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TCAN1042-Q1 CAN Bus Wake Up

Shinichi Yokota
Genius 9715 points
Other Parts Discussed in Thread: TCAN1042-Q1

Hello,

I'd like to ask some questions about TCAN1042-Q1's CAN bus wake-up function.

  • Is it correct to understand that three pulses (filtered dominant, followed by filtered recessive and filtered dominant) are required to acknowledge the wake request?
  • Once an wake up pattern is recognized, will the RXD output go Low every time a filtered dominant is received?
  • Once the TCAN1042-Q1 goes back to normal mode and then enters standby mode again, will the wake up monitor be reset and ready to receive three pulses (wake up pattern) again?
  • Will the TCAN1042-Q1 NOT wake up by one pulse (only filtered dominant)? If the CAN transceiver MUST wake up by one pulse, can the TCAN1042-Q1 NOT be used?

Best regards,
Shinichi Yokota

  • 0
    TI__Mastermind 25705 points

    Shinichi-san,

    It's correct that three pulses are needed to be considered a valid wake request. Once a wake up pattern is recognized, RXD will continue to response to the filtered dominant pulse. That means if the dominant bit time is longer than twk_filter, RXD will go low. If the device goes to standby mode again, another wake up pattern is needed for the device to drive RXD low. Unfortunately the device will NOT response to one pulse wake up pattern.

  • 0 in reply to Hao L
    TI__Genius 9715 points

    Hello,

    By the way, does TI has an automotive CAN transceiver that wakes up from standby mode by receiving a one-pulse (only one filtered dominant) WUP and (fully) supports CAN FD (Flexible Data Rate)?

    Best regards,
    Shinichi Yokota

  • 0 in reply to Shinichi Yokota
    TI__Mastermind 25705 points

    Shinichi-san,

    Unfortunately so far the device that supports FD and has wake-up function is TCAN1042. However in TCAN1042, after the first pattern is detected, RXD will reponses to every filtered dominant pulse, which is same as the one-pulse pattern scheme. So if somehow you can pre-set the first pattern in your system, then only one long dominant on the bus will become a valid wake-up request.

    Regards,
    Hao