Arduino project · Fire, gas and safety · Medium
Intruder Alert with PIR and SMS
When motion is seen in an empty room, the siren sounds and an SMS is sent.
What you will learn
- How a PIR sensor detects motion
- How to build a simple security system
- Why GSM works when Wi-Fi is off
How it works
Motion sets off the buzzer and sends the ALERT SMS.
Try this next
- Add an arming switch.
- Add a keypad.
- Add a camera trigger.
The simulator program and explanation on this page are original. The idea follows a classic Arduino project that students have built for years.
Parts: sensors and actuators (tap to show or hide)
Try the inputs (virtual sensors)
Pins (you can change them)
| Part | Arduino 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.
| # | Colour | From (part and leg) | To |
|---|
Steps run from top to bottom, then start again. While the simulation runs, the active step is highlighted in green.
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.
| # | Item | Qty | Search term | Buy / compare |
|---|
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.
In the real world
An alarm that texts you
The motion sensor sees an intruder. The house alarm sounds and the Arduino sends an SMS to the owner's phone.
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.
- PIR sensor = a person inside the house
- GSM module = sends the text message
- Buzzer = the house alarm