int main(void)
{
    PORTB.DIRSET = PIN4_bm; /* Configure LED Pin as output */
    PORTB.PIN5CTRL = PORT_PULLUPEN_bm; /* Enable pull-up for SW0 pin */
    while(1)
    {
        if (!(PORTB.IN & PIN5_bm)) /* Check switch state */
        {
            PORTB.OUTCLR = PIN4_bm; /* Turn LED off */
        }
        else
        {
            PORTB.OUTSET = PIN4_bm; /* Turn LED on */
        }
    }
}