Dev guide for sensors

Change-Id: Ie8d64974a2b946cfa0fe7297a6ebd6cfe496bc7a

9 files changed, 1869 insertions, 67 deletions

diff --git a/docs/html/guide/guide_toc.cs b/docs/html/guide/guide_toc.cs
index af379de..5ad000c 100644
--- a/docs/html/guide/guide_toc.cs
+++ b/docs/html/guide/guide_toc.cs
@@ -309,14 +309,25 @@
         <a href="<?cs var:toroot ?>guide/topics/clipboard/copy-paste.html">
             <span class="en">Copy and Paste</span>
         </a></li>
-  <!--<li class="toggle-list">
-        <div><a style="color:gray;">Sensors</a></div>
-          <ul>
-            <li><a style="color:gray;">Camera</a></li>
-            <li><a style="color:gray;">Compass</a></li>
-            <li><a style="color:gray;">Accelerometer</a></li>
-          </ul>
-      </li> -->
+      <li class="toggle-list">
+        <div><a href="<?cs var:toroot ?>guide/topics/sensors/index.html">
+              <span class="en">Sensors</span>
+              </a><span class="new">new!</span></div>
+        <ul>
+          <li><a href="<?cs var:toroot ?>guide/topics/sensors/sensors_overview.html">
+              <span class="en">Sensors Overview</span>
+            </a></li>
+          <li><a href="<?cs var:toroot ?>guide/topics/sensors/sensors_motion.html">
+              <span class="en">Motion Sensors</span>
+            </a></li>
+          <li><a href="<?cs var:toroot ?>guide/topics/sensors/sensors_position.html">
+              <span class="en">Position Sensors</span>
+            </a></li>
+          <li><a href="<?cs var:toroot ?>guide/topics/sensors/sensors_environment.html">
+              <span class="en">Environment Sensors</span>
+            </a></li>
+        </ul>
+      </li>
       <li class="toggle-list">
         <div><a href="<?cs var:toroot ?>guide/topics/location/index.html">
                <span class="en">Location and Maps</span>
diff --git a/docs/html/guide/topics/sensors/accelerometer.jd b/docs/html/guide/topics/sensors/accelerometer.jd
deleted file mode 100644
index da760bc..0000000
--- a/docs/html/guide/topics/sensors/accelerometer.jd
+++ /dev/null
@@ -1,18 +0,0 @@
-page.title=Accelerometer
-parent.title=Sensors
-parent.link=index.html
-@jd:body
-
-<div id="qv-wrapper">
-<div id="qv">
-
-  <h2>In this document</h2>
-  <ol>
-
-  </ol>
-
-</div>
-</div>
-
-
-TODO
\ No newline at end of file
diff --git a/docs/html/guide/topics/sensors/camera.jd b/docs/html/guide/topics/sensors/camera.jd
deleted file mode 100644
index 821333e..0000000
--- a/docs/html/guide/topics/sensors/camera.jd
+++ /dev/null
@@ -1,18 +0,0 @@
-page.title=Camera
-parent.title=Sensors
-parent.link=index.html
-@jd:body
-
-<div id="qv-wrapper">
-<div id="qv">
-
-  <h2>Key class</h2>
-  <ol>
-    <li>{@link android.hardware.Camera android.hardware.Camera}</li>
-  </ol>
-  <h2>In this document</h2>
-  <ol>
-    <li>TODO</li>
-  </ol>
-</div>
-</div>
\ No newline at end of file
diff --git a/docs/html/guide/topics/sensors/compass.jd b/docs/html/guide/topics/sensors/compass.jd
deleted file mode 100644
index 1e45d2d..0000000
--- a/docs/html/guide/topics/sensors/compass.jd
+++ /dev/null
@@ -1,18 +0,0 @@
-page.title=Compass
-parent.title=Sensors
-parent.link=index.html
-@jd:body
-
-<div id="qv-wrapper">
-<div id="qv">
-
-  <h2>In this document</h2>
-  <ol>
-
-  </ol>
-
-</div>
-</div>
-
-
-TODO
\ No newline at end of file
diff --git a/docs/html/guide/topics/sensors/index.jd b/docs/html/guide/topics/sensors/index.jd
index 54a0814..e00a5b1 100644
--- a/docs/html/guide/topics/sensors/index.jd
+++ b/docs/html/guide/topics/sensors/index.jd
@@ -2,12 +2,87 @@ page.title=Sensors
 @jd:body
 
 <div id="qv-wrapper">
-<div id="qv">
+  <div id="qv">
+  <h2>Topics</h2>
+    <ol>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_overview.html">Sensors Overview</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_motion.html">Motion Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_position.html">Position
+          Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_environment.html">Environment
+          Sensors</a></li>
+    </ol>
+  <h2>Key classes and interfaces</h2>
+    <ol>
+      <li>{@link android.hardware.Sensor}</li>
+      <li>{@link android.hardware.SensorEvent}</li>
+      <li>{@link android.hardware.SensorManager}</li>
+      <li>{@link android.hardware.SensorEventListener}</li>
+    </ol>
+  <h2>Related samples</h2>
+    <ol>
+      <li><a href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer
+          Play</a></li>
+      <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html">
+API Demos (OS - RotationVectorDemo)</a></li>
+      <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/Sensors.html">API Demos
+(OS - Sensors)</a></li>
+    </ol>
+  </div>
+</div>
 
+<p>Most Android-powered devices have built-in sensors that measure motion, orientation,
+and various environmental conditions. These sensors are capable of providing raw data with high
+precision and accuracy, and are useful if you want to monitor three-dimensional device movement or
+positioning, or you want to monitor changes in the ambient environment near a device. For example, a
+game might track readings from a device's gravity sensor to infer complex user gestures
+and motions, such as tilt, shake, rotation, or swing. Likewise, a weather application might use a
+device's temperature sensor and humidity sensor to calculate and report the dewpoint, or a travel
+application might use the geomagnetic field sensor and accelerometer to report a compass
+bearing.</p>
 
+<p>The Android platform supports four broad categories of sensors:</p>
 
-<h2>Accelerometer</h2>
-<p>The accelerometer sensors allow you to detect the various movements of the device.</p>
+<ul>
+  <li>Motion sensors
+    <p>These sensors measure acceleration forces and rotational forces along three axes. This
+      category includes accelerometers, gravity sensors, gyroscopes, and rotational vector
+      sensors.</p>
+  </li>
+  <li>Environmental sensors
+    <p>These sensors measure various environmental parameters, such as ambient air temperature
+      and pressure, illumination, and humidity. This category includes barometers, photometers, and
+      thermometers.</p>
+  </li>
+  <li>Position sensors
+    <p>These sensors measure the physical position of a device. This category includes
+      orientation sensors and magnetometers.</p>
+  </li>
+</ul>
 
-<h2>Compass</h2>
-<p>The compass provides data on the devices current polar orientation.</p>
\ No newline at end of file
+<p>To access these sensors, you can use the Android sensor framework. The sensor framework provides
+several classes and interfaces that help you perform a wide variety of sensor-related tasks. To
+learn more about the framework and the sensors that are supported on the Android system, read the
+following documents:</p>
+
+<dl>
+  <dt><strong><a href="{@docRoot}guide/topics/sensors/sensors_overview.html">Sensors
+        Overview</a></strong></dt>
+    <dd>Learn how to list the sensors that are on a device, set up sensor event listeners, and
+      acquire sensor data. Also learn best practices for accessing and using sensors.</dd>
+  <dt><strong><a href="{@docRoot}guide/topics/sensors/sensors_motion.html">Motion
+        Sensors</a></strong></dt>
+    <dd>Learn how to use the sensors that provide acceleration data, such as the accelerometer,
+      gravity sensor, and linear acceleration sensor. Also learn how to use the sensors that
+      provide rotational data, such as gyroscopes and rotational vector sensors.</dd>
+  <dt><strong><a href="{@docRoot}guide/topics/sensors/sensors_position.html">Position
+      Sensors</a></strong></dt>
+    <dd>Learn how to use the sensors that provide orientation and compass data, such as the
+      orientation sensor and the geomagnetic field sensor.</dd>
+  <dt><strong><a href="{@docRoot}guide/topics/sensors/environment.html">Environment
+        Sensors</a></strong></dt>
+    <dd>Learn how to use the sensors that provide environmental data, such as the light,
+      humidity, pressure, temperature, and proximity sensors.</dd>
+</dl>
diff --git a/docs/html/guide/topics/sensors/sensors_environment.jd b/docs/html/guide/topics/sensors/sensors_environment.jd
new file mode 100644
index 0000000..93ea4bc
--- /dev/null
+++ b/docs/html/guide/topics/sensors/sensors_environment.jd
@@ -0,0 +1,208 @@
+page.title=Environment Sensors
+parent.title=Sensors
+parent.link=index.html
+@jd:body
+
+<div id="qv-wrapper">
+  <div id="qv">
+  <h2>In this document</h2>
+    <ol>
+      <li><a href="#sensors-using-temp">Using the Light, Pressure, and Temperature
+Sensors</a></li>
+      <li><a href="#sensors-using-humid">Using the Humidity Sensor</a></li>
+    </ol>
+  <h2>Related samples</h2>
+  <ol>
+    <li><a href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer
+        Play</a></li>
+    <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html">
+API Demos (OS - RotationVectorDemo)</a></li>
+    <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/Sensors.html">API Demos
+(OS - Sensors)</a></li>
+  </ol>
+  <h2>See also</h2>
+  <ol>
+    <li><a href="{@docRoot}guide/topics/sensors/index.html">Sensors</a></li>
+    <li><a href="{@docRoot}guide/topics/sensors/sensors_overview.html">Sensors Overview</a></li>
+    <li><a href="{@docRoot}guide/topics/sensors/sensors_position.html">Position Sensors</a></li>
+    <li><a href="{@docRoot}guide/topics/sensors/sensors_motion.html">Motion
+        Sensors</a></li>
+  </ol>
+  </div>
+</div>
+
+<p>The Android platform provides four sensors that let you monitor various environmental properties.
+You can use these sensors to monitor relative ambient humidity, illuminance, ambient pressure, and
+ambient temperature near an Android-powered device. All four environment sensors are hardware-based
+and are available only if a device manufacturer has built them into a device. With the exception of
+the light sensor, which most device manufacturers use to control screen brightness, environment
+sensors are not always available on devices. Because of this, it's particularly important that you
+verify at runtime whether an environment sensor exists before you attempt to acquire data from
+it.</p>
+
+<p>Unlike most motion sensors and position sensors, which return a multi-dimensional array of sensor
+values for each {@link android.hardware.SensorEvent}, environment sensors return a single sensor
+value for each data event. For example, the temperature in &deg;C or the pressure in hPa.
+Also, unlike motion sensors and position sensors, which often require high-pass or low-pass
+filtering, environment sensors do not typically require any data filtering or data processing. Table
+1 provides a summary of the environment sensors that are supported on the Android platform.</p>
+
+<p class="table-caption" id="table1">
+  <strong>Table 1.</strong> Environment sensors that are supported on the Android platform.</p>
+<table>
+  <tr>
+    <th scope="col" style="white-space:nowrap">Sensor</th>
+    <th scope="col" style="white-space:nowrap">Sensor event data</th>
+    <th scope="col" style="white-space:nowrap">Units of measure</th>
+    <th scope="col" style="white-space:nowrap">Data description</th>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE}</td>
+    <td><code>event.values[0]</code></td>
+    <td>&deg;C</td>
+    <td>Ambient air temperature.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_LIGHT}</td>
+    <td><code>event.values[0]</code></td>
+    <td>lx</td>
+    <td>Illuminance.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_PRESSURE}</td>
+    <td><code>event.values[0]</code></td>
+    <td>hPa or mbar</td>
+    <td>Ambient air pressure.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY}</td>
+    <td><code>event.values[0]</code></td>
+    <td>%</td>
+    <td>Ambient relative humidity.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_TEMPERATURE}</td>
+    <td><code>event.values[0]</code></td>
+    <td>&deg;C</td>
+    <td>Device temperature.<sup>1</sup></td>
+  </tr>
+</table>
+
+<p class="note"><sup><strong>1</strong></sup>  Implementations vary from device to
+device. This sensor was deprecated in Android 4.0 (API Level 14).</p>
+
+<h2 id="sensors-using-temp">Using the Light, Pressure, and Temperature Sensors</h2>
+
+<p>The raw data you acquire from the light, pressure, and temperature sensors usually requires no
+calibration, filtering, or modification, which makes them some of the easiest sensors to use. To
+acquire data from these sensors you first create an instance of the {@link
+android.hardware.SensorManager} class, which you can use to get an instance of a physical sensor.
+Then you register a sensor listener in the {@link android.app.Activity#onResume
+onResume()} method, and start handling incoming sensor data in the {@link
+android.hardware.SensorEventListener#onSensorChanged onSensorChanged()} callback method. The
+following code shows you how to do this:</p>
+
+<pre>
+public class SensorActivity extends Activity implements SensorEventListener {
+  private SensorManager mSensorManager;
+  private Sensor mPressure;
+
+  &#64;Override
+  public final void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.main);
+
+    // Get an instance of the sensor service, and use that to get an instance of
+    // a particular sensor.
+    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+    mPressure = mSensorManager.getDefaultSensor(Sensor.TYPE_PRESSURE);
+  }
+
+  &#64;Override
+  public final void onAccuracyChanged(Sensor sensor, int accuracy) {
+    // Do something here if sensor accuracy changes.
+  }
+
+  &#64;Override
+  public final void onSensorChanged(SensorEvent event) {
+    float millibars_of_pressure = event.values[0];
+    // Do something with this sensor data.
+  }
+
+  &#64;Override
+  protected void onResume() {
+    // Register a listener for the sensor.
+    super.onResume();
+    mSensorManager.registerListener(this, mPressure, SensorManager.SENSOR_DELAY_NORMAL);
+  }
+
+  &#64;Override
+  protected void onPause() {
+    // Be sure to unregister the sensor when the activity pauses.
+    super.onPause();
+    mSensorManager.unregisterListener(this);
+  }
+}
+</pre>
+
+<p>You must always include implementations of both the {@link
+android.hardware.SensorEventListener#onAccuracyChanged onAccuracyChanged()} and {@link
+android.hardware.SensorEventListener#onSensorChanged onSensorChanged()} callback methods. Also, be
+sure that you always unregister a sensor when an activity pauses. This prevents a sensor from
+continually sensing data and draining the battery.</p>
+
+<h2 id="sensors-using-humid">Using the Humidity Sensor</h2>
+
+<p>You can acquire raw relative humidity data by using the humidity sensor the same way that you use
+the light, pressure, and temperature sensors. However, if a device has both a humidity sensor
+({@link android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY}) and a temperature sensor ({@link
+android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE}) you can use these two data streams to calculate
+the dew point and the absolute humidity.</p>
+
+<h4>Dew point</h4>
+
+<p>The dew point is the temperature at which a given volume of air must be cooled, at constant
+  barometric pressure, for water vapor to condense into water. The following equation shows how you
+can calculate the dew point:</p>
+
+<pre class="no-pretty-print classic">
+                       ln(RH/100%) + m·t/(T<sub>n</sub>+t)
+t<sub>d</sub>(t,RH) = T<sub>n</sub> · ------------------------------------
+                    m - [ln(RH/100%) + m·t/(T<sub>n</sub>+t)]
+</pre>
+
+<p>Where,</p>
+
+<ul type="none">
+  <li>t<sub>d</sub> = dew point temperature in degrees C</li>
+  <li>t = actual temperature in degrees C</li>
+  <li>RH = actual relative humidity in percent (%)</li>
+  <li>m = 17.62</li>
+  <li>T<sub>n</sub> = 243.12</li>
+</ul>
+
+<h4>Absolute humidity</h4>
+
+<p>The absolute humidity is the mass of water vapor in a given volume of dry air. Absolute
+  humidity is measured in grams/meter<sup>3</sup>. The following equation shows how you
+  can calculate the absolute humidity:</p>
+
+<pre class="no-pretty-print classic">
+                          (RH/100%) · A · exp(m·t/(T<sub>n</sub>+t)
+d<sub>v</sub>(t,RH) = 216.7 · ------------------------------------
+                                    273.15 + t
+</pre>
+
+<p>Where,</p>
+
+<ul type="none">
+  <li>d<sub>v</sub> = absolute humidity in grams/meter<sup>3</sup></li>
+  <li>t = actual temperature in degrees C</li>
+  <li>RH = actual relative humidity in percent (%)</li>
+  <li>m = 17.62</li>
+  <li>T<sub>n</sub> = 243.12 degrees C</li>
+  <li>A = 6.112 hPa</li>
+</ul>
+
diff --git a/docs/html/guide/topics/sensors/sensors_motion.jd b/docs/html/guide/topics/sensors/sensors_motion.jd
new file mode 100644
index 0000000..3f712b2
--- /dev/null
+++ b/docs/html/guide/topics/sensors/sensors_motion.jd
@@ -0,0 +1,454 @@
+page.title=Motion Sensors
+parent.title=Sensors
+parent.link=index.html
+@jd:body
+
+<div id="qv-wrapper">
+  <div id="qv">
+    <h2>In this document</h2>
+    <ol>
+      <li><a href="#sensors-motion-accel">Using the Accelerometer</a></li>
+      <li><a href="#sensors-motion-grav">Using the Gravity Sensor</a></li>
+      <li><a href="#sensors-motion-gyro">Using the Gyroscope</a></li>
+      <li><a href="#sensors-motion-linear">Using the Linear Accelerometer</a></li>
+      <li><a href="#sensors-motion-rotate">Using the Rotation Vector Sensor</a></li>
+    </ol>
+    <h2>Key classes and interfaces</h2>
+    <ol>
+      <li>{@link android.hardware.Sensor}</li>
+      <li>{@link android.hardware.SensorEvent}</li>
+      <li>{@link android.hardware.SensorManager}</li>
+      <li>{@link android.hardware.SensorEventListener}</li>
+    </ol>
+    <h2>Related samples</h2>
+    <ol>
+      <li><a href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer
+      Play</a></li>
+      <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html">
+API Demos (OS - RotationVectorDemo)</a></li>
+      <li><a
+href="{@docRoot}/resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html"
+>API Demos (OS - Sensors)</a></li>
+    </ol>
+    <h2>See also</h2>
+    <ol>
+      <li><a href="{@docRoot}guide/topics/sensors/index.html">Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_overview.html">Sensors Overview</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_position.html">Position Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_environment.html">Environment
+Sensors</a></li>
+    </ol>
+  </div>
+</div>
+
+<p>The Android platform provides several sensors that let you monitor the motion of a device. Two of
+these sensors are always hardware-based (the accelerometer and gyroscope), and three of these
+sensors can be either hardware-based or software-based (the gravity, linear acceleration, and
+rotation vector sensors). For example, on some devices the software-based sensors derive their data
+from the accelerometer and magnetometer, but on other devices they may also use the gyroscope to
+derive their data. Most Android-powered devices have an accelerometer, and many now
+include a gyroscope. The availability of the softare-based sensors is more variable because they
+often rely on one or more hardware sensors to derive their data.</p>
+
+<p>Motion sensors are useful for monitoring device movement, such as tilt, shake, rotation, or
+swing. The movement is usually a reflection of direct user input (for example, a user steering a
+car in a game or a user controlling a ball in a game), but it can also be a reflection of the
+physical environment in which the device is sitting (for example, moving with you while you drive
+your car). In the first case, you are monitoring motion relative to the device's frame of reference
+or your application's frame of reference; in the second case you are monitoring motion relative to
+the world's frame of reference. Motion sensors by themselves are not typically used to monitor
+device position, but they can be used with other sensors, such as the geomagnetic field sensor, to
+determine a device's position relative to the world's frame of reference (see <a
+href="{@docRoot}guide/topics/sensors/sensors_position.html">Position Sensors</a> for more
+information).</p>
+
+<p>All of the motion sensors return multi-dimensional arrays of sensor values for each {@link
+android.hardware.SensorEvent}. For example, during a single sensor event the accelerometer returns
+acceleration force data for the three coordinate axes, and the gyroscope returns rate of rotation
+data for the three coordinate axes. These data values are returned in a <code>float</code> array
+({@link android.hardware.SensorEvent#values}) along with other {@link android.hardware.SensorEvent}
+parameters. Table 1 summarizes the motion sensors that are available on the Android platform.</p>
+
+<p class="table-caption" id="table1">
+  <strong>Table 1.</strong> Motion sensors that are supported on the Android platform.</p>
+<table>
+  <tr>
+    <th scope="col" style="white-space:nowrap">Sensor</th>
+    <th scope="col" style="white-space:nowrap">Sensor event data</th>
+    <th scope="col" style="white-space:nowrap">Description</th>
+    <th scope="col" style="white-space:nowrap">Units of measure</th>
+  </tr>
+  <tr>
+    <td rowspan="3">{@link android.hardware.Sensor#TYPE_ACCELEROMETER}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Acceleration force along the x axis (including gravity).</td>
+    <td rowspan="3">m/s<sup>2</sup></td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Acceleration force along the y axis (including gravity).</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Acceleration force along the z axis (including gravity).</td>
+  </tr>
+  <tr>
+    <td rowspan="3">{@link android.hardware.Sensor#TYPE_GRAVITY}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Force of gravity along the x axis.</td>
+    <td rowspan="3">m/s<sup>2</sup></td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Force of gravity along the y axis.</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Force of gravity along the z axis.</td>
+  </tr>
+  <tr>
+    <td rowspan="3">{@link android.hardware.Sensor#TYPE_GYROSCOPE}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Rate of rotation around the x axis.</td>
+    <td rowspan="3">rad/s</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Rate of rotation around the y axis.</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Rate of rotation around the z axis.</td>
+  </tr>
+  <tr>
+    <td rowspan="3">{@link android.hardware.Sensor#TYPE_LINEAR_ACCELERATION}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Acceleration force along the x axis (excluding gravity).</td>
+    <td rowspan="3">m/s<sup>2</sup></td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Acceleration force along the y axis (excluding gravity).</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Acceleration force along the z axis (excluding gravity).</td>
+  </tr>
+  <tr>
+    <td rowspan="4">{@link android.hardware.Sensor#TYPE_ROTATION_VECTOR}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Rotation vector component along the x axis (x * sin(θ/2)).</td>
+    <td rowspan="4">Unitless</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Rotation vector component along the y axis (y * sin(θ/2)).</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Rotation vector component along the z axis (z * sin(θ/2)).</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[3]</code></td>
+    <td>Scalar component of the rotation vector ((cos(θ/2)).<sup>1</sup></td>
+  </tr>
+</table>
+
+<p class="note"><strong><sup>1</sup></strong> The scalar component is an optional value.</p>
+
+<p>The rotation vector sensor and the gravity sensor are the most frequently used sensors for motion
+detection and monitoring. The rotational vector sensor is particularly versatile and can be used for
+a wide range of motion-related tasks, such as detecting gestures, monitoring angular change, and
+monitoring relative orientation changes. For example, the rotational vector sensor is ideal if you
+are developing a game, an augmented reality application, a 2-dimensional or 3-dimensional compass,
+or a camera stabilization app. In most cases, using these sensors is a better choice than using
+the accelerometer and geomagnetic field sensor or the orientation sensor.</p>
+
+<h3>Android Open Source Project Sensors</h3>
+
+<p>The Android Open Source Project (AOSP) provides three software-based motion sensors: a gravity
+sensor, a linear acceleration sensor, and a rotation vector sensor. These sensors were updated in
+Android 4.0 and now use a device's gyroscope (in addition to other sensors) to improve stability and
+performance. If you want to try these sensors, you can identify them by using the {@link
+android.hardware.Sensor#getVendor} method and the {@link android.hardware.Sensor#getVersion} method
+(the vendor is Google Inc.; the version number is 3). Identifying these sensors by vendor and
+version number is necessary because the Android system considers these three sensors to be secondary
+sensors. For example, if a device manufacturer provides their own gravity sensor, then the AOSP
+gravity sensor shows up as a secondary gravity sensor. All three of these sensors rely on a
+gyroscope: if a device does not have a gyroscope, these sensors do not show up and are not
+available for use.</p>
+
+<h2 id="sensors-motion-accel">Using the Accelerometer</h2>
+
+<p>An acceleration sensor measures the acceleration applied to the device, including the force of
+gravity. The following code shows you how to get an instance of the default acceleration sensor:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+  ...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
+</pre>
+
+<p>Conceptually, an acceleration sensor determines the acceleration that is applied
+to a device (A<sub>d</sub>) by measuring the forces that are applied to the sensor
+itself (F<sub>s</sub>) using the following relationship:</p>
+
+<pre class="no-pretty-print classic">
+A<sub>d</sub> = - ∑F<sub>s</sub> / mass
+</pre>
+
+<p>However, the force of gravity is always influencing the measured acceleration according to
+the following relationship:</p>
+
+<pre class="no-pretty-print classic">
+A<sub>d</sub> = -g - ∑F / mass
+</pre>
+
+<p>For this reason, when the device is sitting on a table (and not accelerating), the
+accelerometer reads a magnitude of g = 9.81 m/s<sup>2</sup>. Similarly, when the device is in
+free fall and therefore rapidly accelerating toward the ground at 9.81 m/s<sup>2</sup>, its
+accelerometer reads a magnitude of g = 0 m/s<sup>2</sup>. Therefore, to measure
+the real acceleration of the device, the contribution of the force of gravity must be removed from
+the accelerometer data. This can be achieved by applying a high-pass filter. Conversely, a low-pass
+filter can be used to isolate the force of gravity. The following example shows how you can do
+this:</p>
+
+<pre>
+public void onSensorChanged(SensorEvent event){
+  // In this example, alpha is calculated as t / (t + dT),
+  // where t is the low-pass filter's time-constant and
+  // dT is the event delivery rate.
+
+  final float alpha = 0.8;
+
+  // Isolate the force of gravity with the low-pass filter.
+  gravity[0] = alpha * gravity[0] + (1 - alpha) * event.values[0];
+  gravity[1] = alpha * gravity[1] + (1 - alpha) * event.values[1];
+  gravity[2] = alpha * gravity[2] + (1 - alpha) * event.values[2];
+
+  // Remove the gravity contribution with the high-pass filter.
+  linear_acceleration[0] = event.values[0] - gravity[0];
+  linear_acceleration[1] = event.values[1] - gravity[1];
+  linear_acceleration[2] = event.values[2] - gravity[2];
+}
+</pre>
+
+<p class="note"><strong>Note:</strong> You can use many different techniques to filter sensor data.
+The code sample above uses a simple filter constant (alpha) to create a low-pass filter. This filter
+constant is derived from a time constant (t), which is a rough representation of the latency that
+the filter adds to the sensor events, and the sensor's event delivery rate (dt). The code sample
+uses an alpha value of 0.8 for demonstration purposes. If you use this filtering method you may need
+to choose a different alpha value.</p>
+
+<p>Accelerometers use the standard sensor <a
+href="{@docRoot}guide/topics/sensors/sensors_overview.html#sensors-coords">coordinate
+system</a>. In practice, this means that the following conditions apply when a device is laying
+flat on a table in its natural orientation:</p>
+
+<ul>
+  <li>If you push the device on the left side (so it moves to the right), the x acceleration value
+is positive.</li>
+  <li>If you push the device on the bottom (so it moves away from you), the y acceleration value is
+positive.</li>
+  <li>If you push the device toward the sky with an acceleration of A m/s<sup>2</sup>, the
+z acceleration value is equal to A + 9.81, which corresponds to the acceleration of the device (+A
+m/s<sup>2</sup>) minus the force of gravity (-9.81 m/s<sup>2</sup>).</li>
+  <li>The stationary device will have an acceleration value of +9.81, which corresponds to the
+acceleration of the device (0 m/s<sup>2</sup> minus the force of gravity, which is -9.81
+m/s<sup>2</sup>).</li>
+</ul>
+
+<p>In general, the accelerometer is a good sensor to use if you are monitoring device motion.
+Almost every Android-powered handset and tablet has an accelerometer, and it uses about 10 times
+less power than the other motion sensors. One drawback is that you might have to implement
+low-pass and high-pass filters to eliminate gravitational forces and reduce noise.</p>
+
+<p>The Android SDK provides a sample application that shows how to use the acceleration sensor (<a
+href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer Play</a>).</p>
+
+<h2 id="sensors-motion-grav">Using the Gravity Sensor</h2>
+
+<p>The gravity sensor provides a three dimensional vector indicating the direction and magnitude of
+gravity. The following code shows you how to get an instance of the default gravity sensor:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY);
+</pre>
+
+<p>The units are the same as those used by the acceleration
+sensor (m/s<sup>2</sup>), and the coordinate system is the same as the one used by the
+acceleration sensor.</p>
+
+<p class="note"><strong>Note:</strong> When a device is at rest, the output of the gravity sensor
+should be identical to that of the accelerometer.</p>
+
+<h2 id="sensors-motion-gyro">Using the Gyroscope</h2>
+<p>The gyroscope measures the rate or rotation in rad/s around a device's x, y,
+and z axis. The following code shows you how to get an instance of the default gyroscope:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_GYROSCOPE);
+</pre>
+
+<p>The sensor's <a
+href="{@docRoot}guide/topics/sensors/sensors_overview.html#sensors-coords">coordinate system</a>
+is the same as the one used for the acceleration sensor. Rotation is positive in the
+counter-clockwise direction; that is, an observer looking
+from some positive location on the x, y or z axis at a device positioned on the origin would report
+positive rotation if the device appeared to be rotating counter clockwise. This is the
+standard mathematical definition of positive rotation and is not the same as the definition for
+roll that is used by the orientation sensor.</p>
+
+<p>Usually, the output of the gyroscope is integrated over time to calculate a rotation describing
+the change of angles over the timestep. For example:</p>
+
+<pre>
+// Create a constant to convert nanoseconds to seconds.
+private static final float NS2S = 1.0f / 1000000000.0f;
+private final float[] deltaRotationVector = new float[4]();
+private float timestamp;
+
+public void onSensorChanged(SensorEvent event) {
+  // This timestep's delta rotation to be multiplied by the current rotation
+  // after computing it from the gyro sample data.
+  if (timestamp != 0) {
+    final float dT = (event.timestamp - timestamp) * NS2S;
+    // Axis of the rotation sample, not normalized yet.
+    float axisX = event.values[0];
+    float axisY = event.values[1];
+    float axisZ = event.values[2];
+
+    // Calculate the angular speed of the sample
+    float omegaMagnitude = sqrt(axisX*axisX + axisY*axisY + axisZ*axisZ);
+
+    // Normalize the rotation vector if it's big enough to get the axis
+    // (that is, EPSILON should represent your maximum allowable margin of error)
+    if (omegaMagnitude > EPSILON) {
+      axisX /= omegaMagnitude;
+      axisY /= omegaMagnitude;
+      axisZ /= omegaMagnitude;
+    }
+
+    // Integrate around this axis with the angular speed by the timestep
+    // in order to get a delta rotation from this sample over the timestep
+    // We will convert this axis-angle representation of the delta rotation
+    // into a quaternion before turning it into the rotation matrix.
+    float thetaOverTwo = omegaMagnitude * dT / 2.0f;
+    float sinThetaOverTwo = sin(thetaOverTwo);
+    float cosThetaOverTwo = cos(thetaOverTwo);
+    deltaRotationVector[0] = sinThetaOverTwo * axisX;
+    deltaRotationVector[1] = sinThetaOverTwo * axisY;
+    deltaRotationVector[2] = sinThetaOverTwo * axisZ;
+    deltaRotationVector[3] = cosThetaOverTwo;
+  }
+  timestamp = event.timestamp;
+  float[] deltaRotationMatrix = new float[9];
+  SensorManager.getRotationMatrixFromVector(deltaRotationMatrix, deltaRotationVector);
+    // User code should concatenate the delta rotation we computed with the current rotation
+    // in order to get the updated rotation.
+    // rotationCurrent = rotationCurrent * deltaRotationMatrix;
+   }
+}
+ </pre>
+
+<p>Standard gyroscopes provide raw rotational data without any filtering or correction for noise and
+drift (bias). In practice, gyroscope noise and drift will introduce errors that need to be
+compensated for. You usually determine the drift (bias) and noise by monitoring other sensors, such
+as the gravity sensor or accelerometer.</p>
+
+<h2 id="sensors-motion-linear">Using the Linear Accelerometer</h2>
+
+<p>The linear acceleration sensor provides you with a three-dimensional vector representing
+acceleration along each device axis, excluding gravity. The following code shows you how to get an
+instance of the default linear acceleration sensor:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_LINEAR_ACCELERATION);
+</pre>
+
+<p>Conceptually, this sensor provides you with acceleration data according to the following
+relationship:</p>
+
+<pre class="no-pretty-print classic">
+linear acceleration = acceleration - acceleration due to gravity
+</pre>
+
+<p>You typically use this sensor when you want to obtain acceleration data without the influence of
+gravity. For example, you could use this sensor to see how fast your car is going. The linear
+acceleration sensor always has an offset, which you need to remove. The simplest way to do this is
+to build a calibration step into your application. During calibration you can ask the user to set
+the device on a table, and then read the offsets for all three axes. You can then subtract that
+offset from the acceleration sensor's direct readings to get the actual linear
+acceleration.</p>
+
+<p>The sensor <a
+  href="{@docRoot}guide/topics/sensors/sensors_overview.html#sensors-coords">coordinate
+system</a> is the same as the one used by the acceleration sensor, as are the units of measure
+(m/s<sup>2</sup>).
+
+<h2 id="sensors-motion-rotate">Using the Rotation Vector Sensor</h2>
+
+<p>The rotation vector represents the orientation of the device as a combination of an angle and an
+axis, in which the device has rotated through an angle θ around an axis (x, y, or z). The following
+code shows you how to get an instance of the default rotation vector sensor:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ROTATION_VECTOR);
+</pre>
+
+<p>The three elements of the rotation vector are expressed as follows:</p>
+
+<pre class="no-pretty-print classic">
+x*sin(θ/2)
+y*sin(θ/2)
+z*sin(θ/2)
+</pre>
+
+<p>Where the magnitude of the rotation vector is equal to sin(θ/2), and the direction of the
+rotation vector is equal to the direction of the axis of rotation.</p>
+
+<div class="figure" style="width:246px">
+  <img src="{@docRoot}images/axis_globe.png" alt="" height="235" />
+  <p class="img-caption">
+    <strong>Figure 1.</strong> Coordinate system used by the rotation vector sensor.
+  </p>
+</div>
+
+<p>The three elements of the rotation vector are equal to the last three components of a unit
+quaternion (cos(θ/2), x*sin(θ/2), y*sin(θ/2), z*sin(θ/2)). Elements of the rotation vector are
+unitless. The x, y, and z axes are defined in the same way as the acceleration sensor. The reference
+coordinate system is defined as a direct orthonormal basis (see figure 1). This coordinate system
+has the following characteristics:</p>
+
+<ul>
+  <li>X is defined as the vector product Y x Z. It is tangential to the
+ground at the device's current location and points approximately East.</li>
+  <li>Y is tangential to the ground at the device's current location and points toward the
+geomagnetic
+North Pole.</li>
+  <li>Z points toward the sky and is perpendicular to the ground plane.</li>
+</ul>
+
+<p>The Android SDK provides a sample application that shows how to use the rotation vector sensor.
+The sample application is located in the API Demos code (<a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html">
+OS - RotationVectorDemo</a>).</p>
\ No newline at end of file
diff --git a/docs/html/guide/topics/sensors/sensors_overview.jd b/docs/html/guide/topics/sensors/sensors_overview.jd
new file mode 100644
index 0000000..3c5e94c
--- /dev/null
+++ b/docs/html/guide/topics/sensors/sensors_overview.jd
@@ -0,0 +1,791 @@
+page.title=Sensors Overview
+parent.title=Sensors
+parent.link=index.html
+@jd:body
+
+<div id="qv-wrapper">
+  <div id="qv">
+    <h2>Quickview</h2>
+    <ul>
+      <li>Learn about the sensors that Android supports and the Android sensor framework.</li>
+      <li>Find out how to list sensors, determine sensor capabilities, and monitor sensor data.</li>
+      <li>Learn about best practices for accessing and using sensors.</li>
+    </ul>
+    <h2>In this document</h2>
+    <ol>
+      <li><a href="#sensors-intro">Introduction to Sensors</a></li>
+      <li><a href="#sensors-identify">Identifying Sensors and Sensor Capabilities</a></li>
+      <li><a href="#sensors-monitor">Monitoring Sensor Events</a></li>
+      <li><a href="#sensors-configs">Handling Different Sensor Configurations</a></li>
+      <li><a href="#sensors-coords">Sensor Coordinate System</a></li>
+      <li><a href="#sensors-practices">Best Practices for Accessing and Using Sensors</a></li>
+    </ol>
+    <h2>Key classes and interfaces</h2>
+    <ol>
+      <li>{@link android.hardware.Sensor}</li>
+      <li>{@link android.hardware.SensorEvent}</li>
+      <li>{@link android.hardware.SensorManager}</li>
+      <li>{@link android.hardware.SensorEventListener}</li>
+    </ol>
+    <h2>Related samples</h2>
+    <ol>
+      <li><a href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer
+      Play</a></li>
+      <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html">
+API Demos (OS - RotationVectorDemo)</a></li>
+      <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/Sensors.html">API Demos
+(OS - Sensors)</a></li>
+    </ol>
+    <h2>See also</h2>
+    <ol>
+      <li><a href="{@docRoot}guide/topics/sensors/index.html">Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_motion.html">Motion Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_position.html">Position
+          Sensors</a></li>
+      <li><a href="{@docRoot}guide/topics/sensors/sensors_environment.html">Environment
+          Sensors</a></li>
+    </ol>
+  </div>
+</div>
+
+<p>Most Android-powered devices have sensors that let you monitor changes in device
+position and motion. Many devices also have sensors that let you determine ambient environmental
+conditions, such as temperature, pressure, humidity, and lighting. You can access these
+sensors and acquire raw sensor data by using the Android sensor framework.</p>
+
+<p>The sensor framework provides several classes and interfaces that help you perform a wide variety
+of sensor-related tasks. For example, you can use the sensor framework to do the following:</p>
+
+<ul>
+   <li>Determine which sensors are available on a device.</li>
+   <li>Determine an individual sensor's capabilities, such as its maximum range, manufacturer, power
+     requirements, and resolution.</li>
+   <li>Acquire raw sensor data and define the minimum rate at which you acquire sensor data.</li>
+   <li>Register and unregister sensor event listeners that monitor sensor changes.</li>
+ </ul>
+
+<p>This topic provides an overview of the sensors that are available on the Android platform.
+It also provides an introduction to the sensor framework.</p>
+
+<h2 id="sensors-intro">Introduction to Sensors</h2>
+
+<p>The Android sensor framework lets you access many types of sensors. Some of these sensors are
+hardware-based and some are software-based. Hardware-based sensors are physical components built
+into a handset or tablet device. They derive their data by directly measuring specific environmental
+properties, such as acceleration, geomagnetic field strength, or angular change. Software-based
+sensors are not physical devices, although they mimic hardware-based sensors. Software-based sensors
+derive their data from one or more of the hardware-based sensors and are sometimes called virtual
+sensors or synthetic sensors. The linear acceleration sensor and the gravity sensor are examples of
+software-based sensors. Table 1 summarizes the sensors that are supported by the Android
+platform.</p>
+
+<p>Few Android-powered devices have every type of sensor. For example, most handset devices and
+tablets have an accelerometer and a magnetometer, but fewer devices have
+barometers or thermometers. Also, a device can have more than one sensor of a given type. For
+example, a device can have two gravity sensors, each one having a different range.</p>
+
+<p class="table-caption" id="table1">
+  <strong>Table 1.</strong> Sensor types supported by the Android platform.</p>
+<table>
+  <tr>
+    <th scope="col" style="white-space:nowrap">Sensor</th>
+    <th scope="col" style="white-space:nowrap">Type</th>
+    <th scope="col" style="white-space:nowrap">Description</th>
+    <th scope="col" style="white-space:nowrap">Common Uses</th>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_ACCELEROMETER}</td>
+    <td>Hardware</td>
+    <td>Measures the acceleration force in m/s<sup>2</sup> that is applied to a device on
+all three physical axes (x, y, and z), including the force of gravity.</td>
+    <td>Motion detection (shake, tilt, etc.).</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE}</td>
+    <td>Hardware</td>
+    <td>Measures the ambient room temperature in degrees Celsius (&deg;C). See note below.</td>
+    <td>Monitoring air temperatures.</td>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_GRAVITY}</td>
+    <td>Software or Hardware</td>
+    <td>Measures the force of gravity in m/s<sup>2</sup> that is applied to a device on all
+      three physical axes (x, y, z).</td>
+    <td>Motion detection (shake, tilt, etc.).</td>
+   </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_GYROSCOPE}</td>
+    <td>Hardware</td>
+    <td>Measures a device's rate of rotation in rad/s around each of the three
+physical axes
+      (x, y, and z).</td>
+    <td>Rotation detection (spin, turn, etc.).</td>
+   </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_LIGHT}</td>
+    <td>Hardware</td>
+    <td>Measures the ambient light level (illumination) in lx.</td>
+    <td>Controlling screen brightness.</td>
+   </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_LINEAR_ACCELERATION}</td>
+    <td>Software or Hardware</td>
+     <td>Measures the acceleration force in m/s<sup>2</sup> that is
+applied to a device on
+      all three physical axes (x, y, and z), excluding the force of gravity.</td>
+    <td>Monitoring acceleration along a single axis.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD}</td>
+    <td>Hardware</td>
+      <td>Measures the ambient geomagnetic field for all three physical axes (x, y, z) in
+&mu;T.</td>
+    <td>Creating a compass.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_ORIENTATION}</td>
+    <td>Software</td>
+     <td>Measures degrees of rotation that a device makes around all three physical axes (x, y, z).
+      As of API level 3 you can obtain the inclination matrix and rotation matrix for
+      a device by using the gravity sensor and the geomagnetic field sensor in conjunction with
+      the {@link android.hardware.SensorManager#getRotationMatrix getRotationMatrix()}
+      method.</td>
+    <td>Determining device position.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_PRESSURE}</td>
+    <td>Hardware</td>
+    <td>Measures the ambient air pressure in hPa or mbar.</td>
+    <td>Monitoring air pressure changes.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_PROXIMITY}</td>
+    <td>Hardware</td>
+    <td>Measures the proximity of an object in cm relative to the view screen of a
+      device. This sensor is typically used to determine whether a handset is being held up to
+      a person's ear.</td>
+    <td>Phone position during a call.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY}</td>
+    <td>Hardware</td>
+    <td>Measures the relative ambient humidity in percent (%).</td>
+    <td>Monitoring dewpoint, absolute, and relative humidity.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_ROTATION_VECTOR}</td>
+    <td>Software or Hardware</td>
+    <td>Measures the orientation of a device by providing the three elements of the device's
+      rotation vector.</td>
+    <td>Motion detection and rotation detection.</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_TEMPERATURE}</td>
+    <td>Hardware</td>
+    <td>Measures the temperature of the device in degrees Celsius (&deg;C). This sensor
+implementation varies across devices and
+this sensor was replaced with the {@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE} sensor in
+API Level 14</td>
+    <td>Monitoring temperatures.</td>
+  </tr>
+</table>
+
+<h3>Sensor Framework</h3>
+
+<p>You can access these sensors and acquire raw sensor data by using the Android sensor framework.
+The sensor framework is part of the {@link android.hardware} package and includes the following
+classes and interfaces:</p>
+
+<dl>
+<dt>{@link android.hardware.SensorManager}</dt>
+<dd>You can use this class to create an instance of the sensor service. This class provides
+various methods for accessing and listing sensors, registering and unregistering sensor event
+listeners, and acquiring orientation information. This class also provides several sensor constants
+that are used to report sensor accuracy, set data acquisition rates, and calibrate sensors.</dd>
+<dt>{@link android.hardware.Sensor}</dt>
+<dd>You can use this class to create an instance of a specific sensor. This class provides various
+methods that let you determine a sensor's capabilities.</dd>
+<dt>{@link android.hardware.SensorEvent}</dt>
+<dd>The system uses this class to create a sensor event object, which provides information about a
+sensor event. A sensor event object includes the following information: the raw sensor data, the
+type of sensor that generated the event, the accuracy of the data, and the timestamp for the
+event.</dd>
+<dt>{@link android.hardware.SensorEventListener}</dt>
+<dd>You can use this interface to create two callback methods that receive notifications (sensor
+events) when sensor values change or when sensor accuracy changes.</dd>
+</dl>
+
+<p>In a typical application you use these sensor-related APIs to perform two basic tasks:</p>
+
+<ul>
+  <li><strong>Identifying sensors and sensor capabilities</strong>
+    <p>Identifying sensors and sensor capabilities at runtime is useful if your application has
+    features that rely on specific sensor types or capabilities. For example, you may want to
+    identify all of the sensors that are present on a device and disable any application features
+    that rely on sensors that are not present. Likewise, you may want to identify all of the sensors
+    of a given type so you can choose the sensor implementation that has the optimum performance
+    for your application.</p>
+  </li>
+  <li><strong>Monitor sensor events</strong>
+    <p>Monitoring sensor events is how you acquire raw sensor data. A sensor event occurs every time
+      a sensor detects a change in the parameters it is measuring. A sensor event provides you
+      with four pieces of information: the name of the sensor that triggered the event, the
+      timestamp for the event, the accuracy of the event, and the raw sensor data that triggered
+      the event.</p>
+  </li>
+</ul>
+
+<h3>Sensor Availability</h3>
+
+<p>While sensor availability varies from device to device, it can also vary between Android
+versions. This is because the Android sensors have been introduced over the course of several
+platform releases. For example, many sensors were introduced in Android 1.5 (API Level 3), but some
+were not implemented and were not available for use until Android 2.3 (API Level 9). Likewise,
+several sensors were introduced in Android 2.3 (API Level 9) and Android 4.0 (API Level 14). Two
+sensors have been deprecated and replaced by newer, better sensors.</p>
+
+<p>Table 2 summarizes the availability of each sensor on a platform-by-platform basis. Only four
+platforms are listed because those are the platforms that involved sensor changes. Sensors that are
+listed as deprecated are still available on subsequent platforms (provided the
+sensor is present on a device), which is in line with Android's forward compatibility policy.</p>
+
+<p class="table-caption" id="table2">
+  <strong>Table 2.</strong> Sensor availability by platform.</p>
+  <table>
+  <tr>
+    <th scope="col">Sensor</th>
+    <th scope="col">Android 4.0 <br>(API Level 14)</th>
+    <th scope="col">Android 2.3 <br>(API Level 9)</th>
+    <th scope="col">Android 2.2 <br>(API Level 8)</th>
+    <th scope="col">Android 1.5 <br>(API Level 3)</th>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_ACCELEROMETER}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE}</td>
+    <td><strong>Yes</strong></td>
+    <td>n/a</td>
+    <td>n/a</td>
+    <td>n/a</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_GRAVITY}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td>n/a</td>
+    <td>n/a</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_GYROSCOPE}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td>n/a<sup>1</sup></td>
+    <td>n/a<sup>1</sup></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_LIGHT}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_LINEAR_ACCELERATION}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td>n/a</td>
+    <td>n/a</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_ORIENTATION}</td>
+    <td><strong>Yes</strong><sup>2</sup></td>
+    <td><strong>Yes</strong><sup>2</sup></td>
+    <td><strong>Yes</strong><sup>2</sup></td>
+    <td><strong>Yes</strong></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_PRESSURE}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td>n/a<sup>1</sup></td>
+    <td>n/a<sup>1</sup></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_PROXIMITY}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_RELATIVE_HUMIDITY}</td>
+    <td><strong>Yes</strong></td>
+    <td>n/a</td>
+    <td>n/a</td>
+    <td>n/a</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_ROTATION_VECTOR}</td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td>n/a</td>
+    <td>n/a</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_TEMPERATURE}</td>
+    <td><strong>Yes</strong><sup>2</sup></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+    <td><strong>Yes</strong></td>
+  </tr>
+</table>
+
+<p class="note"><strong><sup>1</sup></strong> This sensor type was added in Android 1.5 (API Level
+3),
+but it was not available for use until Android 2.3 (API Level 9).</p>
+
+<p class="note"><strong><sup>2</sup></strong> This sensor is available, but it has been
+deprecated.</p>
+
+<h2 id="sensors-identify">Identifying Sensors and Sensor Capabilities</h2>
+
+<p>The Android sensor framework provides several methods that make it easy for you to determine at
+runtime which sensors are on a device. The API also provides methods that let you determine the
+capabilities of each sensor, such as its maximum range, its resolution, and its power
+requirements.</p>
+
+<p>To identify the sensors that are on a device you first need to get a reference to the sensor
+service. To do this, you create an instance of the {@link android.hardware.SensorManager} class by
+calling the {@link android.content.Context#getSystemService getSystemService()} method and passing
+in the {@link android.content.Context#SENSOR_SERVICE SENSOR_SERVICE} argument. For example:</p>
+
+<pre>
+private SensorManager mSensorManager;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+</pre>
+
+<p>Next, you can get a listing of every sensor on a device by calling the
+{@link android.hardware.SensorManager#getSensorList getSensorList()} method and using the {@link
+android.hardware.Sensor#TYPE_ALL} constant. For example:</p>
+<pre>
+List&lt;Sensor&gt; deviceSensors = mSensorManager.getSensorList(Sensor.TYPE_ALL);
+</pre>
+
+<p>If you want to list all of the sensors of a given type, you could use another constant instead of
+{@link android.hardware.Sensor#TYPE_ALL} such as {@link android.hardware.Sensor#TYPE_GYROSCOPE},
+{@link android.hardware.Sensor#TYPE_LINEAR_ACCELERATION}, or
+{@link android.hardware.Sensor#TYPE_GRAVITY}.
+</p>
+
+<p>You can also determine whether a specific type of sensor exists on a device by using the {@link
+android.hardware.SensorManager#getDefaultSensor getDefaultSensor()} method and passing in the type
+constant for a specific sensor. If a device has more than one sensor of a given type, one of the
+sensors must be designated as the default sensor. If a default sensor does not exist for a given
+type of sensor, the method call returns null, which means the device does not have that type of
+sensor. For example, the following code checks whether there's a magnetometer on a device:</p>
+<pre>
+private SensorManager mSensorManager;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+if (mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD) != null){
+  // Success! There's a magnetometer.
+  }
+else {
+  // Failure! No magnetometer.
+  }
+</pre>
+
+<p class="note"><strong>Note:</strong> Android does not require device manufacturers to build any
+particular types of sensors into their Android-powered devices, so devices can have a wide range of
+sensor configurations.</p>
+
+<p>In addition to listing the sensors that are on a device, you can use the public methods of the
+{@link android.hardware.Sensor} class to determine the capabilities and attributes of individual
+sensors. This is useful if you want your application to behave differently based on which sensors or
+sensor capabilities are available on a device. For example, you can use the {@link
+android.hardware.Sensor#getResolution} and {@link android.hardware.Sensor#getMaximumRange}
+methods to obtain a sensor's resolution and maximum range of measurement. You can also use the
+{@link android.hardware.Sensor#getPower} method to obtain a sensor's power requirements.</p>
+
+<p>Two of the public methods are particularly useful if you want to optimize your application for
+different manufacturer's sensors or different versions of a sensor. For example, if your application
+needs to monitor user gestures such as tilt and shake, you could create one set of data filtering
+rules and optimizations for newer devices that have a specific vendor's gravity sensor, and another
+set of data filtering rules and optimizations for devices that do not have a gravity sensor and have
+only an accelerometer. The following code sample shows you how you can use the {@link
+android.hardware.Sensor#getVendor} and {@link android.hardware.Sensor#getVersion} methods to do
+this. In this sample, we're looking for a gravity sensor that lists Google Inc. as the vendor and
+has a version number of 3. If that particular sensor is not present on the device, we try to use the
+accelerometer.</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+
+...
+
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+
+if (mSensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY) != null){
+  List&lt;Sensor&gt; gravSensors = mSensorManager.getSensorList(Sensor.TYPE_GRAVITY);
+  for(int i=0; i&lt;gravSensors.size(); i++) {
+    if ((gravSensors.get(i).getVendor().contains("Google Inc.")) &&
+       (gravSensors.get(i).getVersion() == 3)){
+      // Use the version 3 gravity sensor.
+      mSensor = gravSensors.get(i);
+    }
+  }
+}
+else{
+  // Use the accelerometer.
+  if (mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER) != null){
+    mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
+  }
+  else{
+    // Sorry, there are no accelerometers on your device.
+    // You can't play this game.
+  }
+}
+</pre>
+
+<p>Another useful method is the {@link android.hardware.Sensor#getMinDelay getMinDelay()} method,
+which returns the minimum time interval (in microseconds) a sensor can use to sense data. Any sensor
+that returns a non-zero value for the {@link android.hardware.Sensor#getMinDelay getMinDelay()}
+method is a streaming
+sensor. Streaming sensors sense data at regular intervals and were introduced in Android 2.3 (API
+Level 9). If a sensor returns zero when you call the {@link android.hardware.Sensor#getMinDelay
+getMinDelay()} method, it means the
+sensor is not a streaming sensor because it reports data only when there is a change in the
+parameters it is sensing.</p>
+
+<p>The {@link android.hardware.Sensor#getMinDelay getMinDelay()} method is useful because it lets
+you determine the maximum rate
+at which a sensor can acquire data. If certain features in your application require high data
+acquisition rates or a streaming sensor, you can use this method to determine whether a sensor
+meets those requirements and then enable or disable the relevant features in your application
+accordingly.</p>
+
+<p class="caution"><strong>Caution:</strong> A sensor's maximum data acquisition rate is not
+necessarily the rate at which the sensor framework delivers sensor data to your application. The
+sensor framework reports data through sensor events, and several factors influence the rate at which
+your application receives sensor events. For more information, see <a
+href="#sensors-monitor">Monitoring Sensor Events</a>.</p>
+
+<h2 id="sensors-monitor">Monitoring Sensor Events</h2>
+
+<p>To monitor raw sensor data you need to implement two callback methods that are exposed through
+the {@link android.hardware.SensorEventListener} interface: {@link
+android.hardware.SensorEventListener#onAccuracyChanged onAccuracyChanged()} and {@link
+android.hardware.SensorEventListener#onSensorChanged onSensorChanged()}. The Android system calls
+these methods whenever the following occurs:</p>
+
+<ul>
+  <li><strong>A sensor's accuracy changes.</strong>
+    <p>In this case the system invokes the {@link
+android.hardware.SensorEventListener#onAccuracyChanged onAccuracyChanged()} method, providing
+    you with a reference to the {@link android.hardware.Sensor Sensor} object that changed and the
+    new accuracy of the sensor. Accuracy is represented by one of four status constants:
+    {@link android.hardware.SensorManager#SENSOR_STATUS_ACCURACY_LOW},
+    {@link android.hardware.SensorManager#SENSOR_STATUS_ACCURACY_MEDIUM},
+    {@link android.hardware.SensorManager#SENSOR_STATUS_ACCURACY_HIGH},
+    or {@link android.hardware.SensorManager#SENSOR_STATUS_UNRELIABLE}.</p>
+  </li>
+  <li><strong>A sensor reports a new value.</strong>
+    <p>In this case the system invokes the {@link
+android.hardware.SensorEventListener#onSensorChanged onSensorChanged()} method, providing you with
+a {@link android.hardware.SensorEvent SensorEvent} object. A {@link android.hardware.SensorEvent
+SensorEvent} object
+      contains information about the new sensor data, including: the accuracy of the data, the
+      sensor that generated the data, the timestamp at which the data was generated, and the new
+      data that the sensor recorded.</p>
+  </li>
+</ul>
+
+<p>The following code shows how to use the {@link
+android.hardware.SensorEventListener#onSensorChanged onSensorChanged()} method to monitor data from
+the light sensor. This example displays the raw sensor data in a {@link android.widget.TextView}
+that is
+defined in the main.xml file as <code>sensor_data</code>.</p>
+
+<pre>
+public class SensorActivity extends Activity implements SensorEventListener {
+  private SensorManager mSensorManager;
+  private Sensor mLight;
+
+  &#64;Override
+  public final void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.main);
+
+    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+    mLight = mSensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
+  }
+
+  &#64;Override
+  public final void onAccuracyChanged(Sensor sensor, int accuracy) {
+    // Do something here if sensor accuracy changes.
+  }
+
+  &#64;Override
+  public final void onSensorChanged(SensorEvent event) {
+    // The light sensor returns a single value.
+    // Many sensors return 3 values, one for each axis.
+    float lux = event.values[0];
+    // Do something with this sensor value.
+  }
+
+  &#64;Override
+  protected void onResume() {
+    super.onResume();
+    mSensorManager.registerListener(this, mLight, SensorManager.SENSOR_DELAY_NORMAL);
+  }
+
+  &#64;Override
+  protected void onPause() {
+    super.onPause();
+    mSensorManager.unregisterListener(this);
+  }
+}
+</pre>
+
+<p>In this example, the default data delay ({@link
+android.hardware.SensorManager#SENSOR_DELAY_NORMAL}) is specified when the {@link
+android.hardware.SensorManager#registerListener registerListener()} method is invoked. The data
+delay (or sampling rate) controls the interval at which sensor events are sent to your application
+via the {@link
+android.hardware.SensorEventListener#onSensorChanged onSensorChanged()} callback method. The default
+data delay is suitable for monitoring
+typical screen orientation changes and uses a delay of 200,000 microseconds. You can specify other
+data delays, such as {@link android.hardware.SensorManager#SENSOR_DELAY_GAME} (20,000 microsecond
+delay), {@link android.hardware.SensorManager#SENSOR_DELAY_UI} (60,000 microsecond delay), or {@link
+android.hardware.SensorManager#SENSOR_DELAY_FASTEST} (0 microsecond delay). As of Android 3.0 (API
+Level 11) you can also specify the delay as an absolute value (in microseconds).</p>
+
+<p>The delay that you specify is only a suggested delay. The Android system and other applications
+can alter this delay. As a best practice, you should specify the largest delay that you can because
+the system typically uses a smaller delay than the one you specify (that is, you should choose the
+slowest sampling rate that still meets the needs of your application). Using a larger delay imposes
+a lower load on the processor and therefore uses less power.</p>
+
+<p>There is no public method for determining the rate at which the sensor framework is sending
+sensor events to your application; however, you can use the timestamps that are associated with each
+sensor event to calculate the sampling rate over several events. You should not have to change the
+sampling rate (delay) once you set it. If for some reason you do need to change the delay, you will
+have to unregister and reregister the sensor listener.</p>
+
+<p>It's also important to note that this example uses the {@link android.app.Activity#onResume} and
+{@link android.app.Activity#onPause} callback methods to register and unregister the sensor event
+listener. As a best practice you should always disable sensors you don't need, especially when your
+activity is paused. Failing to do so can drain the battery in just a few hours because some sensors
+have substantial power requirements and can use up battery power quickly. The system
+will not disable sensors automatically when the screen turns off.</p>
+
+<h2 id="sensors-configs">Handling Different Sensor Configurations</h2>
+
+<p>Android does not specify a standard sensor configuration for devices,
+which means device manufacturers can incorporate any sensor configuration that they want into their
+Android-powered devices. As a result, devices can include a variety
+of sensors in a wide range of configurations. For example, the Motorola Xoom has a pressure sensor,
+but the Samsung Nexus S does not. Likewise, the Xoom and Nexus S have gyroscopes, but the HTC Nexus
+One does not. If your application relies on a specific type of sensor, you have to ensure that the
+sensor is present on a device so your app can run successfully. You have two options for ensuring
+that a given sensor is present on a device:</p>
+<ul>
+  <li>Detect sensors at runtime and enable or disable application features as appropriate.</li>
+  <li>Use Android Market filters to target devices with specific sensor configurations.</li>
+</ul>
+
+<p>Each option is discussed in the following sections.</p>
+
+<h4><strong>Detecting sensors at runtime</strong></h4>
+
+<p>If your application uses a specific type of sensor, but doesn't rely on it, you can use the
+sensor framework to detect the sensor at runtime and then disable or enable application features
+as appropriate. For example, a navigation application might use the temperature sensor,
+pressure sensor, GPS sensor, and geomagnetic field sensor to display the temperature, barometric
+pressure, location, and compass bearing. If a device doesn't have a pressure sensor, you can use the
+sensor framework to detect the absence of the pressure sensor at runtime and then disable the
+portion of your application's UI that displays pressure. For example, the following code checks
+whether there's a pressure sensor on a device:</p>
+<pre>
+  private SensorManager mSensorManager;
+  ...
+  mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+  if (mSensorManager.getDefaultSensor(Sensor.TYPE_PRESSURE) != null){
+  // Success! There's a pressure sensor.
+  }
+  else {
+  // Failure! No pressure sensor.
+  }
+</pre>
+
+<h4>Using Android Market filters to target specific sensor configurations</h4>
+
+<p>If you are publishing your application on Android Market you can use the
+  <a href="{@docRoot}guide//topics/manifest/uses-feature-element.html"><code>&lt;uses-feature&gt;
+    </code></a> element in your manifest file to filter your application from devices that do not
+have the appropriate sensor configuration for your application. The
+<code>&lt;uses-feature&gt;</code> element has several hardware descriptors that let you filter
+applications based on the presence of specific sensors. The sensors you can list include:
+accelerometer, barometer, compass (geomagnetic field), gyroscope, light, and proximity. The
+following is an example manifest entry that filters apps that do not have an accelerometer:</p>
+
+<pre>
+&lt;uses-feature android:name="android.hardware.sensor.accelerometer"
+              android:required="true" /&gt;
+</pre>
+
+<p>If you add this element and descriptor to your application's manifest, users will see your
+application on Android Market only if their device has an accelerometer.</p>
+
+<p>You should set the descriptor to <code>android:required="true"</code> only if your application
+relies entirely on a specific sensor. If your application uses a sensor for some functionality, but
+still runs without the sensor, you should list the sensor in the <code>&lt;uses-feature&gt;</code>
+element, but set the descriptor to <code>android:required="false"</code>. This helps ensure that
+devices can install your app even if they do not have that particular sensor. This is also a
+project management best practice that helps you keep track of the features your application uses.
+Keep in mind, if your application uses a particular sensor, but still runs without the sensor,
+then you should detect the sensor at runtime and disable or enable application features as
+appropriate.</p>
+
+<h2 id="sensors-coords">Sensor Coordinate System</h2>
+
+<p>In general, the sensor framework uses a standard 3-axis coordinate system to express data values.
+For most sensors, the coordinate system is defined relative to the device's screen when the device
+is held in its default orientation (see figure 1). When a device is held in its default orientation,
+the X axis is horizontal and points to the right, the Y axis is vertical and points up, and the Z
+axis points toward the outside of the screen face. In this system, coordinates behind the screen
+have negative Z values. This coordinate system is used by the following sensors:</p>
+
+<div class="figure" style="width:269px">
+  <img src="{@docRoot}images/axis_device.png" alt="" height="225" />
+  <p class="img-caption">
+    <strong>Figure 1.</strong> Coordinate system (relative to a device) that's used by the Sensor
+    API.
+  </p>
+</div>
+
+<ul>
+  <li><a
+href="{@docRoot}guide/topics/sensors/sensors_motion.html#sensors-motion-accel">Acceleration
+sensor</a></li>
+<li><a
+href="{@docRoot}guide/topics/sensors/sensors_motion.html#sensors-motion-gravity">Gravity
+sensor</a></li>
+<li><a
+href="{@docRoot}guide/topics/sensors/sensors_motion.html#sensors-motion-gyro">Gyroscope</a></li>
+<li><a
+href="{@docRoot}guide/topics/sensors/sensors_motion.html#sensors-motion-linear">Linear acceleration
+sensor</a></li>
+<li><a
+href="{@docRoot}guide/topics/sensors/sensors_position.html#sensors-pos-mag">Geomagnetic field
+sensor</a></li>
+</ul>
+
+<p>The most important point to understand about this coordinate system is that the axes are not
+swapped when the device's screen orientation changes&mdash;that is, the sensor's coordinate system
+never changes as the device moves. This behavior is the same as the behavior of the OpenGL
+coordinate system.</p>
+
+<p>Another point to understand is that your application must not assume that a device's natural
+(default) orientation is portrait. The natural orientation for many tablet devices is landscape. And
+the sensor coordinate system is always based on the natural orientation of a device.</p>
+
+<p>Finally, if your application matches sensor data to the on-screen display, you need to use the
+{@link android.view.Display#getRotation} method to determine screen rotation, and then use the
+{@link android.hardware.SensorManager#remapCoordinateSystem remapCoordinateSystem()} method to map
+sensor coordinates to screen coordinates. You need to do this even if your manifest specifies
+portrait-only display.</p>
+
+<p>For more information about the sensor coordinate system, including information about how to
+handle screen rotations, see <a
+href="http://android-developers.blogspot.com/2010/09/one-screen-turn-deserves-another.html">One
+Screen Turn Deserves Another</a>.</p>
+
+<p class="note"><strong>Note:</strong> Some sensors and methods use a coordinate system that is
+relative to the world's frame of reference (as opposed to the device's frame of reference). These
+sensors and methods return data that represent device motion or device position relative to the
+earth. For more information, see the {@link android.hardware.SensorManager#getOrientation
+getOrientation()} method, the {@link android.hardware.SensorManager#getRotationMatrix
+getRotationMatrix()} method, <a
+href="{@docRoot}guide/topics/sensors/sensors_position.html#sensors-pos-orient">Orientation
+Sensor</a>, and <a
+href="{@docRoot}guide/topics/sensors/sensors_motion.html#sensors-motion-rotate">Rotation Vector
+Sensor</a>.</p>
+
+<h2 id="sensors-practices">Best Practices for Accessing and Using Sensors</h2>
+
+<p>As you design your sensor implementation, be sure to follow the guidelines that are discussed in
+this section. These guidelines are recommended best practices for anyone who is using the sensor
+framework to access sensors and acquire sensor data.</p>
+
+<h4>Unregister sensor listeners</h4>
+
+<p>Be sure to unregister a sensor's listener when you are done using the sensor or when the sensor
+activity pauses. If a sensor listener is registered and its activity is paused, the sensor will
+continue to acquire data and use battery resources unless you unregister the sensor. The following
+code shows how to use the {@link android.app.Activity#onPause} method to unregister a listener:</p>
+
+<pre>
+private SensorManager mSensorManager;
+  ...
+&#64;Override
+protected void onPause() {
+  super.onPause();
+  mSensorManager.unregisterListener(this);
+}
+</pre>
+
+<p>For more information, see {@link android.hardware.SensorManager#unregisterListener}.</p>
+
+<h4>Don't test your code on the emulator</h4>
+
+<p>You currently can't test sensor code on the emulator because the emulator cannot emulate sensors.
+You must test your sensor code on a physical device. There are, however, sensor simulators that you
+can use to simulate sensor output.</p>
+
+<h4>Don't block the onSensorChanged() method</h4>
+
+<p>Sensor data can change at a high rate, which means the system may call the {@link
+android.hardware.SensorEventListener#onSensorChanged} method quite often. As a best practice, you
+should do as little as possible within the {@link
+android.hardware.SensorEventListener#onSensorChanged} method so you don't block it. If your
+application requires you to do any data filtering or reduction of sensor data, you should perform
+that work outside of the {@link android.hardware.SensorEventListener#onSensorChanged} method.</p>
+
+<h4>Avoid using deprecated methods or sensor types</h4>
+
+<p>Several methods and constants have been deprecated.
+In particular, the {@link android.hardware.Sensor#TYPE_ORIENTATION}
+sensor type has been deprecated. To get orientation data you should use the {@link
+android.hardware.SensorManager#getOrientation getOrientation()} method instead. Likewise, the
+{@link android.hardware.Sensor#TYPE_TEMPERATURE} sensor type has been deprecated. You should use
+the {@link android.hardware.Sensor#TYPE_AMBIENT_TEMPERATURE} sensor type instead on devices
+that are running Android 4.0.</p>
+
+<h4>Verify sensors before you use them</h4>
+
+<p>Always verify that a sensor exists on a device before you attempt to acquire data from it. Don't
+assume that a sensor exists simply because it's a frequently-used sensor. Device manufacturers are
+not required to provide any particular sensors in their devices.</p>
+
+<h4>Choose sensor delays carefully</h4>
+
+<p>When you register a sensor with the {@link android.hardware.SensorManager#registerListener
+registerListener()} method, be sure you choose a delivery rate that is suitable for your
+application or use-case. Sensors can provide data at very high rates. Allowing the system to send
+extra data that you don't need wastes system resources and uses battery power.</p>
\ No newline at end of file
diff --git a/docs/html/guide/topics/sensors/sensors_position.jd b/docs/html/guide/topics/sensors/sensors_position.jd
new file mode 100644
index 0000000..869109b
--- /dev/null
+++ b/docs/html/guide/topics/sensors/sensors_position.jd
@@ -0,0 +1,317 @@
+page.title=Position Sensors
+parent.title=Sensors
+parent.link=index.html
+@jd:body
+
+<div id="qv-wrapper">
+  <div id="qv">
+  <h2>In this document</h2>
+  <ol>
+     <li><a href="#sensors-pos-orient">Using the Orientation Sensor</a></li>
+    <li><a href="#sensors-pos-mag">Using the Geomagnetic Field Sensor</a></li>
+    <li><a href="#sensors-pos-prox">Using the Proximity Sensor</a></li>
+  </ol>
+  <h2>Key classes and interfaces</h2>
+  <ol>
+    <li>{@link android.hardware.Sensor}</li>
+    <li>{@link android.hardware.SensorEvent}</li>
+    <li>{@link android.hardware.SensorManager}</li>
+    <li>{@link android.hardware.SensorEventListener}</li>
+  </ol>
+  <h2>Related samples</h2>
+  <ol>
+    <li><a href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer
+        Play</a></li>
+    <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/RotationVectorDemo.html">
+API Demos (OS - RotationVectorDemo)</a></li>
+    <li><a
+href="{@docRoot}resources/samples/ApiDemos/src/com/example/android/apis/os/Sensors.html">API Demos
+(OS - Sensors)</a></li>
+  </ol>
+  <h2>See also</h2>
+  <ol>
+    <li><a href="{@docRoot}guide/topics/sensors/index.html">Sensors</a></li>
+    <li><a href="{@docRoot}guide/topics/sensors/sensors_overview.html">Sensors Overview</a></li>
+    <li><a href="{@docRoot}guide/topics/sensors/sensors_motion.html">Motion
+        Sensors</a></li>
+    <li><a href="{@docRoot}guide/topics/sensors/sensors_environment.html">Environment
+        Sensors</a></li>
+  </ol>
+  </div>
+</div>
+
+<p>The Android platform provides two sensors that let you determine the position of a device: the
+geomagnetic field sensor and the orientation sensor. The Android platform also
+provides a sensor that lets you determine how close the face of a device is to an object (known as
+the proximity sensor). The geomagnetic field sensor and the proximity sensor are hardware-based.
+Most
+handset and tablet manufacturers include a geomagnetic field sensor. Likewise, handset manufacturers
+usually include a proximity sensor to determine when a handset is being held close to a user's face
+(for example, during a phone call). The orientation sensor is software-based and derives its data
+from the accelerometer and the geomagnetic field sensor.</p>
+
+<p class="note"><strong>Note:</strong> The orientation sensor was deprecated in Android 2.2 (API
+Level 8).</p>
+
+<p>Position sensors are useful for determining a device's physical position in the
+world's frame of reference. For example, you can use the geomagnetic field sensor in
+combination with the accelerometer to determine a device's position relative to
+the magnetic North Pole. You can also use the orientation sensor (or similar sensor-based
+orientation methods) to determine a device's position in your application's frame of reference.
+Position sensors are not typically used to monitor device movement or motion, such as shake, tilt,
+or thrust (for more information, see <a
+href="{@docRoot}guide/topics/sensors/sensors_motion.html">Motion Sensors</a>).</p>
+
+<p>The geomagnetic field sensor and orientation sensor return multi-dimensional arrays of sensor
+values
+for each {@link android.hardware.SensorEvent}. For example, the orientation sensor provides
+geomagnetic
+field strength values for each of the three coordinate axes during a single sensor event. Likewise,
+the orientation sensor provides azimuth (yaw), pitch, and roll values during a single sensor event.
+For more information about the coordinate systems that are used by sensors, see <a
+href="{@docRoot}guide/topics/sensors/sensors_overview.html#sensors-coords">Sensor Coordinate
+Systems</a>. The proximity sensor provides a single value for each sensor event. Table 1 summarizes
+the position sensors that are supported on the Android platform.</p>
+
+<p class="table-caption" id="table1">
+  <strong>Table 1.</strong> Position sensors that are supported on the Android platform.</p>
+<table>
+  <tr>
+    <th scope="col" style="white-space:nowrap">Sensor</th>
+    <th scope="col" style="white-space:nowrap">Sensor event data</th>
+    <th scope="col" style="white-space:nowrap">Description</th>
+    <th scope="col" style="white-space:nowrap">Units of measure</th>
+  </tr>
+  <tr>
+    <td rowspan="3">{@link android.hardware.Sensor#TYPE_MAGNETIC_FIELD}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Geomagnetic field strength along the x axis.</td>
+    <td rowspan="3">&mu;T</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Geomagnetic field strength along the y axis.</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Geomagnetic field strength along the z axis.</td>
+  </tr>
+  <tr>
+    <td rowspan="3">{@link android.hardware.Sensor#TYPE_ORIENTATION}<sup>1</sup></td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Azimuth (angle around the z-axis).</td>
+    <td rowspan="3">Degrees</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[1]</code></td>
+    <td>Pitch (angle around the x-axis).</td>
+  </tr>
+  <tr>
+    <td><code>SensorEvent.values[2]</code></td>
+    <td>Roll (angle around the y-axis).</td>
+  </tr>
+  <tr>
+    <td>{@link android.hardware.Sensor#TYPE_PROXIMITY}</td>
+    <td><code>SensorEvent.values[0]</code></td>
+    <td>Distance from object.<sup>2</sup></td>
+    <td>cm</td>
+  </tr>
+</table>
+
+<p class="note"><sup><strong>1</strong></sup> This sensor was deprecated in Android 2.2 (API Level
+  8). The sensor framework provides alternate methods for acquiring device orientation, which are
+discussed in <a href="#sensors-pos-orient">Using the Orientation Sensor</a>.</p>
+
+<p class="note"><sup><strong>2</strong></sup> Some proximity sensors provide only binary values
+representing near and far.</p>
+
+<h2 id="sensors-pos-orient">Using the Orientation Sensor</h2>
+
+<p>The orientation sensor lets you monitor the position of a device relative to the earth's frame of
+reference (specifically, magnetic north). The following code shows you how to get an instance of the
+default orientation sensor :</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
+</pre>
+
+<p>The orientation sensor derives its data by using a device's geomagnetic field sensor in
+combination with a device's accelerometer. Using these two hardware sensors, an orientation sensor
+provides data for the following three dimensions:</p>
+
+<ul>
+  <li>Azimuth (degrees of rotation around the z axis). This is the angle between magnetic north
+and the device's y axis. For example, if the device's y axis is aligned with magnetic north
+this value is 0, and if the device's y axis is pointing south this value is 180. Likewise, when
+the y axis is pointing east this value is 90 and when it is pointing west this value is 270.</li>
+  <li>Pitch (degrees of rotation around the x axis). This value is positive when the positive z axis
+rotates toward the positive y axis, and it is negative when the positive z axis
+rotates toward the negative y axis. The range of values is 180 degrees to -180
+degrees.</li>
+  <li>Roll (degrees of rotation around the y axis). This value is positive when the positive z axis
+rotates toward the positive x axis, and it is negative when the positive z axis
+rotates toward the negative x axis. The range of values is 90 degrees to -90
+degrees.</li>
+</ul>
+
+<p>This definition is different from yaw, pitch, and roll used in aviation, where the X axis is
+along the long side of the plane (tail to nose). Also, for historical reasons the roll angle is
+positive in the clockwise direction (mathematically speaking, it should be positive in the
+counter-clockwise direction).</p>
+
+<p>The orientation sensor derives its data by processing the raw sensor data from the accelerometer
+and the geomagnetic field sensor. Because of the heavy processing that is involved, the accuracy and
+precision of the orientation sensor is diminished (specifically, this sensor is only reliable when
+the roll component is 0). As a result, the orientation sensor was deprecated in Android 2.2 (API
+level 8). Instead of using raw data from the orientation sensor, we recommend that you use the
+{@link android.hardware.SensorManager#getRotationMatrix getRotationMatrix()} method in conjunction
+with the {@link android.hardware#getOrientation getOrientation()} method to compute orientation
+values. You can also use the {@link android.hardware.SensorManager#remapCoordinateSystem
+remapCoordinateSystem()} method to translate the orientation values to your application's frame of
+reference.</p>
+
+<p>The following code sample shows how to acquire orientation data directly from the orientation
+sensor. We recommend that you do this only if a device has negligible roll.</p>
+
+<pre>
+public class SensorActivity extends Activity implements SensorEventListener {
+
+  private SensorManager mSensorManager;
+  private Sensor mOrientation;
+
+  &#64;Override
+  public void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.main);
+
+    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+    mOrientation = mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION);
+  }
+
+  &#64;Override
+  public void onAccuracyChanged(Sensor sensor, int accuracy) {
+    // Do something here if sensor accuracy changes.
+    // You must implement this callback in your code.
+  }
+
+  &#64;Override
+  protected void onResume() {
+    super.onResume();
+    mSensorManager.registerListener(this, mOrientation, SensorManager.SENSOR_DELAY_NORMAL);
+  }
+
+  &#64;Override
+  protected void onPause() {
+    super.onPause();
+    mSensorManager.unregisterListener(this);
+  }
+
+  &#64;Override
+  public void onSensorChanged(SensorEvent event) {
+    float azimuth_angle = event.values[0];
+    float pitch_angle = event.values[1];
+    float roll_angle = event.values[2];
+    // Do something with these orientation angles.
+  }
+}
+</pre>
+
+<p>You do not usually need to perform any data processing or filtering of the raw data that you
+obtain from an orientation sensor, other than translating the sensor's coordinate system to your
+application's frame of reference. The <a
+href="{@docRoot}resources/samples/AccelerometerPlay/index.html">Accelerometer Play</a> sample shows
+you how to translate acceleration sensor data into another frame of reference; the technique is
+similar to the one you might use with the orientation sensor.</p>
+
+<h2 id="sensors-pos-mag">Using the Geomagnetic Field Sensor</h2>
+
+<p>The geomagnetic field sensor lets you monitor changes in the earth's magnetic field. The
+following code shows you how to get an instance of the default geomagnetic field sensor:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
+</pre>
+
+<p>This sensor provides raw field strength data (in &mu;T) for each of the three coordinate axes.
+Usually, you do not need to use this sensor directly. Instead, you can use the rotation vector
+sensor to determine raw rotational movement or you can use the accelerometer and geomagnetic field
+sensor in conjunction with the {@link android.hardware.SensorManager#getRotationMatrix
+getRotationMatrix()} method to obtain the rotation matrix and the inclination matrix. You can then
+use these matrices with the {@link android.hardware.SensorManager#getOrientation getOrientation()}
+and {@link android.hardware.SensorManager#getInclination getInclination()} methods to obtain azimuth
+and geomagnetic inclination data.</p>
+
+<h2 id="sensors-pos-prox">Using the Proximity Sensor</h2>
+<p>The proximity sensor lets you determine how far away an object is from a device. The following
+code shows you how to get an instance of the default proximity sensor:</p>
+
+<pre>
+private SensorManager mSensorManager;
+private Sensor mSensor;
+...
+mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+mSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);
+</pre>
+
+<p>The proximity sensor is usually used to determine how far away a person's head is from the face
+of a handset device (for example, when a user is making or receiving a phone call). Most
+proximity sensors return the absolute distance, in cm, but some return only near and
+far values. The following code shows you how to use the proximity sensor:</p>
+
+<pre>
+public class SensorActivity extends Activity implements SensorEventListener {
+  private SensorManager mSensorManager;
+  private Sensor mProximity;
+
+  &#64;Override
+  public final void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+    setContentView(R.layout.main);
+
+    // Get an instance of the sensor service, and use that to get an instance of
+    // a particular sensor.
+    mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
+    mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);
+  }
+
+  &#64;Override
+  public final void onAccuracyChanged(Sensor sensor, int accuracy) {
+    // Do something here if sensor accuracy changes.
+  }
+
+  &#64;Override
+  public final void onSensorChanged(SensorEvent event) {
+    float distance = event.values[0];
+    // Do something with this sensor data.
+  }
+
+  &#64;Override
+  protected void onResume() {
+    // Register a listener for the sensor.
+    super.onResume();
+    mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL);
+  }
+
+  &#64;Override
+  protected void onPause() {
+    // Be sure to unregister the sensor when the activity pauses.
+    super.onPause();
+    mSensorManager.unregisterListener(this);
+  }
+}
+</pre>
+
+<p class="note"><strong>Note:</strong> Some proximity sensors return binary values that represent
+"near" or "far." In this case, the sensor usually reports its maximum range value in the far state
+and a lesser value in the near state. Typically, the far value is a value > 5 cm, but this can vary
+from sensor to sensor. You can determine a sensor's maximum range by using the {@link
+android.hardware.Sensor#getMaximumRange} method.</p>
\ No newline at end of file