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CPoir's avatar
CPoir
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6 years ago

CIC interpolator gives no output when stages are a power of 2

Hi folks,

I'm trying to simulate a CIC interpolator. I noticed that when the number of stages is a power of 2 (1,2,4 or 8, since the maximum is 12), I only get zeroes as the output. Any other value for the number of stages is fine. Here are screenshots of my IP configuration:

And here is one of my simulation. The signal_I_tmp is what I feed to the interpolator. It is an 8-bit signed which increments by one at each clock. Then, the interp_valid is the out_valid of the IP and it stays low.

If I only change the number of stages to 3 and choose "rounding up" instead of "none" as the output rounding method, it works:

So would any of you know why the powers of 2 don't work?

Thanks for your time,

Carl

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  • CPoir's avatar
    CPoir
    Icon for New Contributor rankNew Contributor
    6 years ago

    Hi Chee,

    It's been three weeks now since you reproduced the issue. Are the engineers working on it at the moment? What is the estimated time of completion?

    Carl

    • CheepinC_altera's avatar
      CheepinC_altera
      Icon for Regular Contributor rankRegular Contributor
      6 years ago
      Hi Carl, Sorry for keeping you waiting. I still do not receive valid response from Engineering on this. I am currently trying to escalate to expedite the response. Sorry for all the inconvenience. By the way, are you aware of your local FAE support contact? If yes, please feel free to share me his/her email contact. Thank you very much. Best regards, Chee Pin
  • CPoir's avatar
    CPoir
    Icon for New Contributor rankNew Contributor
    6 years ago

    Hi Chee,

    I'm not aware of my local FAE. Did you escalate the issue?

    Carl

  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    Hi Carl,

    Thanks for your update. For your information, I have escalated and seek assistance from Factory on this. However, I have yet to receive any valid response from Factory. I will continue to follow up closely and drive for valid response.

    Sorry for the inconvenience.

  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    Hi Carl,

    I would like to apologize for the delay as I have yet to receive valid response from Factory. I am so sorry for the inconvenience and I will continue to escalate this issue for valid response.

  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago

    Hi Carl,

    For your information, I have yet to receive any valid finding from Factory on this. I believe Factory is currently tied up. I understand that this has been dragging for quite some time. To avoid gating your progress further, just wonder if you would be able to look into using other value which is not power of 2? Sorry for all the inconvenience.