Accelerometer  - AS3

package 
{
    import flash.display.Sprite;
    import flash.display.StageAlign;
    import flash.display.StageScaleMode;
    import flash.events.Event;
    import flash.events.AccelerometerEvent;
    import flash.sensors.Accelerometer;

    public class AccelerometerTest extends Sprite
    {
        private var ball:Sprite;
        private var accelerometer:Accelerometer;        
        private var xSpeed:Number = 0;
        private var ySpeed:Number = 0;
        private const RADIUS = 20;
        
        public final function AccelerometerTest()
        {
            stage.scaleMode = StageScaleMode.NO_SCALE;
            stage.align = StageAlign.TOP_LEFT;
            
            createBall();
                                    
            if (Accelerometer.isSupported)
            {
                accelerometer = new Accelerometer();
                accelerometer.addEventListener(AccelerometerEvent.UPDATE, accUpdateHandler);
                stage.addEventListener(Event.ENTER_FRAME, enterFrameHandler);
            }
        }
        
        private final function createBall():void
        {
             ball = new Sprite();
             ball.graphics.beginFill(0xFF0000);
             ball.graphics.drawCircle(0, 0, RADIUS);
             ball.cacheAsBitmap = true;
             ball.x = stage.stageWidth / 2;
             ball.y = stage.stageHeight / 2;
             addChild(ball);
        }

        private final function enterFrameHandler(event:Event):void
        {
            event.stopPropagation();
            moveBall();
        }
        private final function moveBall():void
        {
            var newX:Number = ball.x + xSpeed;
            var newY:Number = ball.y + ySpeed;
            if (newX < 20)
            {
                ball.x = RADIUS;
                xSpeed = 0;
            }
            else if (newX > stage.stageWidth - RADIUS)
            {
                ball.x = stage.stageWidth - RADIUS;
                xSpeed = 0;
            }
            else
            {
                ball.x += xSpeed;
            }
            
            if (newY < RADIUS)
            {
                ball.y = RADIUS;
                ySpeed = 0;
            }
            else if (newY > stage.stageHeight - RADIUS)
            {
                ball.y = stage.stageHeight - RADIUS;
                ySpeed = 0;
            }
            else
            {
                ball.y += ySpeed;
            }
        }

        private final function accUpdateHandler(event:AccelerometerEvent):void
        {
            xSpeed -= event.accelerationX * 2;
            ySpeed += event.accelerationY * 2;
        }
    }
}