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TMS570LC4357: Failed to set DCAN's INIT bit at passive error state.

Mike Yan1
Prodigy 30 points

Part Number: TMS570LC4357

When DCAN in passive error state, tries to set DCAN's INIT bit to 1 and software reset DCAN. Occasionally, setting DCAN's INIT bit takes a long time which is more than 10 ms before INIT bit is acked.

Does anyone encounter this issue before? What's the approach to fix it?

Also, what's the better way to bring DCAN out of passive error state? How to clear RX errors?

- Thanks

  • 0
    TI__Guru**** 201416 points

    Hi Mike,

    It should not take that long. My test on LS04x device shows that it only takes 93 CPU clock cycles (CPU is 80MHz). 

    The following is my test code. The CAN1 keeps transmitting message to CAN bus, since no ACK, the error increments to 0x80 (passive). When EPass bit is set, the PMU counter starts counting, and Write 1 to Init bit. The PMU stops counting after Init bit gets set:

    while(1)
    {
          canTransmit(canREG1, canMESSAGE_BOX1, &tx_data[0]);

          if((canREG1->ES & 0x20) == 0x20){

       _pmuResetCounters_();
       _pmuStartCounters_(pmuCYCLE_COUNTER);
       canREG1->CTL |= 0x01;

       while((canREG1->CTL & 0x01) != 0x01);

       _pmuStopCounters_(pmuCYCLE_COUNTER);

       /* Get CPU cycle count */

       pmuCount =_pmuGetCycleCount_();

    }

    }

  • 0 in reply to QJ Wang
    Prodigy 30 points

    Hi QJ,

    Setting INIT bit doesn't always take more than 10ms. Usually only happen once after running CanClose() and CanOpen() for a couple of hours. We use CanClose() and CanOpen() to bring CAN out of passive error mode.

    BTW, is there any recommended method to let CAN out of passive error mode?

    - Thanks 

  • 0 in reply to Mike Yan1
    TI__Guru**** 201416 points

    Hello Mike,

    The error count decreases by 1 when correctly transmitted and/or received a message. You need to figure out where the errors are from: ACK error, bit error, stuff error.