Simultaneous BLE connections on WB55

[Akos P]

Hi,

I'm using the STM32WB55 as a BLE peripheral. The goal is to support multiple simultaneous connections with different Centrals, so that the peripheral can broadcast its characteristics to multiple clients.

To accomplish that, my code re-enables advertising after a connection has been established, e.g. in EV_LE_CONN_COMPLETE I call aci_gap_set_discoverable() again.

This works exactly two times (using the custom template generated by CubeMX). However, after the second central connects, additional aci_gap_set_discoverable() calls fail with the error 0x0C.

Any pointers on why this is happening is greatly appreciated.

[Remi QUINTIN]

No update.

What is your use case that requires more than 8 connections?

[BGeig.3]

Uh, thanks for the fast reply Remi 🙂

We develope some kind of exoskeleton, controlled by myoelectric signals.

Therefore the idea is to build several peripherals (>8) as EMG sensors, sending sensor readings to the central device.

The central device (receiving sensor readings) on the other hand is in peripheral role (-> dual role) connected to a tablet (central device for UI).

Moreover the central device acts as some kind of motor controller, doing even more logic.

Do you have any ST solution ideas (love the WB55)?

Greetings

Benjamin

[Remi QUINTIN]

Quite interesting!!

The only way I can see is splitting the network architecture in 2 parts, adding on one of the peripheral devices today a role of master to interface with additional 6 or 7 other peripherals devices. This secondary master device would be connected to the first master as a peripheral or/and would directly connect to the tablet using the second peripheral role possible on a device to reduce any latency when displaying data on the UI.

[BGeig.3]

Thanks, sound like an interesting topology. Didn't think about it till now.

Maybe it's possible to avoid the additional complexity by combining multiple sensors on one peripheral so that the max. of 8 is enough. But right now we don't now and therefore it's good to have a backup solution in mind. 🙏