Hi everyone,
We’re currently developing an OBD reader using an STM32G473, which includes three FDCAN controllers. Each FDCAN interface is connected to a TCAN3413 transceiver.
As part of our testing setup, we built an ECU simulator using an Arduino with an MCP2515 controller and a TJA1050 transceiver, and this simulator works perfectly.
However, we’re facing a major issue when trying to send CAN requests from our STM32-based board to this ECU simulator. We’re not able to make the FDCAN controller operate in Classical CAN 2.0 mode and send messages correctly.
We verified this by checking both the RX and CAN lines of the transceiver with an oscilloscope. The TX signal from the STM32 does not show the expected data pattern.
That said, the transceiver itself is working correctly, when we send data from the Arduino node, the RX pin on the transceiver shows a clean, valid CAN signal. The issue seems to be that the STM32’s FDCAN controller doesn’t properly interpret or transmit standard CAN 2.0 frames, and as a result, we can’t see any valid messages on the microcontroller side.
To make it easier to understand our setup, we’re attaching several images:
- Our clock configuration from STM32CubeMX
- The main.c source file
- The FDCAN1 peripheral configuration we’re currently using
We’d really appreciate any help or insight from the community on how to correctly configure the FDCAN peripheral on the STM32G473 to work in standard CAN 2.0 mode, compatible with MCP2515-based nodes.
Thanks in advance for any advice or configuration examples you can share!
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2025 STMicroelectronics.
* All rights reserved.
*
* This software is licensed under terms that can be found in the LICENSE file
* in the root directory of this software component.
* If no LICENSE file comes with this software, it is provided AS-IS.
*
******************************************************************************
*/
/* 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 ---------------------------------------------------------*/
FDCAN_HandleTypeDef hfdcan1;
FDCAN_HandleTypeDef hfdcan2;
I2C_HandleTypeDef hi2c2;
/* USER CODE BEGIN PV */
FDCAN_TxHeaderTypeDef TxHeader;
FDCAN_RxHeaderTypeDef RxHeader;
FDCAN_TxHeaderTypeDef TxHeader2;
FDCAN_RxHeaderTypeDef RxHeader2;
uint8_t TxData[8];
uint8_t RxData[8];
uint8_t txData[4] = { 0x10, 0x20, 0x30, 0x40 };
uint8_t rxData[4];
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_FDCAN1_Init(void);
static void MX_FDCAN2_Init(void);
static void MX_I2C2_Init(void);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
/* 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_FDCAN1_Init();
MX_FDCAN2_Init();
MX_I2C2_Init();
/* USER CODE BEGIN 2 */
//HAL_TIM_PWM_Start(&htim3, TIM_CHANNEL_2);
// Iniciar FDCAN
if (HAL_FDCAN_Start(&hfdcan1) != HAL_OK) {
Error_Handler();
}
if (HAL_FDCAN_Start(&hfdcan2) != HAL_OK) {
Error_Handler();
}
// Activar notificación de mensajes recibidos
//if (HAL_FDCAN_ActivateNotification(&hfdcan1, FDCAN_IT_RX_FIFO0_NEW_MESSAGE, 0) != HAL_OK) {
// Error_Handler();
//}
if (HAL_FDCAN_ActivateNotification(&hfdcan2, FDCAN_IT_RX_FIFO1_NEW_MESSAGE, 0) != HAL_OK) {
Error_Handler();
}
// Configuración Tx Header
TxHeader.Identifier = 0x123;
TxHeader.IdType = FDCAN_STANDARD_ID;
TxHeader.TxFrameType = FDCAN_DATA_FRAME;
TxHeader.DataLength = FDCAN_DLC_BYTES_8; // 8 bytes de datos
TxHeader.ErrorStateIndicator = FDCAN_ESI_ACTIVE;
TxHeader.BitRateSwitch = FDCAN_BRS_OFF; // Data phase más rápida
TxHeader.FDFormat = FDCAN_CLASSIC_CAN; // CAN-clasico
TxHeader.TxEventFifoControl = FDCAN_NO_TX_EVENTS;
TxHeader.MessageMarker = 0;
// Mensaje inicial
for (uint8_t i = 0; i < 8; i++)
TxData[i] = i;
// Transmitir mensaje
if (HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan1, &TxHeader, TxData) != HAL_OK) {
Error_Handler();
}
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1) {
HAL_Delay(1000);
for (uint8_t i = 0; i < 8; i++)
TxData[i]++;
HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan1, &TxHeader, TxData);
//HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan2, &TxHeader, TxData);
//HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
//if (HAL_I2C_Master_Transmit(&hi2c2, (0x54 << 1), txData, sizeof(txData), HAL_MAX_DELAY) == HAL_OK) {
// HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
//}
//HAL_Delay(500);
// Leer 4 bytes desde el esclavo
//if (HAL_I2C_Master_Receive(&hi2c2, (0x54 << 1), rxData, sizeof(rxData), HAL_MAX_DELAY) == HAL_OK) {
// HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
//}
//HAL_Delay(500);
/* 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};
/** Configure the main internal regulator output voltage
*/
HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the RCC Oscillators according to the specified parameters
* in the RCC_OscInitTypeDef structure.
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV4;
RCC_OscInitStruct.PLL.PLLN = 25;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV6;
RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
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_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSE;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief FDCAN1 Initialization Function
* @PAram None
* @retval None
*/
static void MX_FDCAN1_Init(void)
{
/* USER CODE BEGIN FDCAN1_Init 0 */
/* USER CODE END FDCAN1_Init 0 */
/* USER CODE BEGIN FDCAN1_Init 1 */
/* USER CODE END FDCAN1_Init 1 */
hfdcan1.Instance = FDCAN1;
hfdcan1.Init.ClockDivider = FDCAN_CLOCK_DIV1;
hfdcan1.Init.FrameFormat = FDCAN_FRAME_CLASSIC;
hfdcan1.Init.Mode = FDCAN_MODE_NORMAL;
hfdcan1.Init.AutoRetransmission = DISABLE;
hfdcan1.Init.TransmitPause = DISABLE;
hfdcan1.Init.ProtocolException = DISABLE;
hfdcan1.Init.NominalPrescaler = 1;
hfdcan1.Init.NominalSyncJumpWidth = 13;
hfdcan1.Init.NominalTimeSeg1 = 86;
hfdcan1.Init.NominalTimeSeg2 = 13;
hfdcan1.Init.DataPrescaler = 25;
hfdcan1.Init.DataSyncJumpWidth = 1;
hfdcan1.Init.DataTimeSeg1 = 2;
hfdcan1.Init.DataTimeSeg2 = 1;
hfdcan1.Init.StdFiltersNbr = 1;
hfdcan1.Init.ExtFiltersNbr = 0;
hfdcan1.Init.TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;
if (HAL_FDCAN_Init(&hfdcan1) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN FDCAN1_Init 2 */
FDCAN_FilterTypeDef sFilterConfig;
sFilterConfig.IdType = FDCAN_STANDARD_ID;
sFilterConfig.FilterIndex = 0;
sFilterConfig.FilterType = FDCAN_FILTER_MASK;
sFilterConfig.FilterConfig = FDCAN_FILTER_TO_RXFIFO0;
sFilterConfig.FilterID1 = 0x000;
sFilterConfig.FilterID2 = 0x7ff;
if (HAL_FDCAN_ConfigFilter(&hfdcan1, &sFilterConfig) != HAL_OK) {
Error_Handler();
}
/* USER CODE END FDCAN1_Init 2 */
}
/**
* @brief FDCAN2 Initialization Function
* @PAram None
* @retval None
*/
static void MX_FDCAN2_Init(void)
{
/* USER CODE BEGIN FDCAN2_Init 0 */
/* USER CODE END FDCAN2_Init 0 */
/* USER CODE BEGIN FDCAN2_Init 1 */
/* USER CODE END FDCAN2_Init 1 */
hfdcan2.Instance = FDCAN2;
hfdcan2.Init.ClockDivider = FDCAN_CLOCK_DIV1;
hfdcan2.Init.FrameFormat = FDCAN_FRAME_CLASSIC;
hfdcan2.Init.Mode = FDCAN_MODE_NORMAL;
hfdcan2.Init.AutoRetransmission = DISABLE;
hfdcan2.Init.TransmitPause = DISABLE;
hfdcan2.Init.ProtocolException = DISABLE;
hfdcan2.Init.NominalPrescaler = 1;
hfdcan2.Init.NominalSyncJumpWidth = 13;
hfdcan2.Init.NominalTimeSeg1 = 86;
hfdcan2.Init.NominalTimeSeg2 = 13;
hfdcan2.Init.DataPrescaler = 25;
hfdcan2.Init.DataSyncJumpWidth = 1;
hfdcan2.Init.DataTimeSeg1 = 2;
hfdcan2.Init.DataTimeSeg2 = 1;
hfdcan2.Init.StdFiltersNbr = 1;
hfdcan2.Init.ExtFiltersNbr = 0;
hfdcan2.Init.TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;
if (HAL_FDCAN_Init(&hfdcan2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN FDCAN2_Init 2 */
FDCAN_FilterTypeDef sFilterConfig;
sFilterConfig.IdType = FDCAN_STANDARD_ID;
sFilterConfig.FilterIndex = 0;
sFilterConfig.FilterType = FDCAN_FILTER_MASK;
sFilterConfig.FilterConfig = FDCAN_FILTER_TO_RXFIFO1;
sFilterConfig.FilterID1 = 0x000;
sFilterConfig.FilterID2 = 0x7ff;
if (HAL_FDCAN_ConfigFilter(&hfdcan2, &sFilterConfig) != HAL_OK) {
Error_Handler();
}
/* USER CODE END FDCAN2_Init 2 */
}
/**
* @brief I2C2 Initialization Function
* @PAram None
* @retval None
*/
static void MX_I2C2_Init(void)
{
/* USER CODE BEGIN I2C2_Init 0 */
/* USER CODE END I2C2_Init 0 */
/* USER CODE BEGIN I2C2_Init 1 */
/* USER CODE END I2C2_Init 1 */
hi2c2.Instance = I2C2;
hi2c2.Init.Timing = 0x10805D88;
hi2c2.Init.OwnAddress1 = 0;
hi2c2.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
hi2c2.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
hi2c2.Init.OwnAddress2 = 0;
hi2c2.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
hi2c2.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
hi2c2.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
if (HAL_I2C_Init(&hi2c2) != HAL_OK)
{
Error_Handler();
}
/** Configure Analogue filter
*/
if (HAL_I2CEx_ConfigAnalogFilter(&hi2c2, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
{
Error_Handler();
}
/** Configure Digital filter
*/
if (HAL_I2CEx_ConfigDigitalFilter(&hi2c2, 0) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN I2C2_Init 2 */
/* USER CODE END I2C2_Init 2 */
}
/**
* @brief GPIO Initialization Function
* @PAram None
* @retval None
*/
static void MX_GPIO_Init(void)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOF_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOA, GPIO_PIN_3|GPIO_PIN_5|GPIO_PIN_11|GPIO_PIN_12
|GPIO_PIN_15, GPIO_PIN_RESET);
/*Configure GPIO pin : PA2 */
GPIO_InitStruct.Pin = GPIO_PIN_2;
GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pins : PA3 PA5 PA11 */
GPIO_InitStruct.Pin = GPIO_PIN_3|GPIO_PIN_5|GPIO_PIN_11;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pin : PA4 */
GPIO_InitStruct.Pin = GPIO_PIN_4;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF2_TIM3;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pin : PA9 */
GPIO_InitStruct.Pin = GPIO_PIN_9;
GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pins : PA12 PA15 */
GPIO_InitStruct.Pin = GPIO_PIN_12|GPIO_PIN_15;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_OD;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
/*
void HAL_FDCAN_RxFifo0Callback(FDCAN_HandleTypeDef *hfdcan, uint32_t RxFifo0ITs) {
if ((RxFifo0ITs & FDCAN_IT_RX_FIFO0_NEW_MESSAGE) != 0) {
if (HAL_FDCAN_GetRxMessage(hfdcan, FDCAN_RX_FIFO0, &RxHeader, RxData)
== HAL_OK) {
HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3); // Ejemplo: toggle LED en PA3
}
}
}*/
void HAL_FDCAN_RxFifo1Callback(FDCAN_HandleTypeDef *hfdcan, uint32_t RxFifo1ITs) {
if ((RxFifo1ITs & FDCAN_IT_RX_FIFO1_NEW_MESSAGE) != 0) {
if (HAL_FDCAN_GetRxMessage(hfdcan, FDCAN_RX_FIFO1, &RxHeader, RxData) == HAL_OK) {
HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_3);
}
}
}
/* 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 can add his own implementation to report the HAL error return state */
__disable_irq();
while (1) {
}
/* 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 can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
Question: why FDCAN clock > System clock frequency?
Increase the system clock. Let's say the max frequency at 170MHz using the PLL and keep the FDCAN clock set at 50MHz.
