Ultrasonic Security System

It is a simple tutorial on how to create little a security device using an Arduino.

Warning

This is for Educational and Informational Purposes Only.

Contents

• Setup
  • On Ultrasonic Sensor
  • LEDs
  • Example
• Assembly - Breadboard
• Assembly - Ultrasonic Sensor
• Assembly - LEDs
• Assembly - Buzzer
• Code
• Folders
• Clone
• License

Components

• Arduino UNO
• Breadboard
• Buzzer
• Ultrasonic Sensor - HC-SR04
• Resistor 221 ohm
• LED
• Jumper wires

Project description

Setup

Connect a red wire from the 5V pin on the Arduino to the positive channel of the breadboard. Connect a black wire from the GND pin on the Arduino to the negative channel of the breadboard:

Buzzer = pin 7

On Ultrasonic Sensor:

Echo = pin 3 
Trig = pin 2 

LEDs:

RedLED = pin 4 
YellowLED = pin 5 
GreenLED = pin 6 

Example

#define trigPin 2
#define echoPin 3
#define soundbuzzer 7
#define LEDlampRed 4
#define LEDlampYellow 5
#define LEDlampGreen 6 

The green wires connected to the LEDs should be connected in line to the positive side of the LED, while the negative side of the LED should be connected to the negative channel of the breadboard using a 220 ohm resistor.

Important

Make Sure The Connections Are Made Correctly Otherwise It May Not Work Correctly.

Assembly - Breadboard

Firstly, let's connect the 5V and GND pin on the Arduino to the breadboard. As I mentioned before, be sure that the wire attached to the 5V pin is connected to the positive channel of the breadboard, and the wire attached to the GND pin is connected to the negative channel of the breadboard.

Assembly - Ultrasonic Sensor

Time to connect the HC-SRO4 ultrasonic sensor! A great tip is to place the ultrasonic sensor as far right to the breadboard as possible and make sure that it is facing out. Referring back to the setup picture, you should connect the GND pin on the ultrasonic sensor to the negative channel on the breadboard. Next connect the Trig pin on the sensor to pin 2 on the Arduino and connect the Echo pin on the sensor to pin 3 on the Arduino. Lastly, connect the VCC pin on the ultrasonic sensor to the positive channel on the breadboard. Refer to the picture above if anything gets confusing.

Assembly - LEDs

The next step is to connect the LED's to the breadboard and Arduino. If you need to, I highly recommend that you refer back to the setup picture (Step 2), attaching the LEDs is pretty easy, there's a lot of repetition. Let's first attach the Green LED. So the way to do this, is to connect the anode (the longer leg) to pin 6 on the Arduino with a green wire, and to connect the cathode (the shorter leg) to the negative channel on the breadboard, using a 220 ohm resistor. Then repeat that step for the Yellow and then the Red LED, make sure to connect the anode (the longer leg) of the yellow LED to pin 5 on the Arduino and then connect the anode of the red LED to pin 6. Once you have done that, your setup should look similar to the picture above. Resistors are not absolutely necessary, however they are highly recommended to be used.

Assembly - Buzzer

The last part of the setup for this, is connecting the buzzer to the breadboard and the Arduino. This is one of the easiest parts of the whole setup. All that is required to do is to connect the longer leg of the buzzer to pin 7 of the Arduino using a green wire and then connect the shorter leg of the buzzer to the negative channel of the breadboard using a 220 ohm resistor. It is hıghly recommended to use a resistor in connecting the shorter leg of the buzzer to the negative channel of the breadboard. This greatly reduces the volume of the buzzer and prevent it from dying to quickly.

Code

• Pin Definitions:

  • trigPin is defined as the trigger pin of the ultrasonic sensor.
  • echoPin is defined as the echo pin of the sensor.
  • soundbuzzer is defined as a pin used for an audible alert through a buzzer.
  • LEDlampRed controls a red LED light.
  • LEDlampYellow controls a yellow LED light.
  • LEDlampGreen controls a green LED light.

• sound Variable:

  • The sound variable represents the frequency at which the buzzer will sound.

• setup() Function:

  • It initializes serial communication (9600 baud).
  • Sets the pin modes: trigPin is set as an output, while echoPin, LEDlampRed, LEDlampYellow, LEDlampGreen, and soundbuzzer are set as input/output pins.

Code

void setup() {

    Serial.begin (9600);
    pinMode(trigPin,  OUTPUT);
    pinMode(echoPin, INPUT);
    pinMode(LEDlampRed, OUTPUT);
    pinMode(LEDlampYellow,  OUTPUT);
    pinMode(LEDlampGreen, OUTPUT);
    pinMode(soundbuzzer, OUTPUT);
}

• loop() Function:
  • It performs distance measurement with the ultrasonic sensor.
  • Then, it carries out different actions based on specific distance thresholds:
    • If the measured distance is less than 50 cm, it turns on the green LED.
    • If the measured distance is less than 20 cm, it turns on the yellow LED.
    • If the measured distance is less than 5 cm, it turns on the red LED and activates the buzzer at a specific frequency.
    • If the measured distance is above 5 cm or there is no valid distance measurement, it prints "Outside the permissible range of distances" to the serial monitor and turns off the buzzer.
    • It also prints the measured distance to the serial monitor.

Code

void  loop() {

    long durationindigit, distanceincm;
    
    digitalWrite(trigPin, LOW);  
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);

    durationindigit = pulseIn(echoPin, HIGH);
    distanceincm = (durationindigit/5) / 29.1;
 
    if (distanceincm < 50) {
        digitalWrite(LEDlampGreen, HIGH);
    }
    else {
        digitalWrite(LEDlampGreen,  LOW);
    }
  
    if (distance < 20) {
        digitalWrite(LEDlampYellow,  HIGH);
    }
    else {
        digitalWrite(LEDlampYellow,LOW);
    }

    if (distance  < 5) {
        digitalWrite(LEDlampRed, HIGH);
        sound = 1000;
    }
    else  {
        digitalWrite(LEDlampRed,LOW);
    }
 
    if (distanceincm > 5 ||  distanceinsm <= 0){
        Serial.println("Outside the permissible range of distances");
        noTone(soundbuzzer);
    }
    else {
        Serial.print(distance);
        Serial.println("  cm");
        tone(buzzer, sound);
    }
  
    delay(300);
  }

• It creates a loop with delay(300), so the sensor periodically measures distance and processes the results.

Click To See All Code

Code

#define trigPin 2
#define echoPin 3
#define soundbuzzer 7
#define LEDlampRed 4
#define LEDlampYellow 5
#define LEDlampGreen 6 

int sound  = 500;


void setup() {

    Serial.begin (9600);
    pinMode(trigPin,  OUTPUT);
    pinMode(echoPin, INPUT);
    pinMode(LEDlampRed, OUTPUT);
    pinMode(LEDlampYellow,  OUTPUT);
    pinMode(LEDlampGreen, OUTPUT);
    pinMode(soundbuzzer, OUTPUT);
}

void  loop() {

    long durationindigit, distanceincm;
    
    digitalWrite(trigPin, LOW);  
    delayMicroseconds(2);
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);

    durationindigit = pulseIn(echoPin, HIGH);
    distanceincm = (durationindigit/5) / 29.1;
 
    if (distanceincm < 50) {
        digitalWrite(LEDlampGreen, HIGH);
    }
    else {
        digitalWrite(LEDlampGreen,  LOW);
    }
  
    if (distance < 20) {
        digitalWrite(LEDlampYellow,  HIGH);
    }
    else {
        digitalWrite(LEDlampYellow,LOW);
    }

    if (distance  < 5) {
        digitalWrite(LEDlampRed, HIGH);
        sound = 1000;
    }
    else  {
        digitalWrite(LEDlampRed,LOW);
    }
 
    if (distanceincm > 5 ||  distanceinsm <= 0){
        Serial.println("Outside the permissible range of distances");
        noTone(soundbuzzer);
    }
    else {
        Serial.print(distance);
        Serial.println("  cm");
        tone(buzzer, sound);
    }
  
    delay(300);
}

Folders

You can view the files here

Clone

git clone musarda/Ultrasonic-Security-System

License

This project is licensed under the MIT License.