[NRF52] Question about the MBR and SD dependence

[shaba]

Hey folks,

Is there any dependence between the MBR and the SD version? The reason I ask is because we are working on a product that will be able to update the softdevice as well as the app portions of the image while ideally retaining the MBR.

Do you guys see any issues with this method? We are currently running the 2.0.0 version of the 332 SD with the 2.0.0 MBR. I was going to try downgrading just the first page of flash to the old MBR, but figured I would pose the question in parallel.

[bjorn-spockeli]

No, the MBR is SoftDevice independent, so the approach you're describing should work just fine. In fact, this is how we do it in our bootloader, the MBR is never updated during DFU, just the Softdevice.

-Bjørn

[JeanMBoones]

Thanks for the reply, but let me be more specific. Is it possible to update the SD while leaving the MBR intact and if so, what are the limitations to this? In other words, is the MBR for a given SoftDevice (such as 132) guaranteed to remain compatible with future versions of that SoftDevice (other than changing some configuration register for address forwarding, etc.)? We would like to have the ability to update the SoftDevice in the field while leaving the MBR and our custom bootloader untouched. This is with the goal of always maintaining valid working software in the device regardless of a functional SoftDevice or not.