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CCS/UCD3138064A: What is update rate of filter YN read value?

Part Number: UCD3138064A

Tool/software: Code Composer Studio

Hi TI guys,

I have some question about FILTERYNREAD register update rate.

I have made fast interrupt routine using FILTERYNREAD information. In fast interrupt routine, after comparing FILTERYNREAD, determine whether to do or not to do.

There is no problem when event period of fast interrupt routine is larger than 3msec.

But, when event frequency is faster than 2msec, fast interrupt miss event. 

below code is in fast isr routine.

if (((fiq_data.fault_status_raw & DCOMP2_INT_STATUS_MASK)|(fiq_data.fault_status & DCOMP2_INT_STATUS_MASK))
&&(Filter0Regs.FILTERYNREAD.bit.YN < 1000000)) {

....

}

  • Hi Jinsik, I have forward your question to an AE to help out, you should see a reply soon.

    Regards, Brian

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  • Hello, Jinsik,

    Do you mean the program can't go to fast interrupt if the fault happens for 2ms?  Do you use the digital comparator for under voltage  protection? Can you send me more information?

    Regards,
    Sean

  • In reply to Sean Xu:

    I believe that the value is updated every time the filter is run.  So that would depend on how often you are triggering the front end ADC which is driving the filter.

    Happy Debugging,

    Ian Bower

  • In reply to Sean Xu:

    I am using it for improving dynamic condition. I think fast isr reponse is no problem, cannnot read the variation of filter output.
  • In reply to Ian Bower:

    Sampling rate is 1MHz. Maybe the time filter is run is also 1Mhz.
  • What triggers the fast interrupt?
    This better be trigerred by DPWM end of period interrupt.
    It takes about 450 to 500 nS from the sampling point in the switching cycle till FILTERYNREAD is updated.
    Are you having one sampling point during the switching cycle? Are you having oversampling?
    Or the EADC sampled asynchronus to switching frequency?

    Yitzhak Bolurian

  • In reply to Yitzhak Bolurian:

    fast isr trigger = dcomp2 uv detection
    sampling frequency is asybchronous to switchin gfrequency. samplinf fr = 1MHz, switchin gfrequency = ~ 80kHz
    FILTERREAD register update rate is 500ns. ok. I'll check again.
    Thank you.

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