LE Secure Connections and Legacy Pairing

[WestCoastDaz]

Is it possible to support both LE Secure Connections Just Works pairing and Legacy Just Works pairing in a single device?

My concern at the moment is that if I require LE Secure Connections my product won't be able to connect to most Android devices since my research indicates only ~25% of current Android devices are running a version of Android that supports LE Secure Connections.

Back to my question for example if a device connecting to my product supports LE Secure Connections Just Works Pairing then I want to connect using that security mode. If the device doesn't support LE Secure Connections then I want to fallback to Legacy Just Works pairing.

Thanks, Darren

[Petter Myhre]

It should be possible. Per spec if one of the devices doesn't support LESC LE Legacy pairing should be used:

The SC field is a 1 bit flag. If LE Secure Connections pairing is supported by the device, then the SC field shall be set to 1, otherwise it shall be set to 0. If both devices support LE Secure Connections pairing, then LE Secure Connections pairing shall be used, otherwise LE Legacy pairing shall be used.

Taken from Vol 3, Part H, Section 3.5.1.

[WestCoastDaz]

Petter,

Thanks for the comment and the details on which section of the Bluetooth spec detail this. Does Nordic have any examples of this? Also what is the best way to determine if a connection is using LE Secure connections or not?

Cheers, Darren

[Petter Myhre]

A peripheral example that supports LESC but falls back to legacy Just Works if LESC is not supported by the central device? The best way is to catch the BLE_GAP_EVT_AUTH_STATUS event, and check that auth_status.sm1_levels.lv4 is set.