/*

FUSES:

  Low Fuse:
	0x62    Default
    0xC0	External Oscillator, BOD (write lfuse 0 0xC0)
    0xF7	Full Swing Crystal Oscillator (write lfuse 0 0xF7)
	0xFF    Low Power Crystal Oscillator (untested)

  High Fuse
    0xDF    Default
	0xDC    BOD enabled (4.3V)
	0xCF    watchdog enabled
	0xCC    BOD enabled (4.3V) and watchdog enabled

  Extended Fuse
    0x01    Default

  avrdude -c stk500 -P /dev/ttyS0 -p atmega88 -U flash:w:bha_l2_frontleds.srec
  avrdude -c usbasp -p atmega168p -U flash:w:bha_l2_frontleds.srec

  avrdude -c stk500 -P /dev/ttyS0 -p atmega88 -t
  avrdude -c usbasp -p atmega168p -t
    dump lfuse 0 1
	write lfuse 0 <value>




PINS:
 AVR  Conn   Functions       Usage
   1  P10-3  PD3  OC2B       
   2  P4-13  PD4	     
   3	 GND
   4	 VCC
   5	 GND
   6	 VCC
   7	 PB6  XTAL1      crystal
   8	 PB7  XTAL2      crystal
   9  P8-3   PD5  OC0B       
  10  P6-3   PD6  OC0A       
  11  P4-14  PD7  AIN1
  12  P2-6   PB0  ICP1       bell switch
  13  P2-4   PB1  OC1A       speaker
  14  P2-5   PB2  OC1B       
  15  P1-4   PB3  MOSI/OC2A  ISP
  16  P1-1   PB4  MISO       ISP
  17  P1-3   PB5  SCK	ISP
  18	 AVCC
  19  P4-4   ADC6	    
  20  P4-5   AREF
  21	 GND
  22  P4-6   ADC7	    
  23  P4-7   PC0  ADC0       
  24  P4-8   PC1  ADC1       
  25  P4-9   PC2  ADC2
  26  P4-10  PC3  ADC3
  27  P4-11  PC4  ADC4       
  28  P4-12  PC5  ADC5       
  29  P1-5   PC6  /RESET     ISP
  30	 PD0  RXD        RS485 RX
  31	 PD1  TXD        RS485 TX
  32	 PD2             RS485 driver enable


https://en.wikipedia.org/wiki/Piano_key_frequencies

notes = ( "C", "CIS", "D", "DIS", "E",  "F", "FIS", "G", "GIS", "A", "AIS", "H" )
nlist = []
for i in range( 28, 120 ):
	f = 2**((i-49)/12.) * 440
	icp = int(18.432e6 / 2 / f - 0.5)
	n = notes[(i-28)%12]
	o = (i+8)/12
	if icp < 65536 and f < 15e3:
		nlist.append( ( i, f, icp, n, o ) )

for i, f, icp, n, o in nlist:
	print "\t%s%d," % ( n, o )

for i, f, icp, n, o in nlist:
	print "\t%d, // %s%d %gHz" % ( icp, n, o, f )

*/

#include <inttypes.h>
#include <avr/io.h>
#include <avr/pgmspace.h>

enum {
	PAUSE = 0,
	D3, DIS3, E3, F3, FIS3, G3, GIS3, A3, AIS3, H3,
	C4, CIS4, D4, DIS4, E4, F4, FIS4, G4, GIS4, A4, AIS4, H4,
	C5, CIS5, D5, DIS5, E5, F5, FIS5, G5, GIS5, A5, AIS5, H5,
	C6, CIS6, D6, DIS6, E6, F6, FIS6, G6, GIS6, A6, AIS6, H6,
	C7, CIS7, D7, DIS7, E7, F7, FIS7, G7, GIS7, A7, AIS7, H7,
	C8, CIS8, D8, DIS8, E8, F8, FIS8, G8, GIS8, A8, AIS8, H8,
	C9, CIS9, D9, DIS9, E9, F9, FIS9, G9, GIS9, A9, AIS9
};

const uint16_t notes[] PROGMEM = {
	62764, // D3 146.832Hz
	59242, // DIS3 155.563Hz
	55917, // E3 164.814Hz
	52778, // F3 174.614Hz
	49816, // FIS3 184.997Hz
	47020, // G3 195.998Hz
	44381, // GIS3 207.652Hz
	41890, // A3 220Hz
	39539, // AIS3 233.082Hz
	37320, // H3 246.942Hz
	35225, // C4 261.626Hz
	33248, // CIS4 277.183Hz
	31382, // D4 293.665Hz
	29620, // DIS4 311.127Hz
	27958, // E4 329.628Hz
	26389, // F4 349.228Hz
	24907, // FIS4 369.994Hz
	23509, // G4 391.995Hz
	22190, // GIS4 415.305Hz
	20944, // A4 440Hz
	19769, // AIS4 466.164Hz
	18659, // H4 493.883Hz
	17612, // C5 523.251Hz
	16623, // CIS5 554.365Hz
	15690, // D5 587.33Hz
	14810, // DIS5 622.254Hz
	13978, // E5 659.255Hz
	13194, // F5 698.456Hz
	12453, // FIS5 739.989Hz
	11754, // G5 783.991Hz
	11094, // GIS5 830.609Hz
	10472, // A5 880Hz
	9884, // AIS5 932.328Hz
	9329, // H5 987.767Hz
	8805, // C6 1046.5Hz
	8311, // CIS6 1108.73Hz
	7845, // D6 1174.66Hz
	7404, // DIS6 1244.51Hz
	6989, // E6 1318.51Hz
	6596, // F6 1396.91Hz
	6226, // FIS6 1479.98Hz
	5877, // G6 1567.98Hz
	5547, // GIS6 1661.22Hz
	5235, // A6 1760Hz
	4941, // AIS6 1864.66Hz
	4664, // H6 1975.53Hz
	4402, // C7 2093Hz
	4155, // CIS7 2217.46Hz
	3922, // D7 2349.32Hz
	3702, // DIS7 2489.02Hz
	3494, // E7 2637.02Hz
	3298, // F7 2793.83Hz
	3113, // FIS7 2959.96Hz
	2938, // G7 3135.96Hz
	2773, // GIS7 3322.44Hz
	2617, // A7 3520Hz
	2470, // AIS7 3729.31Hz
	2332, // H7 3951.07Hz
	2201, // C8 4186.01Hz
	2077, // CIS8 4434.92Hz
	1960, // D8 4698.64Hz
	1850, // DIS8 4978.03Hz
	1746, // E8 5274.04Hz
	1648, // F8 5587.65Hz
	1556, // FIS8 5919.91Hz
	1468, // G8 6271.93Hz
	1386, // GIS8 6644.88Hz
	1308, // A8 7040Hz
	1235, // AIS8 7458.62Hz
	1165, // H8 7902.13Hz
	1100, // C9 8372.02Hz
	1038, // CIS9 8869.84Hz
	980, // D9 9397.27Hz
	925, // DIS9 9956.06Hz
	873, // E9 10548.1Hz
	824, // F9 11175.3Hz
	777, // FIS9 11839.8Hz
	734, // G9 12543.9Hz
	692, // GIS9 13289.8Hz
	654, // A9 14080Hz
	617 // AIS9 14917.2Hz
};

typedef struct {
	uint8_t note;
	uint8_t time;
} note_time_t;

const note_time_t tune_1[] PROGMEM = {
#if 0
	{ C4, 5 },
	{ CIS4, 5 },
	{ D4, 5 },
	{ DIS4, 5 },
	{ E4, 5 },
	{ F4, 5 },
	{ FIS4, 5 },
	{ G4, 5 },
	{ GIS4, 5 },
	{ A4, 5 },
	{ AIS4, 5 },
	{ H4, 5 },
	{ C5, 25 },
	{ PAUSE, 50 },
#endif


#if 0
	{ E4, 15 },
	{ D4, 15 },
	{ C4, 15 },
	{ D4, 15 },
	{ E4, 15 },
	{ E4, 15 },
	{ E4, 30 },
	{ D4, 15 },
	{ D4, 15 },
	{ D4, 30 },
	{ E4, 15 },
	{ E4, 15 },
	{ E4, 30 },
	{ E4, 15 },
	{ D4, 15 },
	{ C4, 15 },
	{ D4, 15 },
	{ E4, 15 },
	{ E4, 15 },
	{ E4, 30 },
	{ E4, 15 },
	{ D4, 15 },
	{ D4, 15 },
	{ E4, 15 },
	{ D4, 15 },
	{ C4, 30 },
#endif


#if 0
	{ G3, 10 },
	{ C4, 10 },
	{ D4, 10 },
	{ E4, 20 },
	{ E4, 20 },
	{ PAUSE, 10 },
	{ E4, 10 },
	{ D4, 10 },
	{ E4, 10 },
	{ C4, 20 },
	{ C4, 20 },
	{ PAUSE, 10 },
	{ C4, 10 },
	{ D4, 10 },
	{ E4, 10 },
	{ F4, 20 },
	{ A4, 20 },
	{ PAUSE, 10 },
	{ A4, 10 },
	{ G4, 10 },
	{ F4, 10 },
	{ E4, 20 },
	{ PAUSE, 10 },
	{ C4, 10 },
	{ D4, 10 },
	{ E4, 10 },
	{ F4, 20 },
	{ A4, 20 },
	{ PAUSE, 10 },
	{ A4, 10 },
	{ G4, 10 },
	{ F4, 10 },
	{ E4, 20 },
	{ C4, 20 },
	{ PAUSE, 10 },
	{ C4, 10 },
	{ D4, 10 },
	{ E4, 10 },
	{ F4, 10 },
	{ D4, 10 },
	{ D4, 10 },
	{ E4, 10 },
	{ C4, 20 },
	{ PAUSE, 10 },
#endif


#if 0
	{ A5, 5*1 },
	{ G5, 5*1 },
	{ A5, 5*6 },
	{ PAUSE, 5*3 },
	{ G5, 5*1 },
	{ F5, 5*1 },
	{ E5, 5*1 },
	{ D5, 5*1 },
	{ CIS5, 5*2 },
	{ D5, 5*2 },
	{ PAUSE, 5*6 },
	{ A4, 5*1 },
	{ G4, 5*1 },
	{ A4, 5*6 },
	{ PAUSE, 5*3 },
	{ E4, 5*1 },
	{ F4, 5*1 },
	{ CIS4, 5*1 },
	{ D4, 5*2 },
	{ PAUSE, 5*3 },
#endif


#if 1
#define FFF 5
	{ A6, FFF*1 },
	{ G6, FFF*1 },
	{ A6, FFF*6 },
	{ PAUSE, FFF*3 },
	{ G6, FFF*1 },
	{ F6, FFF*1 },
	{ E6, FFF*1 },
	{ D6, FFF*1 },
	{ CIS6, FFF*2 },
	{ D6, FFF*2 },
	{ PAUSE, FFF*6 },
	{ A5, FFF*1 },
	{ G5, FFF*1 },
	{ A5, FFF*6 },
	{ PAUSE, FFF*3 },
	{ E5, FFF*1 },
	{ F5, FFF*1 },
	{ CIS5, FFF*1 },
	{ D5, FFF*2 },
	{ PAUSE, FFF*6 },
	{ A4, FFF*1 },
	{ G4, FFF*1 },
	{ A4, FFF*6 },
	{ PAUSE, FFF*3 },
	{ G4, FFF*1 },
	{ F4, FFF*1 },
	{ E4, FFF*1 },
	{ D4, FFF*1 },
	{ CIS4, FFF*2 },
	{ D4, FFF*2 },
	{ PAUSE, FFF*6 },
#endif


	{ PAUSE, 0 }
};

typedef struct {
	uint8_t button_state;
	uint8_t button_pressed;
	uint8_t button_shift_bits;
} data_t;

static data_t data;

void initialize()
{
	data.button_state = 0;
	data.button_pressed = 0;
	data.button_shift_bits = 0;

	// timer 1: CTC Top=ICR1, clock/1, toggle OC1A
	TCCR1A = (1<<COM1A0);
	TCCR1B = (1<<WGM13) | (1<<WGM12) | (1<<CS10);
	ICR1 = 20945-1;

	// timer 2: Fast PWM, Top=OCR2A, clock/1024, overflow @ 125Hz
	TCCR2A = (1<<WGM21) | (1<<WGM20);
	TCCR2B = (1<<WGM22) | (1<<CS22) | (1<<CS21) | (1<<CS20);
	OCR2A = 144-1;
}

uint8_t timer2overflow()
{
	uint8_t v = TIFR2 & (1<<TOV2);
	TIFR2 = v;
	return v;
}

uint8_t timing()
{
	if( !timer2overflow() )
	{
		return 0;
	}
	data.button_shift_bits = (data.button_shift_bits << 1) | (PINB & 1);
	if( data.button_shift_bits == 0x00 )
	{
		if( data.button_state == 0 )
		{
			data.button_state = 1;
			data.button_pressed = 1;
		}
	}
	else if( data.button_shift_bits == 0xFF )
	{
		if( data.button_state != 0 )
		{
			data.button_state = 0;
		}
	}
	return 1;
}

uint8_t tune_note( uint8_t ti )
{
	note_time_t nt;

	memcpy_P( &nt, tune_1+ti, sizeof(nt) );
	if( nt.time > 0 )
	{
		if( nt.note != 0 )
		{
			ICR1 = pgm_read_word( &notes[nt.note-1] );
			DDRB |= 1<<PB1;
		}
	}
	return nt.time;
}

#define DIVIDER 5

void ring()
{
	uint8_t ti = 1;
	uint8_t nt;
	uint8_t div = DIVIDER;

	nt = tune_note( 0 );
	while( nt )
	{
		if( timing() )
		{
			div--;
			if( div == 0 )
			{
				div = 5;
				nt--;
				if( nt == 1 )
				{
					DDRB &= ~(1<<PB1);
				}
				else if( nt == 0 )
				{
					nt = tune_note( ti++ );
				}
			}
		}
	}
	data.button_pressed = 0;
}

int main()
{
	initialize();
	while( 1 )
	{
		timing();
		if( data.button_pressed )
		{
			data.button_pressed = 0;
			ring();
		}
	}
}