PIR Sensor with Arduino Virtual Lab

Instructions

Objective:

Learn how a PIR motion sensor detects movement and triggers an LED output.

Steps to Perform:

Click "Start Simulation" to power up the Arduino circuit
Drag the person icon near the PIR sensor to trigger motion detection
Observe how the LED turns ON when motion is detected
Drag the person away to stop the motion
Watch the LED turn OFF when motion ends
Check the Serial Monitor for motion detection messages

Key Concepts:

PIR Sensor: Detects infrared radiation changes from moving objects
Detection Zone: Area where sensor can detect motion (shown in green)
Digital Input: Sensor provides HIGH (motion) or LOW (no motion) signal
Digital Output: Arduino controls LED based on sensor reading
digitalRead(): Reads motion sensor state from digital pin 2
digitalWrite(): Sets LED pin HIGH (ON) or LOW (OFF)

Arduino Code - sketch_pir_sensor.ino

                        /*
  PIR Motion Sensor
  Detects motion and blinks LED
*/

int ledPin = 13;                // choose the pin for the LED
int inputPin = 2;               // choose the input pin (for PIR sensor)
int pirState = LOW;             // we start, assuming no motion detected
int val = 0;                    // variable for reading the pin status

void setup() {
  pinMode(ledPin, OUTPUT);      // declare LED as output
  pinMode(inputPin, INPUT);     // declare sensor as input
  
  Serial.begin(9600);
}

void loop() {
  val = digitalRead(inputPin);  // read input value
  
  if (val == HIGH) {            // check if the input is HIGH
    digitalWrite(ledPin, HIGH); // turn LED ON
    
    if (pirState == LOW) {
      // we have just turned on
      Serial.println("Motion detected!");
      // We only want to print on the output change, not state
      pirState = HIGH;
    }
  } else {
    digitalWrite(ledPin, LOW); // turn LED OFF
    
    if (pirState == HIGH){
      // we have just turned off
      Serial.println("Motion ended!");
      // We only want to print on the output change, not state
      pirState = LOW;
    }
  }
}
                    