Not able to use Port B alternate function (I2C)

[AWong.11]

Hi community,

I am trying to use I2C on the STM32L010RBTX,

during configuration in MX, i realized that when PB8 and PB9 is configured as I2C, the GPIO mode field shows n/a.

And the I2C won't work as well.

However, when i configure to PA9/PA10,

GPIO mode shows alternate function,

which, I2C works perfectly fine under the same code.

I am just using HAL_I2C_IsDeviceReady to check whether it is sending out anything.

Any idea how to make it work on PB8 and PB9?

Much thanks!

[TDK]

Look at the generated code to see if AF is specified. If not, you'll need to add that in manually in the I2C pin initialization code.

CubeMX has a bunch of bugs like this where it initializes the pins but with an uninitialized/zero AF field.

[Imen.D]

Hello @AWong.11​ and welcome to the Community :)

Do you have pull up resistors?

Try changing the mode to push pull mode.

Maybe this FAQ helped you as describes few tips related to I2C : STM32 I2C does not work

Imen

[TDK]

Pin initialization code is in HAL_I2C_MspInit in the stm32l0xx_hal_msp.c file.

[AWong.11]

Thank you so much boss.

Added the AF init in MSP file and it worked.

Some how you've must had encountered these bugs many times:grinning_face_with_sweat:

[AWong.11]

Thank you for the reply Imen.

Problem has been solve and it's a bug of the code gen.

Please take note as well hope this can be mitigated in future updates.

Thanks for the reply anyways.

[Imen.D]

I have passed this issue along to our CubeMx team for review and fix.

Hi @Sara BEN HADJ YAHYA​ , please take this request into consideration. 

Thanks

Imen

[Sara BEN HADJ YAHYA]

Hello @AWong.11​ ,

Thanks for your feedback,

You are right, it is indeed a CubeMX bug.

It seems that the GPIO configuration for I2C is missing from HAL_I2C_MspInit() when Port B is used.

It should be as follow:

void HAL_I2C_MspInit(I2C_HandleTypeDef* hi2c)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(hi2c->Instance==I2C1)
  {
  /* USER CODE BEGIN I2C1_MspInit 0 */
 
  /* USER CODE END I2C1_MspInit 0 */
 
    __HAL_RCC_GPIOB_CLK_ENABLE();
    /**I2C1 GPIO Configuration
    PB8     ------> I2C1_SCL
    PB9     ------> I2C1_SDA
    */
    GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF6_I2C1;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
    /* Peripheral clock enable */
    __HAL_RCC_I2C1_CLK_ENABLE();
  /* USER CODE BEGIN I2C1_MspInit 1 */
 
  /* USER CODE END I2C1_MspInit 1 */
  }
 
}

The missing part should be added in the user section, this will prevent loosing it when the code is regenerated by CubeMX.

  /* USER CODE BEGIN I2C1_MspInit 0 */
 
    __HAL_RCC_GPIOB_CLK_ENABLE();
 
    GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF6_I2C1;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
 
  /* USER CODE END I2C1_MspInit 0 */

With this being said, the issue is now reported to the dev team to be fixed. I will keep you posted.

Internal ticket number: 126421 (This is an internal tracking number and is not accessible or usable by customers).

Thanks for your contribution,

Sara.

[Sara BEN HADJ YAHYA · Accepted solution]

Hello @AWong.11​ ,

This issue is fixed in STM32CubeMX latest release.

V6.7.0 is now available under this Link.

Thanks for your contribution :smiling_face_with_smiling_eyes:

Sara.