Strictly necessary cookies are on by default and cannot be turned off. Functional, Performance and Tracking/targeting/sharing cookies can be turned on below based on your preferences (this banner will remain available for you to accept cookies). You may change your cookie settings by deleting cookies from your browser. Then this banner will appear again. You can learn more details about cookies HERE.
Strictly necessary (always on)
Functional, Performance and Tracking/targeting/sharing (default off)
So I've been working on this small project here and there for awhile and I started taking a more in depth look at some of the results I was getting, and I realized that the arm_cfft_q15.c wasn't returning what it should be.
If I had
q15_t mag_of_fft 
and ADC_samples where samples of a 1kHz wave sampled at 10Khz you would expect the resulting peaks to be at 1/5 pi and 9/5 pi.
which basically says compute the 1024 pt fft of ADC_samples, with the inverse fft bit false and the bit reversal bit true.
which says compute the magnitude of the 1024 pt fft in ADC_samples
I get peaks at 2/5pi and at 8/5 pi?
I have confirmed my results in matlab as well. I have checked my ADC sampling, and just about everything I can think of.
I have also tried the example, but unfortunately they don't tell you the sampling rate and with the white noise they added in to their values it becomes pointless.
what am I doing wrong? I can't imagine arm has got it wrong. as my use is only for the relativity of results to each other and I can always just increase my ADC's clock, this isn't slowing me down, but it is very concerning that I may be mis-interpreting how one of these functions handles things.