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RGroo3's avatar
RGroo3
Icon for New Contributor rankNew Contributor
6 years ago

FFT IP MATLAB C-model seems not bit true

We included the Intel FFT IP (altera_fft_ii) in our Arria 10 and ran into the following 2 issues. The first issue (bug?) is related to the data representation. The core is configured with “Single F...
CheepinC_altera's avatar
CheepinC_altera
Icon for Regular Contributor rankRegular Contributor
6 years ago

Hi,

Sorry for the delay. As I understand it, you are expecting that the bit accurate Matlab model should give the exact output as the Modelsim simulation output. However, from your observation, the floating point output for Matlab model seems has little discrepancy vs the Modelsim output. This seems to be happening for floating point but not fixed point. You are able to replicate this observation with the example design generated by the FFT, the file you share.

Based on my understanding, ideally the bit accurate model should give same output as Modelsim. In this case, I believe it is due to some rounding in the Matlab model. As a workaround, I would recommend you to refer to the Modelsim simulation.

Please feel free to share with me the FFT .qsys or .ip file as well. I would like to file a case to Engineering to look into this and probably for future fix.

Thank you very much.