FDCAN with BRS activated: Problem transmitting 64 Bytes on FDCAN

[GS1]

Hi all,

I am trying to use FDCAN with Baud rate switch (500 kB / 2 MBit) activated and I want to send 64 Byte.

Processor is STM32H7A3. Project was set up with CubeMX V. 6.11.1 and HAL FW_H7 V1.11.2. Clock for FDCAN is 80 MHz.

The problem is that the system only sends with 500 kB and 8 Bytes only.

I am transmitting the data to my PC using a PEAK USB dongle (FDCAN capable with BRS) and in parallel check the messages on a scope. 

I don't know, why it doesn't switch to 2 MBit and I only see  8 Bytes with 500 kBit on my scope and on PCAN-Explorer.

Here my init and transmit code sequences:

FDCAN_HandleTypeDef* phCan;

phCan = &hfdcan1;
phCan->Instance = FDCAN1;

phCan->Init.Mode = FDCAN_MODE_NORMAL; 
phCan->Init.FrameFormat = FDCAN_FRAME_FD_BRS;

phCan->Init.AutoRetransmission = ENABLE;   
phCan->Init.TransmitPause = DISABLE;

phCan->Init.NominalPrescaler = 10;
phCan->Init.NominalSyncJumpWidth = 1;
phCan->Init.NominalTimeSeg1 = 11;
phCan->Init.NominalTimeSeg2 = 4;

phCan->Init.DataPrescaler = 2;
phCan->Init.DataSyncJumpWidth = 1;
phCan->Init.DataTimeSeg1 = 14;
phCan->Init.DataTimeSeg2 = 5;

phCan->Init.MessageRAMOffset = 0;
phCan->Init.StdFiltersNbr = 0;
phCan->Init.ExtFiltersNbr = 0;

phCan->Init.RxFifo0ElmtsNbr = 16; // 0..64
phCan->Init.RxFifo1ElmtsNbr = 16;
phCan->Init.RxBuffersNbr = 10;

phCan->Init.RxFifo0ElmtSize = FDCAN_DATA_BYTES_64;
phCan->Init.RxFifo1ElmtSize = FDCAN_DATA_BYTES_64;
phCan->Init.RxBufferSize = FDCAN_DATA_BYTES_64;


phCan->Init.TxEventsNbr = 0;
phCan->Init.TxBuffersNbr = 0;

phCan->Init.TxFifoQueueElmtsNbr = 16;
phCan->Init.TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;

phCan->Init.TxElmtSize = FDCAN_DATA_BYTES_64;

phCan->msgRam.StandardFilterSA = 0;
phCan->msgRam.ExtendedFilterSA = 0;
phCan->msgRam.RxFIFO0SA = 0;
phCan->msgRam.RxFIFO1SA = 0;
phCan->msgRam.RxBufferSA = 0;
phCan->msgRam.TxEventFIFOSA = 0;
phCan->msgRam.TxBufferSA = 0;
phCan->msgRam.TxFIFOQSA = 0;
phCan->msgRam.TTMemorySA = 0;
phCan->msgRam.EndAddress = 0;
phCan->ErrorCode = 0;


halErr = HAL_FDCAN_Init(phCan);

halErr = HAL_FDCAN_Start(phCan);

----------------------------------

TxHeader.IdType = FDCAN_STANDARD_ID;
TxHeader.TxFrameType = FDCAN_DATA_FRAME;
TxHeader.ErrorStateIndicator = FDCAN_ESI_ACTIVE;

TxHeader.FDFormat = FDCAN_FRAME_FD_BRS;
TxHeader.BitRateSwitch = FDCAN_BRS_ON;

TxHeader.TxEventFifoControl = FDCAN_STORE_TX_EVENTS;//FDCAN_NO_TX_EVENTS;
TxHeader.MessageMarker = 0;

TxHeader.Identifier = 0x55;

TxHeader.DataLength = FDCAN_DLC_BYTES_64;

halErr = HAL_FDCAN_AddMessageToTxFifoQ(phfdcan, &TxHeader, TxData);  // TxData = 64 Bytes

Is there anything missing or wrong?

Thank you for any support or hints.

BR GS

Post edited by the ST moderator to follow the community rule especially for the code sharing.

[mƎALLEm]

Hello,

First, please use </> button to share your code. Please refer to this post: How to insert source code

Second, what is your transceiver allowed bitrate bandwidth?

3rd, what is your clock source? HSI or a crystal?

4th, please call the following before the call of HAL_FDCAN_Start():

  /**
    * Configure and enable Tx Delay Compensation, required for BRS mode.
    * TdcOffset default recommended value: DataTimeSeg1 * DataPrescaler
    * TdcFilter default recommended value: 0
    */
  if (HAL_FDCAN_ConfigTxDelayCompensation(&hfdcan1, (hfdcan1.Init.DataPrescaler * hfdcan1.Init.DataTimeSeg1), 0U) != HAL_OK)
  {
    Error_Handler();
  }

  if (HAL_FDCAN_EnableTxDelayCompensation(&hfdcan1) != HAL_OK)
  {
    Error_Handler();
  }

[LCE]

Don't you need extended ID for BRS? 
So try IdType = FDCAN_EXTENDED_ID

Not sure though...

[GS1]

Hello,

thank you for your help:

- The transceiver is TCAN1042HG and can do up to 5 MBit 

- Clock source for the system is a Crystal 8 MHz, Clocksource for FDCAN is Clock Divider PLL2Q 

- I inserted your code suggestion. However the result is the same as before. Only 8 Byte with 500 kBit arrive

Any other ideas?

BR GS

[GS1]

Hi LCE,

I tried that, but that doesn't solve the problem. It only changes the ID presentation.

BR. GS

[mƎALLEm]

Could you please attach your project? (tomorrow I'm out of office)