bisonde/main.c

#define F_CPU 20000000UL

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <avr/pgmspace.h>
#include "wavetables.h"

const uint16_t NOTE_CYCLES[108] PROGMEM = {
	15420, 14534, 13742, 12950, 12244, 11544, 10920, 10308,  9712,
	        9182,  8670,  8180,  7710,  7294,  6872,  6496,  6122,  5788,
	        5460,  5154,  4868,  4592,  4336,  4090,  3864,  3648,  3442,
	        3248,  3066,  2894,  2730,  2578,  2432,  2296,  2168,  2046,
	        1930,  1822,  1720,  1624,  1532,  1446,  1366,  1290,  1218,
	        1148,  1084,  1024,   966,   912,   860,   812,   768,   724,
	         684,   646,   610,   574,   542,   512,   484,   456,   430,
	         406,   384,   362,   342,   324,   304,   288,   272,   256,
	         242,   228,   216,   204,   192,   182,   172,   162,   152,
	         144,   136,   128,   122,   114,   108,   102,    96,    92,
	          86,    82,    76,    72,    68,    64,    62,    58,    54,
	          52,    48,    46,    44,    42,    38,    36,    34,    32
};

volatile uint8_t pwm_cycle = 0;

// ISR(TIMER1_COMPB_vect)
// {
// }

ISR(TIMER1_OVF_vect)
{
	++pwm_cycle;
}

typedef struct {
	uint16_t pwm_cycle, pwm_num_cycles;
	uint8_t wt;
} oscillator_t;

//the PCINT0_vect vector is used to identify the pin change interrupt.
// ISR(PCINT0_vect)
// {
//     mute = !((PINB & (1 << PB1)));
// }

int main()
{
uint16_t n;
uint8_t d, button_id = 1, line = 0, adc_timer = 0, lfo_volume = 0;
oscillator_t vco = { 0, 0, 0 }, lfo = { 0, 0, 0 };

  //OSCCAL = 83;

	PLLCSR |= 0x6;

	// setup output pins
	DDRB = (1 << DDB4) | (1 << DDB2) | (1 << DDB1) | (1 << DDB0);

	// set line mux pins low and turn op ADC pull-up resistor
	PORTB = ~((1 << PB0) | (1 << PB1) | (1 << PB2)) | (1 << PB3);

	// Set the ADC input to PB2/ADC1, left adjust result
	ADMUX = (3 << MUX0) | (1 << ADLAR);

	// Set the prescaler to clock/8 & enable ADC
	ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0) | (1 << ADEN);

	// Configure counter/timer1 for fast PWM on PB4
  GTCCR = (1 << PWM1B) | (1 << COM1B1);

	// Set Timer 1 prescaler to clock/1 = 64.0MHz.
	TCCR1 = (1 << CS10);

	// Interrupts on OC1A match + overflow
  //TIMSK |= (1 << OCIE1B) | (1 << TOIE1);

	// Interrupts on OC1A overflow
	TIMSK |= (1 << TOIE1);
	OCR1B = 0;
	OCR1C = 255;

	// GIMSK = (1 << PCIE); //Enable Pin Change Interrupts
	// PCMSK = (1 << PCINT1); //Set Pin 2 to cause an interrupt. You can also enable it on multiple pins

	ADCSRA |= (1 << ADSC);  // Start A2D Conversions
	while (1) {
		if(((ADCSRA >> ADSC) & 0x1) == 0) {
			if(adc_timer == 0) {
				d = ADCH;
				switch(line) {
					case 0:
						if(button_id > 0) {
							d /= 5;
							switch(button_id) {
								case 7:
									d += 10;
									break;
								case 6:
									d += 9;
									break;
								case 5:
									d += 7;
									break;
								case 4:
									d += 5;
									break;
								case 3:
									d += 4;
									break;
								case 2:
									d += 2;
									break;
								default:
									break;
							}
							vco.pwm_num_cycles = pgm_read_word_near(NOTE_CYCLES + 21 + d);
						}
						//vco.pwm_num_cycles = 7812;
						break;
					case 1:
						if(button_id > 0) {
							lfo.pwm_num_cycles = 0xffff - (d << 8);
						}
						break;
					case 2:
						lfo_volume = d;
						//lfo_volume = 127;
						break;
					case 3:
						//button_id = (d < 77 ? 7 : (d > 250 ? 0 : (279 - d) / 29));
						if(d >= 241)
							button_id = 0;
						else if(d >= 216)
							button_id = 1;
						else if(d >= 195)
							button_id = 2;
						else if(d >= 173)
							button_id = 3;
						else if(d >= 144)
							button_id = 4;
						else if(d >= 106)
							button_id = 5;
						else if(d >= 42)
							button_id = 6;
						else
							button_id = 7;
						break;
					case 4:
						vco.wt = d / (256 / WAVETABLES_NUM);
						break;
					case 6:
						lfo.wt = d / (256 / WAVETABLES_NUM);
						break;
					default:
						// nop;
						break;
				}

				line = (line + 1) % 8;
				PORTB = (PORTB & ~0x7) | line;
				adc_timer = 1;
			}
			else if(adc_timer == 1) {
				ADCSRA |= (1 << ADSC);  // Start A2D Conversions
				adc_timer = 0;
			}
			else
				++adc_timer;
		}

		cli();
		n = pwm_cycle;
		sei();

		d = 0;

		if(lfo_volume <= 252) {
			vco.pwm_cycle = (vco.pwm_cycle + n) % vco.pwm_num_cycles;
			d += (uint16_t)pgm_read_byte_near(WAVETABLES[vco.wt] + (uint16_t)(((uint32_t)(vco.pwm_cycle)) * WAVETABLES_SIZE / vco.pwm_num_cycles)) * (255 - lfo_volume) >> 8;
		}

		if(lfo_volume > 8) {
			//n += 2;
			lfo.pwm_cycle = (lfo.pwm_cycle + n) % lfo.pwm_num_cycles;
			d += (uint16_t)pgm_read_byte_near(WAVETABLES[lfo.wt] + (uint16_t)(((uint32_t)(lfo.pwm_cycle)) * WAVETABLES_SIZE / lfo.pwm_num_cycles)) * lfo_volume >> 8;
		}

		cli();
		if(button_id > 0)
			OCR1B = d;
		pwm_cycle -= n;
		sei();
	}

	return 0;
}