Communication between nrf52

[phob]

hi, i was looking for example of two nrf52 communication. One is central of course and other one is peripheral. But i have following doubts.

1. If one is central then how peripheral device will connect to central? Are we Searching for that address?
2. Which type of authentication we can give?

[endnode]

Hi phob,

1. Peripheral never connects to Central, the roles are asymmetric. As Peripheral (on GAP layer or Slave on LL layer) you can only hope that something connects to you. Criteria for connecting can be anything: a) Central searches for particular Adv. address. b) Central parses Adv. data and connects to device which indicates particular GATT Service UUID(s) or have some specific Manuf. Specific AD data. c) Central connects to everything what is visible and decides later if it is good target or not. d) Anything else...
2. What do you mean by "type of authentication"? If you want to use BT LE LL encryption and Security Manager layer then you need to initiate pairing in the standard way and that is independent (as far as I understand) on Master/Slave roles on link layer (Peripheral/Central if you want on GAP layer).

Cheers Jan

[phob]

Thanks for clear explanation. May be my question was wrong about authentication. I was having doubt on authentication while connecting to other device.Like one BT device connects to other BT device by sharing pairing PIN code. I was trying to connect my nRF52 dk with mobile's BT without starting Nordic's APP. Which is rejected by controller. But later same mobile and board got connected using Nordic's APP. So, Are they sharing any kind of data(passcode) or something?

[endnode]

No, as far as I know there is pre-shared secrets hardcoded to Nordic's mobile/PC apps and example BLE FWs for nRF51/52. So it was probably limitation on either (or both) sides where Nordic's app initiated Security Manager pairing properly but the other app (or built-in system feature) didn't. Hard to say without having more details (e.g. BLE traces).