Body Motion Detection Using PIR Sensor

Design Overview

The Arduino UNO in this circuit has the following pin connections and purposes:

• D2: Connected to the SIG pin of the PIR sensor. This pin will read the signal from the PIR sensor to detect motion.
• D3: Connected to one end of a 330 Ohm resistor, which is then connected to the anode of a yellow LED. This pin will control the LED.
• D4: Connected to one end of another 330 Ohm resistor, which is then connected to the IN pin of the buzzer. This pin will control the buzzer.
• 5V: Provides power to the VDD pin of the PIR sensor.
• GND: Common ground connection shared with the GND pins of the PIR sensor, the cathode of the LED, and the GND pin of the buzzer.

These connections allow the Arduino UNO to interact with the PIR sensor, control the LED, and control the buzzer.

Working Principle

At temperatures higher than absolute zero (0 Kelvin, or -273.15 °C), thermal energy is released as infrared radiation by all things, including the human body. A thing emits more radiation the hotter it is. Due to its emission at infrared wavelengths, this radiation is invisible to the human eye. Such quantities of infrared radiation are specially detected by the PIR sensor.  You may use the PIR sensor to determine when an animal or human enters or exits the sensors field of view. The majority of contemporary security systems, automated light switches, garage door openers, and other devices that need to respond to motion have this sensor.

As a consequence, the circuit recommends that anytime a body movement is detected, the system first does a few seconds of scanning to guarantee that the body is detected, after which an alarm will sound and the LED yellow will continue to blink until no more motion is detected. The motion-detecting circuit is simple and may be used for energy efficiency, home automation, robotics, access control, and security systems like burglar alarms or trail cameras. 

 

 

 

Code (Tested by Arduino Uno)

 

#define PIRPin 2  //  Arduino Pin 2 = PIR Sensor Output

#define LEDPin 3  // Arduino Pin 3 = LED Anode (+) 

#define SoundPin 4  // Arduino Pin 4 = Buzzer (+)

 

//Variable Declaration

 int PIRSensor;

 

void setup() 

{ 

 

  pinMode(PIRPin,INPUT);  // Configure as digital input

  pinMode(SoundPin,OUTPUT); // Configure as digital output

  pinMode(LEDPin,OUTPUT); // Configure as digital output

 

} 

 

void loop() 

{ 

 

  PIRSensor = digitalRead(PIRPin); // Read Passive Infrared Sensor State (LOW or HIGH)

 

  if(PIRSensor==HIGH)

  { 

    //Motion detected

    // Note:Scan time setting depends on application

    delay(2000);//Lets scan for 2 seconds for False detected 

     if(PIRSensor==HIGH)

    { 

    //Turn on sound and blink LED

    digitalWrite(LEDPin,HIGH);  //Turn ON

    digitalWrite(SoundPin,HIGH); // Turn ON

    delay(1000);

    digitalWrite(LEDPin,LOW);  //Turn OFF

    }

 

  } 

  else

  {

    digitalWrite(LEDPin,LOW);  //Turn OFF

    digitalWrite(SoundPin,LOW); // Turn OFF

  }

 

}