| page.title=Wired audio headset specification |
| @jd:body |
| |
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| <div id="qv-wrapper"> |
| <div id="qv"> |
| <h2>In this document</h2> |
| <ol id="auto-toc"> |
| </ol> |
| </div> |
| </div> |
| |
| <p><em>Version 1.1</em></p> |
| |
| <p>This document specifies the requirements for headsets and mobile devices to |
| function uniformly across the Android ecosystem. It is separated into two |
| sections beginning with the specifications for the headset |
| accessory followed by the specifications for the mobile device.</p> |
| |
| <h2 id=headset_accessory_plug_specifications>Headset Accessory (Plug) Specifications</h2> |
| |
| <p>The requirements in the following section apply to the headset accessory.</p> |
| |
| <h3 id=functions>Functions</h3> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Accessory Support</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>Stereo Audio Out</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Audio in (Mic)</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Ground</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| </tr> |
| </table> |
| |
| <h3 id=control-function_mapping>Control-Function Mapping</h3> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Control Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Accessory Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Description</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>Function A</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Play/pause/hook (Short Press), Trigger Assist (Long Press), Next (double press)</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Function B</p> |
| </td> |
| <td> |
| <p>Optional</p> |
| </td> |
| <td> |
| <p>Vol+</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Function C</p> |
| </td> |
| <td> |
| <p>Optional</p> |
| </td> |
| <td> |
| <p>Vol-</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Function D</p> |
| </td> |
| <td> |
| <p>Optional</p> |
| </td> |
| <td> |
| <p>Reserved (Nexus devices will use this reserved function to launch Google |
| voice search)</p> |
| </td> |
| </tr> |
| </table> |
| |
| <p><strong>Assign functions to buttons as follows</strong>:</p> |
| |
| <ul> |
| <li> All one-button headsets must implement Function A. |
| <li> Headsets with multiple buttons must implement functions according to the |
| following pattern: |
| <ul> |
| <li> 2 functions: A and D |
| <li> 3 functions: A, B, C |
| <li> 4 functions: A, B, C, D |
| </ul> |
| </ul> |
| |
| <h3 id=mechanical>Mechanical</h3> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Accessory Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Notes</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>4 conductor 3.5mm plug</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Ref: EIAJ-RC5325A standard</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>CTIA pinout order (LRGM)</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Except in regions with legal requirements for OMTP pinout</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>OMTP pinout order (LRMG)</p> |
| </td> |
| <td> |
| <p>Optional</p> |
| </td> |
| <td></td> |
| </tr> |
| <tr> |
| <td> |
| <p>Microphone</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Must not be obstructed when operating headset controls</p> |
| </td> |
| </tr> |
| </table> |
| |
| <h3 id=electrical>Electrical</h3> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Accessory Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Description</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>Ear speaker impedance</p> |
| </td> |
| <td> |
| <p><strong>16 ohms or higher</strong></p> |
| </td> |
| <td> |
| <p>Recommend 32 - 300 ohms</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Mic DC resistance</p> |
| </td> |
| <td> |
| <p><strong>1000 ohms or higher</strong></p> |
| </td> |
| <td> |
| <p>Mic characteristics must be compliant with section 5.4 “Audio Recording” of |
| current Android Compatibility Definition Document (CDD)</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Control Function Equivalent impedance*</p> |
| |
| <p>*Total impedance from positive mic terminal to GND when button is pressed with |
| 2.2 V mic bias applied through 2.2 kOhm resistor</p> |
| </td> |
| <td> |
| <p><strong>0 ohm</strong></p> |
| </td> |
| <td> |
| <p>[Function A] Play/Pause/Hook</p> |
| </td> |
| </tr> |
| <tr> |
| <td></td> |
| <td> |
| <p><strong>240 ohm</strong> +/- 1% resistance</p> |
| </td> |
| <td> |
| <p>[Function B]</p> |
| </td> |
| </tr> |
| <tr> |
| <td></td> |
| <td> |
| <p><strong>470 ohm</strong> +/- 1% resistance</p> |
| </td> |
| <td> |
| <p>[Function C] </p> |
| </td> |
| </tr> |
| <tr> |
| <td></td> |
| <td> |
| <p><strong>135 ohm</strong> +/- 1% resistance</p> |
| </td> |
| <td> |
| <p>[Function D]</p> |
| </td> |
| </tr> |
| </table> |
| |
| <p>In the following diagrams, Button A is mapped to Function A, Button B to |
| Function B, and so on.</p> |
| |
| <h3 id=reference_headset_test_circuit_1>Reference Headset Test Circuit 1</h3> |
| |
| <img src="images/headset-circuit1.png" alt="Reference Headset Test Circuit 1" /> |
| <p class="img-caption"><strong>Figure 1.</strong> Reference headset test circuit 1</p> |
| |
| <p class="note"><strong>Note:</strong> The above diagram shows the CTIA pinout |
| for a 4-segment plug. For the OMTP pinout, switch the positions of the MIC and |
| GND segments.</p> |
| |
| <h3 id=reference_headset_test_circuit_2>Reference Headset Test Circuit 2</h3> |
| |
| <p>The second reference circuit shows how the actual resistor values (R1 - R4) |
| are altered to meet this specification.</p> |
| |
| <img src="images/headset-circuit2.png" alt="Reference Headset Test Circuit 2" /> |
| <p class="img-caption"><strong>Figure 2.</strong> Reference headset test circuit 2</p> |
| |
| <p>The actual resistance of the buttons parallel with the microphone (R1-R4) is |
| based on the microphone capsule resistance (Rmic) and the equivalent impedance |
| values (ReqA-ReqD). Use the following formula:</p> |
| |
| <p><em>Rn=(Rmic*ReqN) / (ReqN-Rmic)</em></p> |
| |
| <p>Where R<em>n</em> is the actual resistance of a button, Req<em>N</em> is the |
| equivalent impedance value of that button (provided), and Rmic is the |
| microphone impedance value.</p> |
| |
| <p>The example above assumes a 5 kohm microphone impedance (Rmic). Therefore, to |
| achieve an equivalent R4 impedance of 135 ohm (ReqD), the actual resistor value |
| (R4) needs to be 139 ohms.</p> |
| |
| |
| <h2 id=mobile_device_jack_specifications>Mobile Device (Jack) Specifications</h2> |
| |
| <p class="caution"><strong>Caution:</strong> To achieve compatibility with the |
| headset specification above, devices that include a 4 conductor 3.5mm audio |
| jack must meet the following specifications. Please see the <em>Analog audio |
| ports</em> section of the <a |
| href="{@docRoot}compatibility/android-cdd.pdf">Android Compatibility Definition |
| Document (CDD)</a> for Android compatibility requirements.</p> |
| |
| <p><strong>Headset Jack Functions</strong></p> |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Device Support</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>Stereo Audio Out</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Audio in (Mic)</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Ground</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| </tr> |
| </table> |
| |
| <h3 id=software_mapping>Software mapping</h3> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Device Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Description</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>Function A control event </p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>input event KEY_MEDIA</p> |
| |
| <p>Android key KEYCODE_HEADSETHOOK</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Function D control event</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>input event KEY_VOICECOMMAND</p> |
| |
| <p>Android key KEYCODE_VOICE_ASSIST</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Function B control event</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>input event KEY_VOLUMEUP</p> |
| |
| <p>Android key VOLUME_UP</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Function C control event</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>input event KEY_VOLUMEDOWN</p> |
| |
| <p>Android key VOLUME_DOWN</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Headset insertion detection</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>input event SW_JACK_PHYSICAL_INSERT 7</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Headset type detection</p> |
| </td> |
| <td> |
| <p><strong>Mic</strong></p> |
| </td> |
| <td> |
| <p>input event SW_MICROPHONE_INSERT 4</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Headset type detection</p> |
| </td> |
| <td> |
| <p><strong>No Mic</strong></p> |
| </td> |
| <td> |
| <p>input event SW_HEADPHONE_INSERT 2</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Headset speaker impedance</p> |
| </td> |
| <td> |
| <p><strong>Required Headphone (low)</strong></p> |
| </td> |
| <td> |
| <p>Failure mode is to indicate headphones so that limitation would be on</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Headset speaker impedance</p> |
| </td> |
| <td> |
| <p><strong>Required Line In (high)</strong></p> |
| </td> |
| <td> |
| <p>input event SW_LINEOUT_INSERT 6</p> |
| </td> |
| </tr> |
| </table> |
| |
| <h3 id=mechanical11>Mechanical</h3> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Device Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Description</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>4 conductor 3.5mm jack</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td></td> |
| </tr> |
| <tr> |
| <td> |
| <p>CTIA pinout order (LRGM)</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>3 Pin & Mono Plug Compatible</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>OMTP pinout order (LRMG)</p> |
| </td> |
| <td> |
| <p>Optional but <strong>Strongly Recommended</strong></p> |
| </td> |
| <td></td> |
| </tr> |
| <tr> |
| <td> |
| <p>Headset detect sequence</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Plug insert notification must only be triggered after all contacts on plug are |
| touching their relevant segments. This will prevent unreliable headset |
| detection due to slow insertion. </p> |
| </td> |
| </tr> |
| </table> |
| |
| <h3 id=electrical12>Electrical</h3> |
| |
| <h4 id=general>General</h4> |
| |
| <table> |
| <tr> |
| <th> |
| <p><strong>Function</strong></p> |
| </th> |
| <th> |
| <p><strong>Device Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Notes</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p>Maximum output voltage drive</p> |
| </td> |
| <td> |
| <p>150mV </p> |
| </td> |
| <td> |
| <p>>= 150mV on 32 ohm</p> |
| |
| <p>Test conditions: EN50332-2</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Mic bias resistance </p> |
| </td> |
| <td> |
| <p>Required</p> |
| </td> |
| <td> |
| <p>Flexible on detection method used and microphone bias resistor selection. |
| Require that all button resistance value ranges specified below be detected and |
| related to their respective function</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>Mic bias voltage</p> |
| </td> |
| <td> |
| <p>1.8V - 2.9V</p> |
| </td> |
| <td> |
| <p>To guarantee compatibility to common microphone capsules.</p> |
| </td> |
| </tr> |
| </table> |
| |
| <h4 id=function_impedance_and_threshold_detection>Function Impedance and Threshold Detection</h4> |
| |
| <p>Devices must detect the following resistor ladder on the accessories. The |
| accessories will be tested to the standardized circuit diagram in the diagram |
| illustrated earlier (Reference Headset Test Circuit) where the total impedance |
| is measured from MIC terminal to GND when a button is pressed with 2.2V mic |
| bias applied through 2.2 kOhm resistor. This is the same effective resistance |
| as the button detection circuit with the microphone in parallel with the button |
| resistor.</p> |
| <table> |
| <tr> |
| <th> |
| <p><strong>Button Impedance Level</strong></p> |
| </th> |
| <th> |
| <p><strong>Device Support</strong></p> |
| </th> |
| <th> |
| <p><strong>Notes</strong></p> |
| </th> |
| </tr> |
| <tr> |
| <td> |
| <p><strong>70 ohm or less</strong></p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>[Function A]</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p><strong>110 - 180 ohm </strong></p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>[Function D]</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p><strong>210 - 290 ohm</strong></p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>[Function B]</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p><strong>360 - 680 ohm </strong></p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>[Function C]</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p><strong>Headset speaker impedance level</strong></p> |
| </td> |
| <td></td> |
| <td></td> |
| </tr> |
| <tr> |
| <td> |
| <p>Low Threshold Detection</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Headphone (low) < 1 Kohm</p> |
| </td> |
| </tr> |
| <tr> |
| <td> |
| <p>High Threshold Detection</p> |
| </td> |
| <td> |
| <p><strong>Required</strong></p> |
| </td> |
| <td> |
| <p>Line In (high) > 5 Kohm</p> |
| </td> |
| </tr> |
| </table> |
