s.a.c. redesign, first checkin
Change-Id: I4dead2f18bc5e4a38f204c92198a267c286e775d
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+page.title=Bluetooth
+@jd:body
+
+<!--
+ Copyright 2010 The Android Open Source Project
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+ http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+-->
+<div id="qv-wrapper">
+ <div id="qv">
+ <h2>In this document</h2>
+ <ol id="auto-toc">
+ </ol>
+ </div>
+</div>
+
+
+<p>Android provides a default Bluetooth stack, BlueDroid, that is divided into two layers: The Bluetooth Embedded System (BTE), which implements the core
+Bluetooth functionality and the Bluetooth Application Layer (BTA), which communicates
+with Android framework applications. A Bluetooth system service communicates with the Bluetooth stack through JNI and with applications through
+Binder IPC. The system service provides developers access to various Bluetooth profiles. The following
+diagram shows the general structure of the Bluetooth stack:
+</p>
+
+<p><img src="images/bt.png"></p>
+
+<dl>
+ <dt>Application framework</dt>
+ <dd>At the application framework level is the app's code, which utilizes the <a
+ href="http://developer.android.com/reference/android/bluetooth/package-summary.html">android.bluetooth</a>
+ APIs to interact with the bluetooth hardware. Internally, this code calls the Bluetooth process through
+ the Binder IPC mechanism.</dd>
+
+ <dt>Bluetooth system service</dt>
+ <dd>The Bluetooth system service, located in <code>packages/apps/Bluetooth</code>, is packaged as an Android
+ app and implements the Bluetooth service and profiles at the Android framework layer. This app
+ calls into the HAL layer via JNI.</p>
+
+ <dt>JNI</dt>
+ <dd>The JNI code associated with <a
+ href="http://developer.android.com/reference/android/bluetooth/package-summary.html">android.bluetooth</a> is located in
+ <code>packages/apps/Bluetooth/jni</code>. The JNI code calls into the HAL layer and receives
+ callbacks from the HAL when certain Bluetooth operations occur, such as when devices are
+ discovered.</dd>
+
+ <dt>HAL</dt>
+ <dd>The hardware abstraction layer defines the standard interface that the <a
+ href="http://developer.android.com/reference/android/bluetooth/package-summary.html">android.bluetooth</a> APIs
+ and Bluetooth process calls into and that you must implement to have your bluetooth hardware
+ function correctly. The header files for the Bluetooth HAL is located
+ in the <code>hardware/libhardware/include/hardware/bluetooth.h</code> and
+ <code>hardware/libhardware/include/hardware/bt_*.h</code> files.
+ </dd>
+
+ <dt>Bluetooth stack</dt>
+ <dd>The default Bluetooth stack is provided for you and is located in
+ <code>external/bluetooth/bluedroid</code>. The stack implements the generic Bluetooth HAL as well
+ as customizes it with extensions and configuration changes.
+ </dd>
+
+ <dt>Vendor extensions</dt>
+ <dd>To add custom extensions and an HCI layer for tracing, you can create a libbt-vendor module
+ and specify these components.
+ </dd>
+
+ </dl>
+
+
+<h2 id="implementing">Implementing the HAL</h2>
+<p>The Bluetooth HAL is located in the <code>hardware/libhardware/include/hardware/</code> directory
+ and consists of the following header files:
+
+<ul>
+ <li><code>bluetooth.h</code>: Contains the HAL for the Bluetooth hardware on the device</li>
+ <li><code>bt_av.h</code>: Contains the HAL for the advanced audio profile.</li>
+ <li><code>bt_hf.h</code>: Contains the HAL for the handsfree profile.</li>
+ <li><code>bt_hh.h</code>: Contains the HAL for the HID host profile</li>
+ <li><code>bt_hl.h</code>: Contains the HAL for the health profile</li>
+ <li><code>bt_pan.h</code>: Contains the HAL for the pan profile</li>
+ <li><code>bt_sock.h</code>: Contains the HAL for the socket profile.</li>
+</ul>
+
+</p>
+
+<p>Keep in mind that your Bluetooth implementation is not constrained to the features
+ and profiles exposed in the HAL. You can find the default implementation located
+ in the BlueDroid Bluetooth stack in the <code>external/bluetooth/bluedroid</code> directory,
+ which implements the default HAL and also extra features and customizations.</p>
+</p>
+
+<h2>Customizing the BlueDroid Stack</h2>
+
+<p>If you are using the default BlueDroid stack, but want to make a few customizations, you can
+ do the following things:</p>
+
+<ul>
+ <li>Custom Bluetooth profiles - If you want to add Bluetooth profiles that do not have
+ HAL interfaces provided by Android, you must supply an SDK add-on download to make the profile available to app developers,
+ make the APIs available in the Bluetooth system process app (<code>packages/apps/Bluetooth</code>), and add them
+ to the BlueDroid stack (<code>external/bluetooth/bluedroid</code>).</li>
+ <li>Custom vendor extensions and configuration changes - You can add things such as extra AT commands or device-specific configuration changes
+ by creating a <code>libbt-vendor</code> module. See the <code>vendor/broadcom/libbt-vendor</code> directory
+ for an example.</li>
+ <li>Host Controller Interface (HCI) - You can provide your own HCI by creating a <code>libbt-hci</code> module, which
+ is mainly used for debug tracing. See the <code>external/bluetooth/hci</code> directory for an example.</li>
+</ul>