ble_gap_conn_find_by_addr() function
Searches for a connection with a peer with the specified address. If a matching connection is found, the supplied connection descriptor is filled correspondingly.
Arguments
addr
The ble address of a connected peer device to search for.
out_desc
On success, this is populated with information relating to the matching connection. Pass NULL if you don't need this information.
Return value
0 on success, BLE_HS_ENOTCONN if no matching connection was found.