#include<avr/io.h>
#include<avr/interrupt.h>
#include<avr/signal.h>
#define F_CPU 1000000UL
#include<avr/delay.h>


#define FOR(i,n) for(i=0;i<n;i++) 
#define Limit 255 
#define Fast 5 
int main(void)
{
	DDRB = 3;
	unsigned char i=0, x = 0,j,k,c=1;
	while(1)
	{
		if (x==0)
		{c=c^1;}
		
		FOR(i,Fast)
		{
			FOR(j,x);PORTB = c;
			FOR(k,Limit-x) ; PORTB =c^1;
		}
		x=x+1;	
	}
		
	
}