Remarks

Led
Status
Source code	GitHub
NuGet package

An LED is a diode (a component that attempts to let current flow only one way through it) that emits light when voltage is applied to it. Because it is a diode, it only works when a voltage is applied in one direction.

LEDs commonly have one lead longer (the Cathode) than the other (the Anode). The longer cathode leg indicates that it should be connected to the positive (+) side of a circuit.

Code Example

LedBarGraph ledBarGraph;

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

    // Using an array of Pins 
    IPin[] pins =
    {
         Device.Pins.D11,
         Device.Pins.D10,
         Device.Pins.D09,
         Device.Pins.D08,
         Device.Pins.D07,
         Device.Pins.D06,
         Device.Pins.D05,
         Device.Pins.D04,
         Device.Pins.D03,
         Device.Pins.D02
    };

    ledBarGraph = new LedBarGraph(pins);

    return Task.CompletedTask;
}

public override async Task Run()
{
    Resolver.Log.Info("TestLedBarGraph...");

    float percentage = 0;

    while (true)
    {
        Resolver.Log.Info("Turning them on and off for 200ms using SetLed...");
        for (int i = 0; i < ledBarGraph.Count; i++)
        {
            ledBarGraph.SetLed(i, true);
            await Task.Delay(100);
            ledBarGraph.SetLed(i, false);
        }

        await Task.Delay(1000);

        Resolver.Log.Info("Turning them on using Percentage...");
        while (percentage < 1)
        {
            percentage += 0.10f;
            Resolver.Log.Info($"{percentage}");
            ledBarGraph.Percentage = Math.Min(1.0f, percentage);
            await Task.Delay(100);
        }

        await Task.Delay(1000);

        Resolver.Log.Info("Turning them off using Percentage...");
        while (percentage > 0)
        {
            percentage -= 0.10f;
            Resolver.Log.Info($"{percentage}");
            ledBarGraph.Percentage = Math.Max(0.0f, percentage);
            await Task.Delay(100);
        }

        await Task.Delay(1000);

        Resolver.Log.Info("Charging animation...");
        while (percentage < 1)
        {
            percentage += 0.10f;
            Resolver.Log.Info($"{percentage}");
            ledBarGraph.Percentage = Math.Min(1.0f, percentage);
            ledBarGraph.StartBlink(ledBarGraph.GetTopLedForPercentage());
            await Task.Delay(2000);
        }

        await Task.Delay(1000);

        Resolver.Log.Info("Discharging animation...");
        while (percentage > 0)
        {
            percentage -= 0.10f;
            Resolver.Log.Info($"{percentage}");
            ledBarGraph.Percentage = Math.Max(0.0f, percentage);
            ledBarGraph.StartBlink(ledBarGraph.GetTopLedForPercentage());
            await Task.Delay(2000);
        }

        await Task.Delay(1000);

        Resolver.Log.Info("Blinking for 5 seconds at 500ms on/off...");
        ledBarGraph.StartBlink();
        await Task.Delay(5000);
        ledBarGraph.Stop();

        await Task.Delay(1000);

        Resolver.Log.Info("Blinking for 5 seconds at 200ms on/off...");
        ledBarGraph.StartBlink(TimeSpan.FromMilliseconds(200), TimeSpan.FromMilliseconds(200));
        await Task.Delay(5000);
        ledBarGraph.Stop();

        await Task.Delay(1000);
    }
}

Sample project(s) available on GitHub

Wiring Example

<img src="../../API_Assets/Meadow.Foundation.Leds.Led/Led_Fritzing.svg"

Characteristic	Locus
Inheritance	System.Object > Led
Namespace	Meadow.Foundation.Leds
Assembly	Meadow.Foundation.dll

Syntax

public class Led : ILed

Constructors

Led(IDigitalOutputPort)

Creates a LED through a DigitalOutPutPort from an IO Expander

Declaration

public Led(IDigitalOutputPort port)

Parameters

Type	Name	Description
IDigitalOutputPort	port

Led(IPin)

Creates a LED through a pin directly from the Digital IO of the board

Declaration

public Led(IPin pin)

Parameters

Type	Name	Description
IPin	pin

Properties

IsOn

Gets or sets a value indicating whether this Led is on.

Declaration

public bool IsOn { get; set; }

Property Value

Type	Description
System.Boolean	true if is on; otherwise, false.

Port

Gets the port that is driving the LED

Declaration

protected IDigitalOutputPort Port { get; set; }

Property Value

Type	Description
IDigitalOutputPort	The port

Methods

StartBlink()

Blink animation that turns the LED on (500ms) and off (500ms)

Declaration

public void StartBlink()

StartBlink(TimeSpan, TimeSpan)

Blink animation that turns the LED on and off based on the OnDuration and offDuration values in ms

Declaration

public void StartBlink(TimeSpan onDuration, TimeSpan offDuration)

Parameters

Type	Name	Description
TimeSpan	onDuration
TimeSpan	offDuration

StartBlinkAsync(TimeSpan, TimeSpan, CancellationToken)

Set LED to blink

Declaration

protected Task StartBlinkAsync(TimeSpan onDuration, TimeSpan offDuration, CancellationToken cancellationToken)

Parameters

Type	Name	Description
TimeSpan	onDuration	on duration in ms
TimeSpan	offDuration	off duration in ms
CancellationToken	cancellationToken	cancellation token used to cancel blink

Returns

Type	Description
Task

Stop()

Stops the LED when its blinking and/or turns it off.

Declaration

public void Stop()