/*
 * Control PB5 with the two buttons. One button disables, the other enables.
 * The board uses interrupts for this. PB5 will quickly oscilate between on and
 * off to make cool sounds with a summer.
 */
#define F_CPU 16000000UL
#define __AVR_ATmega328P__
#include <avr/interrupt.h>
#include <avr/io.h>
#include <util/delay.h>

#define MINUTE 60 * 1000
const int TIME = 45 * MINUTE;

int volatile reset = 0;

int alarm();

// code for INT0
ISR(INT0_vect) { reset = 1; }

int main(void) {

  DDRB = 0xff; // write to B
  DDRD = 0;    // read from D

  PORTD |= (1 << PORTD2) | (1 << PORTD3); // pull up D2 and D3

  PORTB = 0; // pull down port B

  // enable external interruprs
  EIMSK |= (1 << INT0);
  EIMSK |= (1 << INT1);

  // trigger when anything changes
  EICRA |= (1 << ISC00); // for INT0
  EICRA |= (1 << ISC10); // for INT1

  sei(); // interrupt magic macro
  while (1) {
    _delay_ms(TIME);
    alarm();
  }
}

int alarm(void) {
  int sound = 0;
  while (!reset) {
    PORTB |= (1 << PORTB5);
    _delay_us(sound);
    PORTB &= ~(1 << PORTB5);
    _delay_us(sound);
    sound++;
    if (sound > 1000) {
      sound = 0;
    }
  }
  reset = 0;
  PORTB &= ~(1 << PORTB5);
  return 0;
}