Tesla Coil Greensleeves

/*
 * TC_Greensleeves.c
 *
 * Created: 11/7/2014 12:31:38 AM
 *  Author: grist.carrigafoyl

 Play Greensleeves on a Microbrute Tesla Coil.

 v 1.00  Starting simple using a fixed pulse width.

 */
#define F_CPU 16000000UL // 16MHz

// Because I'm sick of crawling the datasheet. These should probably go in a header file.
#define T0_MODE_CTC     _BV(WGM01)
#define T0_PRESC_1      _BV(CS00)
#define T0_PRESC_8      _BV(CS01)
#define T0_PRESC_64     _BV(CS01) | _BV(CS00)
#define T0_PRESC_256    _BV(CS02)
#define T0_PRESC_1024   _BV(CS02) | _BV(CS00)

#define T1_MODE_CTC     _BV(WGM12)
#define T1_PRESC_1      _BV(CS10)
#define T1_PRESC_8      _BV(CS11)
#define T1_PRESC_64     _BV(CS11) | _BV(CS10)
#define T1_PRESC_256    _BV(CS12)
#define T1_PRESC_1024   _BV(CS12) | _BV(CS12)

#define T2_MODE_CTC     _BV(WGM21)
#define T2_PRESC_1      _BV(CS20)
#define T2_PRESC_8      _BV(CS21)
#define T2_PRESC_32     _BV(CS21) | _BV(CS20)
#define T2_PRESC_64     _BV(CS22)
#define T2_PRESC_128    _BV(CS22) | _BV(CS20)
#define T2_PRESC_256    _BV(CS22) | _BV(CS21)
#define T2_PRESC_1024   _BV(CS22) | _BV(CS21) | _BV(CS20)


#include <avr/io.h>
#include <avr/interrupt.h>

int pulse_width = 60; // microseconds

// some notes to test with (C2, D2, E2, D2)
#define NUM_NOTES   72
// the notes. Can reach all of these with prescaler 1
const int notes[NUM_NOTES] = {
    20407,
    17160, 15288, 13620, 12134, 13620,
    15288, 18181, 22907, 20407, 18181,
    17160, 20407, 20407, 22907, 20407,
    18181, 22907, 27241, 20407,

    17160, 15288, 13620, 12134, 13620,
    15288, 18181, 22907, 20407, 18181,
    17160, 18181, 20407, 22907, 24269, 22907,
    20407, 20407,

    11453, 11453, 12134, 13620,
    15288, 18181, 22907, 20407, 18181,
    17160, 20407, 20407, 21621, 20407,
    18181, 21621, 27241,

    11453, 11453, 12134, 13620,
    15288, 18181, 22907, 20407, 18181,
    17160, 18181, 20407, 22907, 24269, 22907,
    20407, 20407

};

// note durations: 4 = quarter note, 8 = eighth note, etc
const float noteDurations[NUM_NOTES] = {
    8,
    4, 8, 5.3333333333, 16, 8,
    4, 8, 5.3333333333, 16, 8,
    4, 8, 5.3333333333, 16, 8,
    4, 8, 4, 8,

    4, 8, 5.3333333333, 16, 8,
    4, 8, 5.3333333333, 16, 8,
    5, 16, 8, 5.3333333333, 16, 8,
    2.6666666667, 2.6666666667,

    2.6666666667, 5.333, 16, 8,
    4, 8, 5.333, 16, 8,
    5.3333333333, 16, 8, 5.3333333333, 16, 8,
    2.6666666667, 2.6666666667,

    2.6666666667, 5.3333333333, 16, 8,
    4, 8, 5.3333333333, 16, 8,
    5.3333333333, 16, 8, 5.3333333333, 16, 8,
    2.6666666667, 2.6666666667

};

volatile int note_playing = 0;


int main(void)
{
    int top;
    DDRB |= _BV(PB3); // set pin to output

    // Timer 0 setup. 8 bit, note duration
    TCCR0A = T0_MODE_CTC;
    TIMSK0 |= _BV(OCIE0A);
    OCR0A = 244; // makes a count of 1 pretty close to 1/64th second

    // Timer 1 setup. 16 bit, frequency
    TCCR1B = _BV(WGM12); // ctc mode
    TIMSK1 = _BV(OCIE1A); // Enable Timer 1 COMP A interrupt vector
    // to get OCR1A use F = F_CPU/(2 x Prescaler x (1 + OCR1A))
    //OCR1A = 19261; // have to match with prescaler value
    //TCCR1B |= T1_PRESC_8; // start the frequency timer

    // Timer 2 setup. 8 bit, pulse width.
    TCCR2A = _BV(WGM21); //ctc
    TIMSK2 = _BV(OCIE2A); // enable Timer 2 COMP A interrupt vector
    OCR2A = pulse_width/2; // 16MHz with 32 prescaler

    sei(); // enable global interrupts

    TCCR0B = T0_PRESC_1024; // start the note timer
    while(1)
    {
        for (int i=0; i<NUM_NOTES;i++) {
            OCR1A = notes[i];

            note_playing = 0;
            TCCR1B |= T1_PRESC_1; // start the frequency timer
            top = 128/noteDurations[i];
            while (note_playing < top) {
                // enjoy the melodious tone
            }
            TCCR1B &= ~T1_PRESC_1; // stop the frequency timer
            note_playing = 0; // reset the counter
            while (note_playing < 6) {
                // do nothing
            }
        }
        // a gap between iterations
        note_playing = 0;
        while (note_playing < 300) {
            // A brief pause between tones helps punctuate them.
        }
    }
}


// Interrupt service routines
ISR(TIMER0_COMPA_vect) {
    // Note duration timer
    note_playing++;

}



ISR(TIMER1_COMPA_vect) {
    // Turn on the pin and start the timer to turn it off
    PORTB |= _BV(PB3);
    TCCR2B|= _BV(CS20) | _BV(CS21); // prescaler 32, starts the timer

}

ISR(TIMER2_COMPA_vect) {
    // Turn off the pin and the timer
    PORTB &= ~_BV(PB3);
    TCNT2 = 0; // reset the counter
    TCCR2B = 0; // WGM22 is the only other bit in this register I care about and it's 0 anyway.
}