[BUG?] STM32F3 CAN transmit timeout

Posted on May 12, 2016 at 03:48

Hi,

I just noticed another oddity in the CubeMX HAL drivers:

when I send a CAN message on an empty bus the function HAL_CAN_Transmit(...) waits in a loop for the timeout and then cancel the sending of the frame:

/* Check End of transmission flag */

 

    while(!(__HAL_CAN_TRANSMIT_STATUS(hcan, transmitmailbox)))

 

    {

 

      /* Check for the Timeout */

 

      if(Timeout != HAL_MAX_DELAY)

 

      {

 

        if((Timeout == 0) || ((HAL_GetTick()-tickstart) > Timeout))

 

        {

 

          hcan->State = HAL_CAN_STATE_TIMEOUT;

 

          /* Process unlocked */

 

          __HAL_UNLOCK(hcan);

 

          return HAL_TIMEOUT;

 

        }

 

      }

 

    }

 

 

But if I watch the bus activity, the controller continues to retry sending the message over and over again even though the timeout has occurred.

After having a look at the control registers, I suggest to add the following line to fix this and make the timeout work as expected (by me):

    /* Check End of transmission flag */

 

    while(!(__HAL_CAN_TRANSMIT_STATUS(hcan, transmitmailbox)))

 

    {

 

      /* Check for the Timeout */

 

      if(Timeout != HAL_MAX_DELAY)

 

      {

 

        if((Timeout == 0) || ((HAL_GetTick()-tickstart) > Timeout))

 

        {

 

          hcan->State = HAL_CAN_STATE_TIMEOUT;

 

          /* Process unlocked */

 

          __HAL_UNLOCK(hcan);

 

          hcan->Instance->TSR |= (((uint32_t) 1 << (7 + transmitmailbox * 8))); // TODO: try to stop all retransmission tries

 

          return HAL_TIMEOUT;

 

        }

 

      }

 

    }

 

 

Setting the ABRQx bit in the CAN_TSR register cancels re-transmitting the message in transmit mailbox x.

Seems to work for me. During the loop the message is bein re-sent on the bus and after timeout - silence.

Opinions?

note: I have the ABOM bit SET so there is no hardware bus off management. I still think that after the timeout the retransmission tries should stop.