User's Manual
8 Bluetooth
In-Car Trigger and BWC adopt Bluetooth Low Energy (BLE or Bluetooth 4.0) as the
wireless communication interface between each other. Comparing with Bluetooth 2.1
technology, BLE has the listed features:
Ultra-low power consumption
The BLE maintain the connection between two paired device via a periodically
handshake mechanism instead of sustaining the link continuously, it save the
power to diving the RF component enormously to raise the operating time of BWC.
Low data rate
As a side effect to the periodically handshaking, data transmission between 2
paired devices is not streaming but only small amount periodically. BLE is only
suitable for transferring self-defined remote command but not used to streaming
the video or audio.
8.1 Pairing decision
In-Car Trigger and BWC must perform Bluetooth pairing to setup the Bluetooth
connection, which is trigged by NFC sensing introduced in section 7.2
In Bluetooth pairing procedure, In-Car Trigger first retrieve BWC’s Bluetooth Mac
address via its NFC reader from the NFC tag of BWC, and then it decide to setup
Bluetooth connection to this BWC base on the defined
pairing decision.
In-Car Trigger max support pairing to 2 BWCs with Bluetooth simultaneously, the
pairing decision is designed to which one of these Bluetooth channels will be
allocated for the new-paired BWC, and which BWC will be dis-paired if required
base on the following description of scenario:
A. The Bluetooth mac address retrieved from NFC tag of target BWC will be
compared with the mac address currently paired with both of two Bluetooth
channels. If the address is match, this corresponded Bluetooth channel will be
allocated to pair with the target BWC.
B. Continues from (A). If the mac address mismatch to both of the two Bluetooth
channels, the channel which status currently is not connected to its paired
device will be allocated to pair with the target BWC.
C. Continues from (B). If both Bluetooth channels’ status currently are not
connected, the Bluetooth channel which is the last allocated for pairing will be
reserved, and the other one will be allocated to pair with the target BWC.
D. Continues from (B). If both Bluetooth channels’ status currently are
connected, the one that its paired BWC currently is not recoding will be
allocated to pair with the target BWC.