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read the output of ePWM

Vitor Monteiro
Prodigy 30 points

Hi,

I use the ePWM to control an ac-dc converter.

The control is  based on the comparison of the reference with the triangular carrier at each sampling time interruption.

However, I want to know the result of the comparison in the timer interruption k to use it in the interruption k+1.

Is it possible?

Best regards,

Monteiro

  • 0
    Guru 192875 points

    Hi Monteiro,

    I want to know the result of the comparison in the timer interruption k to use it in the interruption k+1.

    In short you want to get the CMPA value, right?

    Regards,

    Gautam

  • 0
    Intellectual 680 points

    Hi monterio,

              How are you using ePWM, means with triangular Carrier means ePWM internal counter ?

    If you are using ePWM in normal mode you can read CMPA value in Timer ISR and use it for next cycle.

    Other option is generate EPWM interrupt on an event and read CMP value in ISR.

              Please describe further about your requirement.

    Thank You

  • 0
    Prodigy 70 points

    Dear Monteiro

                 i want to generate traingular and 3-sinwaves using f28335 .how to write c- code , will you please help me in this regard.my email id is  anmaheshwarappa@gmail.com.

    an mahesh

  • 0 in reply to anmaheswarappa narappa
    Guru 192875 points

    Mahesh, do start a new thread. You'll be assisted there.

    Regards,

    Gautam

  • 0 in reply to Bhuvaneshwar kanade54447
    Prodigy 30 points

    Hi.

    I know the CMPA value...  EPwm4Regs.CMPA.half.CMPA = ( pwm1);

    I can read the value of CMPA in the time interruption, but is the value that I put there (pwm1).

    I want to know the result of the comparison of CMPA with the ePWM internal counter ( triangular Carrier).

    Tahnk you.

    Monteiro

  • 0 in reply to Vitor Monteiro
    Intellectual 680 points

    Hi,

       you can read ePWM internal counter value .

     

           and in case you are using shadow mode or direct mode reading of CMPA (shadow resister / actual resister) will give you

    Current active value.

     

      If you are interested in active value of CMPA which will cause PWM to change their state you can read this resister.

    By comparing Counter value and CMPA determine in software which transition / state your PWM will take.

    You can keep Timer at twice the frequency of ePWM to make sure you can calculate result of comparison before it

    occurs.

    I hope this answers your questions.

    Thank You

    Thank You

  • 0 in reply to Bhuvaneshwar kanade54447
    Prodigy 30 points

    Hi Bhuvaneshwar.

    Excellent! It works!

    I did "a=EPwm6Regs.TBCTR;" in the timer interruption to obtain the counter value and then I use the variable 'a' to compare with other variable.

    Thank you a lot.

    Best regards,

    Monteiro

  • 0 in reply to Vitor Monteiro
    Guru 192875 points

    That's great, Victor. Please close this thread by verifying Bhuvaneshwar's answer.

    Regards,

    Gautam