https://devzone.nordicsemi.com/f/nordic-q-a/8689/nrf51822-custome-board-crystal-problemHello, My nRF51822 custome board has problem at first programing software with nRF51 DK. So I checked nRF51822 boot sequence and found diffence compare with nRF51422 which is in dev board. &lt;Difference with referecence board,nRF51 DK &gt; 16MHzen-USTelligent Community 13Fri, 14 Aug 2015 07:16:47 GMThttps://devzone.nordicsemi.com/thread/31861?ContentTypeID=1Fri, 14 Aug 2015 07:16:47 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6df9c0a5-f4a6-4c45-934e-decf25e04b1bStefan Birnir Sverrisson<p>Hi Anton</p> <p>Make sure you have valid load capacitors for the crystal. A guide for calculating appropriate values is given on <a href="https://devzone.nordicsemi.com/question/24030/capacitors-for-16mhz-xtal/">this thread</a>.</p><div style="clear:both;"></div>