【stm32U3测评】FDCAN 满载性能实测

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短笛君发布时间：2026-7-5 23:49

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文章简介:	【stm32U3测评】FDCAN 满载性能实测

本次测试会将FDCAN配置为FDCAN模式仲裁段波特率为1Mbps 数据段为8Mbps，基本工程可以参考上一版本中FDCAN配置成classic模式通信的代码

主频调整至96Mbps

配置参数如下

参数	仲裁段 (1 Mbps)	数据段 (8 Mbps)
Prescaler	1	1
TSEG1	63	7
TSEG2	32	4
SJW	32	4


Mode	Normal
Frame Format	FD with BRS （FD + Bit Rate Switching）
Auto Retransmission	Enable
Transmit Pause	Disable
Protocol Exception	Enable

注意模式要配置成Bit Rate Switching

初始化代码如下



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_FD_BRS;
  hfdcan1.Init.Mode = FDCAN_MODE_NORMAL;
  hfdcan1.Init.AutoRetransmission = ENABLE;
  hfdcan1.Init.TransmitPause = DISABLE;
  hfdcan1.Init.ProtocolException = ENABLE;
  hfdcan1.Init.NominalPrescaler = 1;
  hfdcan1.Init.NominalSyncJumpWidth = 32;
  hfdcan1.Init.NominalTimeSeg1 = 63;
  hfdcan1.Init.NominalTimeSeg2 = 32;
  hfdcan1.Init.DataPrescaler = 1;
  hfdcan1.Init.DataSyncJumpWidth = 4;
  hfdcan1.Init.DataTimeSeg1 = 7;
  hfdcan1.Init.DataTimeSeg2 = 4;
  hfdcan1.Init.StdFiltersNbr = 1;
  hfdcan1.Init.ExtFiltersNbr = 0;
  hfdcan1.Init.TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;
  if (HAL_FDCAN_Init(&hfdcan1) != HAL_OK)
  {
    Error_Handler();
  }

还有滤波器配置

void MX_FDCAN1_Config(void)
{
  FDCAN_FilterTypeDef sFilterConfig;

  /* Configure standard filter: accept all standard IDs into Rx FIFO 0 */
  sFilterConfig.IdType       = FDCAN_STANDARD_ID;
  sFilterConfig.FilterIndex  = 0;
  sFilterConfig.FilterType   = FDCAN_FILTER_MASK;
  sFilterConfig.FilterConfig = FDCAN_FILTER_TO_RXFIFO0;
  sFilterConfig.FilterID1    = 0x000;
  sFilterConfig.FilterID2    = 0x000;
  if (HAL_FDCAN_ConfigFilter(&hfdcan1, &sFilterConfig) != HAL_OK)
  {
    Error_Handler();
  }

  /* Set global filter: reject non-matching std/ext frames, filter remote frames */
  if (HAL_FDCAN_ConfigGlobalFilter(&hfdcan1, FDCAN_REJECT, FDCAN_REJECT,
                                   FDCAN_FILTER_REMOTE, FDCAN_FILTER_REMOTE) != HAL_OK)
  {
    Error_Handler();
  }

  /* Tx delay compensation (required for FD + BRS data rates >= 8 Mbps).
     TdcOffset = DataTimeSeg1 = 7 (SSP position in data phase), TdcFilter = 0 */
  if (HAL_FDCAN_ConfigTxDelayCompensation(&hfdcan1, 7, 0) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_FDCAN_EnableTxDelayCompensation(&hfdcan1) != HAL_OK)
  {
    Error_Handler();
  }

  /* Start FDCAN module */
  if (HAL_FDCAN_Start(&hfdcan1) != HAL_OK)
  {
    Error_Handler();
  }
}

以上为FDCAN初始化部分为了测试最大总线负载，我们发送字节填充为64字节

  TxHeader.Identifier          = 0x123;
  TxHeader.IdType              = FDCAN_STANDARD_ID;
  TxHeader.TxFrameType         = FDCAN_DATA_FRAME;
  TxHeader.DataLength          = FDCAN_DLC_BYTES_64;
  TxHeader.ErrorStateIndicator = FDCAN_ESI_ACTIVE;
  TxHeader.BitRateSwitch       = FDCAN_BRS_ON;
  TxHeader.FDFormat            = FDCAN_FD_CAN;
  TxHeader.TxEventFifoControl  = FDCAN_NO_TX_EVENTS;
  TxHeader.MessageMarker       = 0;

  for (uint8_t i = 0; i < 64; i++) {
    TxData[i] = i;
  }

在main主循环中暴力发送

   if (HAL_FDCAN_GetTxFifoFreeLevel(&hfdcan1) > 0) {
      if (HAL_FDCAN_AddMessageToTxFifoQ(&hfdcan1, &TxHeader, TxData) != HAL_OK) {
        BSP_LED_Toggle(LED_RED);
      } else {
        BSP_LED_Toggle(LED_GREEN);
      }

FDCAN盒为busmaster X2 最大支持12Mbps

实测性能如下数据段为64字节峰值发送10K帧/S

理论上限计算

64 字节 FD 帧 + BRS 模式下，一帧的总线上时间消耗：

阶段	内容	比特数	速率	时间
仲裁段	SOF + ID(11) + RRS + IDE + FDF + BRS + ESI + DLC(4) + 填充	~26 bits	1 Mbps	~26 µs
数据段	64×8=512 位数据 + 21 位 CRC + 填充	~600 bits	8 Mbps	~75 µs
帧尾	ACK + DELIM + EOF(7) + IFS(3) + 填充	~14 bits	1 Mbps	~14 µs