Meadow.Foundation.Sensors.Atmospheric.Bme280

Bme280
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The BME280 is a combined temperature, pressure and humidity sensor controlled via I2C or SPI.

Code Example

Bme280 sensor;

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

    //CreateSpiSensor();
    CreateI2CSensor();

    var consumer = Bme280.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.Old?.Humidity is { } oldHumidity &&
                result.New.Temperature is { } newTemp &&
                result.New.Humidity is { } newHumidity)
            {
                return
                (newTemp - oldTemp).Abs().Celsius > 0.5 &&
                (newHumidity - oldHumidity).Percent > 0.05;
            }
            return false;
        }
    );
    sensor.Subscribe(consumer);

    sensor.Updated += (sender, result) =>
    {
        try
        {
            Resolver.Log.Info($"  Temperature: {result.New.Temperature?.Celsius:N2}C");
            Resolver.Log.Info($"  Relative Humidity: {result.New.Humidity:N2}%");
            Resolver.Log.Info($"  Pressure: {result.New.Pressure?.Millibar:N2}mbar ({result.New.Pressure?.Pascal:N2}Pa)");
        }
        catch (Exception ex)
        {
            Resolver.Log.Error(ex, "Error reading sensor");
        }
    };

    return Task.CompletedTask;
}

public override async Task Run()
{
    var conditions = await sensor.Read();
    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($"  Temperature: {conditions.Temperature?.Celsius:N2}C");
    Resolver.Log.Info($"  Pressure: {conditions.Pressure?.Bar:N2}hPa");
    Resolver.Log.Info($"  Relative Humidity: {conditions.Humidity?.Percent:N2}%");

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

void CreateSpiSensor()
{
    Resolver.Log.Info("Create BME280 sensor with SPI...");

    var spi = Device.CreateSpiBus();
    sensor = new Bme280(spi, Device.Pins.D00.CreateDigitalOutputPort());
}

void CreateI2CSensor()
{
    Resolver.Log.Info("Create BME280 sensor with I2C...");

    var i2c = Device.CreateI2cBus();
    sensor = new Bme280(i2c, (byte)Bmx280.Addresses.Default); // SDA pulled up

}

Sample project(s) available on GitHub

Wiring Example

The BME280 can be connected using I2C or SPI. Only 4 wires are required when using I2C:

• 3.3V
• Ground
• SDA
• SCL

Class Bme280

BME280 Temperature, Pressure and Humidity Sensor

Assembly: Bme280.dll

View Source

Declaration

public class Bme280 : PollingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity, Pressure? Pressure)>, IObservable<IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity, Pressure? Pressure)>>, ISamplingSensor<(Temperature? Temperature, RelativeHumidity? Humidity, Pressure? Pressure)>, ISensor<(Temperature? Temperature, RelativeHumidity? Humidity, Pressure? Pressure)>, ITemperatureSensor, ISamplingSensor<Temperature>, ISensor<Temperature>, IHumiditySensor, ISamplingSensor<RelativeHumidity>, ISensor<RelativeHumidity>, IBarometricPressureSensor, ISamplingSensor<Pressure>, ISensor<Pressure>, ISensor, ISamplingSensor, ISpiPeripheral, II2cPeripheral, IDisposable

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

Implements:

Expand

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

Properties

IsDisposed

Is the object disposed

View Source

Declaration

public bool IsDisposed { get; }

TemperatureSampleCount

Temperature oversample count

View Source

Declaration

public Bme280.Oversample TemperatureSampleCount { get; set; }

PressureSampleCount

Pressure oversample count

View Source

Declaration

public Bme280.Oversample PressureSampleCount { get; set; }

HumiditySampleCount

Humidity oversample count

View Source

Declaration

public Bme280.Oversample HumiditySampleCount { get; set; }

Temperature

The temperature from the last reading

View Source

Declaration

public Temperature? Temperature { get; }

Pressure

The pressure, in hectopascals (hPa), from the last reading. 1 hPa is equal to one millibar, or 1/10th of a kilopascal (kPa)/centibar.

View Source

Declaration

public Pressure? Pressure { get; }

Humidity

The humidity, in percent relative humidity, from the last reading..

View Source

Declaration

public RelativeHumidity? Humidity { get; }

DefaultSpiBusSpeed

The default SPI bus speed for the device

View Source

Declaration

public Frequency DefaultSpiBusSpeed { get; }

SpiBusSpeed

The SPI bus speed for the device

View Source

Declaration

public Frequency SpiBusSpeed { get; set; }

DefaultSpiBusMode

The default SPI bus mode for the device

View Source

Declaration

public SpiClockConfiguration.Mode DefaultSpiBusMode { get; }

SpiBusMode

The SPI bus mode for the device

View Source

Declaration

public SpiClockConfiguration.Mode SpiBusMode { get; set; }

DefaultI2cAddress

The default I2C address for the peripheral

View Source

Declaration

public byte DefaultI2cAddress { get; }

Fields

readBuffer

The read buffer

View Source

Declaration

protected Memory<byte> readBuffer

writeBuffer

The write buffer

View Source

Declaration

protected Memory<byte> writeBuffer

configuration

Sensor configuration

View Source

Declaration

protected Bme280.Configuration configuration

Methods

Initialize()

Initialize the sensor

View Source

Declaration

protected void Initialize()

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

Raise events for subscribers and notify of value changes

View Source

Declaration

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

Parameters

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

ReadSensor()

Update the sensor information from the BME280.

View Source

Declaration

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

Returns

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

UpdateConfiguration(Configuration)

Update the configuration for the BME280.

View Source

Declaration

protected void UpdateConfiguration(Bme280.Configuration configuration)

Parameters

Type	Name
Meadow.Foundation.Sensors.Atmospheric.Bme280.Configuration	configuration

Reset()

Reset the sensor.

View Source

Declaration

public void Reset()

ReadCompensationData()

Reads the compensation data.

View Source

Declaration

protected void ReadCompensationData()

GetChipID()

Get the chip ID

View Source

Declaration

public byte GetChipID()

Returns

System.Byte

StartUpdating(TimeSpan?)

Start updating

View Source

Declaration

public override void StartUpdating(TimeSpan? updateInterval = null)

Parameters

Type	Name	Description
System.Nullable<System.TimeSpan>	updateInterval	The update inverval

Dispose()

Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.

View Source

Declaration

public void Dispose()

Dispose(bool)

Dispose of the object

View Source

Declaration

protected virtual void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing	Is disposing

Implements

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