = GYRO_INT1_PIN | GYRO_INT2_PIN;
  GPIO_InitStructure.Mode = GPIO_MODE_INPUT;
  GPIO_InitStructure.Speed = GPIO_SPEED_FREQ_HIGH;
  GPIO_InitStructure.Pull= GPIO_NOPULL;
  HAL_GPIO_Init(GYRO_INT_GPIO_PORT, &GPIO_InitStructure);
  
  SPIx_Init();
}
 
/**
  * @brief  Writes one byte to the GYROSCOPE.
  * @param  pBuffer pointer to the buffer  containing the data to be written to the GYROSCOPE.
  * @param  WriteAddr GYROSCOPE's internal address to write to.
  * @param  NumByteToWrite Number of bytes to write.
  * @retval None
  */
void GYRO_IO_Write(uint8_t* pBuffer, uint8_t WriteAddr, uint16_t NumByteToWrite)
{
  /* Configure the MS bit: 
       - When 0, the address will remain unchanged in multiple read/write commands.
       - When 1, the address will be auto incremented in multiple read/write commands.
  */
  if(NumByteToWrite > 0x01)
  {
    WriteAddr |= (uint8_t)MULTIPLEBYTE_CMD;
  }
  /* Set chip select Low at the start of the transmission */
  GYRO_CS_LOW();
  
  /* Send the Address of the indexed register */
  SPIx_WriteRead(WriteAddr);
  
  /* Send the data that will be written into the device (MSB First) */
  while(NumByteToWrite >= 0x01)
  {
    SPIx_WriteRead(*pBuffer);
    NumByteToWrite--;
    pBuffer++;
  }
  
  /* Set chip select High at the end of the transmission */ 
  GYRO_CS_HIGH();
}
 
/**
  * @brief  Reads a block of data from the GYROSCOPE.
  * @param  pBuffer pointer to the buffer that receives the data read from the GYROSCOPE.
  * @param  ReadAddr GYROSCOPE's internal address to read from.
  * @param  NumByteToRead number of bytes to read from the GYROSCOPE.
  * @retval None
  */
void GYRO_IO_Read(uint8_t* pBuffer, uint8_t ReadAddr, uint16_t NumByteToRead)
{  
  if(NumByteToRead > 0x01)
  {
    ReadAddr |= (uint8_t)(READWRITE_CMD | MULTIPLEBYTE_CMD);
  }
  else
  {
    ReadAddr |= (uint8_t)READWRITE_CMD;
  }
  /* Set chip select Low at the start of the transmission */
  GYRO_CS_LOW();
  
  /* Send the Address of the indexed register */
  SPIx_WriteRead(ReadAddr);
  
  /* Receive the data that will be read from the device (MSB First) */
  while(NumByteToRead > 0x00)
  {
    /* Send dummy byte (0x00) to generate the SPI clock to GYROSCOPE (Slave device) */
    *pBuffer = SPIx_WriteRead(DUMMY_BYTE);
    NumByteToRead--;
    pBuffer++;
  }
  
  /* Set chip select High at the end of the transmission */ 
  GYRO_CS_HIGH();
}  
#endif /* HAL_SPI_MODULE_ENABLED */
 
#ifdef HAL_I2C_MODULE_ENABLED

-Eleon

[Ala1980]

Thanks for the reply, I added the code lines I needed also to define some functions manually (GYRO_IO_Read, SPIx_WriteRead, GYRO_IO_Init, SPIx_Init, SPIx_MspInit) but I am still unable to read the WHO_AM_I register!

Could you please tell me who I can tell the CubeMX to import me the necessary drivers (of L3GD20 and LSM303DLHC) while creating a new project?

[Eleon BORLINI]

Hi @Ala1980​ ,

you can for example check this tutorial to have an idea of how to import predefined libraries in a CubeMX project.

Moreover, I added STM32CubeMX tag for more help from this topic's experts.

-Eleon

[Ala1980]

Thanks for the reply,

my question was, since I am using Cube to generate my code, and since I asked Cube to set the default pin and peripheral settings, why Cube didn't imported all the necessary driver files to my project? (the following files for example: "stm32f3_discovery.c", "l3gd20.c", "stm32f3_discovery_accelerometer.c", "stm32f3_discovery_gyroscope.c")

What is the best way to let Cube import all these files in a clean and smooth way?

[Ala1980]

After manually adding the necessary driver files, I could compile the project and could at least call those functions: GYRO_IO_Init(), L3GD20_ReadID().

The problem is that I dont get the correct value of who_am_i from the function L3GD20_ReadID(), so I get 0x0F instead of 0xD4

[Eleon BORLINI]

It is like you are reading the register of the WHO_AM_I (0x0F) instead of the content... Can you check with reading the content of other registers, for example the CTRL_REG1 (20h) one? The content should be 0x07.

-Eleon

[Ala1980]

Thanks for the reply.

I dont know what was my mistake, but now I can read the correct value of the register (and not the address), also when I read the CTRL_REG1 then I get the correct value of 0x07.

My next problem is in reading the gyro values, so I am using the following block in main() inside main.c:

float AngleRates[3] = {0};

float AngleRateX, AngleRateY, AngleRateZ;

 while (1)

 {

L3GD20_ReadXYZAngRate(AngleRates);

AngleRateX = AngleRates[0];

AngleRateZ = AngleRates[1];

AngleRateY = AngleRates[2];

 }

I got always a fix reading in AngleRateX, AngleRateY, AngleRateZ (-0.49, -0.65, -1.33), and these readings dont change when I move/rotate the board!

Your futher help is highly appreciated.

[Eleon BORLINI]

Hi @Ala1980​ ,

for this purpose, I suggest you to check the C drivers on Github for the L3GD20 (see l3gd20h_read_data_polling.c)

In particular, before reading the output values you have to configure the device with the following procedure:

/* Restore default configuration */
  l3gd20h_dev_reset_set(&dev_ctx, PROPERTY_ENABLE);
  do {
    l3gd20h_dev_reset_get(&dev_ctx, &rst);
  } while (rst);
 
  /* Enable Block Data Update */
  l3gd20h_block_data_update_set(&dev_ctx, PROPERTY_ENABLE);
 
  /* Set full scale */
  l3gd20h_gy_full_scale_set(&dev_ctx, L3GD20H_2000dps);
 
  /* Set Output Data Rate / Power mode */
  l3gd20h_gy_data_rate_set(&dev_ctx, L3GD20H_50Hz);

-Eleon

[Eleon BORLINI]

Hi @Ala1980​ ,

please let me know in case of positive or negative feedback.

-Eleon