Steven Swenson / Mbed 2 deprecated tuner

A program to automatically tune a guitar. Written by Justin Reidhead and Steven Swenson

Dependencies:   FFT FrequencyFinder Motor NewTextLCD PinDetect mbed strings

FrequencyFinder/FrequencyFinder.cpp@8:651fbf5ae98a, 2012-04-20 (annotated)

Committer:
melangeaddict
Date:
Fri Apr 20 21:27:55 2012 +0000
Revision:
8:651fbf5ae98a
Parent:
2:9c0a83c5ded5
Child:
9:2a211133e79a
3:30 april 20;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
melangeaddict 2:9c0a83c5ded5 1 #include "FrequencyFinder.h"
melangeaddict 2:9c0a83c5ded5 2
melangeaddict 2:9c0a83c5ded5 3 using namespace std;
melangeaddict 2:9c0a83c5ded5 4
melangeaddict 2:9c0a83c5ded5 5 FrequencyFinder::FrequencyFinder(PinName input) : _signal_in(input), _dc_offset(p18){
melangeaddict 2:9c0a83c5ded5 6 index=0;
melangeaddict 2:9c0a83c5ded5 7 peak=0;
melangeaddict 2:9c0a83c5ded5 8 frequency_final=0;
melangeaddict 2:9c0a83c5ded5 9 }
melangeaddict 2:9c0a83c5ded5 10
melangeaddict 2:9c0a83c5ded5 11 FrequencyFinder::~FrequencyFinder() {
melangeaddict 2:9c0a83c5ded5 12 ticker.detach();
melangeaddict 2:9c0a83c5ded5 13 }
melangeaddict 2:9c0a83c5ded5 14
melangeaddict 2:9c0a83c5ded5 15 float FrequencyFinder::find_frequency() {
melangeaddict 2:9c0a83c5ded5 16 initialize_array();
melangeaddict 2:9c0a83c5ded5 17 ticker.attach_us(this, &FrequencyFinder::get_data,500);
melangeaddict 2:9c0a83c5ded5 18
melangeaddict 2:9c0a83c5ded5 19 wait(1);
melangeaddict 2:9c0a83c5ded5 20 ticker.detach();
melangeaddict 2:9c0a83c5ded5 21
melangeaddict 2:9c0a83c5ded5 22 vRealFFT(signal_array-1,size);
melangeaddict 2:9c0a83c5ded5 23
melangeaddict 2:9c0a83c5ded5 24 take_abs();
melangeaddict 2:9c0a83c5ded5 25
melangeaddict 2:9c0a83c5ded5 26 int peak = find_peak();
melangeaddict 2:9c0a83c5ded5 27
melangeaddict 2:9c0a83c5ded5 28 float frequency_final=((float)peak)/4.1;
melangeaddict 2:9c0a83c5ded5 29
melangeaddict 2:9c0a83c5ded5 30 return frequency_final;
melangeaddict 2:9c0a83c5ded5 31 }
melangeaddict 2:9c0a83c5ded5 32
melangeaddict 2:9c0a83c5ded5 33 void FrequencyFinder::get_data() {
melangeaddict 2:9c0a83c5ded5 34 if (index<size) {
melangeaddict 2:9c0a83c5ded5 35 signal_array[index]=_signal_in.read();//-0.5);
melangeaddict 2:9c0a83c5ded5 36 index++;
melangeaddict 2:9c0a83c5ded5 37 }
melangeaddict 2:9c0a83c5ded5 38 }
melangeaddict 2:9c0a83c5ded5 39
melangeaddict 2:9c0a83c5ded5 40 void FrequencyFinder::take_abs() {
melangeaddict 2:9c0a83c5ded5 41 //takes the absolute value of the signal
melangeaddict 2:9c0a83c5ded5 42 for (int j=0; j<size; j++) {
melangeaddict 2:9c0a83c5ded5 43 signal_array[j]=abs(signal_array[j]);
melangeaddict 2:9c0a83c5ded5 44 if (j<100)
melangeaddict 2:9c0a83c5ded5 45 signal_array[j]=0;
melangeaddict 2:9c0a83c5ded5 46 else if (j<400)
melangeaddict 8:651fbf5ae98a 47 signal_array[j]=signal_array[j]*5;
melangeaddict 2:9c0a83c5ded5 48 else if (j<600)
melangeaddict 8:651fbf5ae98a 49 signal_array[j]=signal_array[j]*6;
melangeaddict 2:9c0a83c5ded5 50 else if (j<800)
melangeaddict 8:651fbf5ae98a 51 signal_array[j]=signal_array[j]*7;
melangeaddict 2:9c0a83c5ded5 52 else
melangeaddict 8:651fbf5ae98a 53 signal_array[j]=signal_array[j]*8;
melangeaddict 2:9c0a83c5ded5 54 }
melangeaddict 2:9c0a83c5ded5 55 }
melangeaddict 2:9c0a83c5ded5 56
melangeaddict 2:9c0a83c5ded5 57 int FrequencyFinder::find_peak() {
melangeaddict 2:9c0a83c5ded5 58 int i=0;
melangeaddict 2:9c0a83c5ded5 59
melangeaddict 2:9c0a83c5ded5 60 for (int j=0; j<size; j++) {
melangeaddict 2:9c0a83c5ded5 61 if ((signal_array[i]-signal_array[i-1])>100 ) {
melangeaddict 2:9c0a83c5ded5 62 while (
melangeaddict 2:9c0a83c5ded5 63 (signal_array[i]<=signal_array[i+1]) &&
melangeaddict 2:9c0a83c5ded5 64 (signal_array[i]<=signal_array[i+2]) &&
melangeaddict 2:9c0a83c5ded5 65 (signal_array[i]<=signal_array[i+3]) &&
melangeaddict 2:9c0a83c5ded5 66 (signal_array[i]<=signal_array[i+4])) {
melangeaddict 2:9c0a83c5ded5 67 i++;
melangeaddict 2:9c0a83c5ded5 68 }
melangeaddict 2:9c0a83c5ded5 69 return FrequencyFinder::find_max(i);
melangeaddict 2:9c0a83c5ded5 70 }
melangeaddict 2:9c0a83c5ded5 71 i++;
melangeaddict 2:9c0a83c5ded5 72 }
melangeaddict 2:9c0a83c5ded5 73 return FrequencyFinder::find_max(i);
melangeaddict 2:9c0a83c5ded5 74 }
melangeaddict 2:9c0a83c5ded5 75
melangeaddict 2:9c0a83c5ded5 76 int FrequencyFinder::find_max(int position) {
melangeaddict 2:9c0a83c5ded5 77 int index1=position-20;
melangeaddict 2:9c0a83c5ded5 78 int index2=position+20;
melangeaddict 2:9c0a83c5ded5 79 float max=signal_array[index1];
melangeaddict 2:9c0a83c5ded5 80 int max_index=0;
melangeaddict 2:9c0a83c5ded5 81
melangeaddict 2:9c0a83c5ded5 82 for (int a=index1; a<index2; a++) {
melangeaddict 2:9c0a83c5ded5 83 if (signal_array[a]>max) {
melangeaddict 2:9c0a83c5ded5 84 max=signal_array[a];
melangeaddict 2:9c0a83c5ded5 85 max_index=a;
melangeaddict 2:9c0a83c5ded5 86 }
melangeaddict 2:9c0a83c5ded5 87 }
melangeaddict 2:9c0a83c5ded5 88
melangeaddict 2:9c0a83c5ded5 89 return max_index;
melangeaddict 2:9c0a83c5ded5 90 }
melangeaddict 2:9c0a83c5ded5 91
melangeaddict 2:9c0a83c5ded5 92 void FrequencyFinder::initialize_array() {
melangeaddict 2:9c0a83c5ded5 93 index=0;
melangeaddict 2:9c0a83c5ded5 94 for (int w=0; w<size; w++) {
melangeaddict 2:9c0a83c5ded5 95 signal_array[w]=0;
melangeaddict 2:9c0a83c5ded5 96 }
melangeaddict 2:9c0a83c5ded5 97 }