Getting Started to PIR sensor

Here's a complete guide and Arduino code for connecting a PIR (Passive Infrared) sensor to an LCD display using an Arduino, so that the LCD shows "Motion Detected" when motion is sensed.

May 1, 2025

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GPL3+

Home Automation

Security

Tracking

Devices & Components

Arduino Uno Rev3

Male/Male Jumper Wires

I2C LCD display

PIR Sensor

jumper wires male to female

Hardware & Tools

Breadboard, 830 Tie Points

Software & Tools

Arduino IDE

Project description

Code

PIR sensor code

1#include <Wire.h>
2#include <LiquidCrystal_I2C.h>
3
4// Create LCD object with I2C address 0x27, 16 columns, 2 rows
5LiquidCrystal_I2C lcd(0x27, 16, 2);
6
7// PIR sensor pin
8const int pirPin = 2;
9int pirState = LOW;
10
11void setup() {
12  pinMode(pirPin, INPUT);
13
14  // Initialize LCD with proper arguments
15  lcd.begin(16, 2, LCD_5x8DOTS);
16  lcd.backlight();
17  lcd.clear();
18  lcd.setCursor(0, 0);
19  lcd.print("PIR sensor Ready!");
20  delay(2000);
21  lcd.clear();
22}
23
24void loop() {
25  int motion = digitalRead(pirPin);
26
27  if (motion == HIGH) {
28    if (pirState == LOW) {
29      lcd.clear();
30      lcd.setCursor(0, 0);
31      lcd.print("Motion Detected");
32      pirState = HIGH;
33    }
34  } else {
35    if (pirState == HIGH) {
36      lcd.clear();
37      lcd.setCursor(0, 0);
38      lcd.print("Not Detected");
39      pirState = LOW;
40    }
41  }
42
43  delay(500);
44}

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

// Create LCD object with I2C address 0x27, 16 columns, 2 rows
LiquidCrystal_I2C lcd(0x27, 16, 2);

// PIR sensor pin
const int pirPin = 2;
int pirState = LOW;

void setup() {
  pinMode(pirPin, INPUT);

  // Initialize LCD with proper arguments
  lcd.begin(16, 2, LCD_5x8DOTS);
  lcd.backlight();
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("PIR sensor Ready!");
  delay(2000);
  lcd.clear();
}

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

  if (motion == HIGH) {
    if (pirState == LOW) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Motion Detected");
      pirState = HIGH;
    }
  } else {
    if (pirState == HIGH) {
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Not Detected");
      pirState = LOW;
    }
  }

  delay(500);
}

Downloadable files

This is the circuit diagram

Epic Hillar-Turing.png

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