Andrew Durand / Mbed 2 deprecated GT_Tuner

Simple guitar tuner

Dependencies:   mbed

main.cpp@0:490e67fb09c2, 2011-10-24 (annotated)

Committer:
adurand
Date:
Mon Oct 24 23:03:27 2011 +0000
Revision:
0:490e67fb09c2
Child:
1:ae7d0cf78b3e

        

        
Who changed what in which revision?

        

            
                
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    //////////////////////////////////////////





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  //                                          //





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//    Guitar Tuner via Goertzel's Algorithm     //





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//          Created by: Andrew Durand           //





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  //                                          //





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    //////////////////////////////////////////





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#include "mbed.h"





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#include "adc.h"





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#include "NokiaLCD.h"





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#define PI 3.1415





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#define SAMPLE_RATE 24000





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DigitalOut led_low(LED1);





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DigitalOut led_ok(LED2);





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DigitalOut led_high(LED4);





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InterruptIn button1(p12);





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//LCD and Other Random Variables





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NokiaLCD lcd(p5, p7, p8, p9, NokiaLCD::LCD6610); // mosi, sclk, cs, rst, type





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int string_select = 0;





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float high, high1, high2, high3, high4, high5, high6, high7, high8, in_tune, in_tune1, in_tune2, in_tune3,





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low, low1, low2, low3, low4, low5, low6, low7, low8, note;





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char* key;





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int Counter = 0;





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int Buffer[6000];





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float goertzelFilter(int samples[], float freq, int N) {





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    float s_prev = 0.0;





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    float s_prev2 = 0.0;





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    float coeff,normalizedfreq,power,s,k;





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    int i;





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    normalizedfreq = freq / SAMPLE_RATE;





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    coeff = 2*cos(2*PI*normalizedfreq);





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    for (i=0; i<N; i++) {





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        s = samples[i] + coeff * s_prev - s_prev2;





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        s_prev2 = s_prev;





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        s_prev = s;





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    }





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    power = s_prev2*s_prev2+s_prev*s_prev-coeff*s_prev*s_prev2;





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    return power;





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}





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ADC adc(SAMPLE_RATE, 1);





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void sample_audio(int chan, uint32_t value) {





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    Buffer[Counter] = adc.read(p20);





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    Counter += 1;





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}





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void button1_pressed() {





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    string_select++;





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    if (string_select > 5) string_select = 0;





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}





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int main() {





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    //Interupt for Switching Strings





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    button1.mode(PullDown);





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    button1.rise(&button1_pressed);





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    //Setup LCD





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    lcd.background(0xF0000F);





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    lcd.cls();





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    while (1) {





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        switch (string_select) {





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            case 0:





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                note = 82;





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                key= "E2";





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                break;





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            case 1:





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                note = 110;





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                key= "A2";





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                break;





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            case 2:





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                note = 147;





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                key= "D3";





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                break;





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            case 3:





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                note = 196;





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                key= "G3";





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                break;





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            case 4:





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                note = 247;





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                key= "B3";





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                break;





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            case 5:





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                note = 330;





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                key= "E4";





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                break;





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        }





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        //Prepare for burst mode on all ADC pins and set up interrupt handler (using ADC library from Simon Blandford





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        adc.append(sample_audio);





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        adc.startmode(0,0);





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        adc.burst(1);





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        adc.setup(p20,1);





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        //start the interrupt and wait for about 4096 samples





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        adc.interrupt_state(p20,1);





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        wait(.2);





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        //Finsh up - Unset pin 20





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        adc.interrupt_state(p20,0);





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        adc.setup(p20,0);





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        int actual_rate = adc.actual_sample_rate();





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        //for debugging tell the terminal sample rate and how many samples we took





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        printf("Requested max sample rate is %u, actual max sample rate is %u.\n",





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               SAMPLE_RATE, actual_rate);





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        printf("We did %i samples\n",Counter);





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        high1 = goertzelFilter(Buffer, (note+18), Counter);





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        high2 = goertzelFilter(Buffer, (note+16), Counter);





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        high3 = goertzelFilter(Buffer, (note+14), Counter);





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        high4 = goertzelFilter(Buffer, (note+12), Counter);





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        high5 = goertzelFilter(Buffer, (note+10), Counter);





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        high6 = goertzelFilter(Buffer, (note+8), Counter);





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        high7 = goertzelFilter(Buffer, (note+6), Counter);





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        high8 = goertzelFilter(Buffer, (note+4), Counter);





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        in_tune1 =  goertzelFilter(Buffer, (note+0.5), Counter);





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        in_tune2 =  goertzelFilter(Buffer, note, Counter);





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        in_tune3 =  goertzelFilter(Buffer, (note-0.5), Counter);





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        low1 = goertzelFilter(Buffer, (note-4), Counter);





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        low2 = goertzelFilter(Buffer, (note-6), Counter);





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        low3 = goertzelFilter(Buffer, (note-8), Counter);





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        low4 = goertzelFilter(Buffer, (note-10), Counter);





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        low5 = goertzelFilter(Buffer, (note-12), Counter);





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        low6 = goertzelFilter(Buffer, (note-14), Counter);





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        low7 = goertzelFilter(Buffer, (note-16), Counter);





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        low8 = goertzelFilter(Buffer, (note-18), Counter);





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        in_tune = (in_tune1 + in_tune2 + in_tune3)/3;





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        high = (high1 + high2 + high3 + high4 + high5 + high6 + high7 + high8)/8;





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        low = (low1 + low2 + low3 + low4 + low5 + low6 + low7 + low8)/8;





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        if ((in_tune > high) && (in_tune > low)) {





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            led_high = 0;





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            led_ok = 1;





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            led_low = 0;





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        } else if (high > in_tune) {





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            led_high = 1;





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            led_ok = 0;





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            led_low = 0;





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        } else if (low > in_tune) {





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            led_high = 0;





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            led_ok = 0;





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            led_low = 1;





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        } else {





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            led_high = 0;





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            led_ok = 0;





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            led_low = 0;





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        }





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        // Display on the LCD





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        lcd.locate(0,1);





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        lcd.printf("::Guitar Tuner::");





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        lcd.locate(0,3);





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        lcd.printf("Tuning String: %i", (6-string_select));





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        lcd.locate(0,5);





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        lcd.printf("%s at %i Hz",key, (int) note);





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        lcd.locate(5,7);





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        if (led_ok) lcd.printf("In Tune!");





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        else if (led_low) lcd.printf("Too Low ");





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        else if (led_high) lcd.printf("Too High");





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        else lcd.printf("~~~~~");





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        Counter = 0;





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    }





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}