#ifndef F_CPU
#define F_CPU 8000000L
#endif
#include <stdlib.h>
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
//#define 
void display(int i);


	//for 7seg with common cathode
	//unsigned int digits[10] = {0x3F,0x06,0x5B,0x4F,0x66,0x6D,0xFD,0x07,0xFF,0xEF};
	
	//for 7seg with common anode
	unsigned char digits[10] = {0xC0, 0xF9, 0xA4, 0xB0, 0x99, 0x92, 0x02, 0xF8, 0x00, 0x10};
	int i = 0;
	int pause = 0;

ISR(INT0_vect){
	if (pause == 0){
		if (i>8888){
			i = 0;
		} else {
			i++;
		}
	}	
	_delay_ms(0.2);
}

void main(void){
	DDRA = 0xFF; DDRB = 0xFF;

	GIMSK |= 0b01000000;					// Enable INT0
	MCUCR |= 0b00000011;	// Trigger INT0 on rising edge
	sei();				//Enable Global Interrupt

	//PORTA = digits[3];
	while(1) {
		display(i);
		
		/*if (pause == 0){
			if (i>8){
				i = 0;
			} else {
				i++;
			}
		}
		
		if (PB5) {    // is switch open?
			pause = 1;
		} else {
			pause = 0;
		}*/
	}
}

void display(int i){

		int tmp, four, three, two, one;
		float delay = 0.1;
		tmp = i;

		four = tmp/1000; tmp = tmp-1000*four;
		three = tmp/100; tmp = tmp-100*three;
		two = tmp/10;    tmp = tmp-10*two;
		one = tmp%10;    tmp = tmp-one;

		if(i>999){
			PORTB = 0x01;
			PORTA = digits[four];
			_delay_ms(delay);
		}

		if(i>99){
			PORTB = 0x02;
			PORTA = digits[three];
			_delay_ms(delay);
		}

		if(i>9){
			PORTB = 0x04;
			PORTA = digits[two];
			_delay_ms(delay);
		}		
		
		PORTB = 0x08;
		PORTA = digits[one];
		_delay_ms(delay);
}