From Discoverable to Non-discoverable (but still connectable!) using the Advertising Library

[Darrew]

1. Is it possible to configure the parameters of the advertising library (eg. SDK v12.3.0 using SD130 v2.0.1) so that my peripheral device (eg. nRF51) changes after a limited time -say 2 minutes- from limited discoverable into non-discoverable but remaining connectable (still sending advertising packets of connectable type)?

2. According to the standard Core4.2, "...A device in the non-discoverable mode that sends advertising events shall not set the ‘LE General Discoverable Mode’ flag or ‘LE Limited Discoverable Mode’ flag in the Flags AD type..." is it possible to configure a device in this non-discoverable mode and still having the device being able to send advertising packets of connectable type?

[endnode]

Non-discoverable means not connectable.

[Darrew]

The standard Core4.2 says: "... A device configured in non-discoverable mode will not be discovered by any device that is performing either the general discovery procedure or the limited discovery procedure."

moreover,

"...A device in the undirected connectable mode shall accept a connection request from a device performing the auto connection establishment procedure or the general connection establishment procedure."

Both modes are not incompatible.

A device can be in both non-discoverable mode and connectable mode (eg. undirected). In other words, it may allow connections from a peer device performing any connection establishment procedure but it will not be discoverable to those performing any discovery procedure.

[endnode]

I'm afraid your understanding of BT SIG specification contradicts with understanding of other people here on the forum...

[Darrew]

Ok, let's say my device should be discoverable for a limited period of time and connectable all the time. How would you set up the advertising library to do that?

[Ulrich Myhre]

No, i think Darrew is correct here. "Discoverability" is a concept that is easy to misunderstand. When you advertise, every scanner can see that advertisement, period. That's regardless of the contents of the advertisement. But in the PDU, you can set some flags to give a hint to the scanner. What you make out of these hints is up to you, but the other advertisement parameters are largely unaffected by these flags. Some scanners might be on the lookout for general discoverable devices, prioritizing to display those over limited/non-discoverable ones.