This sample lights up an LED with a PWM signal so that a current limiting resistor isn’t needed to prevent the LED from burning out.

Code

using System;
using Microsoft.SPOT;
using SecretLabs.NETMF.Hardware;
using SecretLabs.NETMF.Hardware.Netduino;
using Microsoft.SPOT.Hardware;
using System.Threading;

namespace DrivingLED_w_PWM
{
    /// <summary>
    /// This program illustrates how to drive an LED with a Pulse-Width Modulation
    /// Signal.
    /// </summary>
    public class Program
    {
        public static void Main()
        {
            // Create a PWM signal on Pin 3 @ 1000Hz and a 50% duty cycle
            PWM dutyCyclePwm = new PWM(PWMChannels.PWM_PIN_D3, 1000, .5, false);
            // note that only certain pins support PWM. the PWMChannels enumeration
            // lists the ones that do.

            // Create a PWM signal on the onboard LED by specifying the period and duration 
            // in milliseconds. this will be a 33% duty cycle (on 1/3rd of the time)
            PWM periodDurationPwm = new PWM (PWMChannels.PWM_ONBOARD_LED, 
                3, 1, PWM.ScaleFactor.Milliseconds, false);

            // alternate between the 50% duty cycle and the 33% duty cycle every second
            while (true)
            {
                dutyCyclePwm.Start ();
                Thread.Sleep (1000);
                dutyCyclePwm.Stop ();

                periodDurationPwm.Start ();
                Thread.Sleep (1000);
                periodDurationPwm.Stop ();
            }
        }
    }
}

Netduino Samples Github Repository

Full source code for all of the samples can be found in the Netduino Samples repository on Github.