// Target: m8515

#define OSC			4000000
#define BAUD		9600
//#define UBRR_BAUD	((OSC/(16*BAUD))-1) = 25,03...
#define UBRR_BAUD	25


#include <avr\io.h>
#include <avr\interrupt.h>
#include <avr\signal.h>
#include "usart.h"

#ifndef OCR1A
#define OCR1A OCR1	// 2313 support
#endif

#ifndef WGM12
#define WGM12 CTC1	// 2313 support
#endif

#ifndef	PINC
#define	KEY_INPUT	PIND	// 2313
#else
#define KEY_INPUT	PINC	// Mega8
#endif
#define	LED_DIR		DDRB

//#define XTAL		11059201L	// nominal value
#define XTAL		4000000L	// after measuring deviation: 1.5s/d

#define DEBOUNCE	256L		// debounce clock (256Hz = 4msec)

#define uchar unsigned char
#define uint unsigned int

uchar prescaler;
uchar volatile second;			// count seconds
uchar volatile minuten;
uchar volatile stunden;



void usart_send(uint8_t data);






SIGNAL (SIG_OUTPUT_COMPARE1A)
{


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

    usart_send(second);			
	usart_send(minuten);			
	usart_send(stunden);

#if XTAL % DEBOUNCE					// handle remainder
    OCR1A = XTAL / DEBOUNCE + XTAL % DEBOUNCE - 1; // compare once per second
#endif

  }
}


int main( void )
{
	UBRRH = (unsigned char) (UBRR_BAUD>>8);
	UBRRL = (unsigned char) UBRR_BAUD;

	/* Aktivieren von transmitter */
	UCSRB = (1<<TXEN);

	/* Einstellen des Datenformats: 8 Datenbits, 1 Stoppbit */
	UCSRC = (1<<URSEL)|(1<<UCSZ1)|(1<<UCSZ0);

  LED_DIR = 0xFF;
  DDRA = 0;

  //while( 1 );		// start with key 0 pressed

  TCCR1B = 1<<WGM12^1<<CS10;		// divide by 1
					// clear on compare
  OCR1A = XTAL / DEBOUNCE - 1;
  TCNT1 = 0;
  second = 0;
  minuten=0;
  stunden=0;
  prescaler = (uchar)DEBOUNCE;

  TIMSK = 1<<OCIE1A;
  sei();

  for(;;){

    if( second == 60 )
		{
      		second = 0;
	  		minuten++;
		}
	if(minuten == 60 )
		{
			second = 0;
			minuten = 0;
			stunden++;
		}

	//PORTB = second;
  }
}






//____________________________________________________________________________________
//____________________________________________________________________________________
void usart_send(uint8_t data)
{
		while ( !( UCSRA & (1<<UDRE)) );		// Data Register empty?
		UDR = data;
}