I am using a STM32F030R8 nucleo board and a LSM9DS1 sensor. I'm just starting out learning about this stuff and I am having troubles reading from the sensor. Here are all the details about the problem I am having.
I initialized the peripherals and the I2C protocol using the STM32CUBEMX automatic code generation so that should'nt be a part of the problem. I use Keil IDE. For starters, the datasheet didn't make it clear what the Slave Adress of the Accel+Gyro and Magnetometer but gave a list of possible values (pg. 30 of the datasheet). For the Accel+Gyro, I found online that it must be either 0x6A or 0x6B, depending on the SA0 and it's connection. The problem is that I do not have a SA0 connector on the board of the sensor. So i decided to find out the address by going through all the possibilities and expecting an acnowledge signal.
uint8_t buf[12];
HAL_StatusTypeDef result;
uint8_t i;
//Trying to find out the address of the i2c slave (accelerometer and gyro hopefully)
for (i=1; i<128; i++)
{
/*
* the HAL wants a left aligned i2c address
* &hi2c1 is the handle
* (uint16_t)(i<<1) is the i2c address left aligned
* retries 2
* timeout 2
*/
result = HAL_I2C_IsDeviceReady(&hi2c1, (uint16_t)(i<<1), 2, 2);
if (result != HAL_OK) // HAL_ERROR or HAL_BUSY or HAL_TIMEOUT
{
strcpy((char*) buf, ".");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY); // No ACK received at that address
}
if (result == HAL_OK)
{
strcpy((char*) buf, "(");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
sprintf((char*)buf, "%X h", i);
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY); // Received an ACK at that address
strcpy((char*) buf, ")");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
}
}Suprisingly, only the address 0x69 gives back the ackowledge as you can see in the picture below. Every adress but this is ignored.
So I decided to use this address even though I don't understand how it could possibly be different than what everybody else is saying on the internet. Next was writing to the control register CTRL_REG6_XL so I can turn on the accel and try reading some data (as explained in the datasheet pg. 19). I wrote 0xC0 to the register to activate the accel (pg. 51 - pg. 52).
uint8_t SlaveAdress = 0x69 << 1; // Accel and Gyro I2C Slave Adress that sent acknowledge
uint8_t CTRL_REG6_XL = 0x20; // Control Register to turn on the Accel
uint8_t sent_data = 0xC0; // Setting ODDR_XL2 = 1, ODDR_XL1 = 1, ODDR_XL0 = 0, rest is 0, accel turned on
uint8_t received_data;
buf[0] = CTRL_REG6_XL;
buf[1] = sent_data;
//Writing to the control register to activate the accel
result = HAL_I2C_Master_Transmit(&hi2c1, SlaveAdress, buf, 2, HAL_MAX_DELAY);
if ( result != HAL_OK ) {
strcpy((char*)buf, "There was an error while writing!\r\n");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
} else {
strcpy((char*)buf, "Data sent succesfully!\r\n");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
}Everything went ok as i received no failed messages.
To test if i really did send the data i decided to read back from the same register and see the result.
buf[0] = CTRL_REG6_XL;
buf[1] = 0;
//Reading from the control register that we just wrote to
result = HAL_I2C_Master_Transmit(&hi2c1, SlaveAdress, buf, 1, HAL_MAX_DELAY);
if ( result != HAL_OK ) {
strcpy((char*)buf, "There was an error while writing!\r\n");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
} else {
strcpy((char*)buf, "Data sent succesfully!\r\n");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
}
result = HAL_I2C_Master_Receive(&hi2c1, SlaveAdress, &received_data, 1, HAL_MAX_DELAY);
if ( result != HAL_OK ) {
strcpy((char*)buf, "There was an error while reading!\r\n");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
} else {
strcpy((char*)buf, "Data read succesfully!\r\n");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
}
strcpy((char*)buf, "CTRL_REG6_XL: ");
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);
sprintf((char*)buf, "%X h", received_data);
HAL_UART_Transmit(&huart2, buf, strlen((char*) buf), HAL_MAX_DELAY);The whole process went without error but the data read is wrong. Instead of 0xC0 i get 0x00. I am stuck regarding what do to next.
Any insight is greatly appreciated.
LSM9DS1 Datasheet - https://www.st.com/resource/en/datasheet/lsm9ds1.pdf
