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Issues with CANBUS on STM32F072: Bit Dominant Error

PF-JohnF
Associate

Hello,

I am currently working to get CAN transmission to work on a STM32F072B-DISCO. I am continuously getting a BIT_DOMINANT_ERROR in the LEC of the CAN_ESR when attempting to transmit.

 

I am using a TCAN1044 (https://www.ti.com/lit/ds/symlink/tcan1044v-q1.pdf) as the CAN transceiver with the following connections:

TCAN PIN | Connection
1 | PA12
2 | GND
3 | 5V
4 | PA11
5 | 3V
6 | CANL
7 | CANH
8 | GND

There is also a 120 ohm terminating resistor at both ends CAN Bus, and only one other device is connected, which is a PCAN-USB reader for viewing transmitted CAN messaged. The PCAN was tested previously on another device and works without issues.

Here is my code:

/* USER CODE BEGIN Header */ /* USER CODE END Header */ /* Includes ------------------------------------------------------------------*/ #include "main.h" /* Private includes ----------------------------------------------------------*/ /* USER CODE BEGIN Includes */ /* USER CODE END Includes */ /* Private typedef -----------------------------------------------------------*/ /* USER CODE BEGIN PTD */ /* USER CODE END PTD */ /* Private define ------------------------------------------------------------*/ /* USER CODE BEGIN PD */ /* USER CODE END PD */ /* Private macro -------------------------------------------------------------*/ /* USER CODE BEGIN PM */ /* USER CODE END PM */ /* Private variables ---------------------------------------------------------*/ CAN_HandleTypeDef hcan; /* USER CODE BEGIN PV */ /* USER CODE END PV */ /* Private function prototypes -----------------------------------------------*/ void SystemClock_Config(void); static void MX_GPIO_Init(void); static void MX_CAN_Init(void); /* USER CODE BEGIN PFP */ /* USER CODE END PFP */ /* Private user code ---------------------------------------------------------*/ /* USER CODE BEGIN 0 */ uint8_t egg[8] = {'5',0,0,0,0,0,0,0}; uint32_t TxMailbox; CAN_TxHeaderTypeDef TxHeader; /* USER CODE END 0 */ /** * @brief The application entry point. * @retval int */ int main(void) { /* USER CODE BEGIN 1 */ /* USER CODE END 1 */ /* MCU Configuration--------------------------------------------------------*/ /* Reset of all peripherals, Initializes the Flash interface and the Systick. */ HAL_Init(); /* USER CODE BEGIN Init */ /* USER CODE END Init */ /* Configure the system clock */ SystemClock_Config(); /* USER CODE BEGIN SysInit */ /* USER CODE END SysInit */ /* Initialize all configured peripherals */ MX_GPIO_Init(); MX_CAN_Init(); /* USER CODE BEGIN 2 */ HAL_CAN_Start(&hcan); TxHeader.StdId = 0x056; TxHeader.ExtId = 0x01; TxHeader.RTR = CAN_RTR_DATA; TxHeader.IDE = CAN_ID_STD; TxHeader.DLC = 2; TxHeader.TransmitGlobalTime = DISABLE; uint8_t sleepy; /* USER CODE END 2 */ /* Infinite loop */ /* USER CODE BEGIN WHILE */ while(1){ HAL_Delay(100); HAL_CAN_AddTxMessage(&hcan, &TxHeader, egg, &TxMailbox); HAL_Delay(10); sleepy = HAL_CAN_IsTxMessagePending(&hcan,TxMailbox); } /* USER CODE END WHILE */ /* USER CODE BEGIN 3 */ /* USER CODE END 3 */ } /** * @brief System Clock Configuration * @retval None */ void SystemClock_Config(void) { RCC_OscInitTypeDef RCC_OscInitStruct = {0}; RCC_ClkInitTypeDef RCC_ClkInitStruct = {0}; /** Initializes the RCC Oscillators according to the specified parameters * in the RCC_OscInitTypeDef structure. */ RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI; RCC_OscInitStruct.HSIState = RCC_HSI_ON; RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT; RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON; RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI; RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL6; RCC_OscInitStruct.PLL.PREDIV = RCC_PREDIV_DIV1; if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK) { Error_Handler(); } /** Initializes the CPU, AHB and APB buses clocks */ RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK |RCC_CLOCKTYPE_PCLK1; RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK; RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1; RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1; if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK) { Error_Handler(); } } /** * @brief CAN Initialization Function * @PAram None * @retval None */ 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 = 16; hcan.Init.Mode = CAN_MODE_NORMAL; hcan.Init.SyncJumpWidth = CAN_SJW_1TQ; hcan.Init.TimeSeg1 = CAN_BS1_1TQ; hcan.Init.TimeSeg2 = CAN_BS2_1TQ; hcan.Init.TimeTriggeredMode = DISABLE; hcan.Init.AutoBusOff = ENABLE; 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 */ } /** * @brief GPIO Initialization Function * @PAram None * @retval None */ static void MX_GPIO_Init(void) { /* USER CODE BEGIN MX_GPIO_Init_1 */ /* USER CODE END MX_GPIO_Init_1 */ /* GPIO Ports Clock Enable */ __HAL_RCC_GPIOA_CLK_ENABLE(); /* USER CODE BEGIN MX_GPIO_Init_2 */ /* USER CODE END MX_GPIO_Init_2 */ } /* USER CODE BEGIN 4 */ /* USER CODE END 4 */ /** * @brief This function is executed in case of error occurrence. * @retval None */ void Error_Handler(void) { /* USER CODE BEGIN Error_Handler_Debug */ /* USER CODE END Error_Handler_Debug */ } #ifdef USE_FULL_ASSERT /** * @brief Reports the name of the source file and the source line number * where the assert_param error has occurred. * @PAram file: pointer to the source file name * @PAram line: assert_param error line source number * @retval None */ void assert_failed(uint8_t *file, uint32_t line) { /* USER CODE BEGIN 6 */ /* USER CODE END 6 */ } #endif /* USE_FULL_ASSERT */
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When viewing PA12/CAN_TX pin on an oscilloscope, the voltage remains constant when running. 

When unplugging the other device, the BIT_DOMINANT_ERROR persists.

At this point, I'm not sure if it's a software or hardware issue. Would anybody be able to run this code on their own hardware that is known to work with CAN and verify if it is a hardware or software issue?

Thanks.

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1 ACCEPTED SOLUTION

Accepted Solutions
mÆŽALLEm
ST Employee

Hello @PF-JohnF ,

At a first glance I have two remarks based on what you provide as source code:

1- It's not recommended to use HSI clock as source clock for CAN communication. As you are using STM32F072B-DISCO board, I recommend you to use The clock generated by STLink module through its MCO output and solder the solder bridge SB19 to connect MCO to PF0-OSC_IN of your MCU. You need to configure the RCC source clock in Bypass mode.

2- Your values of BS1 and BS2 are very low. You need to increase them as much as possible in order to let BS1 ~70 to 80% of the bit time. You need to decrease your CAN prescaler to match this requirement.

I've attached a zipped .ioc file for you reference.

- CAN bitrate = 1Mb/s

- SysClock = 48MHz

- External source clock = 8MHz

- CAN prescaler = 3

- BS1 = 12

- BS2 = 3

 

 

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.

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4 REPLIES 4
mÆŽALLEm
ST Employee

Hello @PF-JohnF ,

At a first glance I have two remarks based on what you provide as source code:

1- It's not recommended to use HSI clock as source clock for CAN communication. As you are using STM32F072B-DISCO board, I recommend you to use The clock generated by STLink module through its MCO output and solder the solder bridge SB19 to connect MCO to PF0-OSC_IN of your MCU. You need to configure the RCC source clock in Bypass mode.

2- Your values of BS1 and BS2 are very low. You need to increase them as much as possible in order to let BS1 ~70 to 80% of the bit time. You need to decrease your CAN prescaler to match this requirement.

I've attached a zipped .ioc file for you reference.

- CAN bitrate = 1Mb/s

- SysClock = 48MHz

- External source clock = 8MHz

- CAN prescaler = 3

- BS1 = 12

- BS2 = 3

 

 

To give better visibility on the answered topics, please click on "Accept as Solution" on the reply which solved your issue or answered your question.
PranavGurav
Associate II

Hi @mÆŽALLEm  I am also facing the same issue i tried modifying the clock source to HSE_BYPASS on STM32F407 discovery board. can you give me more details about how to solve this issue

 

PranavGurav
Associate II

Hi @PF-JohnF  Were you able to solve the issue if Yes can you help me as i am also facing same condition. Thank you in advance

Depending on the port/pins you are using, you may need to connect some solder bridges on the back of the board. On the STM32F072 board, I had to solder SB20 and SB23 bridges to connect PA11 and PA12.

There may also be a solder bridge necessary to connect HSE to the microcontroller as well.