PIR sensor HC-SR501 - motion detector 6m

Description

The HC-SR501 PIR motion sensor module is a passive motion detector that responds to changes in infrared radiation in the environment. The PIR motion sensor works by detecting the temperature difference between objects that emit heat and the environment. The sensor is sensitive to the movement of people or animals, making it ideal for applications in alarm systems, lighting automation, or control of electrical devices. It is widely used in projects with microcontrollers, as well as platforms such as Arduino or Raspberry Pi. It can also be used in conjunction with ESP8266, STM32 and AVR systems.

The HC-SR501 PIR motion sensor has a built-in system that detects infrared radiation using a Fresnel lens that focuses the radiation on the detector. The module is equipped with potentiometers that allow you to adjust the duration of the signal after detecting movement and the sensitivity of the sensor, which allows you to adjust the parameters to specific application conditions. Thanks to its small size and low power consumption, this sensor is perfect for projects where energy efficiency and compactness are key.

Principle of Operation

A PIR sensor (passive infrared sensor) works by detecting infrared radiation emitted by objects with a higher temperature than the ambient temperature, such as people or animals. When an object moves within the range of the detector, the change in the intensity of the radiation is recorded, which generates an output signal. The module generates a high output (3.3 V) when it detects movement, and a low output (0 V) when it does not detect any change. Using the potentiometers, the user can set the time for which the output signal is maintained after detecting movement (from 5 to 200 seconds), and adjust the sensitivity of the sensor.

Connection and Use

The HC-SR501 PIR motion sensor module can be easily connected to platforms such as Arduino, Raspberry Pi, STM32 or ESP8266. The module requires a power supply voltage ranging from 5 V to 12 V, which can be supplied from an external source or from the power pin of the development platform. The module's pins are three: power (VCC), ground (GND) and output (OUT). After connecting, the PIR motion sensor is ready to work - just read the output signal from the OUT pin, which will change its state depending on the detected movement.

To connect the sensor to Arduino, you can use the following connection diagram:

• Sensor's VCC pin to the 5V Arduino power supply,
• GND pin to ground (GND),
• OUT pin to any digital Arduino port (e.g. D2).

In the Arduino code, you can read the state of the OUT pin and control, for example, lighting, relays or other electrical devices based on it. Similarly, you can connect the module to Raspberry Pi or other platforms, using the appropriate power and data reading pins. In the case of Raspberry Pi, the sensor can be used to automatically run system tasks, such as taking photos or turning on an alarm.
Application examples

1. Alarm systems – PIR motion sensor is widely used in detecting unauthorized entry into rooms, triggering an alarm or other security measures when movement is detected
2. Lighting automation – thanks to the sensor, the light in the room can be turned on automatically when movement is detected, which allows for energy savings
3. DIY projects with Arduino – PIR sensor can be easily integrated with Arduino projects to create intelligent control systems, such as automatic door opening or starting ventilation
4. Home monitoring and automation – in projects with Raspberry Pi or ESP8266, PIR sensor can be used to monitor activity in the home, send motion notifications, or turn on surveillance cameras
5. Management of electrical devices – connected to a relay, PIR sensor can automatically start electrical devices such as heating, air conditioning or audio devices

Features

• Sensor: LHi778
• Output voltage: 3.3V (high), 0V (low)
• Viewing angle: <140°
• Detection range: up to 7 m
• Signaling time adjustment: 5-200s
• Lens: Fresnel
• Power supply voltage: 5-12V
• Current consumption: <60mA
• Operating temperature: -20~80°C
• Dimensions: 32 x 24mm
• Connectors: goldpin

Description of leads

ZL2AVR (Bascom) and modHC-SR501

To download

• Datasheet
• Diagram of the module
• How does the passive infrared sensor work?
• Article on the portal MIKROKONTROLER.pl "PIR motion sensor using modHC-SR501"
• The article on the portal MIKROKONTROLER.pl "[PROJECT] Triggers the motion shutter - Raspberry Pi and PIR motion sensor"