Class Mpl3115a2 | Meadow.Foundation API website

Remarks

Mpl3115a2
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The MPL3115A2 is a barometric pressure sensor capable of reading both temperature and temperature compensated pressure reading. This sensor includes the following features:

I2C digital interface
24-bit ADC
Altitude and pressure measurements
Temperature sensor

Sample projects available on GitHub

Purchasing

The MPL3115A2 is available on breakout boards and a weather shield:

Code Example

Mpl3115a2? sensor;

public override Task Initialize()
{
    Resolver.Log.Info("Initializing...");

    sensor = new Mpl3115a2(Device.CreateI2cBus());

    var consumer = Mpl3115a2.CreateObserver(
        handler: result =>
        {
            Resolver.Log.Info($"Observer: Temp changed by threshold; new temp: {result.New.Temperature?.Celsius:N2}C, old: {result.Old?.Temperature?.Celsius:N2}C");
        },
        filter: result =>
        {
            //c# 8 pattern match syntax. checks for !null and assigns var.
            if (result.Old?.Temperature is { } oldTemp &&
                result.New.Temperature is { } newTemp)
            {
                return (newTemp - oldTemp).Abs().Celsius > 0.5; // returns true if > 0.5°C change.
            }
            return false;
        }
    );
    sensor.Subscribe(consumer);

    sensor.Updated += (sender, result) => {
        Resolver.Log.Info($"  Temperature: {result.New.Temperature?.Celsius:N2}C");
        Resolver.Log.Info($"  Pressure: {result.New.Pressure?.Bar:N2}bar");
    };

    return Task.CompletedTask;
}

public override async Task Run()
{
    if(sensor == null) { return; }

    var conditions = await sensor.Read();
    Resolver.Log.Info($"Temperature: {conditions.Temperature?.Celsius}°C, Pressure: {conditions.Pressure?.Pascal}Pa");

    sensor.StartUpdating(TimeSpan.FromSeconds(1));
}

Sample project(s) available on GitHub

Interrupt Mode

The application below connects the MPL3115A2 to two interrupt handlers. These interrupt handlers (events) will display the Temperature and Pressure properties when the handlers are triggered. The sensor is checked every 100 milliseconds (the default for the updatePeriod).

public class MeadowApp : App<F7Micro, MeadowApp>
{
    public MeadowApp()
    {
        Console.WriteLine("MPL3115A2 Interrupt Example");
        var mpl3115a2 = new MPL3115A2(temperatureChangeNotificationThreshold: 0.1F);
        mpl3115a2.TemperatureChanged += (s, e) =>
        {
            Console.WriteLine("Temperature: " + mpl3115a2.Temperature.ToString("f2"));
        };
        mpl3115a2.PressureChanged += (s, e) =>
        {
            Console.WriteLine("Pressure: " + mpl3115a2.Pressure.ToString("f2")); 
        };
        Thread.Sleep(Timeout.Infinite);
    }
}

Polling Mode

The following application reads the temperature and pressure every second and displays the result on the debug console:

public class MeadowApp : App<F7Micro, MeadowApp>
{
    public MeadowApp()
    {
        Console.WriteLine("MPL3115A2 Polling Example");
        var mpl3115a2 = new MPL3115A2(updateInterval: 0);
        while (true)
        {
            mpl3115a2.Update();
            Console.WriteLine("Temperature: " + mpl3115a2.Temperature.ToString("f2") + ", Pressure: " + mpl3115a2.Pressure.ToString("f2"));
            Thread.Sleep(1000);
        }
    }
}

Wiring Example

MPL3115A2 configured for polling more data reads:

Characteristic	Locus
Inheritance	System.Object > Mpl3115a2
Implements	ITemperatureSensor IBarometricPressureSensor
Namespace	Meadow.Foundation.Sensors.Atmospheric
Assembly	Mpl3115a2.dll

Syntax

public class Mpl3115a2 : ByteCommsSensorBase<(Units.Temperature? Temperature, Pressure? Pressure)>, ITemperatureSensor, IBarometricPressureSensor

Constructors

Mpl3115a2(II2cBus, Byte)

Create a new MPL3115A2 object with the default address and speed settings

Declaration

public Mpl3115a2(II2cBus i2cBus, byte address = null)

Parameters

Type	Name	Description
II2cBus	i2cBus	I2cBus (Maximum is 400 kHz)
System.Byte	address	Address of the sensor (default = 0x60)

Properties

Pressure

The pressure, from the last reading.

Declaration

public Pressure? Pressure { get; }

Property Value

Type	Description
System.Nullable<Pressure>

Standby

Check if the part is in standby mode or change the standby mode.

Declaration

public bool Standby { get; set; }

Property Value

Type	Description
System.Boolean

Remarks

Changes the SBYB bit in Control register 1 to put the device to sleep or to allow measurements to be made.

Status

Get the status register from the sensor

Declaration

public byte Status { get; }

Property Value

Type	Description
System.Byte

Temperature

The temperature, from the last reading.

Declaration

public Units.Temperature? Temperature { get; }

Property Value

Type	Description
System.Nullable<Units.Temperature>

Methods

RaiseEventsAndNotify(IChangeResult<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>)

Inheritance-safe way to raise events and notify observers.

Declaration

protected override void RaiseEventsAndNotify(IChangeResult<(Units.Temperature? Temperature, Pressure? Pressure)> changeResult)

Parameters

Type	Name	Description
IChangeResult<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>>	changeResult

ReadSensor()

Update the temperature and pressure from the sensor and set the Pressure property.

Declaration

protected override Task<(Units.Temperature? Temperature, Pressure? Pressure)> ReadSensor()

Returns

Type	Description
Task<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>>

Reset()

Reset the sensor

Declaration

public void Reset()

Events

PressureUpdated

Event raised when pressure value changes

Declaration

public event EventHandler<IChangeResult<Pressure>> PressureUpdated

Event Type

Type	Description
EventHandler<IChangeResult<Pressure>>

TemperatureUpdated

Event raised when temperature value changes

Declaration

public event EventHandler<IChangeResult<Units.Temperature>> TemperatureUpdated

Event Type

Type	Description
EventHandler<IChangeResult<Units.Temperature>>