SIGNAL(SIG_INTERRUPT0){
        PORTD ^= (1 << PD6);
}

int main(void){
        //set GLOBAL interrupt enable
        GICR=0xC0;
        MCUCR=0x0F;
        sei();

        PORTD |= (1 << PD2);
        //SET OUTPUT PINS
        //      DDRA |= (0 << PA0);
        //DDRD = 0x78;
        while (1) {
        }
        return 0;
}