TechnoElectronics44

PIR SENSOR

PIR Sensor-passive Infrared Sensor.PIR Sensor is also called a motion sensor because it identifies the motion of a body in front of it but does not give information on who or what moved. PIR Sensor is used to detect living beings either it is a live human being or any live animals, these are mostly used in home automation like automatic room lights control ON/OFF. PIR sensors place an important role in electronic gadgets due to their application.PIR Sensors are very compatible with battery-powered applications because of their minimum size and lower-power operation mode.

Note: PIR Sensor does not radiate the energy, they can detect the radiant energy from the object/radiant energy reflected from the object. This radiant energy is also known as Infrared radiation

Let’s check in to some more functionalities of PIR Sensor.

Model Number: HC-SR501

Other names of PIR Sensor
PID (Passive Infrared Detector), Motion Sensor, Motion Detector, Infrared sensor, Pyro-Electric Sensor, IR-motion sensor.

Other related devices
HC-SR505, 360 ̊ PIR sensor, 120 ̊ PIR infrared body sensor, AM312, AS312.

PIR-SENSOR-HC-SR501

Pin Configuration

Vcc	Battery positive Terminal
D0	Digital Data pin
GND	Battery Negative Terminal

PIR-SENSOR-PINOUT

Features

Repeatable and non-repeatable modes of operation
Sensitive adjustment potentiometer
Timer adjustment potentiometer
Material: Pyroelectric crystal
Covered with Fresnel lenses

Technical specifications

Size: Rectangular
Output: Digital pulse high (3V) when triggered (motion detected) Digital low when idle (no motion detected).
Sensitivity range: up to 20 feet (6 meters) 110° x 70° detection range
Power supply: 5V-12V input voltage for most modules

How PIR Sensors Work

PIR Sensor detects changes in the radiant energy/Infrared radiation. The amount of radiant energy will depend on the object surface and heat emitted by the object. PIR sensor differentiates instantaneously changes (increase) in the temperature, if the temperature is not changed then it is not identify any moving object.

For example, a PIR sensor is fixed at a particular area the room temperature is 35 ̊C, if any the person moved in front of the PIR Sensor the temperature rises above the room temperature only instantaneous of time.

At that point of time-temperature rises from room temperature to body temperature and back to room temperature, the sensor converts the incoming infrared radiation into the output voltage that triggers the device.

Note: In order to detect the moving objects, the temperature should be above the room temperature

Repeatable trigger mode

In this mode, when the object is detected the out is set to HIGH only for a certain time after that time the output voltage goes LOW even the object/person is within the of the PIR sensor, this time period set by the “timing control-potentiometer”. In this mode PIR sensor output irrespectively transition from LOW to HIGH or HIGH to LOW. The range of the PIR sensor is set by the Sensitivity –Potentiometer.

Non-Repeatable trigger mode

In this mode when the object/person is within the range then output set to high as long as the person stays in the sensor range. Output goes LOW only when a person is out of the range. The detecting range of the sensor can vary by using the “sensitivity potentiometer “ as shown in the above figure.

How to work with PIR sensor | Arduino with PIR Sensor

PIR SENSOR

PIR Sensor has three pins Vcc, D0, GND.

Vcc is connected to a 5V pin of Arduino

GND is connected to the GND pin of the Arduino

D0 is connected to any Digital pin(9) of Arduino

RELAY MODULE

Relay module has three pins Vcc, GND, D0

Vcc is connected to a 5V pin of Arduino

GND is connected to the GND pin of the Arduino

D0 is connected to any Digital pin(8) of Arduino

Circuit

Arduino-with-PIR-sensor

CODE

/********************* # PIR SENSOR Example sketch follow us: www.technoelectronics44.com ******************************************************/ #include<SoftwareSerial.h> int PIR_sensor=9; int relay=8; int sensor_value; void setup() { Serial.begin(9600); Serial.print("WELCOME TO TECHNOELECTRONICS44"); pinMode(relay,OUTPUT); digitalWrite(relay,LOW); } void loop() { sensor_value=digitalRead(PIR_sensor); if(sensor_value==LOW) { Serial.println("NORMAL STATE-LIGHT OFF"); digitalWrite(relay,LOW); } if(sensor_value==HIGH) { Serial.println("PERSON DETECTED-LIGHT ON"); digitalWrite(relay,HIGH); } }

Working

In a normal state, the output of the PIR sensor is LOGIC-0, Arduino identifies it as a no object is moving. if the Output voltage transition to LOGIC-1, Arduino identifies it as an object is detected and turned ON the light.

Output

DATASHEET

APPLICATIONS

Home applications
Security alarms
Infrared cameras
Advanced street light applications

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