#include <avr/io.h>
#include <avr/interrupt.h>
#include <stdio.h>
#include <stdlib.h>

#include "lcd.h"

//#define XTAL		1000000L	// auskommentiert, weil schon in der lcd.h gesetzt
#define DEBOUNCE	250L		// debounce clock (250Hz = 4msec)


void InitLCD()
{
	lcd_init(LCD_DISP_ON);
}

void InitTimer1()
{
	TCCR1B = 1<<WGM12^1<<CS10;		// divide by 1
									// clear on compare
  	OCR1A = XTAL / DEBOUNCE - 1;
  	TCNT1 = 0;
  	TIMSK = 1<<OCIE1A;
}

void init()
{
	InitLCD();
	InitTimer1();
}


#define uchar unsigned char
#define uint unsigned int

uchar volatile prescaler;
uchar volatile second;			// count seconds
uchar volatile anzeige;			// Anzeige neu zeichnen


ISR (TIMER1_COMPA_vect)
{
/************************************************************************/
/*			Insert Key Debouncing Here			*/
/************************************************************************/

#if XTAL % DEBOUNCE
  OCR1A = XTAL / DEBOUNCE - 1;		// compare DEBOUNCE - 1 times
#endif
  if( --prescaler == 0 ){
    prescaler = (uchar)DEBOUNCE;
    second++;				// exact one second over
	anzeige = 1;
#if XTAL % DEBOUNCE			// handle remainder
    OCR1A = XTAL / DEBOUNCE + XTAL % DEBOUNCE - 1; // compare once per second
#endif
  }
}

int main(void)
{
	uchar minute = 0;
	uchar hour = 0;
	char zeitdigits[3];	

    init();
	second = 0;
	prescaler = (uchar)DEBOUNCE;
	sei();
    while(1)
    {	
		if (second == 60){
			second = 0;
			minute++;
			if (minute == 60){
				minute = 0;
				hour++;
			}
			if (hour == 24){
				hour = 0;
			}
		}
		if (anzeige & (second != 60)){
			lcd_gotoxy(0,0);
			itoa( hour, zeitdigits, 10);
			if (hour < 10){
				lcd_putc('0');
			}
			lcd_puts(zeitdigits);
			lcd_putc(':');
			itoa( minute, zeitdigits, 10);
			if (minute < 10){
				lcd_putc('0');
			}
			lcd_puts(zeitdigits);
			lcd_putc(':');
			itoa( second, zeitdigits, 10);
			if (second < 10){
				lcd_putc('0');
			}
			lcd_puts(zeitdigits);
			anzeige = 0;
		}
    }
 
    return 0;
}