https://devzone.nordicsemi.com/f/nordic-q-a/98687/nrf52840-dk-ble-peripheral-uart-example-advertisement-led-not-blinkingHello, I am using two nRF52840 DK and flashed them both with the same firmware (ble-peripheral-uart) one is blinking the addvertisement LED that other not. But I can see both of them advertising via nRF mobile appliation. What might be the causeen-USTelligent Community 13Thu, 13 Apr 2023 07:56:53 GMThttps://devzone.nordicsemi.com/thread/420115?ContentTypeID=1Thu, 13 Apr 2023 07:56:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6df72611-8e21-4b9e-b28c-99a8b292624emaveli<p>Interestingly I am able to receive debug information via com port.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/420113?ContentTypeID=1Thu, 13 Apr 2023 07:45:58 GMT137ad170-7792-4731-bb38-c0d22fbe4515:58a887b7-eb85-4723-a78d-58512f2daca2Kenneth<p>Hello,</p> <p>I assume you are using the nRF5 SDK, in that case you can find from the&nbsp;<a href="https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/ble_sdk_app_nus_eval.html#project_uart_nus_eval_test">Testing description</a> that the LED will stop blinking if for instance the board is connected and/or if timeout and go to sleep. So it could be that the board have previously been connected to a peer, and this peer now automatically connect again because it thinks it should. The board may still be visiable in the nRF mobile application if it was picked up for a short period of time before it was connected.</p> <p>If the above is not the case, then I suggest that you for instance try some of the other examples, such as the&nbsp;simple \examples\peripheral\blinky to verify that the hardware works (and not have been damaged somehow).</p> <p>Kenneth</p><div style="clear:both;"></div>