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TMS570LS3137: DCAN1IF1CMD starts one message transmission bus activity never stops

Chuck Wong
Genius 3950 points
Part Number: TMS570LS3137

Hello there,

In my code, I would like to transmit 8 messages of 8 bytes each in the extended CAN BUS mode. All message boxes were initialized as single message (not FIFO) and with data length of 8 bytes, and ready to accept data. After both DCAN1IF1DATA and DCAN1IF1DATB were written with data bytes, I use DCAN1IF1CMD with a message number to launch the transmission.

With the debugger, I step to just before setting DCAN1IF1CMD message number, no activity at the bus, then just step over this line, then the bus is having activities but never stops.

    dcan1if1cmd_bit.DataA         = 1;      // update data A register
    dcan1if1cmd_bit.DataB         = 1;      // update data B register
    dcan1if1cmd_bit.TxRqst_NewDat = 1;      // set transmit request
    dcan1if1cmd_bit.MessageNumber = msgNo;  // set message number


    DCAN1IF1CMD = dcan1if1cmd;      // start the TX process

Anything that I've missed?

  • 0
    TI__Guru**** 197336 points

    Hi Chuck,

    If you want to copy data from IFx registers to message object, please write 1 to WR bit of IFx CMD register.

    If the auto retransmission is enabled, the CAN controller will retransmit frame that has lost arbitration or has been disturbed by error during transmission. You can disable Automatic Retransmission by setting bit DAR in CAN control register.

  • 0 in reply to QJ Wang
    Genius 3950 points

    QJ,

    The CAN module might not receive proper acknowledgement from the bus. We're investigate further and report back at a later time.

    Thanks.

  • +1 in reply to Chuck Wong
    Genius 3950 points

    Just want to update this thread ... the CAN module was indeed not receiving acknowledgement from the bus simulator, therefore the module tries continuously to send the same message again and again, which gives the observed behavior. Now the CAN setup is complete and the timing are as per design.

    Thank you.