No stuffing bit with HAL_CAN on STM32f4

[AGiry.2]

Hello, I m using the CAN bus on a STM32f412. It is connected to a transiver with a CAN analyser linked. I can receive messages without problem but i can t send any messages. Here is ho i configured the CAN :

/*##-1- Configure the CAN peripheral #######################################*/
hcan.Instance = CAN1;
hcan.Init.Prescaler = 10;
hcan.Init.Mode = CAN_MODE_NORMAL;
hcan.Init.SyncJumpWidth = CAN_SJW_1TQ;
hcan.Init.TimeSeg1 = CAN_BS1_3TQ;
hcan.Init.TimeSeg2 = CAN_BS2_1TQ;
hcan.Init.TimeTriggeredMode = DISABLE;
hcan.Init.AutoBusOff = DISABLE;
hcan.Init.AutoWakeUp = DISABLE;
hcan.Init.AutoRetransmission = DISABLE;
hcan.Init.ReceiveFifoLocked = DISABLE;
hcan.Init.TransmitFifoPriority = ENABLE;
	
if (HAL_CAN_Init(&hcan) != HAL_OK)
{
 while(1);
}
	
CAN_FilterTypeDef filter = {0};
filter.FilterIdHigh = 0;
filter.FilterIdLow = 0;
filter.FilterMaskIdHigh = 0;
filter.FilterMaskIdLow = 0;
filter.FilterFIFOAssignment = CAN_RX_FIFO0;
filter.FilterBank = 0;
filter.FilterMode = CAN_FILTERMODE_IDMASK;
filter.FilterScale = CAN_FILTERSCALE_32BIT;
filter.FilterActivation = ENABLE;
filter.SlaveStartFilterBank = 14;
 
if(HAL_CAN_ConfigFilter(&hcan, &filter) != HAL_OK)
{
 while(1);
}
 /*##-3- Start the CAN peripheral ###########################################*/
if(HAL_CAN_Start(&hcan) != HAL_OK)
{
 while(1);
}
/*##-4- Activate CAN RX notification #######################################*/
if (HAL_CAN_ActivateNotification(&hcan, CAN_IT_RX_FIFO0_MSG_PENDING) != HAL_OK)
{
 while(1);
}

in stm32f4xx_hal_msp.c, i have this for the CAN :

void HAL_CAN_MspInit(CAN_HandleTypeDef* hcan)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
 if(hcan->Instance==CAN1)
 {
 /* USER CODE BEGIN CAN1_MspInit 0 */
 
 /* USER CODE END CAN1_MspInit 0 */
 /* Peripheral clock enable */
 __HAL_RCC_CAN1_CLK_ENABLE();
 __HAL_RCC_GPIOA_CLK_ENABLE();
 /**CAN1 GPIO Configuration
 PA11 ------> CAN1_RX
 PA12 ------> CAN1_TX
 */
 GPIO_InitStruct.Pin = GPIO_PIN_11|GPIO_PIN_12;
 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
 GPIO_InitStruct.Pull = GPIO_PULLUP;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
 GPIO_InitStruct.Alternate = GPIO_AF9_CAN1;
 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
 /* CAN1 interrupt Init */
 HAL_NVIC_SetPriority(CAN1_RX0_IRQn, 1, 0);
 HAL_NVIC_EnableIRQ(CAN1_RX0_IRQn);
 /* USER CODE BEGIN CAN1_MspInit 1 */
 
 /* USER CODE END CAN1_MspInit 1 */
 }
}

and when i want to transmit, i do this :

TxHeader.StdId = 0x555;
TxHeader.RTR = CAN_RTR_DATA;
TxHeader.IDE = CAN_ID_STD;
TxHeader.DLC = 8;
TxHeader.TransmitGlobalTime = DISABLE;
for(int i = 0; i < 8; i++)TxData[i] = 0x1;
 
 /* Request transmission */
if(HAL_CAN_GetTxMailboxesFreeLevel(&hcan) != 3)
{
	HAL_CAN_AbortTxRequest(&hcan, 0); 
	HAL_CAN_AbortTxRequest(&hcan, 1); 
	HAL_CAN_AbortTxRequest(&hcan, 2); 
}
HAL_GPIO_TogglePin(LED_vie_Port, LED_vie_Pin);
if(HAL_CAN_AddTxMessage(&hcan, &TxHeader, TxData, &TxMailbox) != HAL_OK) 
{
 /* Transmission request Error */
 Error_Handler();
}

When i try so see frames with an osciloscope i get this :

So you can see the communication abort too early and i think it's because ther isn t stuffing bit.

[Bowman32]

It seems there is no error in your code. Can you please share your project, the clock source and the baud rate to further check the configuration ?

Also, you can refer to CAN example provided in STM32CubeF4 via this link STM32Cube\Repository\STM32Cube_FW_F4_V1.x.y\Projects\STM324xG_EVAL\Examples\CAN\CAN_Networking

I suggest to run this example on your desk.

Bouraoui

[AGiry.2]

Unfortunately, i can t send the whole project. but here is the clock configuration :

void SystemClock_Config(void)
{
 RCC_OscInitTypeDef RCC_OscInitStruct = {0};
 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
 
 /** Configure the main internal regulator output voltage 
 */
 __HAL_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);
 /** Initializes the CPU, AHB and APB busses clocks 
 */
 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI|RCC_OSCILLATORTYPE_LSI;
 RCC_OscInitStruct.HSIState = RCC_HSI_ON;
 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.LSIState = RCC_LSI_ON;
	RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
 RCC_OscInitStruct.PLL.PLLM = 8;
 RCC_OscInitStruct.PLL.PLLN = 100;
 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
 RCC_OscInitStruct.PLL.PLLQ = 4;
 RCC_OscInitStruct.PLL.PLLR = 2;
 HAL_RCC_OscConfig(&RCC_OscInitStruct);
 
 /** Initializes the CPU, AHB and APB busses clocks 
 */
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
 |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
 HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_3);
 
}

And the baud rate is at 1Mbit/s.

I also tested the same configuration in loopback mode and here i hadn't any problem, i received and sent valid frames. Moreover i had the good signal on Rx and Tx pin.