Class PwmLed

Remarks

PwmLed
Status
Source code	GitHub
NuGet package

*PwmLed represents an LED whose voltage (and brightness) is controlled by the duty-cycle of a PWM signal. It can be used both with Leds that have been current limited with in-series resistors, or Leds without resistors.

Controlling an LED via a PWM signal is more power efficient than using a current-limiting resistor. It also provides more control, allowing multiple grades of brightness.

To use PwmLed without a resistor, pass in the forward voltage (voltage drop) of the LED to the forwardVoltage constructor parameter, and the class will limit its output to the maximum forward voltage rating of the LED.

To use with an LED that has a resistor in series, pass 0.0 or TypicalForwardVoltage.ResistorLimited for the forwardVoltage parameter.

Code Example

PwmLedBarGraph pwmLedBarGraph;

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

    // Using an array of Pins that support PWM (D02 - D13)
    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
    };

    pwmLedBarGraph = new PwmLedBarGraph(pins, new Voltage(2.2));

    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 < pwmLedBarGraph.Count; i++)
        {
            await pwmLedBarGraph.SetLed(i, true);
            await Task.Delay(100);
            await pwmLedBarGraph.SetLed(i, false);
        }

        await Task.Delay(1000);

        Resolver.Log.Info("Turning them on using Percentage...");
        while (percentage < 1)
        {
            percentage += 0.01f;
            await pwmLedBarGraph.SetPercentage(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 -= 0.01f;
            await pwmLedBarGraph.SetPercentage(Math.Max(0.0f, percentage));
            await Task.Delay(100);
        }

        await Task.Delay(1000);

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

        await Task.Delay(1000);

        Resolver.Log.Info("Bar blinking with high and low brightness for 5 seconds...");
        await pwmLedBarGraph.StartBlink(TimeSpan.FromMilliseconds(200), TimeSpan.FromMilliseconds(200), 0.75f, 0.25f);
        await Task.Delay(5000);
        await pwmLedBarGraph.StopAnimation();

        await Task.Delay(1000);

        Resolver.Log.Info("Bar pulsing for 5 seconds...");
        await pwmLedBarGraph.StartPulse();
        await Task.Delay(5000);
        await pwmLedBarGraph.StopAnimation();

        await Task.Delay(1000);

        await pwmLedBarGraph.SetBrightness(0);

        await Task.Delay(1000);
    }
}

Characteristic	Locus
Inheritance	object > PwmLed
Implements	IPwmLed IDisposable
Inherited Members	object.Equals(object) object.Equals(object, object) object.GetHashCode() object.GetType() object.MemberwiseClone() object.ReferenceEquals(object, object) object.ToString()
Namespace	Meadow.Foundation.Leds
Assembly	Meadow.Foundation.dll

Type	Name	Description
IPin	pin	Pin
Voltage	forwardVoltage	Forward voltage
CircuitTerminationType	terminationType	Whether the other end of the LED is hooked to ground or High. Typically used for RGB Leds which can have either a common cathode, or common anode. But can also enable an LED to be reversed by inverting the PWM signal.

Type	Name	Description
IPwmPort	pwmPort	Port to control
Voltage	forwardVoltage	Forward voltage of led
CircuitTerminationType	terminationType	Termination type of LED

Type	Name	Description
float	highBrightness	The maximum brightness of the animation
float	lowBrightness	The minimum brightness of the animation

Type	Name	Description
TimeSpan	highBrightnessDuration	The duration the LED stays in high brightness
TimeSpan	lowBrightnessDuration	The duration the LED stays in low brightness
float	highBrightness	The maximum brightness of the animation
float	lowBrightness	The minimum brightness of the animation

Type	Name	Description
TimeSpan	pulseDuration	The pulse animation duration
float	highBrightness	The maximum brightness of the animation
float	lowBrightness	The minimum brightness of the animation

Remarks

Code Example

Wiring Example

Syntax

Constructors

PwmLed(IPin, Voltage, CircuitTerminationType)

Declaration

Parameters

Remarks

Code Example

Wiring Example

PwmLed(IPwmPort, Voltage, CircuitTerminationType)

Declaration

Parameters

Remarks

Code Example

Wiring Example

Properties

Brightness

Declaration

Property Value

Remarks

Code Example

Wiring Example

ForwardVoltage

Declaration

Property Value

Remarks

Code Example

Wiring Example

IsDisposed

Declaration

Property Value

Remarks

Code Example

Wiring Example

IsOn

Declaration

Property Value

Remarks

Code Example

Wiring Example

MAX_FORWARD_VOLTAGE

Declaration

Property Value

Remarks

Code Example

Wiring Example

MIN_FORWARD_VOLTAGE

Declaration

Property Value

Remarks

Code Example

Wiring Example

Port

Declaration

Property Value

Remarks

Code Example

Wiring Example

Methods

Dispose()

Declaration

Remarks

Code Example

Wiring Example

Dispose(bool)

Declaration

Parameters

Remarks

Code Example

Wiring Example

SetBrightness(float)

Declaration

Parameters

Remarks

Code Example

Wiring Example

StartBlink(float, float)