forcing BLE 4.2 and above connection - Avoiding fallback to BLE 4.0

[yes]

We use nRF52832 (S112  / S130) and nRF840 (S140) for our future products

By default server device which supports BLE 4.2 shall fallback to BLE 4.0 and accept connection request from observer device which doesn't support BLE 4.2. 

Can we force BLE 4.2 (and above) connection i.e BLE 4.0 device connection request shall be rejected?

Thanks in advance

[Einar Thorsrud]

yes said:

Due to regulation mater we were required to make sure that only BLE 4.2 connection shall be established and client which sopports only 4.0 shall be rejected or atleast application layer shall be notified.

Strange. What regulation affects this?

yes said:

Can we use LESC for that? Does it fallbacks or connection failed? Can our application be notified?

Not really. You can choose to always require LESC bonding, and the application can disconnect if the peer does not support LESC. However, it is perfectly legal for a BLE device which is 4.2 compliant (or even higher) to not support LESC, since this is an optional feature. So it is not a foolproof way to distinguish between Bluetooth version. (as mentioned before, Bluetooth versions are almost irrelevant, since virtually all features added after 4.0 are optional).