Introduction

A Password Protected Security System is an electronic security solution that allows access only when the correct password is entered. This system replaces traditional locks with a digital authentication mechanism, improving safety and ease of use.

It is commonly used in homes, offices, lockers, and restricted areas.

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Objective of the Project

• To design a secure access control system using a password.
• To prevent unauthorized access.
• To understand keypad interfacing with Arduino.
• To implement basic security logic.

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Working Principle

The system works on password authentication.

Step-by-Step Operation

1. User enters a password using a keypad.
2. Arduino reads and stores the entered digits.
3. The entered password is compared with the stored password.
4. If the password matches, access is granted.
5. If the password is incorrect, access is denied and alarm is triggered.

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Components Required

• Arduino Uno
• 4×4 Keypad
• 16×2 LCD Display
• Buzzer
• Servo Motor / Relay
• Jumper Wires
• Breadboard
• 5V Power Supply

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Circuit Diagram

Keypad Connections

R1 -> D9   C1 -> D5
R2 -> D8   C2 -> D4
R3 -> D7   C3 -> D3
R4 -> D6   C4 -> D2

Servo Motor

Signal -> D10
VCC    -> 5V
GND    -> GND

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Arduino Code for Password Protected Security System

#include <Keypad.h>
#include <LiquidCrystal.h>
#include <Servo.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
Servo lockServo;

const byte ROWS = 4;
const byte COLS = 4;

char keys[ROWS][COLS] = {
  {'1','2','3','A'},
  {'4','5','6','B'},
  {'7','8','9','C'},
  {'*','0','#','D'}
};

byte rowPins[ROWS] = {9, 8, 7, 6};
byte colPins[COLS] = {A0, A1, A2, A3};

Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

String password = "1234";
String input = "";

void setup() {
  lcd.begin(16, 2);
  lockServo.attach(10);
  lockServo.write(0);
  lcd.print("Enter Password");
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    if (key == '#') {
      if (input == password) {
        lcd.clear();
        lcd.print("Access Granted");
        lockServo.write(90);
        delay(3000);
        lockServo.write(0);
      } else {
        lcd.clear();
        lcd.print("Access Denied");
      }
      input = "";
      delay(2000);
      lcd.clear();
      lcd.print("Enter Password");
    } else {
      input += key;
      lcd.setCursor(input.length() - 1, 1);
      lcd.print("*");
    }
  }
}

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Code Explanation

• Keypad captures user input.
• Password is compared with stored password.
• Servo unlocks door if password is correct.
• LCD displays system status.

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Advantages

• Simple and secure
• Low cost
• Easy to implement
• No physical keys required

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Applications

• Door security systems
• Locker systems
• Office access control
• Home automation

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Future Enhancements

• Changeable password
• GSM alert system
• RFID + password security
• Mobile app control

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Conclusion

The Password Protected Security System provides a reliable and efficient way to secure restricted areas. It is an ideal project for students to understand access control and embedded system security.

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