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TM4C1290NCPDT: Bit 1 Error during CAN communication

Koichiro Tashiro
Mastermind 22400 points
Part Number: TM4C1290NCPDT

Hi,

My customer is using TM4C1290NCPDT and CAN module.
They are seeing a lot of “Bit 1 Error” during communication.

According to Data sheet, “Bit 1 Error” means data conflict on the bus.
They monitor data lines and found TX and RX happen same time.

Blue: CAN RX
Purple: CAN TX


 
I thought CAN module handles receive/transmit based on each priority and bus usage.
(i.e. even software triggers both RX and TX, these requests will be treated exclusively.)
Is this not true ? Or customer missed some configurations ?

Thanks and regards,

KoT

  • 0
    TI__Mastermind 22400 points

    Waveform attached.





    Thanks and regards,
    KoT

  • 0 in reply to Koichiro Tashiro
    TI__Guru**** 184346 points
    Hi,
    How many nodes do you have on the bus? Do you have proper resistor termination on the bus? Normally once you are past the arbitration field (assuming your node wins the arbitration) all the rest of nodes on the bus will be in listening/receiving mode. When you get a bus 1 error, this means you have a bus conflict in the non-arbitration fields of the frame. To simplify your debugging I will suggest that you setup one CAN node from the MCU with a CAN analyzer on the bus. Will you see bus 1 error in this configuration? You will then add more nodes one at a time to see how the bus 1 error manifests.
  • 0
    Guru 27665 points

    KoT said:
    They monitor data lines and found TX and RX happen same time.

    It would be a problem if they didn't. CAN modules must monitor the RX to determine if there are priority conflicts (collisions) during transmission of the priority portion of the message (commonly referred to as the ID)

    As suggested I would check termination and cabling between the transceivers (you do have transceivers?).

    Robert