Posted on April 20, 2017 at 15:47 ,
,
Dear Clive,
Thanks for your reply,
I have done fft computation but I got strange results.Please let me know if i did any mistake.
why I am getting the following strange results?
// ADC
,
♯ define ADC_RAW_LENGTH 512
// FFT
,
// ♯ define FFT_SAMPLES 2048
,
♯ define FFT_SIZE ADC_RAW_LENGTH/2
UINT16 ui16ADCRaw[ADC_RAW_LENGTH],ui16ADCCnt = 0,ui16Flag = 0, ui16CalibrateMaxValue = 0,
,
FLOAT32 fl32ADCRaw[ADC_RAW_LENGTH], fl32FFTOut[FFT_SIZE], fl32FFTMaxValue = 0, ,
UINT32 ui32FFTMaxIndex = 0,arm_cfft_radix4_instance_f32 FFT_InitStruc,
,
arm_cfft_instance_f32 FFT_InitStruc_dsp, ,
arm_status status = ARM_MATH_ARGUMENT_ERROR, // default failure//input data collection with timer interrupt from adc
,
void TIM2_IRQHandler(void)
,
{
,
UINT16 ui16ADC_Value = 0 ,
,
TIM_ClearITPendingBit(TIM2, TIM_IT_Update),
ui16ADC_Value = ADC_GetConversionValue(ADC1) ,
,
if((ui16ADCCnt <, ADC_RAW_LENGTH) &,&, (ui16ADC_Value >, 500) )
,
{
,
if((ui16CalibrateMaxValue <, ui16ADC_Value) ) {
,
ui16CalibrateMaxValue = ui16ADC_Value,
,
}
,
fl32ADCRaw[ui16ADCCnt] = (FLOAT32)ui16ADC_Value,
,
ui16ADCCnt++,
,
fl32ADCRaw[ui16ADCCnt] = 0.0,
,
ui16ADCCnt++,
,
}
,
}
,
// FFT calculation
,
status = arm_cfft_radix4_init_f32(&,FFT_InitStruc,FFT_SIZE,0,1),
arm_cfft_radix4_f32(&,FFT_InitStruc, fl32ADCRaw),
arm_cmplx_mag_f32(fl32ADCRaw,fl32FFTOut,FFT_SIZE),
arm_max_f32(fl32FFTOut, FFT_SIZE, &,fl32FFTMaxValue, &,ui32FFTMaxIndex),
,
// input sample data fl32ADCRaw
,
503
,
0
,
507
,
0
,
516
,
0
,
514
,
0
,
524
,
0
,
530
,
0
,
532
,
0
,
537
,
0
,
....
//arm_cfft_radix4_f32 function fl32ADCRaw
,
388595
,
0
,
0
,
0
,
-1186
,
1163
,
-1087
,
0
,
4.66130239e+011
,
-4.66130239e+011
,
-1186
,
-1163
,
4.66130239e+011
,
4.66130239e+011
,
-4.66130239e+011
,
4.66130239e+011
,
0
,
0
,
-4.66130239e+011
,
-4.66130239e+011
,
0
,
0
,
0
,
0
,
nan (0x7fffff) ,
nan (0x7fffff) ,
0
,
0
,
nan (0x7fffff) ,
nan (0x7fffff) ,
nan (0x7fffff) ,
nan (0x7fffff) ,
2.48002616e+012
//arm_cmplx_mag_f32 function fl32FFTOut data
,
5.66332883e+011
,
5.68833212e+011
,
1.86279645e+018
,
7.30765853e+011
,
1.86279645e+018
,
1.86279645e+018
,
0
,
1.86279645e+018
,
0
,
0
,
0
,
0
,
0
,
0
,
0
,
1.16413673e+013
,
0
,
1.67605685e+012
,
6.25887412e+011
,
inf
,
1.60195215e+012
,
inf
,
inf
,
0
,
inf
,
0
,
0
,
0
,
0
,
0
,
0
,
inf
,
0
,
inf ,
inf ,
inf ,
inf ,
inf ,
inf ,
0 ,
inf ,
0
