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FFT Does not work while No. of FFT points greater than 128

JengDa Li
Prodigy 110 points
Other Parts Discussed in Thread: CONTROLSUITE

Hi,

  I import the Control Suite Complex FFT example to Code Composer Studio V5.2. The project is successfully build and work well on the EZDSP F28335 Target board (but with F8235 Core on it) when No. of FFT points is set to be 8, 16, 32, 64 and  128. However,  when the No. of FFT points is set to be 256 or higher. Only the first 256 point address have values.  The remainder are all zero. How can I obtain correct FFT output for No. of FFT points greater than 256?  

  • 0
    TI__Mastermind 20850 points

    Hi,

    Are you are using the FPU library in controlSUITE? It uses a paramterized structure to do the fft which is initialized as follows.

        cfft.CoefPtr = CFFTF32Coef;                //Twiddle factor table
        cfft.InPtr   = CFFTin1Buff;                //Input/output or middle stage of ping-pong buffer
        cfft.OutPtr  = CFFToutBuff;                //Output or middle stage of ping-pong buffer
        cfft.Stages  = CFFT_STAGES;                // FFT stages
        cfft.FFTSize = CFFT_SIZE;                // FFT size

    You might want to check the macros CFFT_SIZE and CFFT_STAGES are changed appropriately in the example.