Nordic bootloader DFU zip file

Question

Hi Sir 
 We plan to implement our own DFU controller on host MCU to upgrade on board DFU module by UART. 
 Zip file will be generated by nrfutil and saved on flash. 
 Can you help me to find DFU zip file format document please? 
 For example, we generate a bootloader+softdevice+application zip file, when start to send bootloader during DFU procedure. 
 Where can I get the bootloader position and size from zip file. 
 How does the zip file descript the bootloader position, size? 
 Thanks.

Hung Bui · Accepted Answer

Hi, 
 Inside the .zip file is the binary files and the init packet file (.dat) . The json file is for human reading. 
 If you combine BL+SD+APP there will be one .bin, .dat file for application and one .bin and .dat for SD+BL. The reason is that for this combination, there will be DFU update with 2 phases, SD+BL first and then APP being updated after. 
 I don't think storing .zip file on flash of the MCU is the best way to do this. Your MCU would need to unzip the file which is not necessary. 
 My suggestion is to unzip it first, and only store the .bin and .dat files on the MCU. You don't need to decode the .dat file or finding what the size of the bootloader is, just simply send the .dat and the .bin. 
 Please try testing updating only the app first, after that you should be able to do combination. 
 Here is an example of DFU master using UART: https://devzone.nordicsemi.com/f/nordic-q-a/36177/the-packet-format-of-serial-dfu-in-sdk-14-2-0-it-s-not-the-same-as-sdk-11-0-0-before

Nordic bootloader DFU zip file

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