How to log data from Android Motion Sensors at a fixed rate

I'm learning the Basics of Android programming.

I have a simple android test application in which i log the accelerometer,magnetometer and the orientation data to an external file while also displaying it. I initiate the logging process on click of a Start button (registerListener for relevant sensors) by calling a method initLogger.

Which looks something similar to this...

public void initLogger(View view)
{
    boolean bFlag = false;

    Button btnStart = (Button)findViewById(R.id.btnStartLog);
    Button btnStop = (Button)findViewById(R.id.btnStopLog);

    btnStart.setEnabled(bFlag);
    btnStop.setEnabled(!bFlag);

    bEnableLogging = true;
    //Start reading the sensor values
    sensorManager.registerListener(this, sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD), SensorManager.SENSOR_DELAY_UI);
    sensorManager.registerListener(this, sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_UI);

   //so on.... 

There is also a Stop button, which shall stop the logging process (and finally unregister by calling unregisterListener for each sensor)

The data retrieval process happens inside the onSensorChanged handler which shall retrieve the data from the relevant sensors, sets the value to the respective UI elements and finally log the data to an external .csv file.

onSensorChanged eventhandler looks something like this ...

public void onSensorChanged(SensorEvent event) {


    // TODO Auto-generated method stub
    // accelerometer
    TextView tAX = (TextView) findViewById(R.id.txtViewAxValue);
    TextView tAY = (TextView) findViewById(R.id.txtViewAyValue);
    TextView tAZ = (TextView) findViewById(R.id.txtViewAzValue);

    // magnetic field
    TextView tMX = (TextView) findViewById(R.id.txtViewMx);
    TextView tMY = (TextView) findViewById(R.id.txtViewMy);