Fareed Mohmed← All projects

Arduino project · Motion and security · Easy

Anti-Theft Alarm with Arming Switch

Switch the alarm ON and the PIR sensor guards the room. Movement sounds the buzzer and lights the red LED. With the switch OFF nothing happens.

What you will learn

  • How an arming switch works
  • How to combine two conditions with a later override
  • How home alarms avoid false alarms when you are home

How it works

Steps 1 and 2 raise the alarm when the PIR sees movement. Steps 3 and 4 cancel it whenever the switch is OFF.

Try this next

  • Add an entry delay.
  • Add a keypad code to disarm.
  • Send an SMS with a GSM module.

The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.

1Choose your Arduino board
2Build the circuit
Parts: sensors and actuators (tap to show or hide)

Try the inputs (virtual sensors)

Pins (you can change them)

PartArduino pin (change it here)How to wire it

Every wire, one by one

Red rail = 5 V from the Arduino 5V pin. Black rail = GND. The coloured wires carry signals. Match the wire colours on the drawing to this list.

#ColourFrom (part and leg)To
3Define the sequence

Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.

4Arduino code





5Parts list and where to buy


Quantities come from the parts you added. The store links open a search for that item on Robu.in, Amazon.in and ThinkRobotics, so you always see what is in stock today. Check the model, voltage and price before you order.


#ItemQtySearch termBuy / compare



6Export








The PDF has the circuit sketch, pin table, every wire, sequence, full code, the parts list with store links, do’s and don’ts for each part, and the safety notes. The project file lets you come back and keep editing.



7Learn: do’s, don’ts, cautions and tips





In the real world
A room with a burglar alarm
Switch the motion sensor on in the simulator. A person walks into the real room and the alarm bell rings with a flashing beacon.
Tip: use the gold tab at the bottom of the circuit drawing to pull the real-world view up over the Arduino board. Your parts stay visible above it, so you can press a button and watch the real scene react.