STM32F042G6Ux CAN issue

[Tonave]

Hello All !

I have an issue with the CAN bus on STM32F042G6. I am using PA11 and PA12 Pins. Here is the configuration part with a 48MHz internal clock :

static void MX_CAN_Init(void)
{

  /* USER CODE BEGIN CAN_Init 0 */

  /* USER CODE END CAN_Init 0 */

  /* USER CODE BEGIN CAN_Init 1 */

  /* USER CODE END CAN_Init 1 */
  hcan.Instance = CAN;
  hcan.Init.Prescaler = 23;
  hcan.Init.Mode = CAN_MODE_NORMAL;
  hcan.Init.SyncJumpWidth = CAN_SJW_1TQ;
  hcan.Init.TimeSeg1 = CAN_BS1_5TQ;
  hcan.Init.TimeSeg2 = CAN_BS2_6TQ;
  hcan.Init.TimeTriggeredMode = DISABLE;
  hcan.Init.AutoBusOff = DISABLE;
  hcan.Init.AutoWakeUp = DISABLE;
  hcan.Init.AutoRetransmission = DISABLE;
  hcan.Init.ReceiveFifoLocked = DISABLE;
  hcan.Init.TransmitFifoPriority = DISABLE;
  if (HAL_CAN_Init(&hcan) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN CAN_Init 2 */

  /* USER CODE END CAN_Init 2 */

}

Here is the remap done by STCube :

void HAL_MspInit(void)
{
  /* USER CODE BEGIN MspInit 0 */

  /* USER CODE END MspInit 0 */

  __HAL_RCC_SYSCFG_CLK_ENABLE();
  __HAL_RCC_PWR_CLK_ENABLE();

  /* System interrupt init*/

  __HAL_REMAP_PIN_ENABLE(HAL_REMAP_PA11_PA12);

  /* USER CODE BEGIN MspInit 1 */

  /* USER CODE END MspInit 1 */
}

void HAL_CAN_MspInit(CAN_HandleTypeDef* hcan)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
  if(hcan->Instance==CAN)
  {
  /* USER CODE BEGIN CAN_MspInit 0 */

  /* USER CODE END CAN_MspInit 0 */
    /* Peripheral clock enable */
    __HAL_RCC_CAN1_CLK_ENABLE();

    __HAL_RCC_GPIOA_CLK_ENABLE();
    /**CAN GPIO Configuration
    PA11     ------> CAN_RX
    PA12     ------> CAN_TX
    */
    GPIO_InitStruct.Pin = GPIO_PIN_11|GPIO_PIN_12;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF4_CAN;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /* USER CODE BEGIN CAN_MspInit 1 */

  /* USER CODE END CAN_MspInit 1 */
  }
}

I can write with the CAN bus it works (verified with oscillo), here is the code for the writing part :

int main(void)
{
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* Configure the system clock */
  SystemClock_Config();

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_CAN_Init();
  MX_CRC_Init();
  /* USER CODE BEGIN 2 */
  if(HAL_CAN_Start(&hcan) != HAL_OK)
    Error_Handler();
  
  TxHeader.StdId = 0x446; 
  TxHeader.ExtId = 0x01; 
  TxHeader.RTR = CAN_RTR_DATA; 
  TxHeader.IDE = CAN_ID_STD; 
  TxHeader.DLC = 2;
  
  CAN_FilterTypeDef canfilterconfig;

  canfilterconfig.FilterActivation = CAN_FILTER_ENABLE;
  canfilterconfig.FilterBank = 18;  // which filter bank to use from the assigned ones
  canfilterconfig.FilterFIFOAssignment = CAN_FILTER_FIFO0;
  canfilterconfig.FilterIdHigh = 0x446<<5;
  canfilterconfig.FilterIdLow = 0;
  canfilterconfig.FilterMaskIdHigh = 0x446<<5;
  canfilterconfig.FilterMaskIdLow = 0x0000;
  canfilterconfig.FilterMode = CAN_FILTERMODE_IDMASK;
  canfilterconfig.FilterScale = CAN_FILTERSCALE_32BIT;
  canfilterconfig.SlaveStartFilterBank = 20;  

  HAL_CAN_ConfigFilter(&hcan, &canfilterconfig);

  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
    HAL_Delay(500);
    HAL_CAN_AddTxMessage(&hcan, &TxHeader, txData, &mail_box);
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

This part is ok !

So now I tried to read the frame sent with this code :

int main(void)
{
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
  /* Configure the system clock */
  SystemClock_Config();

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_CAN_Init();
  MX_CRC_Init();
  /* USER CODE BEGIN 2 */
  if(HAL_CAN_Start(&hcan) != HAL_OK)
    Error_Handler();
  
  TxHeader.StdId = 0x446; 
  TxHeader.ExtId = 0x01; 
  TxHeader.RTR = CAN_RTR_DATA; 
  TxHeader.IDE = CAN_ID_STD; 
  TxHeader.DLC = 2;
  
  CAN_FilterTypeDef canfilterconfig;

  canfilterconfig.FilterActivation = CAN_FILTER_ENABLE;
  canfilterconfig.FilterBank = 18;  // which filter bank to use from the assigned ones
  canfilterconfig.FilterFIFOAssignment = CAN_FILTER_FIFO0;
  canfilterconfig.FilterIdHigh = 0x446<<5;
  canfilterconfig.FilterIdLow = 0;
  canfilterconfig.FilterMaskIdHigh = 0x446<<5;
  canfilterconfig.FilterMaskIdLow = 0x0000;
  canfilterconfig.FilterMode = CAN_FILTERMODE_IDMASK;
  canfilterconfig.FilterScale = CAN_FILTERSCALE_32BIT;
  canfilterconfig.SlaveStartFilterBank = 20;  // how many filters to assign to the CAN1 (master can)

 HAL_CAN_ConfigFilter(&hcan, &canfilterconfig);
 //activate Int
 if (HAL_CAN_ActivateNotification(&hcan, CAN_IT_RX_FIFO0_MSG_PENDING ) != HAL_OK)
 {
   Error_Handler();
 }
 while(1)
 {
 }
}

void HAL_CAN_RxFifo0MsgPendingCallback(CAN_HandleTypeDef *hcan)
 
{
  HAL_CAN_GetRxMessage(hcan, CAN_RX_FIFO0, &RxHeader, Rx); //Receive CAN bus message to canRX buffer 
}

 I don't understand why but it is impossible for me to go in the HAL_CAN_RxFifo0MsgPendingCallback function when a message is received. I checkes the RX Pin with an oscilloscope and the CAN frame is correct on this Pin...

I hope it is clear enough... Do you have any advise to help me ?

I looked everywhere in the datasheet and on forums but impossible to make it works...??

Thank you in advance :).

Tonave

[Tonave]

It is working with both configuration.

Many thanks for your help !!!!!

Tonave

[SofLit]

So to conclude there were two issues: filter config + GPIO config (pull-up not configured for Rx pin in loopback mode).