Meadow.Foundation.Sensors.Atmospheric.Bmp085

Bmp085
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The BMP085 is a high-precision, low-power barometric pressure sensor. The BMP085 offers a measuring range of 300 to 1100 hPa with an absolute accuracy of down to 0.03 hPa. It's based on piezo-resistive technology for EMC robustness, high accuracy and linearity as well as long term stability. This sensor supports a voltage supply between 1.8 and 3.6VDC. It is designed to be connected directly to a micro-controller via the I2C bus.

Code Example

Bmp085? sensor;

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

    sensor = new Bmp085(Device.CreateI2cBus());

    var consumer = Bmp085.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 =>
        {
            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

Wiring Example

To wire a BMP085 to your Meadow board, connect the following:

BMP085	Meadow Pin
GND	GND
SCL	D08 (SCL)
SDA	D07 (SDA)
VCC	3V3

It should look like the following diagram:

Class Bmp085

Bosch BMP085 digital pressure and temperature sensor

Assembly: Bmp085.dll

View Source

Declaration

public class Bmp085 : ByteCommsSensorBase<(Temperature? Temperature, Pressure? Pressure)>, IObservable<IChangeResult<(Temperature? Temperature, Pressure? Pressure)>>, ISamplingSensor<(Temperature? Temperature, Pressure? Pressure)>, ISensor<(Temperature? Temperature, Pressure? Pressure)>, IDisposable, ITemperatureSensor, ISamplingSensor<Temperature>, ISensor<Temperature>, IBarometricPressureSensor, ISamplingSensor<Pressure>, ISensor<Pressure>, ISensor, ISamplingSensor, II2cPeripheral

Inheritance: System.Object -> Meadow.Foundation.ObservableBase<UNIT>

Implements:

Expand

System.IObservable<Meadow.IChangeResult<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>>, Meadow.Peripherals.Sensors.ISamplingSensor<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>, Meadow.Peripherals.Sensors.ISensor<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>, System.IDisposable, Meadow.Peripherals.Sensors.ITemperatureSensor, Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Temperature>, Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Temperature>, Meadow.Peripherals.Sensors.Atmospheric.IBarometricPressureSensor, Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Pressure>, Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Pressure>, Meadow.Peripherals.Sensors.ISensor, Meadow.Peripherals.Sensors.ISamplingSensor, Meadow.Hardware.II2cPeripheral

Properties

DefaultI2cAddress

The default I2C address for the peripheral

View Source

Declaration

public byte DefaultI2cAddress { get; }

Temperature

Last value read from the Pressure sensor

View Source

Declaration

public Temperature? Temperature { get; }

Pressure

Last value read from the Pressure sensor

View Source

Declaration

public Pressure? Pressure { get; }

Methods

RaiseEventsAndNotify(IChangeResult<(Temperature? Temperature, Pressure? Pressure)>)

Raise events for subscribers and notify of value changes

View Source

Declaration

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

Parameters

Type	Name	Description
Meadow.IChangeResult<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>	changeResult	The updated sensor data

ReadSensor()

Calculates the compensated pressure and temperature

View Source

Declaration

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

Returns

System.Threading.Tasks.Task<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>

Implements

• System.IObservable<Meadow.IChangeResult<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>>
• Meadow.Peripherals.Sensors.ISamplingSensor<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>
• Meadow.Peripherals.Sensors.ISensor<System.ValueTuple<System.Nullable<Meadow.Units.Temperature>,System.Nullable<Meadow.Units.Pressure>>>
• System.IDisposable
• Meadow.Peripherals.Sensors.ITemperatureSensor
• Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Temperature>
• Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Temperature>
• Meadow.Peripherals.Sensors.Atmospheric.IBarometricPressureSensor
• Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Pressure>
• Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Pressure>
• Meadow.Peripherals.Sensors.ISensor
• Meadow.Peripherals.Sensors.ISamplingSensor
• Meadow.Hardware.II2cPeripheral