Led

Single color LED.

Info

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 one way. For this reason, LEDs usually have one lead longer (the Cathode) than the other (the Anode). The cathode (longer leg) indicates that it should be hooked to the positive (+) side of a circuit.

Contrary to the PwmLed that you can pass in the forward voltage (voltage drop) of the led to limit its current, to use Led it is required to limit the current to the LED using resistors.

Example

The following example shows how to turn on and off the LED using the IsOn property, and uses a StartBlink(onDuration, offDuration) API method to make the LED blink staying on for 500ms (0.5s) and off for 1000ms (1s):

Code

using System.Threading;
using N = SecretLabs.NETMF.Hardware.Netduino;

namespace LedSample
{
    public class Program
    {
        public static void Main()
        {
            // create a new Led on pin 8
            var led = new Netduino.Foundation.LEDs.Led(N.Pins.GPIO_PIN_D8);

            while(true)
            {
                led.IsOn = true;    // Led ON
                Thread.Sleep(3000); // 3 seconds
                led.IsOn = false;   // Led OFF
                Thread.Sleep(2000); // 2 seconds
                led.IsOn = true;    // Led ON
                Thread.Sleep(1000); // 1 second

                led.StartBlink(500, 1000);
                Thread.Sleep(5000); // 5 seconds
                led.Stop();
            }
        }
    }
}

Circuit

API Reference

Constructors

public Led(Microsoft.SPOT.Hardware.Cpu.Pin pin)

Creates a new Led on the specified pin connected directly to a Netduino.

public Led(IDigitalOutputPort port)

Creates a new Led on the specified pin connected through an IOExpander such as a MCP23008 or a 74HC595 shift register.

Properties

public bool IsOn { get; protected set; }

Returns the value of the LED of whether its on or not.

public IDigitalOutputPort DigitalOut { get; protected set; }

Returns the value of the Led port its connected to.

Methods

public void StartBlink(uint onDuration = 200, uint offDuration = 200)

Start the Blink animation which switches the LED on and off, using the durations provided.

public void Stop()

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