Remarks

Mpl3115a2
Status Status badge: working
Source code GitHub
Datasheet(s) GitHub
NuGet package NuGet Gallery for Mpl3115a2

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

readonly Mpl3115a2 sensor;

public MeadowApp()
{
    Console.WriteLine("Initializing...");

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

    var consumer = Mpl3115a2.CreateObserver(
        handler: result => 
        {
            Console.WriteLine($"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) => {
        Console.WriteLine($"  Temperature: {result.New.Temperature?.Celsius:N2}C");
        Console.WriteLine($"  Pressure: {result.New.Pressure?.Bar:N2}bar");
    };

    ReadConditions().Wait();

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

async Task ReadConditions()
{
    var conditions = await sensor.Read();
    Console.WriteLine($"Temperature: {conditions.Temperature?.Celsius}°C, Pressure: {conditions.Pressure?.Pascal}Pa");
}

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 ObservableBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>> SensorBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>> SamplingSensorBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>> ByteCommsSensorBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>> > Mpl3115a2
Implements IDisposable ITemperatureSensor IBarometricPressureSensor
Inherited Members ByteCommsSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Peripheral ByteCommsSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.ReadBuffer ByteCommsSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.WriteBuffer ByteCommsSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Init(Int32, Int32) ByteCommsSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Dispose(Boolean) ByteCommsSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Dispose() SamplingSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.StartUpdating(Nullable<TimeSpan>) SamplingSensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.StopUpdating() SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Updated SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.samplingLock SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.SamplingTokenSource SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Conditions SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.IsSampling SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.UpdateInterval SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.ReadSensor() SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.RaiseEventsAndNotify(IChangeResult<ValueTuple<Nullable<Units.Temperature>, Nullable<Pressure>>>) SensorBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.Read() ObservableBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.observers ObservableBase<(Nullable<Units.Temperature> Temperature, Nullable<Pressure> Pressure)>.NotifyObservers(IChangeResult<ValueTuple<Nullable<Units.Temperature>, Nullable<Pressure>>>) Meadow.Foundation.ObservableBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>>.Subscribe(IObserver<>) Meadow.Foundation.ObservableBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>>.CreateObserver(Action<>, System.Nullable<Predicate<Meadow.IChangeResult<UNIT>>>)
Namespace Meadow.Foundation.Sensors.Atmospheric
Assembly Mpl3115a2.dll

Syntax

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

Constructors

Mpl3115a2(II2cBus, Byte, Int32)

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

Declaration
public Mpl3115a2(II2cBus i2cBus, byte address = null, int updateIntervalMs = 1000)

Parameters

Type Name Description
II2cBus i2cBus

I2cBus (Maximum is 400 kHz).

System.Byte address

Address of the sensor (default = 0x60).

System.Int32 updateIntervalMs

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>>>

Overrides

Meadow.Foundation.SensorBase<System.ValueTuple<System.Nullable<Units.Temperature>, System.Nullable<Pressure>>>.ReadSensor()

Reset()

Reset the sensor.

Declaration
public void Reset()

Events

PressureUpdated

Declaration
public event EventHandler<IChangeResult<Pressure>> PressureUpdated

Event Type

Type Description
EventHandler<IChangeResult<Pressure>>

TemperatureUpdated

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

Event Type

Type Description
EventHandler<IChangeResult<Units.Temperature>>