HC-SR501 PIR Motion Sensor module

HC-SR501 PIR Motion Sensor module Overview

The HC-SR501 PIR Motion Sensor module is a compact, low-power passive infrared motion detector ideal for security, lighting control, occupancy sensing, and smart home automation. It senses changes in infrared radiation from moving objects and provides a digital output signal that is easy to interface with microcontrollers like Arduino, Raspberry Pi, ESP8266 and ESP32.

Key Features

• Passive Infrared (PIR) technology for reliable motion detection.
• Onboard potentiometers to adjust sensitivity and delay time for flexible behavior in different environments.
• Detection range adjustable up to approximately 7 meters and roughly 120 degree cone angle.
• Digital output (HIGH/LOW) compatible with TTL logic and microcontroller inputs.
• Wide operating voltage range (4.5V to 20V DC) and low idle current for battery applications.
• Compact dimensions (about 32mm x 24mm) for easy integration into projects and enclosures.

Specifications

• Sensor Technology: Passive Infrared (PIR)
• Operating Voltage: 4.5V to 20V DC
• Current Consumption: <50 μA in idle mode, <60 mA in active mode
• Detection Range: Adjustable up to approx. 7 meters (environment dependent)
• Detection Angle: Approx. 120 degree cone
• Output Type: Digital signal (HIGH or LOW)
• Dimensions: Approximately 32mm x 24mm
• Weight: Lightweight

Applications

• Security systems and intruder detection
• Automatic lighting and energy-saving lighting control
• Occupancy sensing for HVAC or power management
• Smart home automation and presence-triggered events
• Robotics and interactive exhibits requiring motion input

Integration and Wiring

The HC-SR501 provides a simple interface: VCC, GND and OUT. Typical wiring examples:

• To Arduino: VCC to 5V, GND to GND, OUT to a digital input pin (use INPUT_PULLUP or external pull-down depending on configuration).
• To Raspberry Pi: VCC to 5V or 3.3V depending on board compatibility, GND to GND, OUT to a GPIO input (confirm voltage tolerance before connecting to 3.3V GPIO).
• To ESP8266/ESP32: Use level-compatible voltage or a level shifter to protect the microcontroller if module is powered at higher voltages.

Example Code Snippet for Arduino

• Connect OUT to digital pin 2, then read digitalRead(2) to detect HIGH when motion is detected.
• Use the delay potentiometer to set how long the output stays HIGH after motion stops.

Tips for Best Performance

• Mount the sensor at 1.8 to 2.5 meters for typical room coverage and reliable detection.
• Avoid pointing the sensor at heat sources or direct sunlight which can cause false triggers.
• Adjust sensitivity for the environment to reduce false positives from small animals or HVAC airflow.
• Test and tune delay time to match the intended application – short for quick retriggers, longer to hold state for lighting control.

Why Choose the HC-SR501 PIR Motion Sensor module

With adjustable sensitivity and delay settings, low power consumption, and a compact form factor, the HC-SR501 is a versatile and affordable motion sensing solution for hobbyists and professionals. It simplifies integration into alarm systems, lighting controllers, and smart home projects while providing dependable motion detection performance.