GT_Tuner - Simple guitar tuner

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Andrew Durand / Mbed 2 deprecated GT_Tuner

Simple guitar tuner

main.cpp@1:ae7d0cf78b3e, 2011-10-26 (annotated)

Committer:: adurand
Date:: Wed Oct 26 02:01:28 2011 +0000
Revision:: 1:ae7d0cf78b3e
Parent:: 0:490e67fb09c2

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User	Revision	Line number	New contents of line
adurand	0:490e67fb09c2	1	//////////////////////////////////////////
adurand	0:490e67fb09c2	2	// //
adurand	0:490e67fb09c2	3	// Guitar Tuner via Goertzel's Algorithm //
adurand	0:490e67fb09c2	4	// Created by: Andrew Durand //
adurand	0:490e67fb09c2	5	// //
adurand	0:490e67fb09c2	6	//////////////////////////////////////////
adurand	0:490e67fb09c2	7
adurand	0:490e67fb09c2	8	#include "mbed.h"
adurand	0:490e67fb09c2	9	#include "adc.h"
adurand	0:490e67fb09c2	10	#include "NokiaLCD.h"
adurand	1:ae7d0cf78b3e	11	#include <math.h>
adurand	0:490e67fb09c2	12	#define PI 3.1415
adurand	0:490e67fb09c2	13	#define SAMPLE_RATE 24000
adurand	0:490e67fb09c2	14
adurand	0:490e67fb09c2	15	DigitalOut led_low(LED1);
adurand	0:490e67fb09c2	16	DigitalOut led_ok(LED2);
adurand	0:490e67fb09c2	17	DigitalOut led_high(LED4);
adurand	0:490e67fb09c2	18	InterruptIn button1(p12);
adurand	0:490e67fb09c2	19
adurand	0:490e67fb09c2	20	//LCD and Other Random Variables
adurand	0:490e67fb09c2	21	NokiaLCD lcd(p5, p7, p8, p9, NokiaLCD::LCD6610); // mosi, sclk, cs, rst, type
adurand	0:490e67fb09c2	22	int string_select = 0;
adurand	1:ae7d0cf78b3e	23	float high, high1, in_tune, in_tune1, in_tune2, in_tune3,
adurand	1:ae7d0cf78b3e	24	low, low1, note, low_mod, high_mod;
adurand	0:490e67fb09c2	25	char* key;
adurand	0:490e67fb09c2	26	int Counter = 0;
adurand	0:490e67fb09c2	27	int Buffer[6000];
adurand	0:490e67fb09c2	28
adurand	0:490e67fb09c2	29	float goertzelFilter(int samples[], float freq, int N) {
adurand	0:490e67fb09c2	30	float s_prev = 0.0;
adurand	0:490e67fb09c2	31	float s_prev2 = 0.0;
adurand	0:490e67fb09c2	32	float coeff,normalizedfreq,power,s,k;
adurand	0:490e67fb09c2	33	int i;
adurand	0:490e67fb09c2	34	normalizedfreq = freq / SAMPLE_RATE;
adurand	0:490e67fb09c2	35	coeff = 2cos(2PI*normalizedfreq);
adurand	0:490e67fb09c2	36	for (i=0; i<N; i++) {
adurand	0:490e67fb09c2	37	s = samples[i] + coeff * s_prev - s_prev2;
adurand	0:490e67fb09c2	38	s_prev2 = s_prev;
adurand	0:490e67fb09c2	39	s_prev = s;
adurand	0:490e67fb09c2	40	}
adurand	0:490e67fb09c2	41	power = s_prev2s_prev2+s_prevs_prev-coeffs_prevs_prev2;
adurand	0:490e67fb09c2	42	return power;
adurand	0:490e67fb09c2	43	}
adurand	0:490e67fb09c2	44
adurand	0:490e67fb09c2	45	ADC adc(SAMPLE_RATE, 1);
adurand	0:490e67fb09c2	46
adurand	0:490e67fb09c2	47	void sample_audio(int chan, uint32_t value) {
adurand	0:490e67fb09c2	48	Buffer[Counter] = adc.read(p20);
adurand	0:490e67fb09c2	49	Counter += 1;
adurand	0:490e67fb09c2	50	}
adurand	0:490e67fb09c2	51
adurand	0:490e67fb09c2	52	void button1_pressed() {
adurand	0:490e67fb09c2	53	string_select++;
adurand	0:490e67fb09c2	54	if (string_select > 5) string_select = 0;
adurand	0:490e67fb09c2	55	}
adurand	0:490e67fb09c2	56
adurand	0:490e67fb09c2	57	int main() {
adurand	0:490e67fb09c2	58	//Interupt for Switching Strings
adurand	0:490e67fb09c2	59	button1.mode(PullDown);
adurand	0:490e67fb09c2	60	button1.rise(&button1_pressed);
adurand	0:490e67fb09c2	61
adurand	0:490e67fb09c2	62	//Setup LCD
adurand	0:490e67fb09c2	63	lcd.background(0xF0000F);
adurand	0:490e67fb09c2	64	lcd.cls();
adurand	0:490e67fb09c2	65
adurand	0:490e67fb09c2	66	while (1) {
adurand	0:490e67fb09c2	67
adurand	0:490e67fb09c2	68	switch (string_select) {
adurand	0:490e67fb09c2	69	case 0:
adurand	0:490e67fb09c2	70	note = 82;
adurand	0:490e67fb09c2	71	key= "E2";
adurand	0:490e67fb09c2	72	break;
adurand	0:490e67fb09c2	73	case 1:
adurand	0:490e67fb09c2	74	note = 110;
adurand	0:490e67fb09c2	75	key= "A2";
adurand	0:490e67fb09c2	76	break;
adurand	0:490e67fb09c2	77	case 2:
adurand	0:490e67fb09c2	78	note = 147;
adurand	0:490e67fb09c2	79	key= "D3";
adurand	0:490e67fb09c2	80	break;
adurand	0:490e67fb09c2	81	case 3:
adurand	0:490e67fb09c2	82	note = 196;
adurand	0:490e67fb09c2	83	key= "G3";
adurand	0:490e67fb09c2	84	break;
adurand	0:490e67fb09c2	85	case 4:
adurand	0:490e67fb09c2	86	note = 247;
adurand	0:490e67fb09c2	87	key= "B3";
adurand	0:490e67fb09c2	88	break;
adurand	0:490e67fb09c2	89	case 5:
adurand	0:490e67fb09c2	90	note = 330;
adurand	0:490e67fb09c2	91	key= "E4";
adurand	0:490e67fb09c2	92	break;
adurand	0:490e67fb09c2	93	}
adurand	0:490e67fb09c2	94
adurand	0:490e67fb09c2	95	//Prepare for burst mode on all ADC pins and set up interrupt handler (using ADC library from Simon Blandford
adurand	0:490e67fb09c2	96	adc.append(sample_audio);
adurand	0:490e67fb09c2	97	adc.startmode(0,0);
adurand	0:490e67fb09c2	98	adc.burst(1);
adurand	0:490e67fb09c2	99	adc.setup(p20,1);
adurand	0:490e67fb09c2	100
adurand	0:490e67fb09c2	101	//start the interrupt and wait for about 4096 samples
adurand	0:490e67fb09c2	102	adc.interrupt_state(p20,1);
adurand	0:490e67fb09c2	103	wait(.2);
adurand	0:490e67fb09c2	104
adurand	0:490e67fb09c2	105	//Finsh up - Unset pin 20
adurand	0:490e67fb09c2	106	adc.interrupt_state(p20,0);
adurand	0:490e67fb09c2	107	adc.setup(p20,0);
adurand	0:490e67fb09c2	108	int actual_rate = adc.actual_sample_rate();
adurand	0:490e67fb09c2	109
adurand	0:490e67fb09c2	110	//for debugging tell the terminal sample rate and how many samples we took
adurand	0:490e67fb09c2	111	printf("Requested max sample rate is %u, actual max sample rate is %u.\n",
adurand	0:490e67fb09c2	112	SAMPLE_RATE, actual_rate);
adurand	0:490e67fb09c2	113	printf("We did %i samples\n",Counter);
adurand	0:490e67fb09c2	114
adurand	1:ae7d0cf78b3e	115	high = 0;
adurand	1:ae7d0cf78b3e	116	low = 0;
adurand	1:ae7d0cf78b3e	117	for (int i=3; i<46; i+=3) {
adurand	1:ae7d0cf78b3e	118	high1 = goertzelFilter(Buffer, (note + i ), Counter);
adurand	1:ae7d0cf78b3e	119	if (high1 > high) high=high1;
adurand	1:ae7d0cf78b3e	120	}
adurand	1:ae7d0cf78b3e	121	for (int i=3; i<46; i+=3) {
adurand	1:ae7d0cf78b3e	122	low1 = goertzelFilter(Buffer, (note - i ), Counter);
adurand	1:ae7d0cf78b3e	123	if (low1 > low) low=low1;
adurand	1:ae7d0cf78b3e	124	}
adurand	1:ae7d0cf78b3e	125	in_tune1 = goertzelFilter(Buffer, (note+1), Counter);
adurand	0:490e67fb09c2	126	in_tune2 = goertzelFilter(Buffer, note, Counter);
adurand	1:ae7d0cf78b3e	127	in_tune3 = goertzelFilter(Buffer, (note-1), Counter);
adurand	1:ae7d0cf78b3e	128
adurand	1:ae7d0cf78b3e	129	if ((in_tune1 > in_tune2) && (in_tune1 > in_tune3)) in_tune = in_tune1;
adurand	1:ae7d0cf78b3e	130	else if ((in_tune2 > in_tune1) && (in_tune2 > in_tune3)) in_tune = in_tune2;
adurand	1:ae7d0cf78b3e	131	else in_tune = in_tune3;
adurand	1:ae7d0cf78b3e	132	// printf("high = %.2f, low = %.2f, in_tune = %.2f", high, low, in_tune);
adurand	1:ae7d0cf78b3e	133	// high_mod = high/in_tune;
adurand	1:ae7d0cf78b3e	134	// low_mod = low/in_tune;
adurand	1:ae7d0cf78b3e	135	// if ((high_mod > .8)&&(low_mod > .8)) {
adurand	1:ae7d0cf78b3e	136	// led_high = 0;
adurand	1:ae7d0cf78b3e	137	// led_ok = 0;
adurand	1:ae7d0cf78b3e	138	// led_low = 0;
adurand	1:ae7d0cf78b3e	139	// }
adurand	0:490e67fb09c2	140	if ((in_tune > high) && (in_tune > low)) {
adurand	0:490e67fb09c2	141	led_high = 0;
adurand	0:490e67fb09c2	142	led_ok = 1;
adurand	0:490e67fb09c2	143	led_low = 0;
adurand	0:490e67fb09c2	144	} else if (high > in_tune) {
adurand	0:490e67fb09c2	145	led_high = 1;
adurand	0:490e67fb09c2	146	led_ok = 0;
adurand	0:490e67fb09c2	147	led_low = 0;
adurand	0:490e67fb09c2	148	} else if (low > in_tune) {
adurand	0:490e67fb09c2	149	led_high = 0;
adurand	0:490e67fb09c2	150	led_ok = 0;
adurand	0:490e67fb09c2	151	led_low = 1;
adurand	0:490e67fb09c2	152	} else {
adurand	0:490e67fb09c2	153	led_high = 0;
adurand	0:490e67fb09c2	154	led_ok = 0;
adurand	0:490e67fb09c2	155	led_low = 0;
adurand	0:490e67fb09c2	156	}
adurand	1:ae7d0cf78b3e	157
adurand	0:490e67fb09c2	158	// Display on the LCD
adurand	0:490e67fb09c2	159	lcd.locate(0,1);
adurand	0:490e67fb09c2	160	lcd.printf("::Guitar Tuner::");
adurand	0:490e67fb09c2	161	lcd.locate(0,3);
adurand	0:490e67fb09c2	162	lcd.printf("Tuning String: %i", (6-string_select));
adurand	0:490e67fb09c2	163	lcd.locate(0,5);
adurand	0:490e67fb09c2	164	lcd.printf("%s at %i Hz",key, (int) note);
adurand	0:490e67fb09c2	165	lcd.locate(5,7);
adurand	0:490e67fb09c2	166	if (led_ok) lcd.printf("In Tune!");
adurand	0:490e67fb09c2	167	else if (led_low) lcd.printf("Too Low ");
adurand	0:490e67fb09c2	168	else if (led_high) lcd.printf("Too High");
adurand	1:ae7d0cf78b3e	169	else lcd.printf("~~~~~~~~");
adurand	0:490e67fb09c2	170
adurand	0:490e67fb09c2	171	Counter = 0;
adurand	0:490e67fb09c2	172
adurand	0:490e67fb09c2	173	}
adurand	0:490e67fb09c2	174
adurand	0:490e67fb09c2	175
adurand	0:490e67fb09c2	176
adurand	0:490e67fb09c2	177	}

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Type:	Program
Mbed OS support:	Mbed 2 deprecated
Created:	24 Oct 2011
Imports:	123
Forks:	1
Commits:	2
Dependents:	0
Dependencies:	1
Followers:	2

main.cpp@1:ae7d0cf78b3e, 2011-10-26 (annotated)

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