#ifndef F_CPU
#define F_CPU 1000000UL
#endif

#include <avr/io.h>
#include <util/delay.h>
int main(void)
{
     DDRA=0b00000001;
while(1)
{
               PORTA=0b00000001;
              _delay_ms(1000);
              PORTA=0b00000000;
            _delay_ms(1000);
}
}