BME680 with STM32F103C8

[handytech · Accepted solution]

I don't have access to the documentation of your I2C library, but you may want to check how the implementation of I2C_Send7bitAddress() handles the slave address alignement.

The BME680 in I2C mode expects the Save Address to be left aligned, with the LSB as R/W bit:

Here is an example of chip ID read I2C transaction (note that in the Analyzer Settings, Address Display is set to "7-bit, address bits only"):

With your library, you may need to manually shift the slave address, e.g.:

I2C_Send7bitAddress(I2C1, (dev_addr << 1), I2C_Direction_Transmitter); // Send slave address for write
//[...]
I2C_Send7bitAddress(I2C1, (dev_addr << 1), I2C_Direction_Receiver); // Send slave address for read

[o_o]

In your screenshot, the initial state of the SCL line is not correct, the start condition is not shown.

Also the BME680 address is 0x76, but that is a 7-bit address. If you change your logic analyzer display settings, you would see that the i2c address that you are currently trying to access is 0x3B.

The combination of these 2 issues, make it look like the BME680 is not answering. I believe the root cause of your issue is a misconfiguration of the i2c master.

[Ruslan]

Thanks guys, I already found where problem was. It is slave address as you wrote. Yesterday, after posting screenshot from LA, I tried to set  gas_sensor.dev_id = 0xEC and  I recieved ack from BME. And now I see your answers for the same thing. In my code I am using  STM32F10x_StdPeriph_Lib_V3.5.0, and in library  I2C_Send7bitAddress realized in such way:

/**
  * @brief  Transmits the address byte to select the slave device.
  * @param  I2Cx: where x can be 1 or 2 to select the I2C peripheral.
  * @param  Address: specifies the slave address which will be transmitted
  * @param  I2C_Direction: specifies whether the I2C device will be a
  *   Transmitter or a Receiver. This parameter can be one of the following values
  *     @arg I2C_Direction_Transmitter: Transmitter mode
  *     @arg I2C_Direction_Receiver: Receiver mode
  * @retval None.
  */
void I2C_Send7bitAddress(I2C_TypeDef* I2Cx, uint8_t Address, uint8_t I2C_Direction)
{
  /* Check the parameters */
  assert_param(IS_I2C_ALL_PERIPH(I2Cx));
  assert_param(IS_I2C_DIRECTION(I2C_Direction));
  /* Test on the direction to set/reset the read/write bit */
  if (I2C_Direction != I2C_Direction_Transmitter)
  {
    /* Set the address bit0 for read */
    Address |= OAR1_ADD0_Set; // Address |= 0x0001
  }
  else
  {
    /* Reset the address bit0 for write */
    Address &= OAR1_ADD0_Reset; // Address &= 0xFFFE
  }
  /* Send the address */
  I2Cx->DR = Address;
}

Now I am  put in this function 0xEC address for writing to and 0xED for reading from BME.