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CMSIS DSP FFT functionality increases size of the project drastically

Question asked by Jay_Shah on Jul 24, 2017
Latest reply on Jul 27, 2017 by Jay_Shah

Hi All, My Question is related to CMSIS DSP Library. i'm working on ADuCM3029 EZ-KIT. I'm using IAR v7.8.1 to build the project. In my application i have an ADC interfaced with the controller, from which i acquire 60 samples and stores it into the buffer. I intend to do math operations (FFT to be specific) on the acquired buffer, I've enabled use CMSIS option and Checked DSP library in the project settings. but the size of my code increases horrendously as soon as I include FFT operation, and becomes ~83 KB from ~9 KB. Is there anything that i'm doing wrong over here? Is there a better way to add FFT functionality to the project without letting the size increase horrendously? 


Along with this, I can see that when FFT function is executed, the array realCoefBQ15 is getting overlapped into one of the SPI descriptor which is causing Bus Fault Error. Since I'm using 64 Point radix 2 FFT, that many twiddle factor coefficients are of no use. I understand it has been defined in that way so that the same array can  be used for upto 4096 points FFT.


Is there any way to avoid this?

rafael.lajara, Ayebenes can you guys look into it and help me out on this? 


Any help will be deeply appreciated.