Parallax PIR

Motion detector.

Parallax PIR

The Parallax PIR detects motion by emitting a high signal when motion is detected. The signal returns to a low state when motion stops.


The parallax PIR sensor is available from Parallax Inc:


The Parallax PIR sensor requires only three connections, power, ground and motion detection signal:

Parallax PIR and Netduino


The following application creates a ParallaxPIR object and attaches interrupt handlers to the OnMotionStart and OnMotionEnd events:

using Microsoft.SPOT;
using Netduino.Foundation.Sensors.Motion;
using SecretLabs.NETMF.Hardware.NetduinoPlus;
using System.Threading;

namespace ParallaxPIRTest
    public class Program
        public static void Main()
            ParallaxPIR pir = new ParallaxPIR(Pins.GPIO_PIN_D8);

            pir.OnMotionStart += pir_OnMotionStart;
            pir.OnMotionEnd += pir_OnMotionEnd;

        static void pir_OnMotionEnd(object sender)
            Debug.Print("Motion stopped.");

        static void pir_OnMotionStart(object sender)
            Debug.Print("Motion detected.");



ParallaxPIR(Cpu.Pin interruptPin)

Create a new ParallaxPIR object with the sensor output connected to the interruptPin.


OnMotionStart and OnMotionEnd

These events are raised when motion is detected OnMotionStart and when it stops OnMotionEnd.