nRF51 Sniffer LTK support

[Eugene]

As far as i understood it supports 4.2 BLE because using it i'm able to see packets between nRF52 central and peripheral boards (HRM example). Is it so?

[Hung Bui]

No, The Legacy BLE pairing (LTK you mentioned) is available from Bluetooth 4.0.

The new encryption/pairing model is the LE Secure connection. But we haven't supported it yet on the nRF52 or nRF51 stack.