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HC-SR501 PIR Motion Sensor Module

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Ekostra Electronics

On April 7, 2025

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HC-SR501 PIR Motion Sensor Module

Passive Infrared Detection for Security and Automation Projects

Introduction

The HC-SR501 PIR Motion Sensor is a pyroelectric infrared sensor that detects movement by measuring changes in infrared radiation. Widely used in security systems, automatic lighting, and energy-saving applications, this module offers adjustable sensitivity and detection range.

Key Features

👁️ Human Detection

Detects movement of humans and animals (body heat)

🔄 Adjustable Settings

Sensitivity and delay time can be customized

⚡ Low Power

Consumes minimal current in operation

🔧 Easy Integration

Works with 5V systems like Arduino and Raspberry Pi

Technical Specifications

Detection Range	3-7 meters (adjustable)
Detection Angle	≤120°
Output Type	Digital (High/Low)
Operating Voltage	4.5V – 20V DC (5V recommended)
Current Consumption	<60μA (standby), 1mA (active)
Output Duration	5-300 seconds (adjustable)
Operating Temperature	-15°C to +70°C

Pin Configuration

Pin	Label	Description	Arduino Connection
1	VCC	Power (5V recommended)	5V
2	OUT	Digital Output (High when motion detected)	D2
3	GND	Ground	GND

Note: The module has two potentiometers for adjusting sensitivity and delay time

Wiring with Arduino

// Basic Connections:
// VCC → 5V
// GND → GND
// OUT → D2 (digital input)

// For best results, mount sensor 2-3 meters above ground

// Basic Connections:

// VCC → 5V

// GND → GND

// OUT → D2 (digital input)

// For best results, mount sensor 2-3 meters above ground

Important: Allow 30-60 seconds for sensor to stabilize after power on

Basic Detection Example

// HC-SR501 PIR Motion Sensor Basic Example
const int pirPin = 2; // OUT pin connected to D2

void setup() {
  Serial.begin(9600);
  pinMode(pirPin, INPUT);
  Serial.println("PIR Sensor Initializing...");
  delay(60000); // 60s initialization period
  Serial.println("Sensor Ready");
}

void loop() {
  if(digitalRead(pirPin) {
    Serial.println("Motion detected!");
    delay(1000); // Prevent multiple detections
  }
}

// HC-SR501 PIR Motion Sensor Basic Example

const int pirPin = 2; // OUT pin connected to D2

void setup() {

Serial.begin(9600);

pinMode(pirPin, INPUT);

Serial.println("PIR Sensor Initializing...");

delay(60000); // 60s initialization period

Serial.println("Sensor Ready");

}

void loop() {

if(digitalRead(pirPin) {

Serial.println("Motion detected!");

delay(1000); // Prevent multiple detections

}

Advanced Features

Adjusting Sensitivity

The sensitivity potentiometer (Sx) controls detection range (clockwise increases range)

Setting Delay Time

The time delay potentiometer (Tx) controls how long output stays high after detection (clockwise increases delay)

Trigger Mode Selection

Jumper setting allows single trigger (L) or repeatable trigger (H) modes

Low Power Monitoring

// Low-power monitoring with interrupt
void setup() {
  attachInterrupt(digitalPinToInterrupt(2), motionDetected, RISING);
  set_sleep_mode(SLEEP_MODE_PWR_DOWN);
}

void motionDetected() {
  // Wake up and handle motion
}