Just messing around with my new FEZ Domino board and I thought I’d post up a quick tutorial on how to use a motion sensor with your board. First thing you will want to understand is interrupt ports. An interrupt port is a port that is listening and waiting for something to happen. For instance voltage levels going up or going down. In this tutorial I use a motion sensor that I got from parallax here. This is a very basic sensor that has voltage tolerance of 3-5v and has one pin that outputs high or low voltage levels. High means its sensed motion. The next part of this project involves a small speaker that outputs a tone to let you know its sensed motion. Nothing loud or anything but just for demonstration purpose. You can get the driver for the tone generation here: http://www.tinyclr.com/downloads/Component/FEZ_Components_Piezo.cs. So here’s the code:

#region motion sensor
            Thread.Sleep(30000);
 
            tone = new FEZ_Components.Piezo(FEZ_Pin.PWM.Di5);
            InterruptPort motion = new InterruptPort((Cpu.Pin)FEZ_Pin.Interrupt.Di1, false, Port.ResistorMode.Disabled, Port.InterruptMode.InterruptEdgeHigh);
            motion.OnInterrupt += new NativeEventHandler(motion_OnInterrupt);
 
            Thread.Sleep(-1);
#endregion
 
 
static void motion_OnInterrupt(uint data1, uint data2, DateTime time)
        {
            tone.Play(400, 1000);
        }

To see more about how to hook the hardware up check out the video:

There needs to be about a thirty second ‘warm up’ time as the sensor gets to know its surroundings and after that the sensor will be ready to be connected to the interrupt port. The interrupt port will listen for the voltage levels to go up and when they do it will play the tone.