How to Use PIR motion sensor: Examples, Pinouts, and Specs

Introduction

A Passive Infrared (PIR) motion sensor detects motion by measuring changes in infrared radiation, typically emitted by warm bodies. It is a low-cost, low-power device widely used in motion detection applications. PIR sensors are commonly found in security systems, automatic lighting, and energy-saving devices. They are ideal for detecting human or animal movement within a specific range.

Explore Projects Built with PIR motion sensor

Use Cirkit Designer to design, explore, and prototype these projects online. Some projects support real-time simulation. Click "Open Project" to start designing instantly!

Arduino UNO Motion Detector with PIR Sensor and LED Indicator

This circuit is a motion detection system using an Arduino UNO, a PIR sensor, and an LED. The PIR sensor detects motion and sends a signal to the Arduino, which then turns on the LED to indicate motion has been detected.

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PIR Motion-Activated LED Light

This circuit is a simple motion-activated LED light system. The HC-SR505 Mini PIR Motion Sensing Module is powered by a 9V battery and detects motion, upon which it sends an output signal to turn on the red LED. The LED and the PIR sensor share a common ground with the battery, completing the circuit.

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Battery-Powered Motion-Activated LED Light with PIR Sensor

This circuit uses a PIR motion sensor to detect movement and subsequently light up a red LED. The PIR sensor is powered by a 9V battery, and its output is connected to the LED through a 10k Ohm resistor to limit the current.

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Arduino UNO with PIR Sensor and Bluetooth Connectivity

This circuit features an Arduino UNO connected to a PIR (Passive Infrared) sensor and an HC-05 Bluetooth module. The PIR sensor detects motion and sends a signal to the Arduino, which then communicates via Bluetooth using the HC-05 module. The embedded code on the Arduino is configured to send a specific message over serial when motion is detected by the PIR sensor.

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Technical Specifications

• Operating Voltage: 4.5V to 20V DC (commonly 5V or 12V)
• Current Consumption: < 60 µA
• Detection Range: 3 to 7 meters (adjustable on some models)
• Detection Angle: ~120° (varies by model)
• Output Signal: Digital (High: 3.3V or 5V, Low: 0V)
• Warm-up Time: ~30 seconds after power-up
• Trigger Modes:
  • Non-retriggering (single pulse)
  • Retriggering (continuous output while motion is detected)

Pin Configuration and Descriptions

Usage Instructions

How to Use the PIR Motion Sensor in a Circuit

1. Power the Sensor: Connect the VCC pin to a 5V or 12V power source and the GND pin to the ground.
2. Connect the Output: Attach the OUT pin to a microcontroller's digital input pin or directly to a device (e.g., an LED or buzzer) for simple applications.
3. Adjust Sensitivity and Delay (if applicable):
   • Use the onboard potentiometers to adjust the detection range and the delay time for the output signal.
4. Wait for Warm-up: Allow the sensor to stabilize for ~30 seconds after powering it on.

Important Considerations and Best Practices

• Avoid Direct Sunlight: PIR sensors are sensitive to infrared radiation, so avoid placing them in direct sunlight or near heat sources.
• Minimize Noise: Ensure the sensor is not exposed to electrical noise or vibrations that could cause false triggers.
• Mounting Height: Install the sensor at an appropriate height (e.g., 2-3 meters) for optimal detection.
• Trigger Modes: Configure the sensor's jumper to select between retriggering and non-retriggering modes based on your application.

Example: Connecting a PIR Sensor to an Arduino UNO

Below is an example of how to connect and use a PIR motion sensor with an Arduino UNO to control an LED.

Circuit Connections

• PIR Sensor:
  • VCC → 5V on Arduino
  • GND → GND on Arduino
  • OUT → Digital Pin 2 on Arduino
• LED:
  • Positive leg → Digital Pin 13 on Arduino (with a 220Ω resistor in series)
  • Negative leg → GND on Arduino

Arduino Code

// PIR Motion Sensor with Arduino Example
// This code turns on an LED when motion is detected by the PIR sensor.

#define PIR_PIN 2       // Define the pin connected to the PIR sensor's OUT pin
#define LED_PIN 13      // Define the pin connected to the LED

void setup() {
  pinMode(PIR_PIN, INPUT);  // Set PIR sensor pin as input
  pinMode(LED_PIN, OUTPUT); // Set LED pin as output
  Serial.begin(9600);       // Initialize serial communication for debugging
}

void loop() {
  int motionDetected = digitalRead(PIR_PIN); // Read the PIR sensor output

  if (motionDetected == HIGH) { // If motion is detected
    digitalWrite(LED_PIN, HIGH); // Turn on the LED
    Serial.println("Motion detected!"); // Print message to serial monitor
  } else {
    digitalWrite(LED_PIN, LOW);  // Turn off the LED
    Serial.println("No motion."); // Print message to serial monitor
  }

  delay(100); // Small delay to stabilize readings
}

Troubleshooting and FAQs

Common Issues

1. False Triggers:

   • Cause: Electrical noise, vibrations, or heat sources near the sensor.
   • Solution: Relocate the sensor to a stable environment away from heat sources and vibrations.

2. No Detection:

   • Cause: Incorrect wiring or insufficient power supply.
   • Solution: Double-check the wiring and ensure the power supply matches the sensor's requirements.

3. Output Signal Stuck High/Low:

   • Cause: Sensor not warmed up or faulty.
   • Solution: Wait for the warm-up period (~30 seconds) or replace the sensor if it remains unresponsive.

FAQs

• Q: Can the detection range be adjusted?

  • A: Yes, many PIR sensors have a potentiometer to adjust the detection range.

• Q: How long does the output signal stay high after motion is detected?

  • A: The duration is adjustable using the delay potentiometer, typically ranging from 5 seconds to 5 minutes.

• Q: Can I use a PIR sensor outdoors?

  • A: Yes, but ensure it is housed in a weatherproof enclosure to protect it from moisture and extreme temperatures.

• Q: What is the difference between retriggering and non-retriggering modes?

  • A: In retriggering mode, the output remains high as long as motion is continuously detected. In non-retriggering mode, the output goes low after the set delay time, even if motion is still present.