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AVasi19's avatar
AVasi19
Icon for New Contributor rankNew Contributor
6 years ago

ModelSim FFT simulation returns nothing but zeros

Hi,

I'm having trouble with simulating FFT in ModelSim.

Althoug i've asserted all input signals (as shown on figure_1(2019.06.20 20-01-25)), output of FFT stuck at zero.

No valids, no SOP/EOP or data.

RST_n and source_ready are always high.

Has anyone encountered such problem or does anyone know a key to resolving it?

Thanks in advance for your replies)

(PS also ModelSim shows warning, represented on figure_2(2019.06.20 20-01-410))

4 Replies

  • AndyN's avatar
    AndyN
    Icon for Occasional Contributor rankOccasional Contributor
    6 years ago

    You probably just need to assert reset at the beginning of your sim to get the core to a known state. From the looks of your screenshot, your reset is never low at the start...

  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago
    Hi, Thanks for Nicol for the explanation on the reset. @Vasilchenko, You can try the reset as recommended by Nicol. For your information, you can also generate the FFT example design (simulation) from the FFT IP -> Generate -> Generate Example Design. You can then run the simulation for the example design and cross check with yours to see if can spot any anomaly. Please let me know if there is any concern. Thank you. Best regards, Chee Pin
  • CheepinC_altera's avatar
    CheepinC_altera
    Icon for Regular Contributor rankRegular Contributor
    6 years ago
    Hi, As I understand it, it has been some time since I last heard from you. I would set this case to closed at this moment. Feel free to file a new case if you have any further question related to this request. Thank you for your understanding. Best regards, Chee Pin