https://devzone.nordicsemi.com/f/nordic-q-a/33542/nrf51-dongle-boot-on-power-without-pressing-the-boot-buttonHi We have a nrf51 dongle for use in a school prosject When the nrf51 dongle is connected to the USB slot in a computer it boots fine without holding the button when powering up the device But we are using the external Vin and ground connections foren-USTelligent Community 13Fri, 20 Apr 2018 11:05:25 GMThttps://devzone.nordicsemi.com/thread/129125?ContentTypeID=1Fri, 20 Apr 2018 11:05:25 GMT137ad170-7792-4731-bb38-c0d22fbe4515:29368470-7053-47c1-a5b3-144cb1b6c394Bj&#248;rn Kvaale<p>It seems like you are resetting the dongle to be able to power it. You should be able to use&nbsp;NVIC_SystemReset(); to reset the dongle in your code (<a href="https://devzone.nordicsemi.com/f/nordic-q-a/293/how-to-reset-the-device">see link</a>). If you are using the softdevice in addition, you can use the&nbsp;sd_nvic_SystemReset() instead. In general, it&#39;s easier to learning to program on Nordic devices by starting with the nrf52 dev kit if possible.</p><div style="clear:both;"></div>