This version (09 Jul 2019 08:11) was approved by Ashwin Radhakrishnan.

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This Module performs N-point FFT on PCM samples. The FFT Output is given in the form of PCMx samples, the Blocksize of which is 3 * Schematic BlockSize.The first Schematic Block Size number of samples in a PCMx output contains the header information to be carried on to the next Module (say in this case IFFT). The header information contains fields such as PCMx type (Standard - No processing done), N.

Input Pins

NameFormat [int/dec] - [control/audio]Function Description
Pin 0: Input decimal - Audio Real Audio Input
Pin 1: Input decimal - Audio Imaginary Audio Input

Output Pins

NameFormat [int/dec] - [control/audio]Function Description
Pin 0: Output(PCMx) decimal - Audio Real FFT Output
Pin 1: Output(PCMx) decimal - Audio Imaginary FFT Output

Grow Algorithm

The module does not support Growth and Add


GUI Control NameDefault ValueRangeFunction Description
FFT Size 64 16 to 1024 Size of the FFT

DSP Parameter Information

GUI Control NameCompiler NameFunction Description
FFT Size Ext_FFTAlgo_SC5xxAlg1N FFT Size


  • Green - Algorithm Name
  • Red - Instance Number (Changes for each instance)
  • Blue - Parameter Name

Algorithm Description

This module computes the Complex FFT of the input. Twiddle factors are computed within the module. FFT output(N Real/Imaginary samples) is packed in the PCMx format with 3 * Schematic BlockSize number of samples. Since memory size depends on the value of N, downloading the Schematic (Link-Compile-Download) is necessary when N value is changed.

Example Schematic

Shown above is an example schematic with Standard FFT/IFFT along with the PCM to PCMx and PCMx to PCM modules. FFT produces N real/imaginary samples. If the PCMx to PCM is grown to R, only the first half will have data while the remaining will have zeroes or junk data and should be ignored for processing.

*Note: Since FFT- Window produces 2*N real/imaginary samples, all the outputs of the PCMx to PCM module will have valid data. The above schematic has to be modified to use all the outputs of PCMx to PCM for FFT with windowing.

Supported ICs

  1. ADSP215xx
  2. ADSPSC5xx
resources/tools-software/sigmastudio/toolbox/frequencydomain/fftstandard.txt · Last modified: 27 Jun 2019 08:52 by Ashwin Radhakrishnan