Meadow.Foundation.Sensors.Temperature.AnalogTemperature

AnalogTemperature
Status
Source code	GitHub
NuGet package

The analog temperature sensor driver can be used with any sensor that has a linear voltage response. It has been tested with the following series of temperature sensors:

• TMP35
• TMP36
• TMP37
• LM35

These sensors exhibit a linear change in the analog voltage for each degree centigrade. This is often presented in the datasheet as follows:

This driver should work with any sensor of this type.

Code Example

AnalogTemperature analogTemperature;

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

    // configure our AnalogTemperature sensor
    analogTemperature = new AnalogTemperature(
        analogPin: Device.Pins.A03,
        sensorType: AnalogTemperature.KnownSensorType.LM35
    );

    //==== IObservable Pattern with an optional notification filter.
    var consumer = AnalogTemperature.CreateObserver(
        handler: result => Resolver.Log.Info($"Observer filter satisfied: {result.New.Celsius:N2}C, old: {result.Old?.Celsius:N2}C"),

        // only notify if the change is greater than 0.5°C
        filter: result =>
        {
            if (result.Old is { } old)
            {
                return (result.New - old).Abs().Celsius > 0.5; // returns true if > 0.5°C change.
            }
            return false;
        }
        // if you want to always get notified, pass null for the filter:
        //filter: null
    );
    analogTemperature.Subscribe(consumer);

    // classical .NET events can also be used:
    analogTemperature.TemperatureUpdated += (sender, result) =>
    {
        Resolver.Log.Info($"Temp Changed, temp: {result.New.Celsius:N2}C, old: {result.Old?.Celsius:N2}C");
    };

    //==== One-off reading use case/pattern
    ReadTemp().Wait();

    // Spin up the sampling thread so that events are raised and IObservable notifications are sent.
    analogTemperature.StartUpdating(TimeSpan.FromMilliseconds(1000));

    return Task.CompletedTask;
}

protected async Task ReadTemp()
{
    var temperature = await analogTemperature.Read();
    Resolver.Log.Info($"Initial temp: {temperature.Celsius:N2}C");
}

Sample project(s) available on GitHub

Wiring Example

To wire a TMP36 to your Meadow board, connect the following:

TMP36	Meadow Pin
GND	GND
IN	A1
VCC	5V

It should look like the following diagram:

Class AnalogTemperature

Provide the ability to read the temperature from the following sensors:

• TMP35 / 36 / 37
• LM35 / 45

Assembly: Meadow.Foundation.dll

View Source

Declaration

public class AnalogTemperature : SamplingSensorBase<Temperature>, IObservable<IChangeResult<Temperature>>, ITemperatureSensor, ISamplingSensor<Temperature>, ISensor<Temperature>, ISensor, ISamplingSensor, IDisposable

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

Implements:
System.IObservable<Meadow.IChangeResult<Meadow.Units.Temperature>>, Meadow.Peripherals.Sensors.ITemperatureSensor, Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Temperature>, Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Temperature>, Meadow.Peripherals.Sensors.ISensor, Meadow.Peripherals.Sensors.ISamplingSensor, System.IDisposable

Properties

AnalogInputPort

View Source

Declaration

protected IAnalogInputPort AnalogInputPort { get; }

SensorCalibration

View Source

Declaration

public AnalogTemperature.Calibration SensorCalibration { get; set; }

Temperature

Current Temperature

View Source

Declaration

public Temperature? Temperature { get; protected set; }

IsDisposed

Is the object disposed

View Source

Declaration

public bool IsDisposed { get; }

Methods

ReadSensor()

Convenience method to get the current temperature. For frequent reads, use StartSampling() and StopSampling() in conjunction with the SampleBuffer.

View Source

Declaration

protected override Task<Temperature> ReadSensor()

Returns

System.Threading.Tasks.Task<Meadow.Units.Temperature>: The temperature averages of the given sample count### StartUpdating(TimeSpan?) Starts continuously sampling the sensor.

This method also starts raising Changed events and IObservable subscribers getting notified. Use the readIntervalDuration parameter to specify how often events and notifications are raised/sent.

View Source

Declaration

public override void StartUpdating(TimeSpan? updateInterval)

Parameters

Type	Name	Description
System.Nullable<System.TimeSpan>	updateInterval	A TimeSpan that specifies how long to

 wait between readings. This value influences how often `*Updated`
 events are raised and `IObservable` consumers are notified. |

StopUpdating()

Stops sampling the temperature

View Source

Declaration

public override void StopUpdating()

VoltageToTemperature(Voltage)

Converts voltage to Temperature

View Source

Declaration

protected Temperature VoltageToTemperature(Voltage voltage)

Returns

Meadow.Units.Temperature: Temperature

Parameters

Type	Name
Meadow.Units.Voltage	voltage

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<Meadow.Units.Temperature>>
• Meadow.Peripherals.Sensors.ITemperatureSensor
• Meadow.Peripherals.Sensors.ISamplingSensor<Meadow.Units.Temperature>
• Meadow.Peripherals.Sensors.ISensor<Meadow.Units.Temperature>
• Meadow.Peripherals.Sensors.ISensor
• Meadow.Peripherals.Sensors.ISamplingSensor
• System.IDisposable