Netduino has an accessible button and a blue LED onboard. This means that you can test code that uses a button or LED circuit without having to build an external one.

The onboard LED is availble via the Pins.ONBOARD_LED enumeration, and turns on briefly when power is turned on, as well as after booting to indicate the OS is operational and the program is ready to run.

The onboard Button is available via Pins.ONBOARD_BTN enumeration, and if not bound to either an InputPort or OutputPort, will reset the Netduino by default when pressed. To disable it, simple assign a port to it.

Note that the Netduino also has a white power LED indicating the board is powered. Boards that are network enabled, such as the N2+, N3 Ethernet, or N3 WiFi also have a network LED that lights up to indicate network traffic.

InputPort and OutputPort

Both the onboard LED and Button are accessible via an OutputPort or InputPort object. For instance, the following example illustrates turning the LED on when the Button is pressed.

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

namespace OnboardButtonAndLed
{
	public class Program
	{
		// An output port allows you to write (send a signal) to a pin
		static OutputPort _led = new OutputPort(Pins.ONBOARD_LED, false);
		// An input port reads the signal from a pin (Should be Pins.ONBOARD_BTN, but there is a bug)
		static InputPort _button = new InputPort((Cpu.Pin)0x15, false, Port.ResistorMode.Disabled);

		static bool _buttonPressed = false;

		public static void Main()
		{
			// turn the LED off initially
			_led.Write(false);

			// run forever
			while (true)
			{
				// set the onboard LED output to be the input of the button
				_led.Write(_button.Read());
			}

		}
	}
}

InterruptPorts

Just as with other digital inputs, the onboard Button can be wired up as an InterruptPort to raise an event when it is pressed. For more information, see the Digital IO guide.

See Also

InterruptPort API Reference