Remarks

RgbPwmLed
Status
Source code	GitHub
NuGet package

RgbPwmLed represents an RGB LED whose color is controlled by the duty-cycle of three PWM signals. Can be used both with LEDs that have been current limited with in-series resistors, or LEDs without resistors.

Controlling an RGB LED via a PWM signal is more power efficient than using a current-limiting resistor, and it provides more control; allowing thousands of different colors, as opposed to the 8 colors of non-PWM powered RGB LED.

To use without resistors, pass in the forward voltages (voltage drop) of each of the LED components to the redLedForwardVoltage, greenLedForwardVoltage, and blueLedForwardVoltage, constructor parameters, and the class will limit its output to the maximum forward voltage rating for those LEDs.

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

Example Code

The following example code loops through the entire 360º of hue spectrum and displays that color on the RGB LED.

public MeadowApp : App<F7Micro, MeadowApp>
{
    public MeadowApp()
    {
        // create a new RgbPwmLed on pin 8
        var pwmLed = new RgbPwmLed(
            redPin: Device.Pins.D11,
            greenPin: Device.Pins.D10,
            bluePin: Device.Pins.D09,
            redLedForwardVoltage: 1.05f,
            greenLedForwardVoltage: 1.5f,
            blueLedForwardVoltage: 1.5f);
        );

        // alternate between blinking and pulsing the LED 
        while (true)
        {
            for (int i = 0; i < 360; i++)
            {
                var hue = ((double)i / 360F);
                Debug.Print(hue.ToString());

                // set the color of the RGB
                rgbPwmLed.SetColor(Color.FromHsba(((double)i / 360F), 1, 1));

                // for a fun, fast rotation through the hue spectrum:
                //Thread.Sleep (1);
                // for a gentle walk through the forest of colors;
                Thread.Sleep(18);
            }
        }
    }
}

Sample projects available on GitHub

Wiring Example

Characteristic	Locus
Inheritance	System.Object > RgbPwmLed
Inherited Members	System.Object.ToString() System.Object.Equals(System.Object) System.Object.Equals(System.Object, System.Object) System.Object.ReferenceEquals(System.Object, System.Object) System.Object.GetHashCode() System.Object.GetType() System.Object.MemberwiseClone()
Namespace	Meadow.Foundation.Leds
Assembly	Meadow.Foundation.dll

Syntax

public class RgbPwmLed

Constructors

RgbPwmLed(IIODevice, IPin, IPin, IPin, Single, Single, Single, CommonType)

Instantiates a RgbPwmLed object with the especified IO device, connected to three digital pins for red, green and blue channels, respectively

Declaration

public RgbPwmLed(IIODevice device, IPin redPwmPin, IPin greenPwmPin, IPin bluePwmPin, float redLedForwardVoltage = 3.3F, float greenLedForwardVoltage = 3.3F, float blueLedForwardVoltage = 3.3F, CommonType commonType = null)

Parameters

Type	Name	Description
IIODevice	device
IPin	redPwmPin
IPin	greenPwmPin
IPin	bluePwmPin
System.Single	redLedForwardVoltage
System.Single	greenLedForwardVoltage
System.Single	blueLedForwardVoltage
CommonType	commonType

RgbPwmLed(IPwmPort, IPwmPort, IPwmPort, Single, Single, Single, CommonType)

Implementation notes: Architecturally, it would be much cleaner to construct this class as three PwmLeds. Then each one's implementation would be self-contained. However, that would require three additional threads during ON; one contained by each PwmLed. For this reason, I'm basically duplicating the functionality for all three in here.

Declaration

public RgbPwmLed(IPwmPort redPwm, IPwmPort greenPwm, IPwmPort bluePwm, float redLedForwardVoltage = 3.3F, float greenLedForwardVoltage = 3.3F, float blueLedForwardVoltage = 3.3F, CommonType commonType = null)

Parameters

Type	Name	Description
IPwmPort	redPwm
IPwmPort	greenPwm
IPwmPort	bluePwm
System.Single	redLedForwardVoltage
System.Single	greenLedForwardVoltage
System.Single	blueLedForwardVoltage
CommonType	commonType

Fields

_animationTask

Declaration

protected Task _animationTask

Field Value

Type	Description
System.Threading.Tasks.Task

cancellationTokenSource

Declaration

protected CancellationTokenSource cancellationTokenSource

Field Value

Type	Description
System.Threading.CancellationTokenSource

isEnabled

Declaration

protected bool isEnabled

Field Value

Type	Description
System.Boolean

maxBlueDutyCycle

Declaration

protected double maxBlueDutyCycle

Field Value

Type	Description
System.Double

maxGreenDutyCycle

Declaration

protected double maxGreenDutyCycle

Field Value

Type	Description
System.Double

maxRedDutyCycle

Declaration

protected double maxRedDutyCycle

Field Value

Type	Description
System.Double

Properties

BlueForwardVoltage

Get the blue LED forward voltage

Declaration

public float BlueForwardVoltage { get; protected set; }

Property Value

Type	Description
System.Single

BluePwm

Get the blue LED port

Declaration

public IPwmPort BluePwm { get; protected set; }

Property Value

Type	Description
IPwmPort

Color

The color the LED has been set to.

Declaration

public Color Color { get; }

Property Value

Type	Description
Color

Common

Is the LED using a common cathode

Declaration

public CommonType Common { get; protected set; }

Property Value

Type	Description
CommonType

GreenForwardVoltage

Get the green LED forward voltage

Declaration

public float GreenForwardVoltage { get; protected set; }

Property Value

Type	Description
System.Single

GreenPwm

Get the green LED port

Declaration

public IPwmPort GreenPwm { get; protected set; }

Property Value

Type	Description
IPwmPort

IsEnabled

Enables / disables the LED but toggling the PWM

TODO: What's the use case for enabling? maybe this should just be State, which would return whether or not it's running.

Declaration

public bool IsEnabled { get; set; }

Property Value

Type	Description
System.Boolean

RedForwardVoltage

Get the red LED forward voltage

Declaration

public float RedForwardVoltage { get; protected set; }

Property Value

Type	Description
System.Single

RedPwm

Get the red LED port

Declaration

public IPwmPort RedPwm { get; protected set; }

Property Value

Type	Description
IPwmPort

Methods

ResetPwms()

Resets all PWM ports

Declaration

protected void ResetPwms()

SetColor(Color)

Sets the current color of the LED.

Declaration

public void SetColor(Color ledColor)

Parameters

Type	Name	Description
Color	ledColor

SetColor(Color, Single)

Declaration

protected void SetColor(Color color, float brightness)

Parameters

Type	Name	Description
Color	color
System.Single	brightness

StartBlink(Color, UInt32, UInt32, Single, Single)

Start the Blink animation which sets the brightness of the LED alternating between a low and high brightness setting, using the durations provided.

Declaration

public void StartBlink(Color color, uint onDuration = 200U, uint offDuration = 200U, float highBrightness = 1F, float lowBrightness = 0F)

Parameters

Type	Name	Description
Color	color
System.UInt32	onDuration
System.UInt32	offDuration
System.Single	highBrightness
System.Single	lowBrightness

StartBlinkAsync(Color, UInt32, UInt32, Single, Single, CancellationToken)

Declaration

protected Task StartBlinkAsync(Color color, uint onDuration, uint offDuration, float highBrightness, float lowBrightness, CancellationToken cancellationToken)

Parameters

Type	Name	Description
Color	color
System.UInt32	onDuration
System.UInt32	offDuration
System.Single	highBrightness
System.Single	lowBrightness
System.Threading.CancellationToken	cancellationToken

Returns

Type	Description
System.Threading.Tasks.Task

StartPulse(Color, UInt32, Single, Single)

Start the Pulse animation which gradually alternates the brightness of the LED between a low and high brightness setting, using the durations provided.

Declaration

public void StartPulse(Color color, uint pulseDuration = 600U, float highBrightness = 1F, float lowBrightness = 0.15F)

Parameters

Type	Name	Description
Color	color
System.UInt32	pulseDuration
System.Single	highBrightness
System.Single	lowBrightness

StartPulseAsync(Color, UInt32, Single, Single, CancellationToken)

Declaration

protected Task StartPulseAsync(Color color, uint pulseDuration, float highBrightness, float lowBrightness, CancellationToken cancellationToken)

Parameters

Type	Name	Description
Color	color
System.UInt32	pulseDuration
System.Single	highBrightness
System.Single	lowBrightness
System.Threading.CancellationToken	cancellationToken

Returns

Type	Description
System.Threading.Tasks.Task

Stop()

Stops any running animations.

Declaration

public void Stop()