What is a PIR Sensor
How Does a PIR Sensor Work
HC-SR501 PIR Sensor Overview
Pinout
Specifications
Hardware Required
Circuit Connections
PIR Sensor to Arduino
The Output of Code
To learn more checkout complete article: PIR Sensor with Arduino
Project Demonstration

Published April 11, 2025 © Apache-2.0

How to Interface HC-SR501 PIR Sensor with Arduino

In this Arduino Tutorial, we will learn how to interface HC-SR501 PIR Sensor with the Arduino Board for detecting motion.

BeginnerFull instructions provided2 hours82

How to Interface HC-SR501 PIR Sensor with Arduino

Things used in this project

Hardware components

Arduino UNO R3

Alphanumeric LCD, 16 x 2

Rotary Potentiometer, 10 kohm

Resistor 220 ohm

PHPoC Bread Board

HC-SR501 PIR Sensor

Connective Wires

Software apps and online services

Arduino IDE

Story

Want to build a project that detects motion like a pro? Whether it's for home automation, intruder alerts, or automatic lighting, the HC-SR501 PIR Sensor is your go-to solution. In this Arduino Tutorial, we will learn how to interface HC-SR501 PIR Sensor with the Arduino Board for detecting motion.

What is a PIR Sensor?

PIR stands for Passive Infrared Sensor, also known as pyroelectric sensors. These detect motion by sensing infrared (IR) radiation — the kind emitted by humans and animals due to body heat.

Unlike ultrasonic or active IR sensors, PIR sensors don't emit signals; instead, they passively monitor the IR heat signature of their environment.

How Does a PIR Sensor Work?

Every object above absolute zero emits some infrared radiation. The pyroelectric sensor in a PIR module detects changes in this IR energy.

A PIR sensor has:

A Pyroelectric Sensor to detect IR changes
A Fresnel Lens to focus and expand its detection field

The sensor has two slots with opposing outputs. When there’s no motion, both sense equal IR and cancel out. But when someone moves in the field of view, the IR pattern changes — one slot detects more or less radiation than the other, resulting in a voltage differential — this change signals motion detected!

HC-SR501 PIR Sensor Overview

This is one of the most popular, beginner-friendly PIR sensors in the Arduino ecosystem.

Pinout:

VCC: Power (5V–20V)
OUT: Digital signal output (HIGH on motion)
GND: Ground

Specifications:

Operating Voltage: 5V–20V

Output Level: HIGH 3.3V / LOW 0V

Detection Distance: 3–7 meters

Detection Angle: < 110°

Time Delay: 3–300 seconds

Blocking Time: ~2.5 seconds

Trigger Mode: Single/Repeatable

Operating Temp: -15 to +70 °C

Hardware Required

Arduino UNO R3- 1

HC-SR501 PIR Sensor- 1

16x2 LCD Display- 1

10k Potentiometer- 1

220Ω Resistor- 1

Breadboard & Jumper Wires- As needed

Circuit Connections

The wiring diagram below shows just how simple it is to connect the PIR sensor to the Arduino. The sensor’s output pin is connected to digital pin 2 on the Arduino. Additionally, a 16×2 LCD display is used to visually indicate whether motion is detected or not, displaying messages like “Motion Detected” or “No Motion”.

PIR Sensor to Arduino:

VCC → 5V
GND → GND
OUT → Digital Pin 2

The Output of Code

To learn more checkout complete article: PIR Sensor with Arduino

Project Demonstration

Code

Arduino Code

/*
How to Interface HC-SR501 PIR Sensor with Arduino
by www.playwithcircuit.com 
*/
#include <LiquidCrystal.h> // We are using JHD 16x2 alphanumeric LCD using HD44780 controller for its controller
LiquidCrystal lcd(12, 11, 6,7,8,9);
int sensorInput = 2;   // Output for PIR sensor input for controller
int sersorReturn=0;
void setup() {
  pinMode(sensorInput, INPUT);   // declare sensor pin as input pin
  // set up the LCD's number of columns and rows:
  lcd.begin(16, 2);
  // set the cursor to (column = 0,row = 0)
  lcd.setCursor(0, 0); 
  lcd.print("PIR Sensor Says:"); 
  // set the cursor to (column = 0,row = 1)
  lcd.setCursor(0, 1);  
}
void loop() {
  sersorReturn = digitalRead(sensorInput);  // read input value
  
  if(sersorReturn == HIGH)
  {
    // set the cursor to (column = 0,row = 1)
    lcd.setCursor(0, 1); 
    lcd.print("Motion Occurs"); 
  }
  else
  {
    // set the cursor to (column = 0,row = 1)
    lcd.setCursor(0, 1); 
    lcd.print("Motion Stops "); 
  }
}

Credits

Rachana Jain

13 projects • 8 followers

I'm an avid Arduino and electronics enthusiast with a passion for tinkering, experimenting, and bringing innovative ideas to life.

How to Interface HC-SR501 PIR Sensor with Arduino