PRATHYUSHAENGI

NEERING COLLEGE
(An Autonomous Institution)
DEPARTMENT OF COMPUTER SCIENCE AND
ENGINEERING

ACADEMIC YEAR: 2024-2025

YEAR/SEM: III/VI

COURSE CODE/NAME: CS3691/EMBEDDED SYSTEMS AND IOT

MINI PROJECT REPORT

ON

IOT-BASED SMART DOOR LOCK SYSTEM

SUBMITTED

BY

111422104026-DEEPA P

111422104027-DEVIPRASAD O

111422104028-DHARANI S

111422104029-DHEEPPTHASHREE S
 PRATHYUSHA
ENGINEERING COLLEGE
(An Autonomous Institution)
DEPARTMENT OF COMPUTER SCIENCE AND
ENGINEERING

BONAFIDE CERTIFICATE

Certified that this project report entitled “Iot-based Smart door lock system” is the

bonafied work of

111422104026-DEEPA P,111422104027-DEVIPRASAD O,

111422104028-DHARANI S,111422104029-DHEEPPTHASHREE S

who carried out the project work as part of the course CS3691/EMBEDDED SYSTEMS

AND IOT.
 TABLE OF CONTENT

S.No Content Page No

1 ABSTRACT

2 OBJECTIVE & SCOPE

3 INTRODUCTION

SYSTEM REQUIREMENTS
4 • HARDWAREREQUIREMENT
• SOFTWARAE REQUIREMENT

5 CIRCUIT DIAGRAM

CODE
6 • PROGRAM
• OUTPUT

7 CONCLUSION

8 REFERENCES
ABSTRACT:
The Smart Door Lock System using IoT is designed to enhance home security by

allowing access through password authentication. This system utilizes an Arduino

microcontroller, a 4x4 keypad for input, and an LCD display to provide user feedback. It

ensures that only authorized users can unlock the door by entering a valid password.

This low-cost, effective system can be implemented in homes, offices, and restricted

areas.

OBJECTIVE & SCOPE:

The primary scope of this project is to provide a secure, accessible, and user-friendly

locking mechanism. This system prevents unauthorized access and can be integrated

with IoT features such as remote control or alerts. The current version focuses on local

access using a keypad but can be expanded with Wi-Fi or GSM modules for remote

functionalities.

INTRODUCTION:

Security is one of the top priorities in today’s smart world. Traditional lock and key

mechanisms are prone to being lost, copied, or tampered with. A Smart Door Lock

System based on IoT technologies provides improved security and ease of use. This

project implements a digital password-protected lock system using Arduino, which acts

as the brain of the system, taking input from the keypad and displaying results on an

LCD.
SYSTEM REQUIREMENTS:

• HARDWARE REQUIREMENT

Arduino Uno

16x2 LCD Display

4x4 Matrix Keypad

Servo motor (for lock mechanism)

Power supply (USB or battery)

• SOFTWARE REQUIREMENTS:

Arduino IDE

Embedded C for Arduino

CIRCUIT DIAGRAM :

The circuit connects the following:

Keypad: Connects to Arduino digital pins (e.g., 2–9)

LCD Display: Uses digital pins (e.g., 10–13 and A0–A1) with potentiometer for contrast

control

Servo Motor: Connected to pin 3 for lock actuation

Power Supply: 5V supply from USB or adapter

#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'}

{'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 {

digitalWrite(buzzer, HIGH);

delay(200);

digitalWrite(buzzer, LOW);

delay(200);

digitalWrite(buzzer, HIGH);

delay(200);

digitalWrite(buzzer, LOW);

delay(200);

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;

resetPassword();

void resetPassword() {

password.reset();

currentPasswordLength = 0;

lcd.clear();

a = 5;

}
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 {

digitalWrite(buzzer, HIGH);

delay(200);

digitalWrite(buzzer, LOW);

delay(200);
 digitalWrite(buzzer, HIGH);

delay(200);

digitalWrite(buzzer, LOW);

delay(200);

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;

resetPassword();

}
OUTPUT

LCD displays “Enter Password”

If correct password is entered, “Access Granted” is shown and lock opens

If wrong password, “Wrong Password” is displayed and lock remains closed

CONCLUSION:

This Smart Door Lock System provides a secure and cost-effective solution for access

control using a password mechanism. It demonstrates the integration of embedded

systems and IoT fundamentals, with further scope for internet-based remote access,

SMS alerts, or mobile app integration for enhanced functionality.

REFERENCES:

Arduino Official Documentation

LiquidCrystal Library – Arduino Reference

Keypad Library for Arduino

Servo Motor Control with Arduino

Smart Door Lock System using Arduino (Project Inspiration)