// count.c 
//The good old counter code.

#include <avr/io.h>
#define F_CPU 1000000UL //1 Mhz clock
#include <util/delay.h>

int main()
{
uint8_t i;
DDRB = 0xFF;  //set port B to all outputs
while(1){
  PORTB++;  // PORTB increments by one
  for(i=0; i<=4; i++) {_delay_ms(100);}  //0.5 sec delay 
  }
}