sysprog-basic/alarm/main.c

62 lines
1.2 KiB
C

/*
* 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;
}