https://devzone.nordicsemi.com/f/nordic-q-a/57918/dfutarg-unable-to-boot-nrf52840-dk-into-dfutarg-dfu-modeI&#39;m trying every permutation. Pressing IF BOOT/RESET button along with BUTTON 4 and powering off and on the board ... then letting the buttons go There is a reset pin ... but how do you use this? I can successful upload all Nordic SDK perpherialen-USTelligent Community 13Tue, 18 Feb 2020 13:22:52 GMThttps://devzone.nordicsemi.com/thread/234927?ContentTypeID=1Tue, 18 Feb 2020 13:22:52 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6d2a0a1f-bf4f-483f-9661-921aabd3f367tesc<p>Hi,</p> <p>Actually there are two microcontrollers on the DK. There is the nRF52840, of course, which the DK is for. Then there is a <a href="https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf52840_dk%2FUG%2Fnrf52840_DK%2Fif_mcu.html">programmer MCU</a> that provides the SEGGER J-Link interface for programming the nRF52840. Holding IF BOOT/RESET pressed while powering the board is for setting that programmer MCU into its firmware upgrade state. It has nothing to do with DFU solutions on the nRF52840.</p> <p>For a complete guide on how to set up and use our DFU bootloader, please have a look at <a href="https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/getting-started-with-nordics-secure-dfu-bootloader">Getting started with Nordic&#39;s Secure DFU bootloader, a step by step guide</a>.</p> <p>Regards,<br />Terje</p><div style="clear:both;"></div>