#include<avr/io.h>
#include<avr/delay.h>
#include <avr/interrupt.h>
#define F_CPU 1000000L
void main()
{
    TCCR0 = ((1<<COM01) | (1<<COM00) | (1<<WGM01) | (1<<WGM00) | (1<<CS01));
    TCNT0 = 0;
    DDRB = _BV(3);
    OCR0 = 0;
    int dec = 0;

    int counter = 0;
    PORTA = _BV(3);

    while(1==1)
    {
        if(TIFR & (1 << OCF0))
        {
            //TIFR |= 1<<OCF0;
            counter++;


            if(counter == 3000)
            {
                if(OCR0 == 0)
                    dec = 0;
                if(OCR0 == 255)
                    dec = 1;

                if(dec)
                    OCR0 -= 5;
                else
                    OCR0 += 5;
                counter = 0;
            }
        }
    }
}