1page.title=USB Headset: Accessory Specification
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19<div id="qv-wrapper">
20  <div id="qv">
21    <h2>In this document</h2>
22    <ol id="auto-toc">
23    </ol>
24  </div>
25</div>
26
27<p>
28This documentation specifies USB headset buttons behavior to function uniformly
29across the Android ecosystem. Device manufacturers should also consult the
30<a href="{@docRoot}devices/audio/usb.html">USB
31Digital Audio</a> page for more information about USB implementation on Android
32and the <a href="http://source.android.com/compatibility/android-cdd.html">Android
33Compatibility Definition Document (CDD)</a> for requirements related to Android
34devices.
35</p>
36<p>There are also specifications for
37<a href="plug-headset-spec.html">3.5 mm headsets</a> for accessory manufacturers and
38<a href="jack-headset-spec.html">3.5 mm jacks</a> for device manufacturers.
39</p>
40<p>
41This documentation specifies the minimum requirements: accessory manufacturers
42are encouraged to add features while keeping these requirements in mind.
43</p>
44<h2 id="control-function-mapping">Control-function mapping</h2>
45<table>
46  <tr>
47   <th>Control Function</th>
48   <th>Accessory Support</th>
49   <th>Description</th>
50  </tr>
51  <tr>
52   <td>Function A</td>
53   <td>Required</td>
54   <td>Play/pause (short press), launch voice assistance (long press), next (double
55       press)</td>
56  </tr>
57  <tr>
58   <td>Function B</td>
59   <td>Optional</td>
60   <td>Vol+</td>
61  </tr>
62  <tr>
63   <td>Function C</td>
64   <td>Optional</td>
65   <td>Vol-</td>
66  </tr>
67  <tr>
68   <td>Function D</td>
69   <td>Optional</td>
70   <td>Launch voice assistance</td>
71  </tr>
72</table>
73<p>
74<strong>Assign functions to buttons as follows:</strong>
75</p>
76<ul>
77  <li>All one-button headsets must implement Function A.</li>
78  <li>Headsets with multiple buttons must implement functions according to the
79      following pattern:
80    <ul>
81      <li>2 functions: A and D</li>
82      <li>3 functions: A, B, C</li>
83      <li>4 functions: A, B, C, D</li>
84    </ul>
85  </li>
86</ul>
87<p class="note">
88<strong>Note</strong>: No key latching allowed. Each key press by the end user
89must generate the corresponding "down" and "up" key event, matching the end user
90action. In other words, the keys for functions A through D are never "latched"
91or implemented to be used as a toggle (where the "up" event only follows "down"
92on a second key press).
93</p>
94<h2 id="software-mapping">Software mapping</h2>
95<p>
96Compatible USB headsets are required to support the following software mappings
97for the headset buttons. Device support is required for the following software
98mappings.
99</p>
100
101<table>
102  <tr>
103   <th>Function</th>
104   <th>Mappings</th>
105   <th>Context</th>
106   <th>Behavior</th>
107  </tr>
108  <tr>
109   <td rowspan="6">Function A</td>
110   <td rowspan="6"><strong>HID usage page</strong>: 0x0C<br>
111       <strong>HID usage</strong>: 0x0CD<br>
112       <strong>Kernel key</strong>: <code>KEY_PLAYPAUSE</code><br>
113       <strong>Android key</strong>: <code>KEYCODE_MEDIA_PLAY_PAUSE</code></td>
114   <td rowspan="2">Media playback</td>
115   <td><strong>Input</strong>: Short press<br>
116       <strong>Output</strong>: Play or pause</td>
117  </tr>
118  <tr>
119   <td><strong>Input</strong>: Long press<br>
120       <strong>Output</strong>: Launch voice assistance<br>
121       <strong>Sends</strong>:
122       <code>android.intent.action.VOICE_SEARCH_HANDS_FREE</code></td>
123  </tr>
124  <tr>
125   <td rowspan="2">Incoming call</td>
126   <td><strong>Input</strong>: Short press<br>
127       <strong>Output</strong>: Accept call</td>
128  </tr>
129  <tr>
130   <td><strong>Input</strong>: Long press<br>
131       <strong>Output</strong>: Reject call</td>
132  </tr>
133  <tr>
134   <td rowspan="2">Ongoing call</td>
135   <td><strong>Input</strong>: Short press<br>
136       <strong>Output</strong>: End call</td>
137  </tr>
138  <tr>
139   <td><strong>Input</strong>: Long press<br>
140       <strong>Output</strong>: Mute or unmute microphone</td>
141  </tr>
142  <tr>
143   <td>Function B</td>
144   <td><strong>HID usage page</strong>: 0x0C<br>
145       <strong>HID usage</strong>: 0x0E9<br>
146       <strong>Kernel key</strong>: <code>KEY_VOLUMEUP</code><br>
147       <strong>Android key</strong>: <code>VOLUME_UP</code></td>
148   <td>Media playback, Ongoing call</td>
149   <td><strong>Input</strong>: Short or long press<br>
150       <strong>Output</strong>: Increases the system or headset volume</td>
151  </tr>
152  <tr>
153   <td>Function C</td>
154   <td><strong>HID usage page</strong>: 0x0C<br>
155       <strong>HID usage</strong>: 0x0EA<br>
156       <strong>Kernel key</strong>: <code>KEY_VOLUMEDOWN</code><br>
157       <strong>Android key</strong>: <code>VOLUME_DOWN</code></td>
158   <td>Media playback, Ongoing call</td>
159   <td><strong>Input</strong>: Short or long press<br>
160       <strong>Output</strong>: Decreases the system or headset volume</td>
161  </tr>
162  <tr>
163   <td>Function D</td>
164   <td><strong>HID usage page</strong>: 0x0C<br>
165       <strong>HID usage</strong>: 0x0CF<br>
166       <strong>Kernel key</strong>: <code>KEY_VOICECOMMAND</code><br>
167       <strong>Android key</strong>: <code>KEYCODE_VOICE_ASSIST</code></td>
168   <td>All. Can be triggered in any instance.</td>
169   <td><strong>Input</strong>: Short or long press<br>
170       <strong>Output</strong>: Launch voice assistance</td>
171  </tr>
172</table>
173
174<h2 id="mechanical">Mechanical</h2>
175<p>
176Accessory manufacturers must follow the requirements for USB connectors
177as specified by <a href="http://www.usb.org/">USB.org</a>.
178</p>
179<p>
180Device manufacturers must follow the requirements in the
181<a href="{@docRoot}compatibility/android-cdd.html#7_7_usb">USB section</a> of
182the Android CDD.
183</p>
184