https://devzone.nordicsemi.com/f/nordic-q-a/17773/will-ota-dfu-nrf51822-overwirte-the-whole-flash-regionHi everyone, I am working on an NRF51822 project which requires the use of non-volatile memory to store user profile (so I think either flash or external EEPROM). As far as I know, I can choose to perform OTA update on bootloader, softdevice and applicationen-USTelligent Community 13Wed, 16 Nov 2016 09:05:39 GMThttps://devzone.nordicsemi.com/thread/68468?ContentTypeID=1Wed, 16 Nov 2016 09:05:39 GMT137ad170-7792-4731-bb38-c0d22fbe4515:5cd964de-bbc0-4f55-bb00-3b57efad9536bjorn-spockeli<p>You can configure the bootloader to retain the app data section, shown on <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v11.0.0/bledfu_memory.html">this</a> page on our Infocenter. In order to configure the bootloader to retain this section you have to set the</p> <pre><code>#define DFU_APP_DATA_RESERVED 0x0000 </code></pre> <p>to the number of bytes(must be a multiple of the flash page size) you want to retain.</p> <p>You&#39;ll find more information on <a href="http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v11.0.0/bledfu_memory_appdata.html">this</a> Infocenter page.</p> <p>Best regards</p> <p>Bjørn</p><div style="clear:both;"></div>