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Dependencies:   mbed

main.cpp@0:f0a3e5729b8f, 2019-10-16 (annotated)

Committer:
gemmaro
Date:
Wed Oct 16 04:09:09 2019 +0000
Revision:
0:f0a3e5729b8f
Child:
1:1bec1c13107e
First commit

Who changed what in which revision?

UserRevisionLine numberNew contents of line
gemmaro 0:f0a3e5729b8f 1 #include "mbed.h"
gemmaro 0:f0a3e5729b8f 2
gemmaro 0:f0a3e5729b8f 3 DigitalOut myled1(LED1);
gemmaro 0:f0a3e5729b8f 4 DigitalOut myled2(LED2);
gemmaro 0:f0a3e5729b8f 5 DigitalOut myled3(LED3);
gemmaro 0:f0a3e5729b8f 6 AnalogIn MicIn(p15);
gemmaro 0:f0a3e5729b8f 7 AnalogOut HeadPhoneOut(p18);
gemmaro 0:f0a3e5729b8f 8
gemmaro 0:f0a3e5729b8f 9 #define DATA_SIZE 15000
gemmaro 0:f0a3e5729b8f 10 #define PI 3.1415926535897932384626433832795
gemmaro 0:f0a3e5729b8f 11 signed short data[DATA_SIZE];
gemmaro 0:f0a3e5729b8f 12
gemmaro 0:f0a3e5729b8f 13 /**
gemmaro 0:f0a3e5729b8f 14 * fs: Frequency Sampling
gemmaro 0:f0a3e5729b8f 15 * offset: AD-C, DA-C
gemmaro 0:f0a3e5729b8f 16 */
gemmaro 0:f0a3e5729b8f 17 Timer t;
gemmaro 0:f0a3e5729b8f 18 int fs = 8000;
gemmaro 0:f0a3e5729b8f 19 int dt_us = 125;
gemmaro 0:f0a3e5729b8f 20 int offset;
gemmaro 0:f0a3e5729b8f 21
gemmaro 0:f0a3e5729b8f 22 int filter_size;
gemmaro 0:f0a3e5729b8f 23 double b[50];
gemmaro 0:f0a3e5729b8f 24 double w[50];
gemmaro 0:f0a3e5729b8f 25
gemmaro 0:f0a3e5729b8f 26 void wait100us(void) {
gemmaro 0:f0a3e5729b8f 27 while (t.read_us() < dt_us) {};
gemmaro 0:f0a3e5729b8f 28 t.reset();
gemmaro 0:f0a3e5729b8f 29 }
gemmaro 0:f0a3e5729b8f 30
gemmaro 0:f0a3e5729b8f 31 void rec(void) {
gemmaro 0:f0a3e5729b8f 32 unsigned short InDat;
gemmaro 0:f0a3e5729b8f 33 int i;
gemmaro 0:f0a3e5729b8f 34
gemmaro 0:f0a3e5729b8f 35 /// recording
gemmaro 0:f0a3e5729b8f 36 myled1 = 1;
gemmaro 0:f0a3e5729b8f 37 for (i = 0; i < DATA_SIZE; ++i) {
gemmaro 0:f0a3e5729b8f 38 InDat = MicIn.read_u16() >> 4;
gemmaro 0:f0a3e5729b8f 39 data[i] = InDat;
gemmaro 0:f0a3e5729b8f 40 wait100us();
gemmaro 0:f0a3e5729b8f 41 }
gemmaro 0:f0a3e5729b8f 42 myled1 = 0;
gemmaro 0:f0a3e5729b8f 43 }
gemmaro 0:f0a3e5729b8f 44
gemmaro 0:f0a3e5729b8f 45 void get_offset(void) {
gemmaro 0:f0a3e5729b8f 46 unsigned short InDat;
gemmaro 0:f0a3e5729b8f 47 double a = 0;
gemmaro 0:f0a3e5729b8f 48 int i;
gemmaro 0:f0a3e5729b8f 49 for (i = 0; i < 1000; ++i) {
gemmaro 0:f0a3e5729b8f 50 InDat = MicIn.read_u16() >> 4;
gemmaro 0:f0a3e5729b8f 51 a += (double)InDat;
gemmaro 0:f0a3e5729b8f 52 wait100us();
gemmaro 0:f0a3e5729b8f 53 }
gemmaro 0:f0a3e5729b8f 54 offset = (unsigned int)(a / 1000);
gemmaro 0:f0a3e5729b8f 55 printf("%d\n\r", offset);
gemmaro 0:f0a3e5729b8f 56 }
gemmaro 0:f0a3e5729b8f 57
gemmaro 0:f0a3e5729b8f 58 void hanning_window(int window_size) {
gemmaro 0:f0a3e5729b8f 59 int i;
gemmaro 0:f0a3e5729b8f 60 for (i = 0; i < window_size; ++i) {
gemmaro 0:f0a3e5729b8f 61 w[i] = 0.5 - 0.5 * cos(2 * PI * ((i + 1) - 0.5) / window_size);
gemmaro 0:f0a3e5729b8f 62 }
gemmaro 0:f0a3e5729b8f 63 }
gemmaro 0:f0a3e5729b8f 64
gemmaro 0:f0a3e5729b8f 65 int lps(int k, int offsets, int fc) {
gemmaro 0:f0a3e5729b8f 66 if (k == offsets) {
gemmaro 0:f0a3e5729b8f 67 return 2 * fc;
gemmaro 0:f0a3e5729b8f 68 }
gemmaro 0:f0a3e5729b8f 69 return 2 * fc * sin(2 * PI * fc * (k - offsets)) / (2 * PI * fc * (k - offsets));
gemmaro 0:f0a3e5729b8f 70 }
gemmaro 0:f0a3e5729b8f 71
gemmaro 0:f0a3e5729b8f 72 int high_pass_filter(int k, int offsets, int fc) {
gemmaro 0:f0a3e5729b8f 73 if (k == offsets) {
gemmaro 0:f0a3e5729b8f 74 return 1 - 2 * fc;
gemmaro 0:f0a3e5729b8f 75 }
gemmaro 0:f0a3e5729b8f 76 return -2 * fc * sin(2 * PI * fc * k) / (2 * PI * fc * k);
gemmaro 0:f0a3e5729b8f 77 }
gemmaro 0:f0a3e5729b8f 78
gemmaro 0:f0a3e5729b8f 79 int band_pass_filter(int k, int offsets, int fc1, int fc2) {
gemmaro 0:f0a3e5729b8f 80 if (k == offsets) {
gemmaro 0:f0a3e5729b8f 81 return 2 * (fc2 - fc1);
gemmaro 0:f0a3e5729b8f 82 }
gemmaro 0:f0a3e5729b8f 83 return 2 * fc2 * sin(2 * PI * fc2 * k) / (2 * PI * fc2 * k) - 2 * fc1 * sin(2 * PI * fc1 * k) / (2 * PI * fc1 * k);
gemmaro 0:f0a3e5729b8f 84 }
gemmaro 0:f0a3e5729b8f 85
gemmaro 0:f0a3e5729b8f 86 int band_eliminate_filter(int k, int offsets, int fc1, int fc2) {
gemmaro 0:f0a3e5729b8f 87 if (k == offsets) {
gemmaro 0:f0a3e5729b8f 88 return 1 - 2 * (fc2 - fc1);
gemmaro 0:f0a3e5729b8f 89 }
gemmaro 0:f0a3e5729b8f 90 return 2 * fc1 * sin(2 * PI * fc1 * k) / (2 * PI * fc1 * k) - 2 * fc2 * sin(2 * PI * fc2 * k) / (2 * PI * fc2 * k);
gemmaro 0:f0a3e5729b8f 91 }
gemmaro 0:f0a3e5729b8f 92
gemmaro 0:f0a3e5729b8f 93 void fir_lpf(int fs, int fe, int delta) {
gemmaro 0:f0a3e5729b8f 94 int offsets;
gemmaro 0:f0a3e5729b8f 95 int k;
gemmaro 0:f0a3e5729b8f 96 float fc, delta_s;
gemmaro 0:f0a3e5729b8f 97
gemmaro 0:f0a3e5729b8f 98 fc = (((float)fe +(float)delta / 2) / fs);
gemmaro 0:f0a3e5729b8f 99 delta_s = ((float)delta / fs);
gemmaro 0:f0a3e5729b8f 100 filter_size = (int)(3.1 / delta_s);
gemmaro 0:f0a3e5729b8f 101 if (filter_size % 2 == 0) filter_size += 1;
gemmaro 0:f0a3e5729b8f 102 hanning_window(filter_size);
gemmaro 0:f0a3e5729b8f 103
gemmaro 0:f0a3e5729b8f 104 offsets = (filter_size - 1) / 2;
gemmaro 0:f0a3e5729b8f 105 for (k = 0; k < filter_size; ++k) {
gemmaro 0:f0a3e5729b8f 106 b[k] = lps(k, offsets, fc);
gemmaro 0:f0a3e5729b8f 107 }
gemmaro 0:f0a3e5729b8f 108
gemmaro 0:f0a3e5729b8f 109 for (k = 0; k < filter_size; ++k) {
gemmaro 0:f0a3e5729b8f 110 b[k] *= w[k];
gemmaro 0:f0a3e5729b8f 111 }
gemmaro 0:f0a3e5729b8f 112 }
gemmaro 0:f0a3e5729b8f 113
gemmaro 0:f0a3e5729b8f 114 int main() {
gemmaro 0:f0a3e5729b8f 115 unsigned short InDat, OutDat;
gemmaro 0:f0a3e5729b8f 116 int fe = 100;
gemmaro 0:f0a3e5729b8f 117 int delta = 1000;
gemmaro 0:f0a3e5729b8f 118 int fs = 8000;
gemmaro 0:f0a3e5729b8f 119 int n, k;
gemmaro 0:f0a3e5729b8f 120 double y;
gemmaro 0:f0a3e5729b8f 121
gemmaro 0:f0a3e5729b8f 122 /// Timer interrupt
gemmaro 0:f0a3e5729b8f 123 t.start();
gemmaro 0:f0a3e5729b8f 124 t.reset();
gemmaro 0:f0a3e5729b8f 125 get_offset();
gemmaro 0:f0a3e5729b8f 126
gemmaro 0:f0a3e5729b8f 127 /// Filter parameter
gemmaro 0:f0a3e5729b8f 128 myled1 = 1;
gemmaro 0:f0a3e5729b8f 129 fir_lpf(fs, fe, delta);
gemmaro 0:f0a3e5729b8f 130 myled1 = 0;
gemmaro 0:f0a3e5729b8f 131
gemmaro 0:f0a3e5729b8f 132 while(1) {
gemmaro 0:f0a3e5729b8f 133 myled2 = 1;
gemmaro 0:f0a3e5729b8f 134 rec();
gemmaro 0:f0a3e5729b8f 135 wait(2);
gemmaro 0:f0a3e5729b8f 136 myled2 = 0;
gemmaro 0:f0a3e5729b8f 137
gemmaro 0:f0a3e5729b8f 138 /// filter
gemmaro 0:f0a3e5729b8f 139 myled3 = 1;
gemmaro 0:f0a3e5729b8f 140 for (n = filter_size; n < DATA_SIZE; ++n) {
gemmaro 0:f0a3e5729b8f 141 y = 0;
gemmaro 0:f0a3e5729b8f 142 for (k = 0; k < filter_size; ++k) {
gemmaro 0:f0a3e5729b8f 143 y += (int)(b[k] * (data[n - k] - offset));
gemmaro 0:f0a3e5729b8f 144 }
gemmaro 0:f0a3e5729b8f 145 InDat = y + offset;
gemmaro 0:f0a3e5729b8f 146 OutDat = InDat >> 2;
gemmaro 0:f0a3e5729b8f 147 HeadPhoneOut.write_u16(OutDat << 6);
gemmaro 0:f0a3e5729b8f 148 wait100us();
gemmaro 0:f0a3e5729b8f 149 }
gemmaro 0:f0a3e5729b8f 150 myled3 = 0;
gemmaro 0:f0a3e5729b8f 151 }
gemmaro 0:f0a3e5729b8f 152 }