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TMS320F28335: EPWM sync with different frequency

Wayne Huang
Genius 16675 points
Part Number: TMS320F28335


Champs,

I am asking this for our customers.

If EPWM1 (master) is set at 100 KHz and EPWM2 (slave) is set at 50 KHz, can EPWM2 be sync by EPWM1 at counter = 0?

Conversely, if EPWM1 is set at 50 KHz, and EPWM2 is set at 100 KHz, can EPWM2 be sync by EPWM1 at counter=0?

Wayne Huang

  • 0
    TI__Mastermind 42195 points
    Wayne,
    Well, both will allow you to sync the PWMs, but using the 100KHz to sync the 50KHz PWM will probably not work as you want it to.

    When sync'ing two PWMs you always need to use the Slower PWM as the master. If the faster PWM is the master then it will effectively reset the slower PWM's TBCTR before you want it to.

    For example if ePWM1 has a TBPRD of 500 and ePWM2 TBPRD of 1000 with a phase offset of zero between the PWMs. If you send a sync pulse from ePWM1 at TBCTR=0 then the TBCTR of PWM2 will be reset from 500 to 0. This will happen every period, so effectively PWM2 will never count above 500.

    Regards,
    Cody