https://devzone.nordicsemi.com/f/nordic-q-a/11768/how-to-start-dfu-bootloader-from-application-without-using-ble-dfu-serviceI have make over your bootloader example to create my own without BLE support in bootloader (new programs are send in application instead of in dfu bootloader). Bootloader works fine the only problem that I still can&#39;t handle is how to start bootloaderen-USTelligent Community 13Mon, 08 Feb 2016 14:24:04 GMThttps://devzone.nordicsemi.com/thread/44499?ContentTypeID=1Mon, 08 Feb 2016 14:24:04 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5cf5e05e-8d55-4cd3-924a-7fa72fa4eb62run_ar<p>32bit cpu architecture (e.g. each register is 32bit), but only 8 bits are used (as is shown in the reference manual).</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/44498?ContentTypeID=1Mon, 08 Feb 2016 13:07:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c3cbfe2d-90f1-4d77-bbc6-942e22043a05Al Bundy<p>That works, thanks. By the way what is the length of GPREGRET ? In documentation it is said that it is 8 bit long but in your bootloader example you use <code>uint32_t</code>.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/44497?ContentTypeID=1Mon, 08 Feb 2016 12:10:45 GMT137ad170-7792-4731-bb38-c0d22fbe4515:59b5f20b-4973-4df6-b480-1ab7be865a39run_ar<p>When are you getting a hardfault in this case? Note that for the serial bootloader you only need to call:</p> <pre><code>err_code = sd_power_gpregret_set(10); nvic reset </code></pre> <p>Then you are done. Note that when you enter the bootloader you need to remove this check:<br /> <code>if (init_softdevice)</code>.</p><div style="clear:both;"></div>