BLE 4.2 support

[Roei]

Hi,

I'm working on nrf52840. As far as I understand, that device supports connection to peers with BLE 4.2 at least.

However, I'm able to connect via my phone, which contains BLE 4.1.

1) How is it possible?

2) Do I have an option to recognize the BLE version of my peer, after connection?

Thanks!

[Simonr]

Hi

The nRF52840 supports Bluetooth 5.0. The Bluetooth specification allows all BLE devices to connect to one another even if they're not the same version. Devices supporting newer versions of BLE will not be able to use the features specific to the newer versions when connected to older devices, but there's nothing stopping them from connecting to older BLE versions.

Best regards,

Simon

[Roei]

In terms of security, I would like that devices with BLE under 4.2 will not be able to connect.

Can I solve this issue with defining MITM protection?

[Simonr]

Hi

Implementing something that was released in Bluetooth 4.2 should prevent your device from being connected to Bluetooth 4.1 devices. If you, for example, implement LESC (Low Energy Secure Connections) in your application, only BLE 4.2 devices and newer will be able to connect to your device. This can be done by setting the SEC_PARAM_LESC define to 1 in your application. Many of our examples do this already, see I.E. the ble_app_gls example.

Best regards,

Simon