https://devzone.nordicsemi.com/f/nordic-q-a/120270/board-not-powering-oni have connected usb type(b) to j3 and kept the switch to usb but no advertsing happens and i have also connected external supply 3v to p21 the board is not on . only while connecting usb with j2 and keeping the switch on the vdd mode board works . whetheranyen-USTelligent Community 13Fri, 28 Mar 2025 13:35:31 GMThttps://devzone.nordicsemi.com/thread/529538?ContentTypeID=1Fri, 28 Mar 2025 13:35:31 GMT137ad170-7792-4731-bb38-c0d22fbe4515:f147c207-7b5d-426d-93bd-ddac44be999fElfving<p>Hi,</p> <p></p> [quote user=""]ave also kept the nrf only to default siwtch in both ways but no board powersup. [/quote] <p>So the <a href="https://docs.nordicsemi.com/bundle/ug_nrf52840_dk/page/UG/dk/nrf_only_mode.html">nRF Only switch</a> should not be necessary here.&nbsp;</p> <p><a href="https://devzone.nordicsemi.com/f/nordic-q-a/63679/nrf-52840-dk-battery-level-reading/259796">This older post by a coworker explains the difference between these power settings better than I could.</a></p> <p>On my side, if I power a nRF52840DK here with the USB on the side, and with the &quot;nRF Power Source&quot; switch set to &quot;USB&quot;, I do still see advertisement, as well as seeing a faint light from the LEDs, given that you are running something on the nRF that are supposed to use these. <a href="https://devzone.nordicsemi.com/f/nordic-q-a/41129/nrf52840-dk-in-high-voltage-mode/159958">Note that the LEDs would be more faint&nbsp;as the USB side connector would power set VDD to 1.8V.</a>&nbsp;</p> <p>Does it work for you as soon as you switch the nRF Power source to VDD?</p> <p>I&#39;ve tested this on my side with the LBS sample and the nRF Connect app, could you try the same thing, just to compare?</p> <p>Regards,</p> <p>Elfving</p><div style="clear:both;"></div>