PIR sensor: everything you need to know

PIR sensor

One of the sensors with the most applications, especially in the field of security, is the PIR sensor. Another new sensor joining the list of components, and which we also talk about when we deal with the model HC-SR501, one of the practical sensors that you can use with your arduino board for a multitude of projects, such as creating a home alarm for your home or business.

The PIR sensor is very simple in terms of connection and programming, but you can verify that it exists multitude of applications in which it can be applied for your DIY projects. And in this introductory guide you will understand everything essential about this type of sensors ...

What is PIR sensor and working principle

fresnel lens

Un PIR sensor It is a type of sensor that uses IR, that is, infrared. Based on this radiation, it will work by detecting movements or proximity. All thanks to the elements of which it is integrated to capture the presence of people or movement, also that of animals and other objects.

All based on the low IR radiation emitted by the bodies of objects, people or pets. And that will be captured by this type of sensors with great precision. Same principle used by other devices, such as thermography devices, night vision cameras, etc.

In addition, this type of sensor can be configured to adjust its sensitivity, so that it can have more or less scope. For example, some sensors can have a movement or presence detection range from 3 meters to 7 meters or more, and with ranges of 90-110º. This allows detecting movement in a good range, allowing its installation on any wall, for example.

On the other hand, the PIR sensor will be covered by a dome-shaped shield. This is nothing but the call Fresnel lens. That is, a lens named after the French physicist who invented it, Augustin-Jean Fresnel, and thanks to which you can achieve that large focal aperture without the need for other lenses of greater weight and volume than would be needed using a lens. conventional.


motion sensor, PIR sensor

If you wonder what a PIR sensor can be used for, the truth is that it has a multitude of applications where it might be necessary to use this type of device. For example:

  • Autonomous robots that need to detect objects or people to avoid obstacles.
  • Autonomous vehicles that need to detect movement or the presence of something.
  • Alarm systems in which it is activated when it detects the presence of something. Also video surveillance systems could be activated to record what happens when they detect movement, door openers, smart doorbells, etc.
  • Automated systems that turn on the light when someone is detected, or open the doors automatically.
  • Devices that alert or generate some type of activity when an event occurs, such as your pet being nearby, or someone close to the PIR sensor.
  • Others.

Buy a PIR sensor

PIR sensor

Depending on what you are looking for you will have several alternatives in the market. For example, if you are a maker and you are looking for an electronic component to adapt it to an electronic project, then you have several models, such as:

On the other hand, it is likely that what interests you is working with a PIR sensor ready to use in your alarm system or to turn on the lights automatically, etc. In this case, the ideal is that you use a commercial PIR sensor like these others:

  • SEBSON, PIR-based motion sensor for outdoor installation. With a range of up to 12 meters away, with a 180º angle, adjustable in orientation, and anchored to the wall.
  • PIR LKM, a practical battery-powered PIR sensor to install wherever you need it, with a range of 11 meters, 110º horizontal angle and 60º vertically.
  • No products found., one of the well-known brands in smart security and presenting this wireless PIR motion sensor and ideal for alarms. With up to 100 meters of range and for indoor use.
  • Dioche, a sensor protected against the elements for use both inside and outside the home. With a wide range to avoid blind spots and with alert via mobile app.
  • Zerone, 360º PIR sensor that can be installed in the hole of a spotlight in the ceiling, replacing one of the recessed spotlights you have in your home or office. In addition, it seems that a conventional bulb will go unnoticed.
  • Tellur Smart, another one that you can connect to WiFi, like any other IoT device for remote control from your mobile or to generate actions in other connected devices when it detects movement, such as turning on a smart switch, etc.

As you can see, these systems they are quite cheap, so for a few euros you can have one or more at home to create the system you need.

Using a PIR sensor with Arduino

Screenshot of Arduino IDE

If you want to use a PIR sensor with Arduino, I recommend you read the article about the HC-SR501. There I explained how it could be used and integrated with a project with Arduino. In case you have purchased another PIR sensor model, I recommend reading the datasheet and pinout on that specific model, but it should not represent a too relevant difficulty, and what was said in that article can serve as a basis for adapting it to the new sensor ...

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