• Locked Locked
  • Replies 15 replies
  • Subscribers 120 subscribers
  • Views 17281 views
  • Users 0 members are here
2025 survey

We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.

Options
Related
How was your experience today?
This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

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
  • in reply to Daniel White

    Hi Dan,

    Thanks for your interest. Yes, the CMSIS version I'm using is a bit older, because this is the DSP library for SM32F4 supplied by ST. It can be downloaded from ST website. I'll try the new version of CMSIS DSP library and let you know the results.

    Regarding floating point library “libarm_cortexM4lf_math.a”, I've already used for FFT functions, and it is obvious that the performance increases.

    Best regards,

    Ibrahim

Reply
  • in reply to Daniel White

    Hi Dan,

    Thanks for your interest. Yes, the CMSIS version I'm using is a bit older, because this is the DSP library for SM32F4 supplied by ST. It can be downloaded from ST website. I'll try the new version of CMSIS DSP library and let you know the results.

    Regarding floating point library “libarm_cortexM4lf_math.a”, I've already used for FFT functions, and it is obvious that the performance increases.

    Best regards,

    Ibrahim

Children