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LAUNCHXL-F280039C: device hang up issue and cause PWM continue high even if after device reset

Terry Deng
Intellectual 2485 points
Part Number: LAUNCHXL-F280039C

Dear Sir

My customer has mature product base on F280049 and already MP, now they just transfer from F280049 to F280039, and found a strange issue that F280039 will hang up after running for a while. While device hang up, the PWM will stop running and continue high or low, even after device generate reset signal, the PWM still keep continue high or low. 

Below is the waveform for reference. The Blue, Green and Yellow color is PWM signal, and Red color is Reset signal.  We can see the Green color PWM signal change to continue high suddenly, and keep high even after reset signal.  

I check customer firmware setting that PWM FREE-SOFT bit set to 11 (free run) and TZ set to force low for both PWMA&B.  So I think the PWM should be always continue running or all turn off. I cannot understand why PWM will continue high even after device reset.

May I get expert advice what any possible condition maybe cause device PWM continue high?

 

  • 0
    TI__Guru 52010 points

    1. The reason behind the EPWM stopping, is it:

    a. the TBCLK is stopped and the EPWM is stuck in it's last state? or maybe EPWM clock is stopped?

    b. a TRIP CBC/OST has occured?

    2. Do you possibly have DEADBAND enabled? that could be switching the polarity of the signal using the INVERT feature?

    3. After a device reset, does the EPWM start generating a pulse at all?

    4. In the code, is the pinmux accidently modified?

  • 0 in reply to Nima Eskandari
    TI__Intellectual 2485 points

    Hi Nima

    Thanks your advice. I try to provide more information according.

    1, a, we try to use either crystal or intosc as system clock source, both condition will happen same issue. I think intosc should be not easy affected stop, so what will cause TBCLK stopped?

        b, TRIP set to be turn off both PWM A & B, so all PWM should be continue low under TRIP occurred. That is strange some PWM come to continue high while issue happen

    2, Yes, customer firmware enable deadband and PWM A & B is invert. However why PWM do not return low even after Reset? I think the deadband should be return to reset value as disable

    3, No, even after reset, the PWM do not generate pulse and just continue keep low or high

    4, I think pinmux accidently modified should be very few probability, however customer system recur the PWM continue high issue in many times. So I think issue should related to other reason

  • 0 in reply to Terry Deng
    TI__Guru 52010 points

    Terry,

    Can you have the debugger connected while this issue occurs?

    If yes:

    1. Is the TBCLKSYNC enabled?

    2. Is the TBCTR counting (changing values)?

    Nima

  • 0 in reply to Nima Eskandari
    TI__Intellectual 2485 points

    Hi Nima

    While PWM halt issue occurs, the power module will be damager because PWM continue high and power supply will be off. So we cannot connect debugger in this case.

    However sometime PWM halt in continue low, in this case we can connect debugger after issue occurs. We found the PC register value is in bootrom wait mode, and all register are turn to reset value, the RESC register value show XRSn bit as 1. So I suspect the device has been abnormal trigger reset pin and go into bootrom wait mode. However I think the PWM should be stop because device already reset, so I still cannot explain why sometime PWM continue high while halt issue occurs.

  • 0 in reply to Terry Deng
    TI__Guru 52010 points

    Okay so let's say the device is reset and then stuck in wait mode.

    What does the HW connection on your board look like from your EPWM GPIOs to the power module?

    If the device is reset, the GPIO should automatically go into input mode.