trying to set Pin GPIO19 to high we do this // initialisation outr(PIO_PER, _BV(19)); outr(PIO_OER, _BV(19)); // set Pin high outr(PIO_SODR, _BV(19)); the PIN actually goes high, but retrurns to low as soon as the thread goes into sleep mode. why ? (we testet other pins with the same result)