STM32G4 FDCAN mask filter not working on STM32G474

[RoLie]

I have developed a custom board with an STM32G474RE controller. Since the controller only features FDCAN, I am using it in normal mode. Connected to this is a CAN controller (not FD). Sending and receiving messages work without any issues. However, as several nodes will be connected to the bus later, I use extended IDs and want to filter the received messages using a mask, as some information is encoded bitwise in the identifier. The controller should only react to messages intended for it. Unfortunately, I can't get the filters to work. I must be doing something wrong or misunderstanding something.

I created a very simple program to upload here. I would expect that when receiving, FilterIndex 0 allows the data through. But it is always Filter 63. When I set HAL_FDCAN_ConfigGlobalFilter, nothing happens in the HAL_FDCAN_RxFifo0Callback, which makes sense in that case.

The CAN is configured in FDCAN_MODE_INTERNAL_LOOPBACK for testing. Even when I configure the filter like this, FilterIndex 0 doesn't catch the message:

sFilterConfig.FilterID1 = 0x12346578;
sFilterConfig.FilterID2 = 0x1FFFFFFF;

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 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 hfdcan2;

/* USER CODE BEGIN PV */
FDCAN_TxHeaderTypeDef TxHeader;
uint8_t TxData[8];

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_FDCAN2_Init(void);
/* USER CODE BEGIN PFP */

void FDCAN2_FilterConfig_and_Start(void);
void Send(uint32_t id, uint64_t data);

void FDCAN2_FilterConfig_and_Start() {

	FDCAN_FilterTypeDef sFilterConfig;

	sFilterConfig.IdType = FDCAN_EXTENDED_ID;
	sFilterConfig.FilterIndex = 0;
	sFilterConfig.FilterType = FDCAN_FILTER_MASK;
	sFilterConfig.FilterConfig = FDCAN_FILTER_TO_RXFIFO0;
	sFilterConfig.FilterID1 = 0x12346578;
	sFilterConfig.FilterID2 = 0x1FFFFFFF;

	if (HAL_FDCAN_ConfigFilter(&hfdcan2, &sFilterConfig) != HAL_OK) {
		Error_Handler();
	}
/*
	if (HAL_FDCAN_ConfigGlobalFilter(&hfdcan2, FDCAN_REJECT, FDCAN_REJECT, FDCAN_REJECT_REMOTE, FDCAN_REJECT_REMOTE) != HAL_OK) {
		Error_Handler();
	}
*/
	if (HAL_FDCAN_Start(&hfdcan2) != HAL_OK) {
		Error_Handler();
	}

	if (HAL_FDCAN_ActivateNotification(&hfdcan2, FDCAN_IT_RX_FIFO0_NEW_MESSAGE, 0) != HAL_OK) {
		Error_Handler();
	}
}

void HAL_FDCAN_RxFifo0Callback(FDCAN_HandleTypeDef *hfdcan, uint32_t RxFifo0ITs) {
    FDCAN_RxHeaderTypeDef rxHeader;
    uint8_t rxData[8];

    if (HAL_FDCAN_GetRxMessage(&hfdcan2, FDCAN_RX_FIFO0, &rxHeader, rxData) == HAL_OK)
    {
        uint32_t filter_index = rxHeader.FilterIndex;
        uint32_t RxId = rxHeader.Identifier;
    }
}

void Send(uint32_t id, uint64_t data) {
    uint8_t TxData[8];

    for (int i = 0; i < 8; i++) {
    	TxData[i] = (data >> (56 - (8 * i))) & 0xFF;
    }

    TxHeader.Identifier = id;

    if(HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan2, &TxHeader, TxData) != HAL_OK) {
    	Error_Handler();
    }
}
/* 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_FDCAN2_Init();
  /* USER CODE BEGIN 2 */
  FDCAN2_FilterConfig_and_Start();
  Send(0x12345678, 0xAAAAAAAAAAAA);
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* 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_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  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_HSI;
  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_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief FDCAN2 Initialization Function
  *  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_INTERNAL_LOOPBACK;
  hfdcan2.Init.AutoRetransmission = DISABLE;
  hfdcan2.Init.TransmitPause = DISABLE;
  hfdcan2.Init.ProtocolException = DISABLE;
  hfdcan2.Init.NominalPrescaler = 2;
  hfdcan2.Init.NominalSyncJumpWidth = 1;
  hfdcan2.Init.NominalTimeSeg1 = 3;
  hfdcan2.Init.NominalTimeSeg2 = 4;
  hfdcan2.Init.DataPrescaler = 1;
  hfdcan2.Init.DataSyncJumpWidth = 1;
  hfdcan2.Init.DataTimeSeg1 = 1;
  hfdcan2.Init.DataTimeSeg2 = 1;
  hfdcan2.Init.StdFiltersNbr = 0;
  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 */
	TxHeader.IdType = FDCAN_EXTENDED_ID;
	TxHeader.TxFrameType = FDCAN_DATA_FRAME;
	TxHeader.DataLength = FDCAN_DLC_BYTES_8;
	TxHeader.ErrorStateIndicator = FDCAN_ESI_ACTIVE;
	TxHeader.BitRateSwitch = FDCAN_BRS_OFF;
	TxHeader.FDFormat = FDCAN_CLASSIC_CAN;
	TxHeader.TxEventFifoControl = FDCAN_NO_TX_EVENTS;
	TxHeader.MessageMarker = 0;
  /* USER CODE END FDCAN2_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  *  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_GPIOB_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 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.
  *   file: pointer to the source file name
  *   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 */

I would appreciate some help!

[SofLit]

Hello,

I didn't understand this statement: "FilterIndex 0 allows the data through. But it is always Filter 63."

What do you want to achieve? receiving only a frame with the extended ID 0x12345678?

[RoLie]

I configured FilterIndex 0 to filter the Id. I tried this, that should filter if exact 0x12345678 is received:

sFilterConfig.FilterID1 = 0x12346578;
sFilterConfig.FilterID2 = 0x1FFFFFFF;

 and this, that should match any Id:

sFilterConfig.FilterID1 = 0x00000000;
sFilterConfig.FilterID2 = 0x00000000;

In both cases HAL_FDCAN_RxFifo0Callback is called and rxHeader.FilterIndex (at line 94) is always 63 and not 0. FilterIndex 63 means no filter matched the Id. In this example I just want:

If identifier 0x12345678 is received, that FilterIndex 0 matches. But it doesn't. In the final software I'll need multiple filters. But my problem is, that this simple filter doesn't work as I expect.

[SofLit · Accepted solution]

Hello,

You didn't set the Extended filter number:

 hfdcan2.Init.ExtFiltersNbr = 0;

The number is set to 0. You need to set it at least to 1.

I've created a simple project where extended ID and standard ID are filtered.

You need just to comment / uncomment 

#define USE_EXTENDED_ID

You can also play with the different parameters:

#define USE_EXTENDED_ID
#define FILTER_INDEX_NB         0
#if defined (USE_EXTENDED_ID) 
  #define CAN_EXT_ID_TO_SEND    0x12346578
  #define CAN_EXT_ID_TO_FILTER  0x12346578
#else
  #define CAN_STD_ID_TO_SEND    0x123
  #define CAN_STD_ID_TO_FILTER  0x123
#endif

You can modify the ID to send to let it different from the ID to filter to validate that the frame will not be received.

Hope it helps.

[RoLie]

Thank you very much!

I didn't set

hfdcan2.Init.ExtFiltersNbr

I have 4 Filters and set it to 4. Now it works perfectly!

Why do I have to set it, only when I'm using extended IDs?

Is there any documentation, apart from this two sentences in the HAL documentation?

uint32_t FDCAN_InitTypeDef::ExtFiltersNbr
//Specifies the number of extended Message ID filters. This parameter must be a number between 0 and 8

[SofLit]

---

@RoLie wrote:

Is there any documentation, apart from this two sentences in the HAL documentation?

---

The reference manual section "44 FD controller area network (FDCAN)"