// returns the peak frequency
uint16_t fftSingleCycle() {
// 10 bits to 6 bits unsigned, range [0, 63]
// then shift so have range [-32, 31]
uint16_t start_t = TMR0;
for (int i = 0; i < FFT_LEN; i++)
fftReal[i] = readADC();
uint16_t stop_t = TMR0;
// pre-process for the fft
for (int i = 0; i < FFT_LEN; i++)
fftReal[i] = (int16_t)((uint16_t)fftReal[i] >> 4) - 31;
// Timer clock is Fosc/4, so do >>2
sample_freq = (_XTAL_FREQ << (FFT_LEN_BITS))/((stop_t > start_t)
? (stop_t - start_t)
: (65536 - start_t + stop_t));
// Reset the imaginary array
for (int i = 0; i < FFT_LEN; i++)
fftImag[i] = 0;
max_index = optfft(fftReal, fftImag);
peak_freq = (max_index * sample_freq) >> (FFT_LEN_BITS+2);
return (uint16_t)peak_freq;
}
void ekgProcess(void* taskDataPtr) {
EKGData* ekgDataPtr = (EKGData*) taskDataPtr;
unsigned int freq = 0;
while(1)
{
EKGData* ekgDataPtr = (EKGData*) taskDataPtr;
// scale buffer input
for(int i = 0; i < 256; i++)
{
ekgDataPtr->EKGRawTempBuf[i] = 0;
ekgDataPtr->EKGRawBuf[i] = (ekgDataPtr->EKGRawBuf[i] >> 4) - 32;
}
freq = optfft(ekgDataPtr->EKGRawBuf,ekgDataPtr->EKGRawTempBuf);
freq = Fs*freq / N;
//UARTprintf("Freq: %d\n",freq);
cBuffPut(ekgDataPtr->EKGFreqBuf,&freq);
vTaskSuspend(NULL);
}
}
