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Original question:

MCU-PLUS-SDK-AM263X: ePWM triggers SOC ADC 4 times per period.

MCU-PLUS-SDK-AM263X: EPWM SOC trigger with delay

Oleg Chaichenko
Prodigy 140 points
Part Number: MCU-PLUS-SDK-AM263X

Hi TI team,

I used for triggering SOC PWM, but I need to add some delay (200 us) between rising edge of PWM and SOC. Could you please help me, how to do it in correct way?

Regards!

  • 0
    TI__Expert 6995 points

    Hello Oleg,

    In you use case, which event of the following events is used for generating rising edge of PWM?

    CTR=zero, CTR=PRD, CTR=CMPA, CTR=CMPB, T1, T2, SW force

    EPWM SOCA/SOCB events can be generated using DCAEVT1.soc, CTR=zero, CTR=PRD, CTRU/D=CMPA/B, CTRU/D=CMPB/CMPD

    You may configure one of the CMPA/B/C/D events with an offset of 200us (with respect to the event used for rising edge generation) and use it to generate EPWM SOCA/SOCB.

    For example:

    If CTR=zero is used to generate rising edge, you may configure CMPA as 40000 (40000*5ns = 200,000ns) and configure ETSEL[SOCASEL], ETSEL[SOCASELCMP] to select CMPA as source for EPWM SOCA.

    Thanks

    K.Sanjeev

  • 0 in reply to Sanjeev Karaiyan
    Prodigy 140 points

    Hi Sanjeev Karaiyan!

    I need to measure ADC with period (PWM_period / 4) per PWM_period, and I need need some delay between rissing edge of PWM and measurement. I am looking for the best and simplest method.

    I think the best choice will be triggering ADC from another PWM, wich will working in another frequency as described here: e2e.ti.com/.../4855865

    If you agree about this solution I will close this ticket.

    Thanks for your answer.
    Regards!

  • +1 in reply to Oleg Chaichenko
    TI__Expert 6995 points

    Hello Oleg,

    Is the rising edge of PWM generated at a fixed point of time within every PWM period? (example: start of PWM cycle (CTR=0) or a fixed CMPA/CMPB)

    Or is the rising edge of PWM modulated every cycle? (example: by updating CMPA/CMPB every PWM period)

    If it is fixed for every PWM cycle, then I agree with this solution. A second EPWM (running with period/4 and synced to EPWM1) can be used to generate ADC SOC triggers to sample 4 times per period.

    Thanks

    K.Sanjeev

  • 0 in reply to Sanjeev Karaiyan
    Prodigy 140 points

    Hi Sanjeev Karaiyan!

    Will be at fixed time.

    Thanks!