Why nordic doesn't integrate ble mesh inside the softdevice?

[Mitch996]

Hello, let it be clear that I could be wrong on this, but so far, based on the example provided by the nordic semi, I got the impression that the ble mesh is built almost entirely on top of the ble stack (i.e. the softdevice) with access layer, network bearers' implementation visible in the source code.

Why is that? Actually I was expecting more or less almost everything got integrated into a special sort of softdevice exposing very limited customization potential and only a limited amount of high level APIs, which would be beneficial in at least 2 ways: 1. easy to pick up 2. stability.

Can someone please shed some light on this topic?

Also there is no S140 softdevice included in the official nordic example project, can I take it as a sign that it's still under development/not yet fully compatible?

[Thomas Stenersen]

Hi Mitch996,

You're right that the Nordic mesh stack isn't bundled as its own SoftDevice. There are several reasons for this, one is that the mesh stack doesn't actually have a lot in common with the standard SoftDevice. For example, in the mesh stack we need fine control over the advertiser and scanner, but none of the very precise real-time radio control that the SoftDevice do when managing connections. Also, from the bearer layer up, the protocol and software requirements are vastly different for mesh than standard BLE. We also recognized that a mesh device needs to be highly customizable and that favors a more open model than the SoftDevice. The SoftDevice is currently only used for it's Timeslot API.

I agree with your benefits of the SoftDevice model. Hopefully we've managed to make our top-level APIs easy to understand and use, such that you wouldn't need to know the nitty-gritty details of the internals of the stack.

In the v0.9.1-Alpha release there isn't support for the S140 as indicated here. However, the stack should still run with no problems on both the nRF52840 and nRF52810, not supported simply means it hasn't been tested with the other devices/SoftDevices.

Hope this shed some light on your questions.

Best regards,
Thomas

[aaronxu]

I would like Nordic keep mesh stack open source, rather than make it closed. This is the biggest difference between other silicon supplier, and I believe that lots of people like such kind of open source.