How to pair 2 nRF52832 devices with each other always and not with other devices

[ani]

Hello

I am having 3 nRF52832 devices and I have to pair any two of them with each other and not with the third one.The third device or any other device should not get connect with the 1st and 2nd devices and only 1st and 2nd devices should be paired with each other whenever we are powering the devices.

what is the procedure to do above process?

[Hung Bui]

Hi, 

You would need to use bonding and whitelisting so that the devices will reject connection from devices outside of the whitelist. 

This feature is supported by the softdevice and implemented in the peer manager libary: https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/lib_pm_functionality.html?cp=5_0_3_2_7_1_2#lib_pm_functionality_whitelist

You can refer to our example ble_app_hids_mouse (or keyboard). In the example, after bonding we will do directed advertising and after that will do whitelisting advertising,  after the whitelist advertising timeout, it will advertise in normal mode. 
To be able to make sure there will be no other device to connect to your device, you can disable the timeout to normal mode. Only advertise in whitelisting mode. 

[ani]

Hello,

what can we do in the case of mesh?

[Hung Bui]

Please clearly describe your application. There is no concept of "getting connected" between 2 devices in Bluetooth mesh.