Field upgrade from nRF5 SDK to Zephyr

[dav01]

Looking for the best ways upgrading from a nRF5 SDK / SoftDevice based design to Zephyr.
in my case, the nordic bootloader / upgrade process is configured for UART.

It would make most sense to let the bootloader stay and only wipe the SD + application area, replacing this with the zephyros based app.
i.e nice not having to rewrite the bootloader area (to mcuboot) to avoid potential bricks.

Anyone successfully done this? 

[Hung Bui]

Hi David, 

What you proposed should work. Since the bootloader only need the MBR to work you can remove the softdevice by using sd_req 0x00 in the .zip . 

In addition you would need to modify the Zephyr app so that it would compile to be located after the MBR instead of address 0x000000

[dav01]

Hi, sounds simple. Have anyone at nordic tried?

I'm thinking also about the signing step required by the nordic boot-loader prior to upgrading.

[Hung Bui]

Yes we did test this. Thinking of the Zephyr as a normal non-softdevice application and you would do signing the same way as you generate the .zip package for normal Nordic SDK application. The only change needed is in your Zephyr application is to link the application at the correct address.