// blinky.c
#include <avr/io.h>    	// Standard AVR header
#include <avr/delay.h> 	// Delay loop functions

int main(void) 
{
  DDRA = 0xFF;    // PORTA is output 
  while (1) {
    for (int i=1; i<=128; i*=2) 
    {
      PORTA = i;
      _delay_loop_2(30000);
    }
    for (int i=128; i>1; i/=2) 
    {
      PORTA = i;
      _delay_loop_2(30000);
    }
  }
}