Best service choise for packet exchange between 2 nRF51822

[Fabien Comte]

Hello,

I have 2 nRF51822 with S130. One is central, the other is device.

I want to exchange custom data between these 2 devices after connection. What is service best choise ? (i want datagrams like UDP but with acknowledgement).

Can both sides initiate a transfert ?

[Petter Myhre]

You use GATT to transfer data. The peripheral ("device") is usually a GATT server and the central is usally a GATT client.

Both can initate a transfer, and all transfers are acked in the link layer. The client can transfer data to the server by writing to it. The client can also read data on the server.

The server can transfer data by sending notifications and indications to the client.

[Fabien Comte]

Thank you for the response. I imagined that you must use services on GATT (like NUS) but you say that it's not mandatory and i can use raw GATT, right ?