How to Set Up a Password-Protected Door Lock System with Arduino

This guide will walk you through setting up a password-protected door lock system using an Arduino Uno, a 4×4 keypad, an LCD display, a servo motor, and a buzzer. This system is designed to unlock or lock a door based on the correct password entered on the keypad. The setup is simple yet effective for securing your belongings.

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Components Needed:

• Arduino Uno
• 4×4 Keypad
• 16×2 I2C LCD Display
• Servo Motor
• Buzzer
• Jumper Wires
• Breadboard (optional)

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Circuit Diagram

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Step 1: Wiring the Components

1. Keypad: Connect the keypad pins to the Arduino digital pins as follows:
   • Pin 1 to Arduino pin 2
   • Pin 2 to Arduino pin 3
   • Pin 3 to Arduino pin 4
   • Pin 4 to Arduino pin 5
   • Pin 5 to Arduino pin 6
   • Pin 6 to Arduino pin 7
   • Pin 7 to Arduino pin 8
   • Pin 8 to Arduino pin 9
2. LCD Display: Connect the 16×2 LCD to the Arduino using the I2C protocol.
   • Connect the SDA pin of the LCD to the A4 pin on the Arduino.
   • Connect the SCL pin of the LCD to the A5 pin on the Arduino.
   • Connect VCC to 5V and GND to GND.
3. Servo Motor: Connect the servo motor’s control wire to Arduino pin 10, power wire to 5V, and ground wire to GND.
4. Buzzer: Connect the positive lead of the buzzer to pin 11 and the negative lead to GND.

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Step 2: Code Upload

1. Open the Arduino IDE.
2. Copy and paste the provided code (available at the end of this guide) into the Arduino IDE.
3. Make sure to install the required libraries, including Servo, LiquidCrystal_I2C, Keypad, and Password. To install libraries, go to Sketch > Include Library > Manage Libraries, search for each library, and install it.
4. Once everything is set, connect the Arduino to your computer, select the correct board and port, and upload the code.

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Step 3: How the System Works

• Password Input: The system prompts the user to enter a password on the LCD display. You’ll see “Enter Password” on the screen.
• Password Verification: If the entered password matches the predefined one (0123 in the code), the servo motor unlocks the door by rotating to the unlock position, and the buzzer gives a confirmation beep.
• Incorrect Password: If the entered password is incorrect, the buzzer will beep multiple times, and the display will show “Wrong Password! Please Try Again.”
• Door Lock/Unlock: After a successful entry, pressing D on the keypad will toggle between locking and unlocking the door.

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Step 4: Testing the System

1. Power up the Arduino and watch the LCD. It should display “Welcome to Door Lock System” initially.
2. After 3 seconds, it will ask for the password.
3. Enter 0123 using the keypad to test the unlocking mechanism.
4. Use the D key to lock or unlock the door repeatedly, ensuring the servo responds accurately.

Code

Here’s the full code to run this project:

#include <Servo.h>
#include <LiquidCrystal_I2C.h>
#include <Keypad.h>
#include <Password.h>

#define buzzer 11

Servo servo;
LiquidCrystal_I2C lcd(0x27, 16, 2);

String newPasswordString; //hold the new password
char newPassword[6]; //charater string of newPasswordString
byte a = 5;
bool value = true;

Password password = Password("0123"); //Enter your password

byte maxPasswordLength = 6;
byte currentPasswordLength = 0;
const byte ROWS = 4; // Four rows
const byte COLS = 4; // Four columns

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

byte rowPins[ROWS] = {2, 3, 4, 5};
byte colPins[COLS] = {6, 7, 8, 9};

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

void setup() {
  Serial.begin(9600);
  pinMode(buzzer, OUTPUT);
  servo.attach(10);
  servo.write(50);
  lcd.init();
  lcd.backlight();
  lcd.setCursor(3, 0);
  lcd.print("WELCOME TO");
  lcd.setCursor(0, 1);
  lcd.print("DOOR LOCK SYSTEM");
  delay(3000);
  lcd.clear();
}

void loop() {
  lcd.setCursor(1, 0);
  lcd.print("ENTER PASSWORD");

  char key = keypad.getKey();
  if (key != NO_KEY) {
    delay(60);
    if (key == 'C') {
      resetPassword();
    } else if (key == 'D') {
      if (value == true) {
        doorlocked();
        value = false;
      } else if (value == false) {
        dooropen();
        value = true;
      }
    } else {
      processNumberKey(key);
    }
  }
}

void processNumberKey(char key) {
  lcd.setCursor(a, 1);
  lcd.print("*");
  a++;
  if (a == 11) {
    a = 5;
  }
  currentPasswordLength++;
  password.append(key);

  if (currentPasswordLength == maxPasswordLength) {
    doorlocked();
    dooropen();
  }
}

void dooropen() {
  if (password.evaluate()) {
    digitalWrite(buzzer, HIGH);
    delay(300);
    digitalWrite(buzzer, LOW);
    servo.write(50);
    delay(100);
    lcd.setCursor(0, 0);
    lcd.print("CORRECT PASSWORD");
    lcd.setCursor(0, 1);
    lcd.print("DOOR OPENED");
    delay(2000);
    lcd.clear();
    a = 5;
  } else {
    wrongPassword();
  }
  resetPassword();
}

void doorlocked() {
  if (password.evaluate()) {
    digitalWrite(buzzer, HIGH);
    delay(300);
    digitalWrite(buzzer, LOW);
    servo.write(110);
    delay(100);
    lcd.setCursor(0, 0);
    lcd.print("CORRECT PASSWORD");
    lcd.setCursor(2, 1);
    lcd.print("DOOR LOCKED");
    delay(2000);
    lcd.clear();
    a = 5;
  } else {
    wrongPassword();
  }
  resetPassword();
}

void wrongPassword() {
  for (int i = 0; i < 3; i++) {
    digitalWrite(buzzer, HIGH);
    delay(200);
    digitalWrite(buzzer, LOW);
    delay(200);
  }
  lcd.setCursor(0, 0);
  lcd.print("WRONG PASSWORD!");
  lcd.setCursor(0, 1);
  lcd.print("PLEASE TRY AGAIN");
  delay(2000);
  lcd.clear();
  a = 5;
}

void resetPassword() {
  password.reset();
  currentPasswordLength = 0;
  lcd.clear();
  a = 5;
}

Hope You’ve Successfully Built Your Door Lock System !

If you follow all the steps carefully, I am sure your door lock system will work. And if it doesn’t work, then you will see again whether your words are wrong or not

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