FFT implementation sinewave
Hi everyone. This is the first time I have to implement the FFT of a signal and I can't understand a few things.
I wrote this code that "should" calculate the coefficients of the FFT of a sine wave in that I create with the DAC (the DAC code to generate sinewave works, I measured it with oscilloscope) and I kindly ask for some opinions on how to solve these 3 problems:
1) The warning in the FFT instruction arm_rfft_fast_f32 that says: "passing arguments 2 and 3 of 'arm_rfft_fast_f32' from incompatible pointer type"
2) If the code below that I wrote to calculate fftBufOut, in which the real and complex coefficients of the FFT of the sine wave should be present, is correct
3) I don't see the coefficients inside fftBufOut right in the "Expressions" tab .. why?
Below there are the only lines of code I wrote in the entire project:
/* USER CODE BEGIN PD */
#define FFT_BUFFER_SIZE 2048
arm_rfft_fast_instance_f32 fftHandler;
float fftBufIn[FFT_BUFFER_SIZE];
float fftBufOut[FFT_BUFFER_SIZE];
uint8_t fftIndex = 0;
uint8_t fftFlag = 0;
/* USER CODE END PD *
void get_sineval_FFT() {
int i = 0;
//-----------------------------------------------------------------------------------------------
for (i = 0; i < FFT_BUFFER_SIZE; i++) {
sine_val[i] = ((sin(i*2*PI/samples) + 1)*(4096/2)); //100Hz
fftIndex++;
if (fftIndex == FFT_BUFFER_SIZE) {
//perform FFT
arm_rfft_fast_f32(&fftHandler, &sine_val, &fftBufOut, 0);
fftFlag = 1;
fftIndex = 0; //reset FFT array index
}
}
//-----------------------------------------------------------------------------------------------
}
...below there is an empty main with while(1);