CAN Bus Tx packets missing [STM32F303x]

[gbigden]

Posted on February 08, 2016 at 12:37

Problem with the CAN Tx dropping packets.

I am testing by sending 8192 packets to a CAN Bus analyzer. each test packet is less than 8 data bytes. After about 60 packets have been sent at 250kBaud about half of the remaining are dropped. No indication of errors.Anything obvious I am doing wrong here?void setupCAN( void ){  float baudrate = (float)Calibrate.CAN_Baudrate, quanta, prescalar;  uint8_t initStatus = CAN_InitStatus_Failed;    CAN_DeInit( CAN1 );      //CAN cell init   CANInit.CAN_TTCM = DISABLE;  CANInit.CAN_ABOM = DISABLE;  CANInit.CAN_AWUM = DISABLE;  CANInit.CAN_NART = DISABLE;//  CANInit.CAN_NART = ENABLE;  CANInit.CAN_RFLM = ENABLE;            //Discard incoming messages on FIFO overrun  CANInit.CAN_TXFP = ENABLE;            //Use as a FIFO where the priority order is given by the transmit request order  CANInit.CAN_Mode = CAN_Mode_Normal;    CANInit.CAN_SJW = CAN_SJW_1tq;  CANInit.CAN_BS1 = CAN_BS1_9tq;  CANInit.CAN_BS2 = CAN_BS2_1tq;  quanta = 11;  prescalar = 32768000 / (baudrate * quanta);  CANInit.CAN_Prescaler = (uint16_t)( prescalar + 0.5 );        //Make sure we round to nearest whole number  initStatus = CAN_Init(CAN1, &CANInit);  if (initStatus == CAN_InitStatus_Failed) {Error.canRxError = true; Error.canTxError = true;}    //CAN filter init ''FIFO0'' - we are only going to use this one in practice                                     CANFilter.CAN_FilterNumber = 0;  CANFilter.CAN_FilterMode =  CAN_FilterMode_IdMask;  CANFilter.CAN_FilterScale = CAN_FilterScale_32bit;  CANFilter.CAN_FilterIdHigh = Calibrate.CAN_FilterIdHigh;   CANFilter.CAN_FilterIdLow = Calibrate.CAN_FilterIdLow;   CANFilter.CAN_FilterMaskIdHigh = Calibrate.CAN_FilterMaskIdHigh;  CANFilter.CAN_FilterMaskIdLow = Calibrate.CAN_FilterMaskIdLow;  CANFilter.CAN_FilterFIFOAssignment = 0;  CANFilter.CAN_FilterActivation = ENABLE;  CAN_FilterInit(&CANFilter);    //Filling out the defaults in the Tx struct for CAN bus  CANTxMessage.DLC = 8;                         //Default number of data bytes to send  CANTxMessage.ExtId = 0;                       //No extended ID  CANTxMessage.IDE = CAN_ID_STD;                //Base Frame identifier  CANTxMessage.RTR = CAN_RTR_DATA;              //Remote transmission request for data frame  CANTxMessage.StdId = Calibrate.CAN_stdID;     //Our frame ID for data transmitted from the SoS board }  /////////////////////////////////////////////////////////////////////////////  /// @brief The CAN bus transmit string function  /// @note We just break the string into 8 byte chunks and transmit them  /// If we cannot exactly divide by 8 then we pad the last few bytes with 0  /// Remember we are sending ASCII and 0 is a clear ''non data'' byte  /// @param[in] pStr Pointer to the string  /// @param[in] numBytes Number of bytes to send  /// @return Boolean pass or fail - false==fail, true==pass  /////////////////////////////////////////////////////////////////////////////bool stringToCAN( char* pStr, int numBytes ){  int i;  char data;  uint8_t mailBoxNumber=CAN_TxStatus_NoMailBox, dlc=8, canTxStatus=CAN_TxStatus_Failed;  bool status=PASS;    while (numBytes > 0)  {    watchdog();                         // Kick the dog on long data dumps    if (numBytes < 8)     {      dlc = numBytes;                   //Number of bytes, less than 8, that remain to be sent      CANTxMessage.DLC = dlc;     }    else    {      CANTxMessage.DLC = 8;     }    for (i=0; i<dlc; i++)    {      data = *(pStr++);      CANTxMessage.Data[i] = data;      numBytes--;    }        while( mailBoxNumber == CAN_TxStatus_NoMailBox )             //Only transmit when mailbox is available    {        mailBoxNumber = CAN_Transmit( CAN1, &CANTxMessage );     }    canTxStatus = CAN_TxStatus_Pending;    while( canTxStatus == CAN_TxStatus_Pending )    {      canTxStatus = CAN_TransmitStatus(CAN1, mailBoxNumber);     }    if (canTxStatus == CAN_TxStatus_Failed)     {      Error.canTxError = true;    }      }  return( status );} #bxcan #!stm32

[gbigden]

Posted on February 09, 2016 at 11:33

Update - If I put a 1mS delay between packet transmissions I do not lose packets. Looks like I am overwriting the Tx buffer somehow

[Walid FTITI_O]

Posted on February 10, 2016 at 17:06

Hi bigden.gary,

Thanks for your feedback and contribution by putting the solution you found.

It seems you are using standard library, so Take a look to the

CAN_Networking

 example which include similar use case at this path :

stm32f30x_dsp_stdperiph_lib\STM32F30x_DSP_StdPeriph_Lib\Projects\STM32F30x_StdPeriph_Examples\CAN\CAN_Networking

-Hannibal-

Problem with the CAN Tx dropping packets.

I am testing by sending 8192 packets to a CAN Bus analyzer. each test packet is less than 8 data bytes. After about 60 packets have been sent at 250kBaud about half of the remaining are dropped. No indication of errors. Anything obvious I am doing wrong here? void setupCAN( void ) {   float baudrate = (float)Calibrate.CAN_Baudrate, quanta, prescalar;   uint8_t initStatus = CAN_InitStatus_Failed;      CAN_DeInit( CAN1 );        //CAN cell init    CANInit.CAN_TTCM = DISABLE;   CANInit.CAN_ABOM = DISABLE;   CANInit.CAN_AWUM = DISABLE;   CANInit.CAN_NART = DISABLE; //  CANInit.CAN_NART = ENABLE;   CANInit.CAN_RFLM = ENABLE;            //Discard incoming messages on FIFO overrun   CANInit.CAN_TXFP = ENABLE;            //Use as a FIFO where the priority order is given by the transmit request order   CANInit.CAN_Mode = CAN_Mode_Normal;      CANInit.CAN_SJW = CAN_SJW_1tq;   CANInit.CAN_BS1 = CAN_BS1_9tq;   CANInit.CAN_BS2 = CAN_BS2_1tq;   quanta = 11;   prescalar = 32768000 / (baudrate * quanta);   CANInit.CAN_Prescaler = (uint16_t)( prescalar + 0.5 );        //Make sure we round to nearest whole number   initStatus = CAN_Init(CAN1, &CANInit);   if (initStatus == CAN_InitStatus_Failed) {Error.canRxError = true; Error.canTxError = true;}     //CAN filter init ''FIFO0'' - we are only going to use this one in practice                                      CANFilter.CAN_FilterNumber = 0;   CANFilter.CAN_FilterMode =  CAN_FilterMode_IdMask;   CANFilter.CAN_FilterScale = CAN_FilterScale_32bit;   CANFilter.CAN_FilterIdHigh = Calibrate.CAN_FilterIdHigh;    CANFilter.CAN_FilterIdLow = Calibrate.CAN_FilterIdLow;    CANFilter.CAN_FilterMaskIdHigh = Calibrate.CAN_FilterMaskIdHigh;   CANFilter.CAN_FilterMaskIdLow = Calibrate.CAN_FilterMaskIdLow;   CANFilter.CAN_FilterFIFOAssignment = 0;   CANFilter.CAN_FilterActivation = ENABLE;   CAN_FilterInit(&CANFilter);     //Filling out the defaults in the Tx struct for CAN bus   CANTxMessage.DLC = 8;                         //Default number of data bytes to send   CANTxMessage.ExtId = 0;                       //No extended ID   CANTxMessage.IDE = CAN_ID_STD;                //Base Frame identifier   CANTxMessage.RTR = CAN_RTR_DATA;              //Remote transmission request for data frame   CANTxMessage.StdId = Calibrate.CAN_stdID;     //Our frame ID for data transmitted from the SoS board  }   /////////////////////////////////////////////////////////////////////////////   /// @brief The CAN bus transmit string function   /// @note We just break the string into 8 byte chunks and transmit them   /// If we cannot exactly divide by 8 then we pad the last few bytes with 0   /// Remember we are sending ASCII and 0 is a clear ''non data'' byte   /// @param[in] pStr Pointer to the string   /// @param[in] numBytes Number of bytes to send   /// @return Boolean pass or fail - false==fail, true==pass   ///////////////////////////////////////////////////////////////////////////// bool stringToCAN( char* pStr, int numBytes ) {   int i;   char data;   uint8_t mailBoxNumber=CAN_TxStatus_NoMailBox, dlc=8, canTxStatus=CAN_TxStatus_Failed;   bool status=PASS;      while (numBytes > 0)   {     watchdog();                         // Kick the dog on long data dumps     if (numBytes < 8)      {       dlc = numBytes;                   //Number of bytes, less than 8, that remain to be sent       CANTxMessage.DLC = dlc;      }     else     {       CANTxMessage.DLC = 8;      }     for (i=0; i<dlc; i++)     {       data = *(pStr++);       CANTxMessage.Data[i] = data;       numBytes--;     }          while( mailBoxNumber == CAN_TxStatus_NoMailBox )             //Only transmit when mailbox is available     {         mailBoxNumber = CAN_Transmit( CAN1, &CANTxMessage );      }     canTxStatus = CAN_TxStatus_Pending;     while( canTxStatus == CAN_TxStatus_Pending )     {       canTxStatus = CAN_TransmitStatus(CAN1, mailBoxNumber);      }     if (canTxStatus == CAN_TxStatus_Failed)      {       Error.canTxError = true;     }        }   return( status ); }

[gbigden]

Posted on February 10, 2016 at 17:23

Thanks, but they apparently make it work using this bit of code:

        CAN_Transmit(CANx, &TxMessage);        Delay();With the delay just being a loop decrementing from 0xFFF.Which is just a totally crap. In no way does it help maximize bus throughput or stability, and anyone putting that into a production bit of code ought to be fired.

[Walid FTITI_O]

Posted on April 05, 2016 at 15:13

Hi bigden.gary,

Your feedback has been reported internally. -Hannibal-