Bluetooth in Android 4.2 and 4.3 (I): overview

From Android 4.2, the Bluetooth Stack has undergone a major change: From bluez to bluedroid jointly developed by Google and Broadcom (of course, the core part is still Broadcom, google is mainly engaged in the upper-layer framework ). You can use http://source.android.com/devices/javasth.htmlto obtain a new Bluetooth
Stack architecture. In general, there are few relevant documents, mainly by reading the code for in-depth understanding.

Compared with bluez, bluedroid has the following advantages:

1. The hierarchy is clear. Each profile is unified to the upper-layer interface to facilitate the addition of a new profile; the Hal layer is added to facilitate migration.
2. With the release removed, the Java code of the framework directly calls the native code of bluedroid.

However, bluedroid in Android 4.2 has fewer functions than bluez in Android 4.1. For example, it does not support avrcp 1.3 and has many bugs. For example, some Bluetooth headsets cannot redial the last phone. Most importantly, bluedroid 4.2 does not support ble. However, there have been many improvements in the just-released Android 4.3, and avrcp 1.3 and ble are supported.

Currently, some Android 4.1 or 4.2 devices support Ble, but they all adopt their own vendor solutions. For example, Bluetooth Stack uses bluez 5.x, and then provides vendor ble Android SDK. now Android 4.3 has been released. From the future development trend, if someone wants to learn Bluetooth in Android, It is recommended not to study bluez any more. It is best to switch to bluedroid.

The distribution of Bluetooth-related codes in Android 4.2 is as follows:

Android. Bluetooth	Frameworks/base/CORE/Java/Android/Bluetooth	Implements public API for the Bluetooth adapter and profiles
Bluetooth System Service	Packages/apps/Bluetooth/src	Implements service and profiles at the android fraework Layer
Bluetooth JNI	Packages/apps/Bluetooth/JNI	Defines Bluetooth adapter and profiles service JNI: callinto Hal and calls es callback from Hal
Bluetooth hal	Hardware/libhardware/include/hardware/BT _ *. H files	Defines the standard interface that the Android. Bluetooth adapter and profiles APIs
Bluetooth Stack	External/Bluetooth/bluedroid	Implement Bluetooth Stack: core and profiles

Taking Pan profile as an example, we can look at the distribution of code and the naming of classes and files:

Android. Bluetooth	Frameworks	Public class implements thpan implements thprofile
Bluetooth System Service	Packages/apps	Public class panservice extends profileservice
Bluetooth JNI	Packages/apps	Com_android_bluetooth_pan.cpp
Bluetooth hal	Hardware/libhardware	Include/hardware/bt_pan.h
Bluetooth Stack	External/Bluetooth	Bluedroid/btif/src/btif_pan.c (implements bt_pan.h)
		Bluedroid/BTA/PAN (Broadcom BTA)
		Bluedroid/stack/PAN (Broadcom BTE)