A passive infrared sensor (PIR sensor) is a type of sensor that detects infrared radiation (IR) emitted by objects in its field of view. PIR sensors are often used in motion detectors, security alarms, and automatic lighting applications.
Working of PIR sensor
A PIR sensor works by detecting changes in the amount of infrared radiation impinging upon it. When an object, such as a person, passes in front of the sensor, the temperature at that point in the sensor’s field of view will rise from room temperature to body temperature, and then back again. This change in temperature is detected by the sensor and can be used to trigger an alarm or other action.
Applications of PIR sensor
PIR sensors are used in a wide variety of applications, including:
- Motion detectors: PIR sensors are used in motion detectors to detect the presence of people or other objects in a given area. Motion detectors can be used for security purposes, such as to detect intruders in a home or business, or for automatic lighting applications, such as to turn on lights when someone enters a room.
- Security alarms: PIR sensors are used in security alarms to detect the presence of intruders. When a PIR sensor detects motion, it can trigger an alarm, such as a siren or a loud noise, to alert people to the presence of an intruder.
- Automatic lighting: PIR sensors are used in automatic lighting applications to turn on lights when someone enters a room or area. This can save energy and improve safety by ensuring that lights are only on when they are needed.
- Pet door: PIR sensors can be used to activate a pet door, allowing pets to come and go as they please.
- Game controllers: PIR sensors can be used in game controllers to detect the movement of a player’s hands. This can be used to control the movement of a character in a video game, for example.
- Other applications: PIR sensors can be used in a variety of other applications, such as:
- Fire detection: PIR sensors can be used to detect the heat from a fire, which can be used to trigger an alarm or other action.
- HVAC control: PIR sensors can be used to detect the presence of people in a room, which can be used to adjust the temperature or other settings of the HVAC system.
- Agriculture: PIR sensors can be used to monitor the growth of plants or crops, or to detect pests or diseases.
How to use PIR sensor
To use a PIR sensor, you will need to connect it to a power source and to a microcontroller or other device that can interpret the sensor’s output. The specific wiring and programming requirements will vary depending on the specific sensor and device you are using.
Once the sensor is connected and programmed, it will be able to detect motion and trigger an alarm or other action. The sensitivity of the sensor can be adjusted to control how easily it detects motion.
Interfacing of Arduino with PIR sensor
To interface an Arduino with a PIR sensor, you will need to connect the sensor to the Arduino’s digital input pins. The specific wiring requirements will vary depending on the specific sensor you are using.
Once the sensor is connected, you can use the Arduino’s built-in digital input functions to read the sensor’s output. The sensor’s output will be either HIGH or LOW, depending on whether or not it is detecting motion.
You can use this information to trigger an alarm or other action. For example, you could use the sensor to turn on a light when someone enters a room.
- PIR sensors are not perfect. They can be affected by factors such as temperature, humidity, and light.
- PIR sensors can be used to detect motion over a wide range of distances. The specific range will vary depending on the specific sensor.
- PIR sensors are relatively inexpensive and easy to use. They are a popular choice for a variety of applications.