Software update using MCUBoot from another MCU?

[ecsfang]

Hi!

In our current project, we have started to use the Connect SDK.

We have a an application CPU with a modem running our main software and uses the nRF52833 for local connectivity and sensor hub.

Our plan is to FOTA update the nRF by downloading the new package to the modem and updating the nRF using UART between the application CPU and the nRF, by setting the nRF in DFU mode and transfer the file from the app CPU to the nRF.

Do you have some description of the protocol or some C source code that we can run in our application CPU for transferring the new FW to nRF over UART?

We found some code doing this (like the "newtmgr"), but it is intended for larger hosts like a PC or web service, and we only want a simple solution with the possibility to hand over the signed files to the nRF.

Or would you suggest another approach?

Best regards,

Thomas

[Carl Richard]

Hello, ecsfang!

Thanks for reaching out. What comes to mind here is the management subsystem of Zephyr, which based on the Simple Management Protocol (SMP). The Zephyr specific bindings for SMP can be found at zephyr/subsus/mgmt/mcumgr, with implementation for serial transfer. Using this you should be able to implement a SMP client on your application MCU that can interact with the nRF52, running the SMP server sample.

We don't have much in terms of sample code for this, but you could look into the Central DFU SMP sample which implements a BLE SMP client. In addition this case may be relevant when it comes to encoding.

Best regards,
Carl Richard