ktimer.c

/* 14 august 2014
 * Oleg Terentiev t.oleg@ymail.com
 *       *------*
 * rst  -|      |-  V+
 *  PB3 -|      |- PB2
 *  PB4 -|      |- PB1 plus 1 minute
 * gnd  -|      |- PB0 plus 5 minutes
 *       *------*
 * PB3, PB4 - both connect to buzzer
 * PB[0,1] - buttons-to-GND
 */

#include <avr/io.h>
#include <avr/interrupt.h>
#include <util/delay.h>
#include <avr/sleep.h>
#include <avr/wdt.h>

FUSES =
    {
        .low  = LFUSE_DEFAULT,
        .high = HFUSE_DEFAULT
    }; /* hfuse=0xff, lfuse=0x6A */

#define T1MIN (60*2)
#define T5MIN (T1MIN*5)

#define PushTime (4*2+4*2)

#define NOPRESS 0b11
#define T1PRESS 0b01
#define T5PRESS 0b10
#define ALLPRESS 0b00
#define FALSE 0
#define TRUE (!FALSE)

int16_t time    __attribute__ ((section (".noinit")));

int16_t timestored    __attribute__ ((section (".noinit")));

uint8_t buttons __attribute__ ((section (".noinit")));

void beep_low (uint8_t time);
void beep_mid (uint8_t time);
void beep_high(uint8_t time);

int main (void)
{
uint8_t tmp;
	ACSR |= 1<<ACD; // disable comparator
	cli();
	/* ADCSRA &= ~(1<<ADEN); // default by reset */
	wdt_enable(WDTO_500MS);

	if ( bit_is_set(MCUSR, WDRF)) {	// reset by WDT
		// tune I/O
		DDRB =  0b00011100;
		PORTB = 0b00000111;
		asm("nop");

		buttons = PINB & 0x03;
		switch (buttons) {

		case ALLPRESS: // long beep, reset time
			time = -PushTime;
			timestored = -PushTime;
			beep_low(250);
			set_sleep_mode(SLEEP_MODE_PWR_DOWN);
			sleep_enable();
			sleep_cpu();
			break;

		case T1PRESS: // beep, add time, sleep
			timestored = timestored + T1MIN;
			time = timestored;
			beep_mid(100);
			set_sleep_mode(SLEEP_MODE_PWR_DOWN);
			sleep_enable();
			sleep_cpu();
			break;

		case T5PRESS: // beep, add time, sleep
			timestored = timestored + T5MIN;
			time = timestored;
			beep_high(150);
			set_sleep_mode(SLEEP_MODE_PWR_DOWN);
			sleep_enable();
			sleep_cpu();
			break;

		case NOPRESS:
			if (time > 0) {
				time--;
			} else 	if ( time == 0 ) { // it is TIME! beep for 1 minute!
				//wdt_disable(); // no working!

				wdt_enable(WDTO_2S);

				tmp = 1; /* seconds */
				while ( tmp > 0 ){
					PORTB =  (0<<PB2);
//					_delay_ms(250);
//					beep_high(250);
					_delay_ms(1000);
					wdt_reset();
					PORTB =  (1<<PB2);
					_delay_ms(1500);
					wdt_reset();
					PORTB =  (0<<PB2);
					_delay_ms(1000);
					PORTB =  (1<<PB2);
					wdt_reset();
//					_delay_ms(250);
//					beep_low(250);
					wdt_reset();
					tmp--;
				}

				time = timestored;
				wdt_enable(WDTO_500MS);
			}
			set_sleep_mode(SLEEP_MODE_PWR_DOWN);
			sleep_enable();
			sleep_cpu();
			break;
		default:
			beep_high(200);
			beep_high(200);
			beep_high(200);
			break;
		}

	} else { // no WDT reset
		// first ON, no calibration
		time = -PushTime;
		timestored = -PushTime;
		set_sleep_mode(SLEEP_MODE_PWR_DOWN);
		sleep_enable();
		sleep_cpu();
	}
}

void beep_low(uint8_t time) /* in milliseconds. 500 Hz */
{
uint8_t tmp;
	tmp = time>>2;
	while ( --tmp > 0){
		PORTB |=  (1<<PB3);
		PORTB &= ~(1<<PB4);
		_delay_us(2000);
		PORTB &= ~(1<<PB3);
		PORTB |=  (1<<PB4);
		_delay_us(2000);
	}
}

void beep_mid(uint8_t time) /* in milliseconds. 1 kHz */
{
uint8_t tmp;
	tmp = time>>1;
	while ( --tmp > 0){
		PORTB |=  (1<<PB3);
		PORTB &= ~(1<<PB4);
		_delay_us(1000);
		PORTB &= ~(1<<PB3);
		PORTB |=  (1<<PB4);
		_delay_us(1000);
	}
}

void beep_high(uint8_t time) /* in milliseconds. 2 kHz */
{
uint8_t tmp;
	tmp = time;
	while ( --tmp > 0){
		PORTB |=  (1<<PB3);
		PORTB &= ~(1<<PB4);
		_delay_us(500);
		PORTB &= ~(1<<PB3);
		PORTB |=  (1<<PB4);
		_delay_us(500);
	}
}