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Embedded Sensor – Passive Infrared Sensor (PIR)

  • PIR – Passive InfraRed Sensor
  • PIR consists of a Pyroelectric sensor which generates energy when exposed to heat.
  • The module covered with Fresnel Lense Cover.
  • BISS0001 micro Power PIR Motion Detector IC.

Infrared Application

  • Passive Infrared Detector for Anti Theft security alarm system.
  • Passive Infrared Detector based Light On/OFF.
  • Automatic Light  ON/OFF.
  • Many other motion Detection Application.

Different PIR Modules

The HC-SR501 PIR Sensor Module

  • Working voltage : 5v to 20V DC
  • Range : 3 to 7 meters
  • Induction Lens size: 23mm.
  • PCB Size: 32mm x24mm.
  • Pins Details
    • Ground pin
    • VCC pin
    • The output pin detects an object when it is at a high logic level.
  • Two potentiometers.
    • One for adjusting the sensitivity of the sensor
    • Adjust the time for the output signal to stay high when an object is detected from 0.3 seconds up to 5 minutes.
  • Jumper Settings (Selecting the trigger modes)
    • non-repeatable trigger – when the sensor output is high and the delay time is over, the output will automatically change from high to low level.
    • Repeatable trigger –  will keep the output high all the time until the detected object is present in sensor’s range

Arduino Example code :

Circuit

Code

/* Arduino PIR Motion Sensor Tutorial */
/* www.ArunEworld.com */

int pirSensor = 8;
int relayInput = 7;

void setup() {
  pinMode(pirSensor, INPUT);
  pinMode(relayInput, OUTPUT);
}

void loop() {
  int sensorValue = digitalRead(pirSensor);
  if (sensorValue == HIGH) {
    digitalWrite(relayInput, LOW); // The Relay Input works Inversely
  }
}

Code Explanation

This Arduino code is for a PIR (Passive Infrared) motion sensor setup, where a relay is controlled based on motion detection. Here’s an explanation of each part:

SectionExplanation
CommentsThe code includes comments providing information about the purpose of the code and its source.
Variable Declaration– pirSensor = 8;: Declares a variable pirSensor and assigns pin 8 to it for reading the PIR sensor’s output. – relayInput = 7;: Declares a variable relayInput and assigns pin 7 to it for controlling the relay.
Setup FunctionInitializes the pins: – Sets pirSensor pin as INPUT to receive data from the PIR sensor. – Sets relayInput pin as OUTPUT to control the relay.
Loop Function– Reads the digital state from the pirSensor pin to check for motion detection. – If motion is detected (sensor value is HIGH), it turns on the relay by setting the relayInput pin LOW.
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