DFU with a compressed LZ4 file

[Markus Arnoldsson]

Hello! 

I am working on a FOTA solution for the nRF52DK, I have followed this example: https://devzone.nordicsemi.com/guides/nrf-connect-sdk-guides/b/software/posts/ncs-dfu

The FOTA works using the nRF Device Manager application and a binary image file.

For the project, it is planned to compress the binary image file with lz4 and in the bootloader of the MCU include a decompressor.

However, in nRF Device Manager it says invalid file when trying to flash the compressed image.

Does anyone have a recommendation to solve this? Other plans work as well, in general what is needed is for a lz4 compressed file to be flashed onto the MCU.

[Aleksander Nowakowski]

Hello,

The app is checking few first bytes of the binary and it's expecting to find there a Magic value. If your binary is compressed, encrypted, etc, it will fail and return an error. 

I recommend downloading the source code of the app and removing the code with the checks.

[Markus Arnoldsson]

Hello I am looking into this solution.

I tried removing check from ImageUploadFragment but still invalid.

Noticed now there is also a ImageUpgradeFragment, should I remove check there aswell? Iif so is there a simple way to do it?

https://github.com/NordicSemiconductor/Android-nRF-Connect-Device-Manager/blob/main/sample/src/main/java/io/runtime/mcumgr/sample/fragment/mcumgr/ImageUpgradeFragment.java 

https://github.com/NordicSemiconductor/Android-nRF-Connect-Device-Manager/blob/main/sample/src/main/java/io/runtime/mcumgr/sample/fragment/mcumgr/ImageUploadFragment.java 

Appreciate the help

[Aleksander Nowakowski]

Remove the check everywhere you need. The ImageUploadFragment uploads a single bin file, while ImageUpgradeFragment is able to perform the complete DFU with validating, uploading one or more files, sending test/confirm commands and reset, using the FirmwareUpgradeManager.