/
arm_fft_bin_example_f32.c
executable file
·152 lines (125 loc) · 4.74 KB
/
arm_fft_bin_example_f32.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
/* ----------------------------------------------------------------------
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* $Date: 29. November 2010
* $Revision: V1.0.3
*
* Project: CMSIS DSP Library
* Title: arm_fft_bin_example_f32.c
*
* Description: Example code demonstrating calculation of Max energy bin of
* frequency domain of input signal.
*
* Target Processor: Cortex-M4/Cortex-M3
*
*
* Version 1.0.3 2010/11/29
* Re-organized the CMSIS folders and updated documentation.
*
* Version 1.0.1 2010/10/05 KK
* Production release and review comments incorporated.
*
* Version 1.0.0 2010/09/20 KK
* Production release and review comments incorporated.
* ------------------------------------------------------------------- */
/**
* @ingroup groupExamples
*/
/**
* @defgroup FrequencyBin Frequency Bin Example
*
* \par Description
* \par
* Demonstrates the calculation of the maximum energy bin in the frequency
* domain of the input signal with the use of Complex FFT, Complex
* Magnitude, and Maximum functions.
*
* \par Algorithm:
* \par
* The input test signal contains a 10 kHz signal with uniformly distributed white noise.
* Calculating the FFT of the input signal will give us the maximum energy of the
* bin corresponding to the input frequency of 10 kHz.
*
* \par Block Diagram:
* \image html FFTBin.gif "Block Diagram"
* \par
* The figure below shows the time domain signal of 10 kHz signal with
* uniformly distributed white noise, and the next figure shows the input
* in the frequency domain. The bin with maximum energy corresponds to 10 kHz signal.
* \par
* \image html FFTBinInput.gif "Input signal in Time domain"
* \image html FFTBinOutput.gif "Input signal in Frequency domain"
*
* \par Variables Description:
* \par
* \li \c testInput_f32_10khz points to the input data
* \li \c testOutput points to the output data
* \li \c fftSize length of FFT
* \li \c ifftFlag flag for the selection of CFFT/CIFFT
* \li \c doBitReverse Flag for selection of normal order or bit reversed order
* \li \c refIndex reference index value at which maximum energy of bin ocuurs
* \li \c testIndex calculated index value at which maximum energy of bin ocuurs
*
* \par CMSIS DSP Software Library Functions Used:
* \par
* - arm_cfft_radix4_init_f32()
* - arm_cfft_radix4_f32()
* - arm_cmplx_mag_f32()
* - arm_max_f32()
*
* <b> Refer </b>
* \link arm_fft_bin_example_f32.c \endlink
*
*/
/** \example arm_fft_bin_example_f32.c
*/
#include "arm_math.h"
#define TEST_LENGTH_SAMPLES 2048
/* -------------------------------------------------------------------
* External Input and Output buffer Declarations for FFT Bin Example
* ------------------------------------------------------------------- */
extern float32_t testInput_f32_10khz[TEST_LENGTH_SAMPLES];
static float32_t testOutput[TEST_LENGTH_SAMPLES/2];
/* ------------------------------------------------------------------
* Global variables for FFT Bin Example
* ------------------------------------------------------------------- */
uint32_t fftSize = 1024;
uint32_t ifftFlag = 0;
uint32_t doBitReverse = 1;
/* Reference index at which max energy of bin ocuurs */
uint32_t refIndex = 213, testIndex = 0;
/* ----------------------------------------------------------------------
* Max magnitude FFT Bin test
* ------------------------------------------------------------------- */
int32_t main(void)
{
arm_status status;
arm_cfft_radix4_instance_f32 S;
float32_t maxValue;
status = ARM_MATH_SUCCESS;
/* Initialize the CFFT/CIFFT module */
status = arm_cfft_radix4_init_f32(&S, fftSize,
ifftFlag, doBitReverse);
/* Process the data through the CFFT/CIFFT module */
arm_cfft_radix4_f32(&S, testInput_f32_10khz);
/* Process the data through the Complex Magnitude Module for
calculating the magnitude at each bin */
arm_cmplx_mag_f32(testInput_f32_10khz, testOutput,
fftSize);
/* Calculates maxValue and returns corresponding BIN value */
arm_max_f32(testOutput, fftSize, &maxValue, &testIndex);
if(testIndex != refIndex)
{
status = ARM_MATH_TEST_FAILURE;
}
/* ----------------------------------------------------------------------
** Loop here if the signals fail the PASS check.
** This denotes a test failure
** ------------------------------------------------------------------- */
if( status != ARM_MATH_SUCCESS)
{
while(1);
}
while(1); /* main function does not return */
}
/** \endlink */