Introduction

Learn how to build a basic motion detector using a Passive Infrared (PIR) sensor. When motion is detected, the Arduino triggers an LED to light up as an alert.

Required Components

• PIR sensor (e.g., HC-SR501)
• Arduino board
• LED
• 220-ohm resistor
• Breadboard
• Jumper wires

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Wiring Diagram

Follow this wiring setup:

• PIR Sensor: VCC to 5V, GND to GND, OUT to digital pin 2.
• LED: Connect the positive leg to pin 13 via a 220-ohm resistor, and the negative leg to GND.

Arduino Code

#include 

const int pirPin = 2;    // PIR sensor output pin
const int ledPin = 13;   // LED pin

void setup() {
    pinMode(pirPin, INPUT);
    pinMode(ledPin, OUTPUT);
    Serial.begin(9600);
}

void loop() {
    int motion = digitalRead(pirPin);
    if (motion == HIGH) {
        digitalWrite(ledPin, HIGH);  // Turn on LED
        Serial.println("Motion detected!");
    } else {
        digitalWrite(ledPin, LOW);   // Turn off LED
    }
    delay(100);
}
            

Applications

• Home security systems
• Automated lighting
• Motion-activated alerts

Conclusion

By following this tutorial, you can use a PIR sensor to create motion detection systems for various projects. Try experimenting with adding sound or notifications!