SoftDevice Central Role Support

[Jonathan Gordon]

Is there a plan to support the BLE central role in the software stack?

As it is now, I absolutely cannot use the nRF51822 since the S110 stack does not support operating as a BLE central. However, I really like Nordic's support for open toolchains.

If support for this is planned, is there any kind of super-unofficial schedule for when that would be?

Thanks

[RK]

Have you looked at the S120 softdevice which does exactly that?

[Jonathan Gordon]

Oh, beautiful! It looks like this was announced in the last week or two haha. Thanks for pointing this out.

Now from having skimmed the information for all of 5 minutes, it doesn't look like the S120 software stack supports both roles, just central and observer. That means you could not do any switching between central and peripheral to allow multi-hop BLE networks like is possible with the cc2540.

Am I correct about that?

[RK]

End of November I think, I saw it a while ago but didn't realize what it was for a while.

Yes central-only. Don't know if there are plans for something to do both at the same time, having an 8-channel central is quite good going, although it's currently a bit of a memory hog (leaves you 6kB of RAM to play with)

[Jonathan Gordon]

Hmm, that is a bit troubling. I am skeptical 6kB of RAM would be enough for my application. I find it a little unbalanced to offer 256kB of code space and only 16kB of RAM. Does it always leave only 6kB even if I only wanted to support 2 channels for example? I guess if it is statically compiled and linked the answer is yes, it will always take up that much room. Shame they don't release source code and allow us to specify build settings =P

Nonetheless, this is great news that it supports the central role and I will more than likely be purchasing a development kit now, before I was basically stuck with TI where they force you buy a $$$$ toolchain+IDE suite.

[RK]

Yep - that's why I highlighted it. It's still beta right now, perhaps the memory usage will come down. I agree that in general you need MORE RAM for a central. You can be creative and use unused flash to store more static data, and remember that 10kB of RAM the softdevice is using does contain a lot of data you don't have to store.

Welcome back from the dark side. I fiddled about with TI as well. I've been so impressed by Nordic's dev kit, support for gcc and the quality of the documentation I would never go back.

[Jonathan Gordon]

Good to hear, thanks RK.

I suppose one could do something super insane and keep non-volatile storage with both SoftDevice binaries and implement some form of a bootloader which dynamically switches between roles by programming the different SoftDevice... but that would introduce a TON of latency between role switches.

I'll post a new question asking if anybody knows of plans to support role switching. Marking your answer as correct, but do you mind if I ask what your product application is?