PIR Motion Sensor

Alarms area unit quite common today, a lot of individuals have alarms within the whole house. however what if you wish your internal alarm? for instance, you’ll wish to prevent your siblings from coming into your space, this project can assist you to build a straightforward PIR motion detector mistreatment the Arduino Uno board.

What is a PIR Sensor?

PIR sensor detects a person’s being traveling within approximately 10m from the sensor. this is often a mean value because the actual detection range is between 5m and 12m.PIR is fundamentally made from a pyroelectric sensor, which may detect levels of infrared . for varied essential projects or items that require to get when a private has left or entered the world. PIR sensors are incredible, they’re flat control and minimal effort, have a good lens range, and are simple to interface with.

PIR sensors allow you to sense motion, nearly always wont to detect whether a person has moved in or out of the sensors range. they’re small, inexpensive, low-power, easy to use and do not wear out. For that reason, they’re commonly found in appliances and gadgets utilized in homes or businesses. they’re often mentioned as PIR, “Passive Infrared”, “Pyroelectric”, or “IR motion” sensors.

Most PIR sensors have a 3-pin connection at the side or bottom. One pin is going to be ground, another is going to be signal and therefore the last pin is going to be power. Power is typically up to 5V. Sometimes bigger modules don’t have direct output and instead just operate a relay which case there are ground, power, and therefore the two switch associations. Interfacing PIR with a microcontroller is extremely easy and straightforward. The PIR acts as a digital output so all you would like to try to to is listening for the pin to flip high or low. The motion is often detected by checking for a high signal on one I/O pin. Once the sensor warms up the output will remain low until there’s motion, at which era the output will swing high for a few seconds, then return low. If motion continues the output will cycle during this manner until the sensors line of sight of still again. The PIR sensor needs a warm-up time with a selected end goal to capacity fittingly. this is often due to the settling time included in studying nature’s domain. this might be anyplace from 10-60 seconds.

How to use PIR Motion Sensor

The PIR sensor stands for Passive Infrared sensor. it’s a low-cost sensor that will detect the presence of citizenry or animals. This sensor has three output pins Vcc, Output, and Ground as shown within the pin diagram above. Since the output pin is 3.3V TTL logic it is often used with any platforms like Arduino, Raspberry, PIC, ARM, 8051.

The module is often powered from voltage 4.5V to 20V but, typically 5V is employed. Once the module is powered allow the module to calibrate itself for a couple of minutes, 2 minutes maybe a well-settled time. Then observe the output on the output pin. Before we analyze the output we’d like to understand that there are two operating modes during this sensor like Repeatable(H) and Non- Repeatable(L) and mode. The Repeatable mode is the default mode.

The output of the sensor can be set by shorting any two pins on the left of the module. The sensor in the figure above has two built-in potentiometers to adjust the delay trim (the potentiometer at the left) and the sensitivity (the potentiometer at the right).

The HC-SR501 PIR Sensor Module

The module has simply 3 pins, a Ground ANd a VCC for powering the module ANd an output pin which supplies high logic level if an object is detected. conjointly it’s 2 potentiometers. One for adjusting the sensitivity of the detector and also the difference for adjusting the time the signaling stays high once the object is detected. now is adjusted from zero.3 seconds up to five minutes.


The module has 3 additional pins with a jumper between 2 of them. These pins are for choosing the trigger modes. the primary one is termed “non-repeatable trigger” and works like this: once the detector output is high and also the delay time is over, the output can mechanically modification from high to low level. the opposite mode known as “repeatable trigger” can keep the output high all the time till the detected object is a gift in sensors vary.

The projects are available at PIR Motion Sensor

5 Features

  1. Supply Voltage – 5V.
  2. Delay Time Adjustable.
  3. Standard TTL Output.
  4. Complete with PIR, Motion Detection.
  5. Dual Element Sensor with Low Noise and High Sensitivity.


PIR Sensor IC

The PIR sensor IC consists of 3 pins-  Vcc, Ground, and Output.

7 areas of Applications of PIR Sensors  

  • All outdoor Lights
  • Lift Lobby
  • Multi Apartment Complexes
  • Common staircases
  • For Basement or Covered Parking Area
  • Shopping Malls
  • For garden lights