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Safe way to restart debug session? Power electronics destroyed when restarting debug session

Niclas Samuelsson
Intellectual 490 points
Other Parts Discussed in Thread: TMS320F28035

Hello! I'm doing a project involving a boost PFC converter with TMS320F28035. The code which we have works for the most part, but on 3 occasions there has been an overcurrent upon resetting the debug session which destroyed some parts in the high current path. Somehow the PWM duty cycle for the boost MOSFETS must be very high when that happens, but I find it hard to analyze..

I am only wondering if there are any unsafe ways of resetting the debug session? Can PWM give unpredictable outputs somehow? What procedure should I follow after I made some change in code and want to run debug again?

BR

  • 0
    TI__Mastermind 41365 points

    Niclas,

    you will need to determine what is actually causing it, then we can go about fixing the issue. See the insights and questions below.

    • Were the parts destroyed before or after the reset?
      • Is it possible that the over current condition wasn't handled correctly or quickly enough? The parts could have been destroyed before the device was even reset.

    1. On power up it is often required to add a pull-down or pull-up resistor to keep the PWM outputs in a safe state.
    2. When you halt the device's execution the PWM's output will behave according to the value in "FREE_SOFT".
      1. It can freeze the PWM after a cycle, at a period boundary, or allow it to continue running freely.
    3. If you put a value into the TB counter that is larger than the value in the TBPRD register then the PWM will be stuck in one state until the TB counter is rewritten or it overflows.

    If you have not validated your software yet, I wouldn't recommend driving power electronics until at least all safety functions have been implemented and verified. You may be able to do this using a controlCARD, however sometimes the fastest way to get back to debugging is to de-solder the FETs on your board.

    Regards,
    Cody 

  • 0 in reply to Cody Watkins
    TI__Mastermind 41365 points
    Has this been resolved?
    If so, what was the cause?

    Regards,
    Cody