1 <html devsite> 2 <head> 3 <title>3.5 mm Headset Jack: Device Specification</title> 4 <meta name="project_path" value="/_project.yaml" /> 5 <meta name="book_path" value="/_book.yaml" /> 6 </head> 7 <body> 8 <!-- 9 Copyright 2017 The Android Open Source Project 10 11 Licensed under the Apache License, Version 2.0 (the "License"); 12 you may not use this file except in compliance with the License. 13 You may obtain a copy of the License at 14 15 http://www.apache.org/licenses/LICENSE-2.0 16 17 Unless required by applicable law or agreed to in writing, software 18 distributed under the License is distributed on an "AS IS" BASIS, 19 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 20 See the License for the specific language governing permissions and 21 limitations under the License. 22 --> 23 24 25 26 27 <p>To achieve compatibility with the <a href="plug-headset-spec.html">3.5 mm plug 28 headset specification</a>, devices that include a 4 conductor 3.5 mm audio jack 29 must meet the following specifications. For Android compatibility requirements, 30 refer to the <em>Analog audio ports</em> section of the <a 31 href="/compatibility/android-cdd.html#7_8_audio">Android CDD</a>.</p> 32 33 <h2 id="headset_jack_functions">Functions</h2> 34 35 <table> 36 <tr> 37 <th>Function</th> 38 <th>Device Support</th> 39 </tr> 40 <tr> 41 <td>Stereo Audio Out</td> 42 <td>Required</td> 43 </tr> 44 <tr> 45 <td>Audio in (Mic)</td> 46 <td>Required</td> 47 </tr> 48 <tr> 49 <td>Ground</td> 50 <td>Required</td> 51 </tr> 52 </table> 53 54 <h2 id="software_mapping">Software mapping</h2> 55 56 <table> 57 <tr> 58 <th style="width:33%">Function</th> 59 <th style="width:33%">Device Support</th> 60 <th style="width:33%">Description</th> 61 </tr> 62 <tr> 63 <td>Function A control event</td> 64 <td>Required</td> 65 <td>Input event: <code>KEY_MEDIA</code> 66 <p>Android key: <code>KEYCODE_HEADSETHOOK<code></p></td> 67 </tr> 68 <tr> 69 <td>Function D control event</td> 70 <td>Required</td> 71 <td>Input event: <code>KEY_VOICECOMMAND</code> 72 <p>Android key: <code>KEYCODE_VOICE_ASSIST</code></p></td> 73 </tr> 74 <tr> 75 <td>Function B control event</td> 76 <td>Required</td> 77 <td>Input event: <code>KEY_VOLUMEUP</code> 78 <p>Android key: <code>VOLUME_UP</code></p></td> 79 </tr> 80 <tr> 81 <td>Function C control event</td> 82 <td>Required</td> 83 <td>Input event: <code>KEY_VOLUMEDOWN</code> 84 <p>Android key: <code>VOLUME_DOWN</code></p></td> 85 </tr> 86 <tr> 87 <td>Headset insertion detection</td> 88 <td>Required</td> 89 <td>Input event: <code>SW_JACK_PHYSICAL_INSERT 7</code></td> 90 </tr> 91 <tr> 92 <td rowspan="2">Headset type detection</td> 93 <td>Mic</td> 94 <td>Input event: <code>SW_MICROPHONE_INSERT 4</code></td> 95 </tr> 96 <tr> 97 <td>No Mic</td> 98 <td>Input event: <code>SW_HEADPHONE_INSERT 2</code></td> 99 </tr> 100 <tr> 101 <td rowspan="2">Headset speaker impedance</td> 102 <td>Required Headphone (low)</td> 103 <td>Failure mode is to indicate headphones so limitation would be on</td> 104 </tr> 105 <tr> 106 <td>Required Line In (high)</td> 107 <td>Input event: <code>SW_LINEOUT_INSERT 6</code></td> 108 </tr> 109 </table> 110 111 <h2 id="mechanical11">Mechanical</h2> 112 113 <table> 114 <tr> 115 <th style="width:33%">Function</th> 116 <th style="width:33%">Device Support</th> 117 <th style="width:33%">Description</th> 118 </tr> 119 <tr> 120 <td>4 conductor 3.5 mm jack</td> 121 <td>Required</td> 122 <td></td> 123 </tr> 124 <tr> 125 <td>CTIA pinout order (LRGM)</td> 126 <td>Required</td> 127 <td>3 Pin & Mono Plug Compatible</td> 128 </tr> 129 <tr> 130 <td>OMTP pinout order (LRMG)</td> 131 <td>Optional but strongly recommended</td> 132 <td></td> 133 </tr> 134 <tr> 135 <td>Headset detect sequence</td> 136 <td>Required</td> 137 <td>Plug insert notification must be triggered only after all contacts on 138 plug are touching their relevant segments (this prevents unreliable headset 139 detection due to slow insertion.</td> 140 </tr> 141 </table> 142 143 <h2 id="electrical12">Electrical</h2> 144 145 <h3 id="general">General</h3> 146 147 <table> 148 <tr> 149 <th style="width:33%">Function</th> 150 <th style="width:33%">Device Support</th> 151 <th style="width:33%">Notes</th> 152 </tr> 153 <tr> 154 <td>Maximum output voltage drive</td> 155 <td>150mV</td> 156 <td>>= 150mV on 32 ohm 157 <p>Test conditions: EN50332-2</p></td> 158 </tr> 159 <tr> 160 <td>Mic bias resistance</td> 161 <td>Required</td> 162 <td>Flexible on detection method used and microphone bias resistor 163 selection. Require that all button resistance value ranges specified below 164 be detected and related to their respective function</td> 165 </tr> 166 <tr> 167 <td>Mic bias voltage</td> 168 <td>1.8V - 2.9V</td> 169 <td>To guarantee compatibility to common microphone capsules.</td> 170 </tr> 171 </table> 172 173 <h3 id="function_impedance_and_threshold_detection">Function impedance and 174 threshold detection</h3> 175 176 <p>Devices must detect the following resistor ladder on the accessories. The 177 accessories will be tested to the standardized circuit diagram in the diagram 178 illustrated earlier (Reference Headset Test Circuit) where the total impedance 179 is measured from MIC terminal to GND when a button is pressed with 2.2V mic 180 bias applied through 2.2 kOhm resistor. This is the same effective resistance 181 as the button detection circuit with the microphone in parallel with the button 182 resistor.</p> 183 184 <table> 185 <tr> 186 <th style="width:40%">Button Impedance Level</th> 187 <th style="width:20%">Device Support</th> 188 <th style="width:40%">Notes</th> 189 </tr> 190 <tr> 191 <td>70 ohm or less</td> 192 <td>Required</td> 193 <td>[Function A]</td> 194 </tr> 195 <tr> 196 <td>110 - 180 ohm</td> 197 <td>Required</td> 198 <td>[Function D]</td> 199 </tr> 200 <tr> 201 <td>210 - 290 ohm</td> 202 <td>Required</td> 203 <td>[Function B]</td> 204 </tr> 205 <tr> 206 <td>360 - 680 ohm</td> 207 <td>Required</td> 208 <td>[Function C]</td> 209 </tr> 210 </table> 211 212 <table> 213 <tr> 214 <th style="width:40%">Headset Speaker Impedance Level</th> 215 <th style="width:20%">Device Support</th> 216 <th style="width:40%">Notes</th> 217 </tr> 218 <tr> 219 <td>Low Threshold Detection</td> 220 <td>Required</td> 221 <td>Headphone (low) < 1 Kohm</td> 222 </tr> 223 <tr> 224 <td>High Threshold Detection</td> 225 <td>Required</td> 226 <td>Line In (high) > 5 Kohm</td> 227 </tr> 228 </table> 229 230 <table> 231 <tr> 232 <th style="width:40%">4-Segment Plug Detection Resistance (between 3rd and 4th segment)</th> 233 <th style="width:20%">Device Support</th> 234 <th style="width:40%">Notes</th> 235 </tr> 236 <tr> 237 <td>4-Segment Plug Threshold</td> 238 <td>Required</td> 239 <td>Resistance >= 100 ohms</td> 240 </tr> 241 <tr> 242 <td>3-Segment Plug Threshold</td> 243 <td>Required</td> 244 <td>Resistance < 100 ohms</td> 245 </tr> 246 </table> 247 248 </body> 249 </html> 250
