NucleoL476 and FFT ARm lib

[Seth1er]

hello all,

I try to use the arm lib to make a FFt but I d'ont understand it well and so I can't.

I need some help on it.

first, I make a acquisition of a signal (form a generator).

the signal is at 30KHz.

I sample with the STM32 at 1MHz.

I use a DMA to add and transert the signal to the DAC

now I want to know precisely the frequency of the signal, so I think to use FFT.

I init the fft cmd,

 arm_rfft_fast_init_f32(&fft_handler, 4096);

and then, use this one

 arm_rfft_fast_f32(&fft_handler, adc_val, fft_out_buf,0);

I don't understand after that how to found the frequency of my signal.

edit, sorry the message was created empty

[Tesla DeLorean]

Is there a question?

The CMSIS directories for CubeL4 will contain the DSP library, this is usable on CM4 parts.

[Seth1er]

yes sorry I click to quickly. I edit it now

[Rob.Riggs]

This seems like a general DSP question about how one uses an FFT rather than something specific about how the ARM Math library's FFT implementation works. That's a bit off-topic for this forum. A better place for this question may be dsp.stackexchange.com.

[Seth1er]

in fact both.

I try to use the FFT with my nucleo but I can't. the CMSIS site dont give a lot of information. just the command.

I can't found a simple example on use a fft on a sinus sample by the ADC.

but thank for the link, I will check

[ChahinezC]

Hello @Seth1er​,

I recommend you checking the applications on the AN4841 with the X-CUBE-DSPDEMO firmware package that demonstrates the usage of DSP including an FFT example and an FIR example to show a full integration with the STM32 families using its peripherals.

You can as well take advantage of using free ST IDE; STM32CubeIDE, by referring to the Configuring DSP libraries on STM32CubeIDE article.

Chahinez.