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TMS320F280037C: External clock failure affect on CAN

Mathew J Manavalan
Prodigy 210 points

Part Number: TMS320F280037C

Hello,

We are using the external clock source (20MHz crystal) for our controller which uses CAN as well.

In the event of a failure of the crystal, we understand that if the MCD (Missing Clock Detection) is enabled, the system will switch over to the 10MHz internal clock as the source.

In order to keep the CAN working after this failure, what needs to be done ?

Thanks!

Mathew

  • 0
    TI__Mastermind 19795 points

    Hi Matthew,

    I will confirm with the CAN experts, but I believe there are two items that need to occur (not necessarily in this order):

    1. The CAN bit timing must be changed (CAN_BTR register for example) based on the changed input clock speed.

      a. You can technically also just scale the SYSCLK to match the old input clock speed for CAN, but it is likely better to do the baud rate change since the SYSCLK is used by other items.

    2. Change the CLKSRCCTL2.CANABCLKSEL bits to use the SYSCLK instead of XTAL.

    You may also need to clear any CAN errors that may have occurred during the clock failure.

    I will verify the above with the other CAN experts to make sure nothing is missing.

    Regards,

    Vince

  • +1 in reply to Vince
    TI__Mastermind 19795 points

    Hi Matthew,

    I have just verified that the above post is sufficient for missing clock change over.

    I will close this thread now.

    Regards,

    Vince