https://devzone.nordicsemi.com/f/nordic-q-a/30047/custom-bootloader-nrf52832I&#39;ve got an mBed application that includes a softdevice (s132 - 2.0.1) that is installed at 0x00000-0x520000 and works as required. I created a test bootloader using the example &quot;blinky&quot; from the nRF52 SDK14 (no softdevice). I load this at 0x78000. Whenen-USTelligent Community 13Wed, 31 Jan 2018 03:41:53 GMThttps://devzone.nordicsemi.com/thread/119341?ContentTypeID=1Wed, 31 Jan 2018 03:41:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:d6687ede-6d2a-45cb-8591-85e74b5872b2NewAce<p>OK, figured it out. I&#39;m using the IoT bootloader example in SDK 14.2 (/examples/iot/bootloader) and configured the Makefile to set the MAIN_APPLICATION_START_ADDR to 0x1c000 and CODE_REGION_1_START to 0x1c000 as well. In main.c, I only have some led blinking to confirm that I am in the bootloader before calling nrf_bootloader_app_start(MAIN_APPLICATION_START_ADDR) and that&#39;s it. I am not calling nrf_bootloader_init(). The main application at 0x1c000 is then called. The main application uses mBed with BLE and this works as required. Hope this helps someone else.</p><div style="clear:both;"></div>