User's Manual

Enhanced Class 1 Bluetooth v2.1 Module
User’s Guide
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145
CONN-GUIDE-BT740_v0.2
Is PIN
High?
Assert
RTS
Wait for data
to arrive from
Module
Deassert
RTS
Configure to wake
up when PIN
goes high
Go to Sleep
PIN goes high
Wake up
and
Assert RTS
Figure 13-2: CPU power saving strategy
13.8.3 Out of Band (OOB) Pairing
When two devices pair using the legacy procedure or the simple secure pairing method, the end result is
that they both end up with the same 16 byte random key. This key is subsequently used to authenticate
and encrypt subsequent connections. This means the list of pairing kept in each device as a minimum,
needs to store the peer Bluetooth address along with the 16 byte link key.
The Bluetooth specifications do not mandate that this link key shall only generate/exchange over the
Bluetooth radio, and in fact mention ‘Out-Of-Band’ (OOB) pairing as a valid means of expediting the
pairing of two devices.
The specification does not describe how the OOB pairing occurs.