#include <avr/io.h>

void setup() {
   PORTA.DIRSET = 0xff;
}

void loop() {
        PORTA.OUT=0b00001000;      // LED on
        delay(1000); // delay 1000ms (1 s)
        PORTA.OUT=0x00; //LED off
        delay(1000); // delay 1000ms (1 s)

} // end program