.. highlight:: java

Barometer
=========
Select MbientLab boards are equipped with Bosch environmental sensors, either the 
`BMP280 <https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf>`_ or the 
`BME280 <https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf>`_.  These devices measure absolute barometeric pressure 
and can also measure :doc:`temperature <temperature>`.  

For pressuring sensing both devices have similar configuration parameters with the exception of slightly different available standby times.  Developer's 
can use either the `IBarometerBmp280 <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Sensor_1_1IBarometerBmp280.html>`_ or 
`IBarometerBme280 <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Sensor_1_1IBarometerBme280.html>`_ subclasses to configure the 
device with their respective standby enum values, or use the 
`IBarometerBosch <http://mbientlab.com/docs/metawear/csharp/1/interfaceMbientLab_1_1MetaWear_1_1Sensor_1_1IBarometerBosch.html>`_ base class for barometer agnostic apps.  

::

    using MbientLab.MetaWear.Sensor;

    IBarometerBosch baroBosch = metawear.GetModule<IBarometerBosch>();

Configuration
-------------
There are 3 parameters working in conjunction to control the noise, output resolution, and sampling rate:

* Oversampling  
* Infinite impulse filter (iir) coefficient  
* Standby time

The datasheets for the `BMP280 <https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-12.pdf>`_ (table 14 and 15) and 
`BME280 <https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BME280_DS001-11.pdf>`_ (section 5.5) have recommended settings for 
different use cases.

::

    using MbientLab.MetaWear.Sensor.BarometerBosch;

    // configure the barometer with suggested values for 
    // indoor navigation
    barometer.Configure(os = Oversampling.UltraHigh, coeff: IirFilerCoeff._16, standbyTime: 0.5f);

Pressure Data
-------------
Pressure data reported by the firmware is in Pascals (pa) and interpreted as a float value by the app side.

::

    await barometer.Pressure.AddRouteAsync(source => 
        source.Stream(data => Console.WriteLine("Pressure (Pa) = " + data.Value<float>()))
    );

Altitude Data
-------------
Altitude data reported by the firmware is in meters (m) and interpreted as a float value by the app side.

::

    await barometer.Altitude.AddRouteAsync(source => 
        source.Stream(data => Console.WriteLine("Altitude (m) = " + data.Value<float>()))
    );