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TMS320F28P650DK: Considerations when using software one-shot trip

Wayne Huang
Genius 15635 points
Part Number: TMS320F28P650DK

Tool/software:

Hi champs,

I am asking this for our customer.

The user wonders if there is any limitation/concern/consideration when using software one-shot trip of EPWM.

That is,

EPWMx.TZFRC.OST

EPWMx.TZCLR.OST

1)

For example, if a PWM period is 1 sec and this PWM is 100% duty on, and the user uses EPWMx.TZFRC.OST and then use to EPWMx.TZCLR.OST to trip it low and then clear alternatively every 1 ms.

Is it possible to have on and off and on and off like that?

2) As long as the user uses EPWMx.TZFRC.OST and then TZFLG.OST=1, it means the one-shot trip is effective until the user uses EPWMx.TZCLR.OST to clear TZFLG.OST. Is our understanding correct?

  • 0
    TI__Genius 9605 points

    Hi Wayne,

    Yes you can use one-shot trip to set the trip event and then clear the flag to clear the action applied that's possible.

    Although the TZFRC.OST will work only if EPWMCLKDIV is /1 as mentioned in thread here - https://e2e.ti.com/support/microcontrollers/c2000-microcontrollers-group/c2000/f/c2000-microcontrollers-forum/1345272/tms320f28p650dk-unexpected-results-of-force-trip-action 

    Other option is to use T1/T2 action events generated from the Digital compare submodule and take actions based on the events

    Thanks

  • 0 in reply to Prarthan Bhatt
    TI__Genius 15635 points

    Hi Bhatt,

    That explains it.

    After setting EPWMCLKDIV = /1, we found our issue has been resolved.

    ClkCfgRegs.PERCLKDIVSEL.bit.EPWMCLKDIV = 0; // EPWMCLK = 200MHz /1 of PLLSYSCLK

    Questions:

    1) On F2837x, where SYSCLK = 200 MHz and EPWM = 100 MHz max . Is there also such an issue? EPWMCLK cannot be set /1 there.

    2) On F2838x, where SYSCLK = 200 MHz and EPWM = 200 MHz max. Is there also such an issue?

    3) On F28P65x, where SYSCLK = 200 MHz and EPWM = 200 MHz max, have we documented this in errata or TRM note? This is critical because many users would just use EPWMx.TZFRC.OST without realizing this issue.

    4) On F29H85x/P58x, where SYSCLK = 200 MHz and EPWM = 200 MHz max. Is there also such an issue?