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TMS320F28035: Multisampling of an ADC channel in a PWM cycle

Yasin Cetin
Intellectual 330 points
Part Number: TMS320F28035

Hi,

I want to sample an ADC channel multiple times in one PWM cycle.

I can trig any ADC channel in anywhere in my PWM timer counter now. But I want to trig and sample same channel in many times within a pwm period.

I tried to explain by drawing below.

Is there any solution for this? 

 

Thanks and best regards

Yasin

  • 0
    TI__Mastermind 42085 points

    Yasin,

    do you have an extra PWM channel? One common thing to do is to configure a PWM at a higher frequency which can create multiple samples across the period of your primary carrier waveform.

    Regards,
    Cody

  • 0 in reply to Cody Watkins
    Intellectual 330 points

    Yes Cody, I have extra PWM channels and still tryin to configure them to make adjustments as I described above. I was wonder is there any other solution exist.

  • 0 in reply to Yasin Cetin
    TI__Mastermind 42085 points

    Yasin,

    so you can change the SOC's in the interrupt of the faster PWM, that should work for your purpose.

     

    Now depending on how close you want your samples together, you could possibly trigger all three SOCs off of one PWM event. Because the ADC works in a round robin fashion SOC1 will always happen first followed by SOC2 and then SOC3 even if they are all trigger by the same source.

    You can then adjust the sample and hold window using the ACQPS value to space out your samples. SOC2 will have to wait one sample and hold window after SOC1 and so on. Of course the width of eachwindow will be limited by the maximum ACQPS value.

     

    Regards,
    Cody