S130 max concurrent central connections

[Cetin Mericli]

I am developing an application where a repeater unit connects to a number of other units, gets some info, aggregates it and broadcasts it as a peripheral unit (in a tree structure, the consolidated readings are propagated all the way up to a main receiver unit). Considering S130 as a combination of S110 and S120, I've always assumed that the max. number of concurrent connections are 8 (as it is in S120). However, when I try to connect more than 3 peripherals, I get NRF_ERROR_INTERNAL. I recently noticed that in the softdevice specification document for S130, it says max 3 central connections. I am using S130 v0.9 alpha, and nRF SDK 7.1.

So my question is two fold: i) is it true that S130 only supports up to 3 concurrent central connections? and ii) if so, what can I do to remedy that.

Many thanks in advance!

[Ulrich Myhre]

The S120 2.0.0 has both a central and a peripheral included, but you cannot run both concurrently like with S130.

With the S120, you should be able to enable the SoftDevice as a (8-link) central, aggregate data, then disable the SoftDevice and enable it as a peripheral (S110-like). You are then able to broadcast any data you have saved, although all states and data related to the SoftDevice will be reset when disabling/enabling the SoftDevice.

Could this potentially solve your problem?

[Cetin Mericli]

Hi Ulrich,

Thanks for the reponse. I thought of that alternative. In the worst case it could be a fallback but the fact that you should be able to orchestrate 8 peripheral connections, disconnect, connect as a peripheral, and repeat the prcess is probably not very power friendly (I forgot to write but the system has to operate for a prolonged period when installed).

If there were a way of saving and resuming the soft device state (similar to the activation record concept in programming languages), things could have been slightly easier.