This recipe will show how to use the accelerometer to measure a device’s motion in three dimensions.

1. Create a new Xamarin.Android application named MotionDetector.

2. Edit Main.axml so that it contains a single TextView:

   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
       android:orientation="vertical"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent">
       <TextView
           android:id="@+id/accelerometer_text"
           android:layout_width="fill_parent"
           android:textAppearance="?android:attr/textAppearanceLarge"
           android:layout_height="wrap_content"
           android:text="TEXT"
           android:layout_marginLeft="15dp"
           android:layout_marginRight="15dp"
           android:layout_marginTop="30dp" />
   </LinearLayout>
   

3. Add some instance variables to Activity1.cs:

    static readonly object _syncLock = new object();
    SensorManager _sensorManager;
    TextView _sensorTextView;
   

4. Have Activity1 implement the interface ISensorEventListener and implement the methods for the interface:

    public void OnAccuracyChanged(Sensor sensor, SensorStatus accuracy)
    {
        // We don't want to do anything here.
    }
    
    public void OnSensorChanged(SensorEvent e)
    {
        lock (_syncLock)
        {
            _sensorTextView.Text = string.Format("x={0:f}, y={1:f}, z={2:f}", e.Values[0], e.Values[1], e.Values[2]);
        }
    }
   

5. Change OnCreate and get a reference to the SensorManager:

    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);
        SetContentView(Resource.Layout.Main);
        _sensorManager = (SensorManager) GetSystemService(Context.SensorService);
        _sensorTextView = FindViewById<TextView>(Resource.Id.accelerometer_text);
    }
   

6. Override OnResume so that the application will listen to updates from the accelerometer. The Activity will begin listening to updates from the accelerometer:

    protected override void OnResume()
    {
        base.OnResume();
        _sensorManager.RegisterListener(this,
                                        _sensorManager.GetDefaultSensor(SensorType.Accelerometer),
                                        SensorDelay.Ui);
    }
   

7. Override OnPause so that the Activity will stop listening to the accelerometer when the application is not active. This is done to reduce the drain on the battery and to preserve battery life:

    protected override void OnPause()
    {
        base.OnPause();
        _sensorManager.UnregisterListener(this);
    }
   

8. Run the application on a device. As the device is moved around, the accelerometer values will display on the screen.

The accelerometer returns values that describe the changes in acceleration along the three axes of the coordinate system measured in m/s². These axes are show in the diagram below: