# FFTComplex32bIP on dsPIC33(CK): examples or documentation?

Hello all,

I got the 16-bit complex FFT (using FFTComplexIP(), and TwidFactorInit(), BitReverseComplex(), SquareMagnitudeCplx() ) successfully running on a dsPIC33CK device, using the updated library provided by Microchip support, and the excellent "application note" TB3141 of 2015.

I need more dynamic range in the magnitude for smaller-magnitude signals (which I confirmed in MATLAB I could get by 32bit, using the same, 12bit input data from the ADC), so I want to try FFTComplex32bIP(). The 33CK devices should have enough power even for 32bit, since a 512-point 16bit FFT takes less than 0.5 ms.

There are several very old threads on this topic, all commenting: the lack of source code examples, lack of documentation, some fundamental uncertainty whether FFTComplex32bIP() only works for 1024 array size despite having arguments allowing variable size, uncertain data composition of complex (long) input vectors, unknown twiddle factor calculation, unknown bit-reverse calculation, etc. No solutions are in the forum to these questions.

By now, has anyone a complex 32bit FFT successfully running on any dsPIC33? could you share your source code? or is there any other documentation on 32bit complex FFT on dsPIC available by now?

thank you.

post edited by u741 - 2019/02/24 15:19:00