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CAN communication Bus busy check in C2000 series

Dheeraj Kunnath
Intellectual 350 points

Other Parts Discussed in Thread: TMS320F2808

I would like to know the method of checking CAN Bus busy status in C2000 series

  • 0
    TI__Guru* 95315 points

    What part number does your question pertain to?

  • 0 in reply to Hareesh Janakiraman
    Intellectual 350 points

    Hi Hareesh,

    TMS320F2808 is the uC I am using for the project,

    And my doubt is If more than 3 nodes(running with firmware with different slave ID) try to access bus priority will goes to the least numbered ID, at this point remaining nodes will wait for bus free condition in data link layer or do I need to handle the situation in application layer?

  • 0 in reply to Dheeraj Kunnath
    TI__Guru* 95315 points
    All this is automatically handled by the CAN protocol. Once you transfer the data to be transmitted to the (transmit) mailbox RAM and set the corresponding TRSn bit, there is nothing you need to do. The node constantly monitors the bus, resolves any contention and transmits the data. i.e. in the case of lost arbitration or errors during transmission, re-transmission is automatic. Your code doesn’t have to do anything special to handle this situation. My app.note SPRA876 points to some excellent material on CAN in the References section. There are also tons of training material online that explain the protocol.
  • 0 in reply to Hareesh Janakiraman
    Intellectual 350 points

    Hi Hareesh,

    Thanks for your input,

     So when mailbox RAM will get update ?Only after a successful data transfer? how many retry will execute for the data transfer?

  • 0 in reply to Dheeraj Kunnath
    TI__Guru* 95315 points

    So when mailbox RAM will get update? Only after a successful data transfer?

    Answer--> Sorry, I don’t understand what you are asking here. Your post is about a Transmit mailbox. It will get updated whenever your code writes to it. Are you asking about setting of the TA bit? If so, it is after transmission is successful.

     

    How many retry will execute for the data transfer?

    Answer--> In case of lost arbitration, retries will be forever. In case of error, it is a bit more complicated, depending on who is the source of error.