void fft_init(){
fft.InBuf = &sampleBuffer[0];
fft.OutBuf = &outBuffer[0];
fft.CosSinBuf = &TwiddleBuffer[0];
fft.FFTSize = FFT_SIZE;
fft.FFTStages = FFT_STAGES;
fft.MagBuf = &MagBuffer[0];
RFFT_f32_sincostable(&fft);
}
void performFFT()
{
fft.InBuf = SampleTable; /* Input data buffer */
fft.OutBuf = OutBuffer; /* FFT output buffer */
fft.CosSinBuf = TwiddleBuffer; /* Twiddle factor buffer */
fft.FFTSize = DATA_LENGTH; /* FFT length */
fft.FFTStages = FFT_STAGES; /* FFT Stages */
fft.MagBuf = spectraTable; /* Magnitude buffer */
RFFT_f32_sincostable(&fft); /* Initialize Twiddle Buffer */
RFFT_f32u(&fft); /* Calculate output */
RFFT_f32_mag(&fft); /* Calculate magnitude */
}
void main(void)
{
Uint16 i;
InitSysCtrl();
DINT;
InitPieCtrl();
IER = 0x0000;
IFR = 0x0000;
InitPieVectTable();
EINT; // Enable Global interrupt INTM
ERTM; // Enable Global realtime interrupt DBGM
// Clear input buffers:
for(i=0; i < RFFT_SIZE; i++)
{
RFFTin1Buff[i] = 0.0f;
}
// Generate sample waveforms:
Rad = 0.0f;
for(i=0; i < RFFT_SIZE; i++)
{
RFFTin1Buff[i] = sin(Rad) + cos(Rad*2.3567); //Real input signal
//FFTImag_in[i] = cos(Rad*8.345) + sin(Rad*5.789);
Rad = Rad + RadStep;
}
rfft.FFTSize = RFFT_SIZE;
rfft.FFTStages = RFFT_STAGES;
rfft.InBuf = &RFFTin1Buff[0]; //Input buffer
rfft.OutBuf = &RFFToutBuff[0]; //Output buffer
rfft.CosSinBuf = &RFFTF32Coef[0]; //Twiddle factor buffer
rfft.MagBuf = &RFFTmagBuff[0]; //Magnitude buffer
RFFT_f32_sincostable(&rfft); //Calculate twiddle factor
for (i=0; i < RFFT_SIZE; i++)
{
RFFToutBuff[i] = 0; //Clean up output buffer
}
for (i=0; i < RFFT_SIZE/2; i++)
{
RFFTmagBuff[i] = 0; //Clean up magnitude buffer
}
RFFT_f32(&rfft); //Calculate real FFT
// OutBuf[0] = real[0]
// OutBuf[1] = real[1]
// OutBuf[2] = real[2]
// ………
// OutBuf[N/2] = real[N/2]
// OutBuf[N/2+1] = imag[N/2-1]
// ………
// OutBuf[N-3] = imag[3]
// OutBuf[N-2] = imag[2]
// OutBuf[N-1] = imag[1]
//
RFFT_f32_mag(&rfft); //Calculate magnitude
// MagBuf[0] = magnitude[0]
// MagBuf[1] = magnitude[1]
// MagBuf[2] = magnitude[2]
// ………
// MagBuf[N/2] = magnitude[N/2]
// MagBuf[N/2+1] = magnitude[N/2+1]
// rfft.PhaseBuf = &RFFTmagBuff[0]; //Use magnitude buffer
// RFFT_f32_phase(&rfft); //Calculate phase
// Just sit and loop forever (optional):
for(;;);
} //End of main
/**********************************************************************
* Function: main()
*
* Description: Main function for C2833x Real-time RFFT
**********************************************************************/
void main(void)
{
Uint16 i,j;
float32 freq; // Frequency of single-frequency-component signal
//--- CPU Initialization
InitSysCtrl(); // Initialize the CPU (FILE: SysCtrl.c)
InitGpio(); // Initialize the shared GPIO pins (FILE: Gpio.c)
InitPieCtrl(); // Initialize and enable the PIE (FILE: PieCtrl.c)
//--- Peripheral Initialization
InitAdc(); // Initialize the ADC (FILE: Adc.c)
// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
EALLOW; // This is needed to write to EALLOW protected register
PieVectTable.ADCINT = &adc_isr;
EDIS; // This is needed to disable write to EALLOW protected registers
rfft_adc.Tail = &rfft.OutBuf; //Link the RFFT_ADC_F32_STRUCT to
//RFFT_F32_STRUCT. Tail pointer of
//RFFT_ADC_F32_STRUCT is passed to
//the OutBuf pointer of RFFT_F32_STRUCT
rfft.FFTSize = RFFT_SIZE; //Real FFT size
rfft.FFTStages = RFFT_STAGES; //Real FFT stages
rfft_adc.InBuf = &AdcBuf[0]; //Input buffer
rfft.OutBuf = &RFFToutBuff[0]; //Output buffer
rfft.CosSinBuf = &RFFTF32Coef[0]; //Twiddle factor
rfft.MagBuf = &RFFTmagBuff[0]; //Magnitude output buffer
RFFT_f32_sincostable(&rfft); //Calculate twiddle factor
//Clean up output buffer
for (i=0; i < RFFT_SIZE; i++)
{
RFFToutBuff[i] = 0;
}
//Clean up magnitude buffer
for (i=0; i < RFFT_SIZE/2; i++)
{
RFFTmagBuff[i] = 0;
}
//--- Enable global interrupts
asm(" CLRC INTM, DBGM"); // Enable global interrupts and realtime debug
//--- Main Loop
while(1) // endless loop - wait for an interrupt
{
if(FFTStartFlag) // If one frame data ready, then do FFT
{
RFFT_adc_f32u(&rfft_adc); // This version of FFT doesn't need buffer alignment
RFFT_f32_mag(&rfft); // Calculate spectrum amplitude
j = 1;
freq = RFFTmagBuff[1];
for(i=2;i<RFFT_SIZE/2+1;i++)
{
//Looking for the maximum valude of spectrum magnitude
if(RFFTmagBuff[i] > freq)
{
j = i;
freq = RFFTmagBuff[i];
}
}
freq = F_PER_SAMPLE * (float)j; //Convert normalized digital frequency to analog frequency
FFTStartFlag = 0; //Start collecting the next frame of data
}
asm(" NOP");
}
} //end of main()
