https://devzone.nordicsemi.com/f/nordic-q-a/103571/nrf52840-dk-led-1-5-blinking-when-set-to-usb-power-modeI have a new NRF52840 DK Board that I just got out of the box. When I switch the power source to pull from the USB, LED 1-5 rapidly blink (Faster than the pulse that LED 5 gives you when a board is in bootloader mode). I can switch the power source backen-USTelligent Community 13Fri, 08 Sep 2023 11:22:17 GMThttps://devzone.nordicsemi.com/thread/445120?ContentTypeID=1Fri, 08 Sep 2023 11:22:17 GMT137ad170-7792-4731-bb38-c0d22fbe4515:205aa677-48ad-4a88-8299-6ae7ec47facbVidar Berg<p>Hello,</p> <p></p> <p>When selecting the USB supply, ensure you have another USB cable connected to the nRF USB port shown in the picture below. Otherwise, the nRF52840 will not be powered and LED1-4 will not be driven to a defined state.</p> <p><img style="max-height:240px;max-width:320px;" src="https://devzone.nordicsemi.com/resized-image/__size/640x480/__key/communityserver-discussions-components-files/4/pastedimage1694171748426v1.png" alt=" " /></p> <p><a title="nRF52840 power source" href="https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/power_source.html?cp=5_0_4_7_2_3">nRF52840 power source</a></p> [quote user=""]The only downside to this is that I cannot enter bootloader on this device when I switch to VDD.[/quote] <p>Are you trying to enter Bootloader mode on the interface chip or on the nRF52840 target chip?&nbsp;</p> <p>Best regards,</p> <p>Vidar</p><div style="clear:both;"></div>