Password based door locking system using Arduino nano.

OBJECTIVE

The password door locking system aims to grant entry upon correct password input within 5 minutes of the door being locked.

MODULES REQUIRED

Arduino nano
LCD 16 x 2
Buzzer
Keypad
Servo
Potentiometer

SCHEMATIC DIAGRAM

SCHEMATIC CONNECTION

Connect keypad :

Connect the 1 to 8 of the keypad to the D1 to D7 pins on the Arduino nano.

Connect servo :

Connect the Gnd of the servo to the Gnd pin on the Arduino nano.

Connect the v+ of the servo to the 5V pin on the Arduino nano

Connect the pwm of the servo to the D9 pin on the Arduino.

Connect potentiometer :

Connect the Gnd of the potentiometer to the GND pin on the Arduino nano.

Connect the sig pin of the potentiometer to the V0 pin on the lcd display

Connect the vcc of the potentiometer to the 5v on the Arduino nano.

Connect Buzzer:

Connect the +ve pin of the buzzer to the D8 pin on the Arduino nano

Connect the -ve pin of the buzzer to the Gnd pin on the servo .

Connect Lcd:

Connect the vs pin of the Lcd to the GND pin on the Arduino nano.

Connect the VS pin and RW pin together and then connect them to the LCD.

Connect the RW pin and k pin together and then connect them to the LCD.

Connect the VDD pin and A pin together and then connect them to the LCD.

Connect the RS pin of the lcd to the A0 pin on the Arduino nano .

Connect the E pin of the lcd to the A1 pin on the Arduino nano .

Connect the D4 pin of the lcd to the A2 pin on the Arduino nano .

Connect the D5 pin of the lcd to the A3 pin on the Arduino nano .

Connect the D6 pin of the lcd to the A4 pin on the Arduino nano .

Connect the D7 pin of the lcd to the A5 pin on the Arduino nano .

To begin your project, click this template link:

Simulate on Wokwi

ARDUINO CODE


#include (Keypad.h)
#include (LiquidCrystal.h)
#include (Servo.h)

Servo myservo;
LiquidCrystal lcd(A0, A1, A2, A3, A4, A5);

const byte rows = 4, cols = 3;
char keys[rows][cols] = {
  {'1','2','3'}, {'4','5','6'}, {'7','8','9'}, {'*','0','#'}
};
byte rowPins[rows] = {1, 2, 3, 4};
byte colPins[cols] = {5, 6, 7};
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, rows, cols);

const char* password = "4567";
int currentPos = 0, redLED = 10, greenLED = 11, buzzer = 8, failCount = 0;

void setup() {
  Serial.begin(9600);
  lcd.begin(16, 2);
  myservo.attach(9);
  pinMode(redLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(buzzer, OUTPUT);
  welcomeScreen();
}

void loop() {
  char key = keypad.getKey();
  if (key) {
    lcd.clear(); lcd.setCursor(0, 0);
    lcd.print("PASSWORD:");
    lcd.setCursor(0, 1);
    for (int i = 0; i <= currentPos; i++) lcd.print("*");
    beep();

    if (key == password[currentPos]) {
      currentPos++;
      if (currentPos == 4) {
        unlockDoor();
        currentPos = 0;
        failCount = 0;
      }
    } else {
      failCount++;
      wrongPassword();
      currentPos = 0;
      if (failCount == 5) waitPunishment(15000, "15 SECONDS");
      if (failCount == 8) waitPunishment(60000, "1 MINUTE");
    }
  }
}

void welcomeScreen() {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("*ENTER THE CODE*");
  lcd.setCursor(1, 1);
  lcd.print("TO _/_ (OPEN)!!");
}

void unlockDoor() {
  lcd.clear();
  lcd.print("Access Granted");
  lcd.setCursor(4, 1);
  lcd.print("WELCOME!!");
  buzzPattern();
  moveServo(90, 0);
  delay(2000);
  countdownBeep();
  moveServo(0, 90);
  welcomeScreen();
}

void moveServo(int start, int end) {
  int step = (start < end) ? 5 : -5;
  for (int pos = start; pos != end + step; pos += step) {
    myservo.write(pos);
    delay(15);
  }
}

void wrongPassword() {
  lcd.clear();
  lcd.setCursor(1, 0); lcd.print("CODE INCORRECT");
  lcd.setCursor(4, 1); lcd.print("GET AWAY!!!");
  Serial.println("Unauthorized access attempt.");
  digitalWrite(redLED, HIGH); digitalWrite(buzzer, HIGH);
  delay(2000);
  digitalWrite(redLED, LOW); digitalWrite(buzzer, LOW);
  welcomeScreen();
}

void beep() {
  digitalWrite(buzzer, HIGH); delay(50);
  digitalWrite(buzzer, LOW);
}

void buzzPattern() {
  for (int i = 0; i < 4; i++) {
    digitalWrite(buzzer, HIGH); delay(80);
    digitalWrite(buzzer, LOW); delay(80);
  }
}

void countdownBeep() {
  for (int i = 5; i > 0; i--) {
    lcd.clear();
    lcd.setCursor(2, 0); lcd.print("GET IN WITHIN:");
    lcd.setCursor(6, 1); lcd.print(i);
    digitalWrite(buzzer, HIGH); delay(100);
    digitalWrite(buzzer, LOW); delay(900);
  }
  for (int i = 0; i < 4; i++) {
    digitalWrite(buzzer, HIGH); delay(50);
    digitalWrite(buzzer, LOW); delay(50);
  }
  lcd.clear();
  lcd.print("RE-LOCKING...");
  delay(1000);
  lcd.clear(); lcd.setCursor(4, 0);
  lcd.print("LOCKED!");
  delay(1000);
}

void waitPunishment(unsigned long timeMs, const char* msg) {
  lcd.clear();
  lcd.setCursor(2, 0); lcd.print("WAIT FOR");
  lcd.setCursor(4, 1); lcd.print(msg);
  digitalWrite(buzzer, HIGH);
  delay(timeMs);
  digitalWrite(buzzer, LOW);
  lcd.clear();
  lcd.print("Enjoyed that?");
  delay(2000);
  welcomeScreen();
}

INSTRUCTIONS

Assemble the circuit by connecting all components as shown in the schematic diagram.

On the left side of the screen, open sketch.ino and write your Arduino code.

After completing the circuit and writing the code, click the green Play button to start the simulation.

Enter the correct password to unlock the door within 5 minutes after locking.

WORKING PRINCIPLE

The working principle of this project is that the door unlocks only when the correct password is entered within 5 minutes after it has been locked.

Project Link

for your reference.