In this project, learners explore how home security systems work using Arduino to keep people and property safe. They build a mini home security alarm that detects movement with a PIR sensor and triggers alerts using buzzers and LEDs. We have included extra challenges that encourage learners to experiment with alert types and sensitivity, making learning fun and hands-on. Through this experience, learners develop problem-solving skills, safety awareness, and confidence while discovering how sensors, logic, and alerts power real-world systems like burglar alarms, smart lights, and modern smart homes.

Here’s how different components connect:

PIR Motion Sensor

Sends a HIGH signal when movement is detected.

• VCC → connects to the 5V on the Arduino

• GND → connects to the GND on the Arduino

• OUT → connects to the digital Pin 2 on the Arduino.

Red LED

• Connect the long leg (positive/anode) of the LED to one end of the 220Ω resistor

• Connect the other end of the resistor to digital pin 9 on the Arduino.

• Connect the short leg (negative/cathode) of the LED to GND.

The Buzzer (Sound Alarm)

When motion is detected, the buzzer will sound Alarm

• Connect the positive (+) pin of the buzzer to digital pin 8 on the Arduino.

• Connect the negative (–) pin of the buzzer to GND on the Arduino

Open the Arduino IDE on your computer and type this code:

int pirPin = 2;
int ledPin = 9;
int buzzerPin = 8;

void setup() {
pinMode(pirPin, INPUT);
pinMode(ledPin, OUTPUT);
pinMode(buzzerPin, OUTPUT);
}

void loop() {
int motionDetected = digitalRead(pirPin);

if (motionDetected == HIGH) {
digitalWrite(ledPin, HIGH);
digitalWrite(buzzerPin, HIGH);
delay(3000); // Alarm duration
} else {
digitalWrite(ledPin, LOW);
digitalWrite(buzzerPin, LOW);
}
}

1. Connect your Arduino Uno to your computer using the USB cable
2. In the Arduino IDE, go to:

• Tools → Board → Arduino Uno
• Tools → Port → (Select your Arduino port)

3. Click the Upload button (the right arrow icon).
4. Watch your project come to life!

• Alarm always ON

  • Wait 30–60 seconds for PIR sensor calibration

  • Reduce sensor sensitivity

• No alarm when moving

  • Check PIR OUT pin connection

  • Ensure correct power supply

• LED not lighting

  • Check LED direction and resistor

• Buzzer too loud

  • Reduce alarm duration

• How motion sensors detect people

• How alarm systems work

• How Arduino uses conditions to make decisions

• The importance of home safety

• Basic electronics and coding skills

• Add a delay before alarm activates

• Add a button to arm/disarm the system

• Add multiple motion sensors

• Use WiFi to send alerts

• Create a cardboard house model