https://devzone.nordicsemi.com/f/nordic-q-a/26647/how-to-recognize-that-the-dfu-process-is-runningHello, I would like to signalize that the DFU process is running. I mean when I start to upload the application into the CPU, then a LED (for example) is ON, after uploading the LED is OFF. When the process is brokem the LED must be OFF. Pleaseen-USTelligent Community 13Tue, 07 Nov 2017 12:07:46 GMThttps://devzone.nordicsemi.com/thread/104838?ContentTypeID=1Tue, 07 Nov 2017 12:07:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:614fa070-a181-46ac-ae86-25d972b0d362Hung Bui<p>Hi Jiri,</p> <p>Could you tell which SDK you used ?</p> <p>Following information applied for SDK v12 and up.</p> <p>Currently, after the DFU bootloader advertise and get connected. We will switch the LEDs when there is BLE_GAP_EVT_CONNECTED event. Please have a look at ble_evt_handler() inside nrf_ble_dfu.c</p> <p>If you want to have more indication, especially when the image is sent, not only when the bootloader is connected, I think you can add the code to turn on the LED after dfu_handle_prevalidate() success in dfu_handle_signed_command() inside dfu_req_handling.c</p> <p>This is the point when we validated the init packet is correct and wait for the actual image to be sent.</p><div style="clear:both;"></div>