https://devzone.nordicsemi.com/f/nordic-q-a/68512/first-time-dfuI am adding the secure DFU bootloader examples/dfu/secure_bootloader/pca10056_s140_ble/ to my existing BLE UART peripheral project. I am using SDK 16.0.0 and nrf52840. I used mergehex to merge the bootloader, application and softdevice hex files intoen-USTelligent Community 13Thu, 19 Nov 2020 12:28:28 GMThttps://devzone.nordicsemi.com/thread/280884?ContentTypeID=1Thu, 19 Nov 2020 12:28:28 GMT137ad170-7792-4731-bb38-c0d22fbe4515:eb160f3c-c571-43fe-ae71-9117cbb5f103Einar Thorsrud<p>Hi,</p> [quote user=""]<p><span>I used mergehex to merge the bootloader, application and softdevice hex files into one file, and programmed the chip using the nrf programmer.</span></p> <p><span>After programming, I found the chip is staying in the dfu mode and broadcasting as &quot;dfutarg&quot;. I have to upload a zip file to exit the dfu mode.</span></p>[/quote] <p>That is expected, as you have not flashed a valid bootloader settings page. In that case, the bootloader is not aware that a valid application is present and cannot start it. In order to avoid having to perform a DFU update to get the app running you need to generate the BL settings page as described under <a href="https://infocenter.nordicsemi.com/topic/ug_nrfutil/UG/nrfutil/nrfutil_settings_generate_display.html">Generating and displaying bootloader settings</a>, and flash that together with the app, bootloader and SoftDevice.</p><div style="clear:both;"></div>