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: