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Motion Sensor (PIR) | NexaLearn IoT Lab | NexaLearn

Safety Sensors20 دقيقة

Motion Sensor (PIR)

Detecting people's movement to build an alarm or smart lighting system.

Lesson Content

A Passive Infrared (PIR) sensor measures changes in infrared heat from warm objects in its field. When a person moves within its view, the sensor sends a HIGH signal to the Arduino's digital pin. The sensor usually has two potentiometers to adjust detection range and how long the HIGH signal stays active.

Components Needed

Arduino UnoHC-SR501 PIR Sensor

Wiring Notes

VCC to 5V, GND to GND, and the middle signal pin to a digital pin like 2.

Code Example

const int pirPin = 2;
const int ledPin = 13;
void setup() {
  pinMode(pirPin, INPUT);
  pinMode(ledPin, OUTPUT);
  Serial.begin(9600);
  Serial.println("Calibrating PIR...");
  delay(30000); // يحتاج 30 ثانية ليتكيف مع حرارة الغرفة
}
void loop() {
  if (digitalRead(pirPin) == HIGH) {
    digitalWrite(ledPin, HIGH);
    Serial.println("Motion Detected!");
  } else {
    digitalWrite(ledPin, LOW);
  }
}

Common Mistakes

Testing the sensor immediately after powering Arduino. The sensor needs a warm-up time of 30 to 60 seconds to recognize the room environment before it stabilizes.

Next Lesson

Sound Alarm (Buzzer)