https://devzone.nordicsemi.com/f/nordic-q-a/76720/nrf-connect-programmer-vs-j-flash-toolHello there, if i download a hex-file to the NRF52840-Dongle with the J-Link (Lite) tool, the dongle always remains in bootloader mode (red led is flashing). But if i download the SAME Hex-file with the programmer tool from the nrf connect SDK, theen-USTelligent Community 13Fri, 25 Jun 2021 11:34:33 GMThttps://devzone.nordicsemi.com/thread/317215?ContentTypeID=1Fri, 25 Jun 2021 11:34:33 GMT137ad170-7792-4731-bb38-c0d22fbe4515:15732ab8-57ac-43e0-a7f6-50f8d65c61b2Vidar Berg<p>Hello,</p> <p>I assume you are programming the hex file through DFU over USB when you use the programmer app? This is a bit different from flashing the hex file directly through the debug interface (with a J-link). Because when you do DFU, the bootloader will&nbsp; automatically update the checksum value used for boot validation (the bootloader verifies the checksum of the application image before deciding to start it on every boot&nbsp; - <span><a title="Boot validation" href="https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/lib_secure_boot.html?cp=8_1_3_5_0_8_1#secure_boot_validation">Boot validation</a></span>). </p> <p>If you want to program the application with the J-link, you also need to generate and program the bootloader settings page along with it, see <span><a title="Generating and displaying bootloader settings" href="https://infocenter.nordicsemi.com/topic/ug_nrfutil/UG/nrfutil/nrfutil_settings_generate_display.html?cp=10_7_6">Generating and displaying bootloader settings</a>.</span></p> <p>In case you have not seen it, we have a tutorial specifically for programming of the 52840 dongle here: <a href="https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial">https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/nrf52840-dongle-programming-tutorial</a></p> <p>Best regards,</p> <p>Vidar</p> <p></p> <p></p><div style="clear:both;"></div>