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