.. highlight:: java

BMP280 Barometer
================

The `Bmp280Barometer <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Bmp280Barometer.html>`_ class is an extension of the Barometer class that interacts specifically with the BMP280 chip, the sensor on the MetaWear R Pro board.

Sensor Configuration
--------------------

Sensor configuration is handled with a `Bmp280Barometer.ConfigEditor <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Bmp280Barometer.ConfigEditor.html>`_.  The sensor has three paremeters to set: filter mode, pressure oversampling, and standby time.

::

    import com.mbientlab.metawear.module.Bmp280Barometer;
    import com.mbientlab.metawear.module.Bmp280Barometer.*;
    
    Bmp280Barometer bmp280Module= mwBoard.getModule(Bmp280Barometer.class);
    
    // Set filter coefficient to 4 for IIR filter
    // Set oversampling mode to low power
    // Set standby time to 125ms
    bmp280Module.configure()
        .setFilterMode(FilterMode.AVG_4)
        .setPressureOversampling(OversamplingMode.LOW_POWER)
        .setStandbyTime(StandbyTime.TIME_125)
        .commit();

Pressure Sampling
-----------------

To `start <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Barometer.html#start()>`_ pressure sampling, call the `start <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Barometer.html#start()>`_ method, and conversely, to `stop <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Barometer.html#stop()>`_ sampling, call `stop <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Barometer.html#stop()>`_.  Data is interpreted as a float and reported as pascals (Pa).

::

    import com.mbientlab.metawear.module.Bmp280Barometer;
    
    final Bmp280Barometer bmp280Module= mwBoard.getModule(Bmp280Barometer.class);
    bmp280Module.routeData().fromPressure().stream("pressure_stream").commit()
        .onComplete(new CompletionHandler<RouteManager>() {
            @Override
            public void success(RouteManager result) {
                result.subscribe("pressure_stream", new RouteManager.MessageHandler() {
                    @Override
                    public void process(Message msg) {
                        Log.i("MainActivity", String.format("Pressure= %.3fPa", 
                                msg.getData(Float.class)));
                    }
                });
                bmp280Module.start();
            }
        });

Altitude Sampling
-----------------

Altitude can be computed by using the pressure data from the sensor.  To enable altitude calculations along with pressure sampling, call `enableAltitudeSampling <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Bmp280Barometer.html#enableAltitudeSampling()>`_ method, and conversely, to disable altitude calculations, call `disableAltitudeSampling <https://mbientlab.com/docs/metawear/android/2/com/mbientlab/metawear/module/Bmp280Barometer.html#disableAltitudeSampling()>`_.  Data is interpreted as a float and reported in meters (m).

::

    import com.mbientlab.metawear.module.Bmp280Barometer;
    
    final Bmp280Barometer bmp280Module= mwBoard.getModule(Bmp280Barometer.class);
    bmp280Module.routeData().fromAltitude().stream("altitude_stream").commit()
        .onComplete(new CompletionHandler<RouteManager>() {
            @Override
            public void success(RouteManager result) {
                result.subscribe("altitude_stream", new RouteManager.MessageHandler() {
                    @Override
                    public void process(Message msg) {
                        Log.i("MainActivity", String.format("Altitude= %.3fm", 
                                msg.getData(Float.class)));
                    }
                });
                bmp280Module.enableAltitudeSampling();
                bmp280Module.start();
            }
        });