Remarks

Dht12
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The DHT12 is a low-cost humidity and temperature sensor that communicates over the I2C bus. It measures humidity from 20 to 95% with an accuracy of +/- 5% relative humidity with a resolution of 0.1%. Temperature range is from -20 to 60 degrees celcius with an accuracy of +/- 0.5 degrees and a resolution of 0.1.

Code Example

Dht12? sensor;

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

    sensor = new Dht12(Device.CreateI2cBus());

    var consumer = Dht12.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 += (object sender, IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)> e) =>
    {
        Resolver.Log.Info($"  Temperature: {e.New.Temperature?.Celsius:N2}C");
        Resolver.Log.Info($"  Relative Humidity: {e.New.Humidity:N2}%");
    };

    return Task.CompletedTask;
}

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

    var conditions = await sensor.Read();
    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($"  Temperature: {conditions.Temperature?.Celsius:N2}C");
    Resolver.Log.Info($"  Relative Humidity: {conditions.Humidity?.Percent:N2}%");

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

Sample project(s) available on GitHub

Wiring Example

To wire a DHT12 to your Meadow board, connect the following:

DHT12	Meadow Pin
GND	GND
VCC	3V3
SCL	D08 (SCL Pin)
SDA	D07 (SDA Pin)

Characteristic	Locus
Inheritance	object ObservableBase<(Temperature? Temperature, RelativeHumidity? Humidity)> SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)> PollingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)> ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)> DhtBase > Dht12
Implements	IObservable<IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>> ISamplingSensor<(Temperature? Temperature, RelativeHumidity? Humidity)> ISensor<(Temperature? Temperature, RelativeHumidity? Humidity)> IDisposable ITemperatureSensor ISamplingSensor<Temperature> ISensor<Temperature> IHumiditySensor ISamplingSensor<RelativeHumidity> ISensor<RelativeHumidity> II2cPeripheral
Inherited Members	DhtBase.TemperatureUpdated DhtBase.HumidityUpdated DhtBase.Temperature DhtBase.Humidity DhtBase.WasLastReadSuccessful DhtBase.RaiseEventsAndNotify(IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>) DhtBase.ReadSensor() ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.BusComms ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.ReadBuffer ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.WriteBuffer ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Init(int, int) ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Dispose(bool) ByteCommsSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Dispose() PollingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.StartUpdating(TimeSpan?) PollingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.StopUpdating() SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.samplingLock SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Updated SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.SamplingTokenSource SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Conditions SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.IsSampling SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.UpdateInterval SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.ReadSensor() SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.RaiseEventsAndNotify(IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>) SamplingSensorBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Read() ObservableBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.observers ObservableBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.NotifyObservers(IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>) ObservableBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.Subscribe(IObserver<IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>>) ObservableBase<(Temperature? Temperature, RelativeHumidity? Humidity)>.CreateObserver(Action<IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>>, Predicate<IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>>) object.Equals(object) object.Equals(object, object) object.GetHashCode() object.GetType() object.MemberwiseClone() object.ReferenceEquals(object, object) object.ToString()
Namespace	Meadow.Foundation.Sensors.Atmospheric
Assembly	Dhtxx.dll

Syntax

public class Dht12 : DhtBase, IObservable<IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)>>, ISamplingSensor<(Temperature? Temperature, RelativeHumidity? Humidity)>, ISensor<(Temperature? Temperature, RelativeHumidity? Humidity)>, IDisposable, ITemperatureSensor, ISamplingSensor<Temperature>, ISensor<Temperature>, IHumiditySensor, ISamplingSensor<RelativeHumidity>, ISensor<RelativeHumidity>, II2cPeripheral

Constructors

Dht12(II2cBus, byte)

Create a new Dht12 object

Declaration

public Dht12(II2cBus i2cBus, byte address = 92)

Parameters

Type	Name	Description
II2cBus	i2cBus	I2C bus (default = 100 KHz)
byte	address	Address of the Dht12 (default = 0x27)

Remarks

Dht12
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The DHT12 is a low-cost humidity and temperature sensor that communicates over the I2C bus. It measures humidity from 20 to 95% with an accuracy of +/- 5% relative humidity with a resolution of 0.1%. Temperature range is from -20 to 60 degrees celcius with an accuracy of +/- 0.5 degrees and a resolution of 0.1.

Code Example

Dht12? sensor;

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

    sensor = new Dht12(Device.CreateI2cBus());

    var consumer = Dht12.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 += (object sender, IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)> e) =>
    {
        Resolver.Log.Info($"  Temperature: {e.New.Temperature?.Celsius:N2}C");
        Resolver.Log.Info($"  Relative Humidity: {e.New.Humidity:N2}%");
    };

    return Task.CompletedTask;
}

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

    var conditions = await sensor.Read();
    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($"  Temperature: {conditions.Temperature?.Celsius:N2}C");
    Resolver.Log.Info($"  Relative Humidity: {conditions.Humidity?.Percent:N2}%");

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

Sample project(s) available on GitHub

Wiring Example

To wire a DHT12 to your Meadow board, connect the following:

DHT12	Meadow Pin
GND	GND
VCC	3V3
SCL	D08 (SCL Pin)
SDA	D07 (SDA Pin)

Properties

DefaultI2cAddress

The default I2C address for the peripheral

Declaration

public byte DefaultI2cAddress { get; }

Property Value

Type	Description
byte

Remarks

Dht12
Status
Source code	GitHub
Datasheet(s)	GitHub
NuGet package

The DHT12 is a low-cost humidity and temperature sensor that communicates over the I2C bus. It measures humidity from 20 to 95% with an accuracy of +/- 5% relative humidity with a resolution of 0.1%. Temperature range is from -20 to 60 degrees celcius with an accuracy of +/- 0.5 degrees and a resolution of 0.1.

Code Example

Dht12? sensor;

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

    sensor = new Dht12(Device.CreateI2cBus());

    var consumer = Dht12.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 += (object sender, IChangeResult<(Temperature? Temperature, RelativeHumidity? Humidity)> e) =>
    {
        Resolver.Log.Info($"  Temperature: {e.New.Temperature?.Celsius:N2}C");
        Resolver.Log.Info($"  Relative Humidity: {e.New.Humidity:N2}%");
    };

    return Task.CompletedTask;
}

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

    var conditions = await sensor.Read();
    Resolver.Log.Info("Initial Readings:");
    Resolver.Log.Info($"  Temperature: {conditions.Temperature?.Celsius:N2}C");
    Resolver.Log.Info($"  Relative Humidity: {conditions.Humidity?.Percent:N2}%");

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

Sample project(s) available on GitHub

Wiring Example

To wire a DHT12 to your Meadow board, connect the following:

DHT12	Meadow Pin
GND	GND
VCC	3V3
SCL	D08 (SCL Pin)
SDA	D07 (SDA Pin)