Can peripheral find out if another potential central is present?

[TBone]

Hi,

I have a scenario where we may want a peripheral (using S110 softdevice) to switch connections between 2 centrals, depending on whether the centrals are present or not.

P = peripheral; C1 = central #1; C2 = central #2

Here is the question: If P is connected to C1, can it still send directed advertising to C2, and if so, can the P application layer be notified if C2 sends a scan request to P?

Thanks for any help.

[Stefan Birnir Sverrisson]

Hi

When a peripheral is in a connection with a central, it can not connect with another central. A peripheral can only maintain one connection. However, a peripheral device can advertise while in a connection in a scannable mode. That means that any central can send a scan request and get a scan response from an advertising nRF51 peripheral which is in a connection at the same time, see this thread.

When a peripheral is in a connection and is also advertising in a scannable mode, the S110 softdevice will automatically handle the scan request and respond with a scan response packet, the application will not receive any event for this. However, with the upcoming S110 v8.0 softdevice and nRF51 SDK v8.0, it will be possible for the application to receive RSSI event when a nearby central sends scan request. That way, the peripheral is able to detect if an active scanner is in vicinity when the peripheral is in a connection at the same time.

Update 19.5.2015 How to advertise in a scannable mode and receive RSSI events when a central sends a scan request is described on this thread.