Product Description

The HC-SR501 PIR Motion Sensor Module is a popular passive infrared motion detector for microcontroller and automation applications. It uses a pyroelectric sensing element to detect changes in infrared radiation within its field of view.

When a moving warm object, such as a person, crosses the sensing area, the module switches its OUT pin to a digital HIGH state for a configurable period. When no motion is detected, the output returns LOW after the configured delay.

Features

• Passive infrared motion detection
• Integrated Fresnel lens
• Adjustable detection sensitivity
• Adjustable output delay
• Selectable trigger mode
• Simple 3-pin interface
• Digital HIGH/LOW output
• Suitable for Arduino and other microcontroller projects
• Low-cost solution for motion-triggered automation

Applications

• Automatic lights and switches
• Home automation systems
• Security alarm prototypes
• Intrusion detection projects
• Energy-saving lighting
• Robotics motion detection
• Automatic doors and access systems
• Smart-home projects
• Arduino and Raspberry Pi projects
• Educational electronics experiments

Interface

• VCC: Power input
• OUT: Digital motion-detection output
• GND: Ground

Important Notes

The HC-SR501 detects changes in infrared radiation and is therefore primarily a motion detector, rather than a general-purpose proximity or distance sensor. A stationary person may eventually stop triggering the module.

Detection performance can be affected by temperature, installation position, environmental conditions, airflow, direct sunlight, and nearby heat sources. Allow the module to stabilize after power-up before relying on its output.

Product specifications can vary between HC-SR501 production batches, so users should verify the actual module markings and operating requirements before integrating it into a final design.