FFT module on k210 and data organization



  • Hi,

    i'm using the k210 to run a STFT using the hardware FFT module. When doing a 512 FFT on real-data i expect to have symmetry after the 256th samples but when i actually display the result, i have symmetry after the 128 samples. Is there any special data organization on the output of the FFT module that needs to be taken into account ?

    Thanks


  • Global Moderator |  Mod

    Hi, both Left and Right channel data will be received by i2s logic(driver). So you should drop Left or Right channel data according to your application. 16 bits or 32 bits means SINGLE channel data sample length, NOT double channels data sample length. Thanks.



  • Hi,

    i have found my bug which does not seem to relate to the FFT module but the channel layout in the i2s receive function. You can try the code here :

    https://github.com/jpiat/stft_lcd.git

    The issue was that in the i2s receive function channels are interlaced as RLRLRLR each sample being on 32bit even when sample width is set to 16bit.