Product Info

Bluetooth Serial Module

AT Command Set

Date : 3 Feb 03 Issue No : 1.9 Doc No : XRBLU020-001SW-0 Page 37 of 38

14.3 Example 3: Trusted Device Management

14.3.1 Background

Bluetooth provides for secure connections through the use of link keys. The link keys are 128 bit entities

which are uniquely created for each BT device via the device’s Bluetooth address. Since all BT addresses

are unique, this results in unique keys.

The link keys are ‘private’ objects and as such are never exposed via the AT interface. They at all times

remain within the serial device. Therefore the serial module allows link key management by using

Bluetooth addresses as handles.

The device has a database of link keys. Each record in the database has two fields. One field contains the

Bluetooth address and the other contains the 128 bit link key. Only the address field is viewable.

The following subsections describe AT command sequence for typical pairing functions.

14.3.2 Obtain a new Link Key

This process will obtain a new link key for a remote device whose address is 123456789012 and whose

pin code is known to be 12345.

AT Command Response Comment

AT+BTW12345678901

PIN? 123456789012 This is sent to the host every 2000ms

PIN? 123456789012

AT+BTK=”12345” OK Pairing complete. The link key is stored in a volatile

cache

PIN 0 123456789012 Pairing successful

14.3.3 Store link key in trusted device database

This process assumes that the procedure described in “Obtain a new link key” has been done and there

exists a link key in the cache, and that the database is not full.

AT Command Response Comment

AT+BTT OK

14.3.4 List trusted device database

This process assumes that the procedure described in “Obtain a new link key” has been done and there

exists a link key in the cache, and that the database is not full.

AT Command Response Comment

AT+BTT? 123456789012

123456789013

123456789014

123456789015

123456789016