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

volatile uint8_t id;
volatile uint8_t state;
volatile int8_t dir = -1;

ISR(TIMER2_OVF_vect)
{
	if(state == 0){
	  PORTC &= ~(1<<id);
	}else{
	  PORTC |= (1<<id);
	  id = (id + dir) % 8;
	}
	
	state = (state+1) % 2;
}

ISR(PCINT1_vect){
	if(dir == 1)
		dir = -1;
	else
		dir = 1;
}

int main(void) {
 DDRC = (0xff);
 PORTC = (0xff);
 
 
 DDRB &= ~_BV(DDB0);
 PORTB |= _BV(PORTB0);
 
 // timer int
 TCCR2B |= _BV(CS22) | _BV(CS21) | _BV(CS20);
 TIMSK2 |= _BV(TOIE2);
 
 EICRA |= _BV(ISC11) | _BV(ISC10);
 EIMSK |= _BV(INT1);
 
 // enable for pin 8 - PB0
 PCMSK1 |= _BV(PCINT8);
 PCICR   |= _BV(PCIE1);
 
 sei();
 
 for(;;);

 return 0;
}