https://devzone.nordicsemi.com/f/nordic-q-a/30339/dfu-init-packet-fields-descriptionHi, if I correct understood DFU process first of all it need to send &quot;Init packet&quot; and after that it need to send FW image. And for that reason in DFU packages is 3 files *.dat (init packet), *.bin (FW image) and manifest file description about firsten-USTelligent Community 13Mon, 12 Feb 2018 12:11:37 GMThttps://devzone.nordicsemi.com/thread/120561?ContentTypeID=1Mon, 12 Feb 2018 12:11:37 GMT137ad170-7792-4731-bb38-c0d22fbe4515:709f0dfa-0870-4583-8c5e-6b8adddb6208ivansanchez<p>For the DFU process you need just two files: the init packet, and the firmware image.</p> <p>It is possible to run more than one DFU procedure onto a device, so to keep track of the order of those DFU procedures, <code>nrfutilc</code> creates a .json manifest of the init packets and firmware images for each one.</p> <p>As for the format of the init packets, let me quote from <a href="http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v14.2.0%2Fsdk_app_serial_dfu_bootloader.html&amp;cp=4_0_0_4_4_2_1&amp;anchor=lib_bootloader_dfu_init">http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v14.2.0%2Fsdk_app_serial_dfu_bootloader.html&amp;cp=4_0_0_4_4_2_1&amp;anchor=lib_bootloader_dfu_init</a> :</p> <blockquote>The required contents of the init packet are defined in the protocol buffer file <code>dfu-cc.proto</code>. The following fields of the init packet are checked during the validation of the init packet:</blockquote> <p>About the size anc crc32 of the firmware image: that information has to be inside the init packet. Think of the init packet as metadata for the firmware image.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/120551?ContentTypeID=1Mon, 12 Feb 2018 11:23:23 GMT137ad170-7792-4731-bb38-c0d22fbe4515:902bc88c-94ce-4781-b96f-bc7164dc849damicus<p>I&#39;m still waiting an answer</p><div style="clear:both;"></div>