STM32H750 FDCAN Not transmiting

[VCasa.3]

Dear Sirs,

I am implementing an interface between an STM32H750 and a CanBus device of an electric bike. I have the FDCAN peripheral configured to 250kbit/s (FDCAN clock is 48MHz)

I have to interface with devices that use Extended Frames, but the speed is fixed to 250bit/s, so I wanted to use normal mode.

First I ninitialize the peripheral as:

// Configure TX Header for FDCAN2
  CAN_TxHeader.Identifier = 0x03;
  CAN_TxHeader.IdType = FDCAN_EXTENDED_ID;
  CAN_TxHeader.TxFrameType = FDCAN_DATA_FRAME;
  CAN_TxHeader.DataLength = FDCAN_DLC_BYTES_8;
  CAN_TxHeader.ErrorStateIndicator = FDCAN_ESI_ACTIVE;
  CAN_TxHeader.BitRateSwitch = FDCAN_BRS_OFF;
  CAN_TxHeader.FDFormat = FDCAN_FD_CAN;
  CAN_TxHeader.TxEventFifoControl = FDCAN_NO_TX_EVENTS;
  CAN_TxHeader.MessageMarker = 0;

  /* Configure standard ID reception filter to Rx buffer 0 */
  CAN_FilterConfig.IdType = FDCAN_EXTENDED_ID;
  CAN_FilterConfig.FilterIndex = 0;
  CAN_FilterConfig.FilterType = FDCAN_FILTER_DUAL;
  CAN_FilterConfig.FilterID2 = 0x0;
  CAN_FilterConfig.RxBufferIndex = 0;

  if(HAL_FDCAN_ConfigFilter(&hfdcan2, &CAN_FilterConfig) != HAL_OK)
  {
	  Error_Handler();
  }

  if(HAL_FDCAN_Start(&hfdcan2)!= HAL_OK)
  {
	  Error_Handler();
  }

  if (HAL_FDCAN_ActivateNotification(&hfdcan2, FDCAN_IT_RX_FIFO1_NEW_MESSAGE, 0) != HAL_OK)
  {
	  /* Notification Error */
	  Error_Handler();
  }

  if(HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan2, &CAN_TxHeader, &CAN_TxData[0]) != HAL_OK)
  {
	  Error_Handler();
  }

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and then in a FreeRTOS task I send data:

void canBus(void *argument)
{
  /* USER CODE BEGIN canBus */
	HAL_StatusTypeDef rtv = HAL_ERROR;
  /* Infinite loop */
  for(;;)
  {
	  // Send the HeartBeat Message to the controller
	  CAN_TxHeader.DataLength = FDCAN_DLC_BYTES_4;
	  CAN_TxData[0] = 0x05;
	  CAN_TxData[1] = 0x03;
	  CAN_TxData[2] = 0x00;
	  CAN_TxData[3] = 0x01;
	  rtv = HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan2, &CAN_TxHeader, &CAN_TxData[0]);

	  // Check is there are Received Messages in the CAN RX FIFO
	if (can_rx_message_available != 0)
	{
		// Process them
		canBusMsgProcess();
		can_rx_message_available = 0;
	}

    osDelay(1000);
  }
  /* USER CODE END canBus */
}

Debugging the code, placing a breakpoint, I get that rtv is always HAL_OK, and if with the oscilloscope I monitor the CAN_TX pins, there is activity, but then in the bus, there is no activity (CANH/CANL lines)

I have been going back and forth with this for days, and I do not know what can be problem.

Is it something with initialization? Probably with the FIFO?

I do not want to filter Messages on the Bus, as this will interface with a lot of different devices.

Thank you so much in advance,

Best regards

[mƎALLEm · Accepted solution]

Hello,

What frame format your CAN bus needs to support classic or FD?

I see in your code:

CAN_TxHeader.FDFormat = FDCAN_FD_CAN;

Are you sure it's FD?

You didn't share your CAN initialization code.

I suggest to share your project so we can check all the parameters and config.

Please remove all the stuff not related to the CAN. Keep only the minimal but a complete project that let others run a test.

[VCasa.3]

Changing this:

CAN_TxHeader.FDFormat = FDCAN_FD_CAN;

Fixed the issue

Thank you so much!