Door / Window Sensors

Difficulty Level

Introduction

A door contact sensor is the most common type of sensor in a home security system. Knowing if and when a door was opened will be your best indicator if somebody was in your house when you were away.

Contact Sensor Types

There are two main types of door/window contact sensors: recessed or surface mounted. Recessed contact sensors are your best option if you can get a wire to them as it is more difficult to tamper with them. However if you don't have a wire run into your door/window trim, a surface mounted option will work just fine.

Recessed Contact Switch

Surface Mount Contact Switch

Wiring Diagrams

The hookup for a door or window sensor only takes two wires. One wire goes to GND and the other goes to any GPIO pin on your board.

Note: It doesn't matter which wire you connect to ground (GND). They can be interchanged and will work the same.

• Main Board
• Expansion Board

• Black wire: Connected to GND (ground)
• Orange wire: Connected to any available GPIO pin

• Black wire: Connected to GND (ground)
• Orange wire: Connected to any available digital pin

Note

In this example, the main system board (Raspberry Pi) is connected to an expansion board (Arduino Mega) via I2C. See our tutorial on Expanion Boards for more details.

Finished Result

Below is a simple setup example of a door contact sensor connected to a Raspberry Pi on GPIO-23.