https://devzone.nordicsemi.com/f/nordic-q-a/23136/pca10056-flash-the-merge-hexQ1 I compile sdk13.0.0 generate nrf52840_xxaa.hex(app), nrf52840_xxaa_s140.hex(bootloader). I used merge tool make a hex file, then burn the file into PCA10056 DK by nrfjprog, but system reset entry DFU mode. mergehex -m s140_nrf52840_5.0.0-2.alpha_softdeviceen-USTelligent Community 13Tue, 04 Jul 2017 08:33:48 GMThttps://devzone.nordicsemi.com/thread/90994?ContentTypeID=1Tue, 04 Jul 2017 08:33:48 GMT137ad170-7792-4731-bb38-c0d22fbe4515:155f3a05-2c13-4e99-812c-58e829ec242aStian R&#248;ed Hafskjold<p><strong>Q1</strong> The problem is that it is the bootloaders task to validate the application based on CRC during boot, also it needs to set an &quot;application present&quot; flag so it knows there is an application there. This is automatically done when you first flash the bootloader, then use the bootloader to upload the application. If you want to merge the application and bootloader <em>before</em> flashing, a settings page must be generated with the correct info about the application. This settings page will go in the last flash page after the bootloader (<a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v13.1.0/lib_bootloader.html#lib_bootloader_memory">memory layout</a>)</p> <p>To generate the settings page you can use the <strong>nrfutils</strong> tool. Please see this link: <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.tools/dita/tools/nrfutil/nrfutil_settings_generate_display.html">infocenter.nordicsemi.com/.../nrfutil_settings_generate_display.html</a></p> <p>The settings page must then be merged with application (and SD) and bootloader using <strong>mergehex</strong>, and then flashed using <strong>nrfjprog</strong></p> <p><strong>Q2</strong> nRFgo studio has some internal checks that fail with certain types of hex files. We are working on a solution to this. Meanwhile, we recommend using <strong>nrfjprog</strong> instead.</p><div style="clear:both;"></div>