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TCAN1145-Q1: Relationship between wake-up frame and arbitration

Kian Lin
Expert 4220 points
Part Number: TCAN1145-Q1

Hi,

I want to ask a question.

I knew selective wake using arbitration 11-bits data to wake transceiver. But if WUF occupies the function of the arbitration? The reason I ask this question is if WUF wake two nodes, how to allocate their priority? 

Thanks!

BRs
Kian
  • 0
    TI__Guru 74252 points

    Kian,

    A wake-up frame has the same frame structure as a standard CAN frame, it has all of the start-of-frame bits, along with ID, and data if configured as such. The ID is actually part of the confirmation by the transceiver that it is a correct wake-up frame, so considering priority for a wake-up frame would be the same as a standard CAN frame, and then you configure the TCAN1145-Q1 to wake up on the specific ID for that wake-up frame.

    Please let me know if you have any other questions.

    Regards,

    Eric Hackett

  • 0 in reply to Eric Hackett
    TI__Expert 4220 points

    Hi Eric,

    Thanks for your reply.

    If two 1145 have same Wakeup ID, if we use the don't care bit to allocate priority between them?

    BRs

    Kian

  • +1 in reply to Kian Lin
    TI__Guru 53555 points

    Hi Kian,

    Arbitration is used to establish priority between two nodes that are actively transmitting. Both nodes will drive their ID on the bus and the node with the smaller value (most dominant bits sooner) will win arbitration and continue to send its data. The node that loses arbitration will stop trying the transmit and wait until the next frame window before trying to transmit again. 

    When a transceiver is in sleep mode with partial networking active, it is not capable of transmitting any information on the CAN bus.These nodes are only able to receive frames and will use the received data to determine if it is time to wake up - therefore they do not participate in arbitration. If a WUF is driven on the CAN bus, any node that is configured to wake to that frame will wake at the same time 

    Let me know if this is clear and if you have any more questions. 

    Regards, 
    Eric Schott