I just got a new case for my Kindle Fire. It's pretty good for the US $22.70 that I paid for it (including shipping).

The case has a large circular hole in the top, left corner. After doing some research, I found that this hole is for the Kindle Fire's ambient light sensor. My Kindle is running version 6.2.2_user3205220 of the operating system, and the light sensor is not used to automatically control the display brightness, even though Amazon's FAQ states that a light sensor is supported.

I had hoped to write an app to address this issue, but the light sensor appears to be completely disabled, at least in operating system version that I'm running. I hope Amazon will see the light, and correct this issue in the future.

Here's the code I wrote to determine if the light sensor is accessible:

package com.ericbt.AutoDimmer;

import java.util.List;

import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.util.Log;

public class AutoDimmerActivity extends Activity {
	private SensorManager sensorManager;
	private SensorEventListener sensorEventListener;
	private Sensor lightSensor;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }

	@Override
	protected void onPause() {
		Log.i("AutoDimmer", "onPause");
		
		sensorManager.unregisterListener(sensorEventListener, lightSensor);
		
		super.onPause();
	}

	@Override
	protected void onResume() {
		Log.i("AutoDimmer", "onResume");

		initialize();
		
		sensorManager.registerListener(sensorEventListener, lightSensor, SensorManager.SENSOR_DELAY_UI);
		
		super.onResume();
	}
	
	private void initialize() {
		Log.i("AutoDimmer", "initialize");
		
		if (sensorManager == null) {
			Log.i("AutoDimmer", "initialize, initializing");
			
	        sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
	        lightSensor = sensorManager.getDefaultSensor(Sensor.TYPE_LIGHT);
	        
	        List<Sensor> allSensors = sensorManager.getSensorList(Sensor.TYPE_ALL);
	        
	        for (Sensor sensor : allSensors) {
	        	Log.i("AutoDimmer", String.format("Sensor: %s %d", sensor.getName(), sensor.getType()));
	        }
	        
	        if (lightSensor == null) {
	        	Log.i("AutoDimmer", "Light Sensor: NULL");
	        }
	        else {
		        Log.i("AutoDimmer", String.format("Light Sensor: %s %s", lightSensor.getName(), lightSensor.getVendor()));
		        
		        sensorEventListener = new SensorEventListener() {
					public void onSensorChanged(SensorEvent event) {
						StringBuilder message = new StringBuilder("onSensorChanged ");
						
						for (float value : event.values) {
							message.append(value);
							message.append(' ');
						}
						
						
						Log.i("AutoDimmer", message.toString());
					}
					
					public void onAccuracyChanged(Sensor sensor, int accuracy) {
						Log.i("AutoDimmer", "onAccuracyChanged");
					}
				};
	        	}
		}
	}
}

AndroidManifest.xml:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.ericbt.AutoDimmer"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk android:minSdkVersion="7" />
    <uses-permission android:name="android.hardware.sensor.light"/>

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name" >
        <activity
            android:name=".AutoDimmerActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Four sensors are accessible to the app, but not the ambient light sensor: