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Problem with arm_cfft_f32()

Pierre Bellier
Note: This was originally posted on 27th August 2013 at http://forums.arm.com

Hello,

I'm new in the field of ARM and I need some help. I try to make a FFT on a Cortex-M4 with fpu. I tried two examples given with the CMSIS library, an old one which uses arm_cfft_radix4_f32() and a new one with arm_cfft_f32(). The two examples compile well. The old code with arm_cfft_radix4_f32() works quite good. That function is deprecated so I would like to use arm_cfft_f32() but I don't get the right data at the end.

The program makes a FFT of a given signal and should detect the peak in magnitude at refIndex = 213. It's ok with the deprecated function arm_cfft_radix4_f32() but not with arm_cfft_f32(). I get refIndex = 861. I tried to change the 'doBitReverse' value from 1 to 0 but nothing changed I have exactly the same result at the output of arm_cfft_f32().

I didn't find the same issue on the web. Is there a known problem with arm_cfft_f32() ? Could someone explain me what I'm doing wrong ?

Thanks,
Pierre.


Parents
  • Note: This was originally posted on 27th August 2013 at http://forums.arm.com

    Hi,

    May I ask what compilers are being used? I just recompiled the cortex M4lf library (with Keil) and the fft example (which I zipped up and attached) and got 213.  I looked at your attachments and I don't notice anything different that should matter.  I can't attach the .lib file to this forum because it's larger than 2.3MB.  If you'd like, I can email you the lib file I just made if you message me your email address. 

    Dan
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  • Note: This was originally posted on 27th August 2013 at http://forums.arm.com

    Hi,

    May I ask what compilers are being used? I just recompiled the cortex M4lf library (with Keil) and the fft example (which I zipped up and attached) and got 213.  I looked at your attachments and I don't notice anything different that should matter.  I can't attach the .lib file to this forum because it's larger than 2.3MB.  If you'd like, I can email you the lib file I just made if you message me your email address. 

    Dan
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