今天看一下Brillo系统中的bluetooth模块。

• Brillo系统Bluetooth框架

由于Brillo系统复用了Android系统相当一部代码，与Bluetooth相关的代码也基本上复用了。在brillo-m10-dev分支中，Bluetooth协议栈的代码存放在system/bt目录下，而bluetoothtbd系统服务相关的代码也是在这个目录中，具体位于system/bt/service目录下，同时在这个目录下，会生成下面这几个模块：

1. bluetoothtbd

2. bluetooth-cli

3. bt-example-hr-server – Heart Rate GATT service example

Android系统bluetooth框架：

图片来自：https://source.android.com/devices/bluetooth.html

由于Brillo系统只有native的代码，所以在图中其实只包含Bluetooth Stack与Vendor Extensions这两个部份。另外还包含bluetoothtbd模块，用于配置bluetooth模块，建立GATT service或者GATT client。

• Bluetooth相关的一些命令

1. 相关的帮助信息：

$ adb shell
# bluetooth-cli                                                                                                                                                                                                   
Fluoride Command-Line Interface

Type "help" to see possible commands.

[FCLI] help

	help			Display this message
	disable			Disable Bluetooth
	enable			Enable Bluetooth
	get-state		Get the current adapter state
	is-enabled		Return if Bluetooth is enabled
	get-local-address	Get the local adapter address
	set-local-name		Set the local adapter name
	get-local-name		Get the local adapter name
	adapter-info		Print adapter properties
	supports-multi-adv	Whether multi-advertisement is currently supported
	register-ble		Register with the Bluetooth Low Energy interface
	unregister-ble		Unregister from the Bluetooth Low Energy interface
	unregister-all-ble	Unregister all clients from the Bluetooth Low Energy interface
	register-gatt		Register with the Bluetooth GATT Client interface
	unregister-gatt		Unregister from the Bluetooth GATT Client interface
	connect-le		Connect to LE device (-h for options)
	disconnect-le		Disconnect LE device (-h for options)
	set-mtu		Set MTU (-h for options)
	start-adv		Start advertising (-h for options)
	stop-adv		Stop advertising
	start-le-scan		Start LE device scan (-h for options)
	stop-le-scan		Stop LE device scan

2. 查看Bluetooth adapter的相关信息：

[FCLI] adapter-info
Adapter Properties: 
	Address: 00:00:00:00:A5:AD
	State: ADAPTER_STATE_ON
	Name: QCOM-BTD
	Multi-Adv. supported: true

可以看到设设备是支持Multi-Adv的。

3. 作为一个Bluetooth – Central

通过bluetooth-cli提供的start-le-scan, stop-le-scan, connect-le, disconnect-le去扫描、关连相关的ble外设：

[FCLI] start-le-scan
Command status: success
[FCLI] stop-le-scan
Command status: success
[FCLI] start-le-scan -d
Command status: success
Scan result: [FC:CD:6E:4B:8D:24] - RSSI: -57 - Record: 0201060A0947616C61787920413903030D18[FCLI] 
[FCLI] connect-le FC:CD:6E:4B:8D:24
Command status: success
Connection state: [FC:CD:6E:4B:8D:24 connected: true ] - status: 0 - client_id: 5[FCLI]

4. 能否作为一个Bluetooth Perheral呢：

[FCLI] register-ble
Command status: success
Registered BLE client with ID: 4[FCLI]
[FCLI] start-adv -n -t -c
Command status: success
Advertising start status: success

如果你的手机支持BLE，可以在蓝牙列表中找到一个名为QCOM_BTD的一个设备。

• 运行sample app – bt-example-hr-server

在system/bt/service/下面有一个bt-example-hr-server的sample app，可以通过它来学习如何开发一个简单的BLE server app。先编译出来push到DragonBoard 410c中看看效果：

$ mmm system/bt/service
$ adb remount
$ adb sync system
$ adb shell bt-example-hr-server
[0321/155621:INFO:server_main.cpp(92)] Starting GATT Heart Rate Service sample
[0321/155621:INFO:heart_rate_server.cpp(228)] Heart Rate server registered - server_if: 4
[0321/155621:INFO:heart_rate_server.cpp(229)] Populating attributes
[0321/155621:INFO:heart_rate_server.cpp(302)] Initiated EndServiceDeclaration request
[0321/155621:INFO:heart_rate_server.cpp(325)] Heart Rate service added
[0321/155621:INFO:server_main.cpp(128)] Heart Rate service started successfully

做完这些之后，你还需要通过bluetooth-cli开启ble adv(start-adv)，不然手机没办法扫描到这个ble外设。

手机相关的app可以使用development/samples/browseable/BluetoothLeGatt @ android-5.1.1_r15中的代码。通过这个App，你可以连接ble设备，查看设备所提供的服务(Heart Rate Service)：

• 相关的参考文档：

1. https://source.android.com/devices/bluetooth.html