Digital Code Lock using Arduino

Security is a major concern in our day to day life, and digital locks have became an important part of these security systems. One such digital code lock is imitated in this project using arduino board and a matrix keypad. 

 

Components

  1. Arduino
  2. Keypad Module
  3. Buzzer
  4. 16x2 LCD
  5. BC547 Transistor
  6. Resistor (1k)
  7. Bread board
  8. Power
  9. Connecting wires

 

In this circuit we have used multiplexing technique to interface keypad for input the password in the system. Here we are using 4x4 keypad which contains 16 key. If we want to use 16 keys then we need 16 pin for connection to arduino but in multiplexing technique we need to use only 8 pin for interfacing 16 keys. So that it is a smart way to interface a keypad module. [Also check: Keypad Interfacing with Arduino]

 

Multiplexing Technique: Multiplexing technique is a very efficient way to reduce number of pins used with the microcontroller for providing input or password or numbers. Basically this technique is used in two ways - one is row scanning and other one is colon scanning. But in this arduino based project we have used keypad library so we do not need to make any multiplexing code for this system. We only need to use keypad library for providing input.

 

Circuit Description

Circuit of this project is very simple which contains Arduino, keypad module, buzzer and LCD. Arduino controls the complete processes like taking password form keypad module, comparing passwords, driving buzzer and sending status to LCD display. Keypad is used for taking password. Buzzer is used for indications and LCD is used for displaying status or messages on it. Buzzer is driven by using a NPN transistor.

Electronic Code Lock Circuit Diagram

Keypad module’s Column pins are directly connected to pin 4, 5, 6, 7 and Row pins are connected to 3, 2, 1, 0 of arduino uno. A 16x2 LCD is connected with arduino in 4-bit mode. Control pin RS, RW and En are directly connected to arduino pin 13, GND and 12. And data pin D4-D7 is connected to pins 11, 10, 9 and 8 of arduino. And one buzzer is connected at pin 14(A1) of arduino through a BC547 NPN transistor.

 

Working

We have used inbuilt arduino’s EEPROM to save password, so when we run this circuit first time program read a garbage data from inbuilt arduino’s EEPROM and compare it with input password and give a message on LCD that is Access Denied because password does not match. For solving this problem we need to set a default password for the first time by using programming given below:

for(int j=0;j<4;j++)
EEPROM.write(j, j+49);
lcd.print("Enter Ur Passkey:");
lcd.setCursor(0,1);
for(int j=0;j<4;j++)
pass[j]=EEPROM.read(j);

This will set password “1234” to EEPROM of Arduino.

After running it first time we need to remove this from program and again write the code in to the arduino and run. Now your system will run fine. And for your second time used password is now “1234”. Now you can change it by pressing # button and then enter your current password and then enter your new password. 

 

When you will enter your password, system will compare your entered password with that password that is stored in EEPROM of arduino. If match is occurred then LCD will show “access granted” and if password is wrong then LCD will “Access Denied” and buzzer continuously beep for some time. And buzzer is also beep a single time whenever user will press any button from keypad.

 

Programming Description

In code we have used keypad library for interfacing keypad with arduino.

#include <Keypad.h>
#include<LiquidCrystal.h>
#include<EEPROM.h>
const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns

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

byte rowPins[ROWS] = {3, 2, 1, 0}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {4, 5, 6, 7}; //connect to the column pinouts of the keypad

//initialize an instance of class NewKeypad
Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS); 

We have included LCD library for LCD interfacing and for interfacing EEPROM we have included library EEPROM.h., and then initialized variable and defined pins for components.

#define buzzer 15

LiquidCrystal lcd(13,12,11,10,9,8);

char password[4];

char pass[4],pass1[4];

int i=0;

char customKey=0;

And then we initialized LCD and give direction to pins in setup function

void setup()
{
  lcd.begin(16,2);
  pinMode(led, OUTPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(m11, OUTPUT);
  pinMode(m12, OUTPUT);
  lcd.print("  Electronic ");
  lcd.setCursor(0,1);
  lcd.print("  Keypad Lock ");
  delay(2000);
  lcd.clear();
  lcd.print("Enter Ur Passkey:");
  lcd.setCursor(0,1);

After this we read keypad in loop function

  customKey = customKeypad.getKey();
  if(customKey=='#')
  change();
  if (customKey)
  {
     password[i++]=customKey;
     lcd.print(customKey);
     beep();
  }

And then compare password with save password using string compare method.

 if(i==4)
  {
    delay(200);
    for(int j=0;j<4;j++)
    pass[j]=EEPROM.read(j);
    if(!(strncmp(password, pass,4)))
    {
      digitalWrite(led, HIGH);
      beep();
      lcd.clear();
      lcd.print("Passkey Accepted");
      delay(2000);
      lcd.setCursor(0,1);
      lcd.print("#.Change Passkey");
      delay(2000);
      lcd.clear();
      lcd.print("Enter Passkey:");
      lcd.setCursor(0,1);
      i=0;
      digitalWrite(led, LOW);
    }

This is password change function and buzzer beep function

void change()
{
  int j=0;
  lcd.clear();
  lcd.print("UR Current Passk");
  lcd.setCursor(0,1);
  while(j<4)
  {
    char key=customKeypad.getKey();
    if(key)
    {
      pass1[j++]=key;
      lcd.print(key);

void beep()
{
  digitalWrite(buzzer, HIGH);
  delay(20);
  digitalWrite(buzzer, LOW);
}
Code: 

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

#define buzzer 15
LiquidCrystal lcd(13,12,11,10,9,8);

char password[4];
char pass[4],pass1[4];
int i=0;
char customKey=0;

const byte ROWS = 4; //four rows
const byte COLS = 4; //four columns

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

byte rowPins[ROWS] = {3, 2, 1, 0}; //connect to the row pinouts of the keypad
byte colPins[COLS] = {4, 5, 6, 7}; //connect to the column pinouts of the keypad

//initialize an instance of class NewKeypad
Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS); 

void setup()
{
  lcd.begin(16,2);
  pinMode(led, OUTPUT);
  pinMode(buzzer, OUTPUT);
  pinMode(m11, OUTPUT);
  pinMode(m12, OUTPUT);
  lcd.print("  Electronic ");
  lcd.setCursor(0,1);
  lcd.print("  Keypad Lock ");
  delay(2000);
  lcd.clear();
  lcd.print("Enter Ur Passkey:");
  lcd.setCursor(0,1);
  for(int j=0;j<4;j++)
  EEPROM.write(j, j+49);
  for(int j=0;j<4;j++)
  pass[j]=EEPROM.read(j);
}
  
void loop()
{
  customKey = customKeypad.getKey();
  if(customKey=='#')
  change();
  if (customKey)
  {
     password[i++]=customKey;
     lcd.print(customKey);
     beep();
  }
  if(i==4)
  {
    delay(200);
    for(int j=0;j<4;j++)
    pass[j]=EEPROM.read(j);
    if(!(strncmp(password, pass,4)))
    {
      digitalWrite(led, HIGH);
      beep();
      lcd.clear();
      lcd.print("Passkey Accepted");
      delay(2000);
      lcd.setCursor(0,1);
      lcd.print("#.Change Passkey");
      delay(2000);
      lcd.clear();
      lcd.print("Enter Passkey:");
      lcd.setCursor(0,1);
      i=0;
      digitalWrite(led, LOW);
    }
    
    else
    {
      digitalWrite(buzzer, HIGH);
      lcd.clear();
      lcd.print("Access Denied...");
      lcd.setCursor(0,1);
      lcd.print("#.Change Passkey");
      delay(2000);
      lcd.clear();
      lcd.print("Enter Passkey:");
      lcd.setCursor(0,1);
      i=0;
      digitalWrite(buzzer, LOW);
    }
  }
}

void change()
{
  int j=0;
  lcd.clear();
  lcd.print("UR Current Passk");
  lcd.setCursor(0,1);
  while(j<4)
  {
    char key=customKeypad.getKey();
    if(key)
    {
      pass1[j++]=key;
      lcd.print(key);
      beep();
    }
    key=0;
  }
  delay(500);
  
  if((strncmp(pass1, pass, 4)))
  {
    lcd.clear();
    lcd.print("Wrong Passkey...");
    lcd.setCursor(0,1);
    lcd.print("Better Luck Again");
    delay(1000);
  }
  else
  {
    j=0;
    
  lcd.clear();
  lcd.print("Enter New Passk:");
  lcd.setCursor(0,1);
  while(j<4)
  {
    char key=customKeypad.getKey();
    if(key)
    {
      pass[j]=key;
      lcd.print(key);
      EEPROM.write(j,key);
      j++;
      beep();
    }
  }
  lcd.print("  Done......");
  delay(1000);
  }
  lcd.clear();
  lcd.print("Enter Ur Passk:");
  lcd.setCursor(0,1);
  customKey=0;
}

void beep()
{
  digitalWrite(buzzer, HIGH);
  delay(20);
  digitalWrite(buzzer, LOW);
}

Video: 

Comments (33)

  • shiela's picture
    shiela

    hi, i'm planning on making your digital code lock using arduino. i want to use a solenoid lock but i dont know the circuit diagram. can you help me? thanks

    Nov 28, 2015
  • suhail's picture
    suhail

    When reset the password is default password.but we are the followers of yours need when we reset the changed password must be there

    Jan 10, 2016
  • suhail's picture
    suhail

    first upload the code
    then remove these lines
    for(int j=0;j<4;j++)
    EEPROM.write(j, j+49);
    the reupload it its work fine

    Apr 07, 2016
  • Vinsen's picture
    Vinsen

    can i know what is the m11 and m12 as output? what are those. i am new to arduino please help:)

    Apr 09, 2016
  • ROLLS's picture
    ROLLS

    compilation terminated.

    exit status 1
    Error compiling for board Arduino/Genuino Uno.
    hello, please help. this is the error message i got when i tried verifying the full code on my arduino software

    Apr 30, 2016
  • harish's picture
    harish

    #include <Keypad.h>
    this line is correct or not
    because my arduino software
    it show
    compilation terminated

    exit status 1
    error compilation for board arduino/genuino uno
    what is that mean?

    May 14, 2016
  • Rupa's picture
    Rupa

    This is ok and have a problem what if someone pressed only 2 digit and left. How will you reset your system to execute from setup again

    Jul 27, 2016
  • Satayprakash's picture
    Satayprakash

    #include <Keypad.h>
    this line is correct or not
    because my arduino software
    it show

    Aug 13, 2016
  • dianne's picture
    dianne

    how to encrypt the passkey

    Oct 10, 2016
  • Radek's picture
    Radek

    Dobrý den,
    vyzkoušel jsem Váš návrh Digital Code Lock using Arduino,a funguje velice pěkně.
    Bylo by možné, aby se v pracovním módu ukazovaly při vkládání pouze hvězdičky, aby na display nebylo vidět heslo? Je možné doplnit kód o zprovoznění pinMode(m11, OUTPUT);
    pinMode(m12, OUTPUT); pinMode(led, OUTPUT);?
    Jinak jsem nadšený z Vašeho řešení pomocí Arduino Uno a LCD, opravdu pěkné.
    Radek

    Nov 18, 2016
  • abdullah's picture
    abdullah

    led was not declared in this scope

    Dec 27, 2016
  • Ibtahaj ali's picture
    Ibtahaj ali

    pinMode(led, OUTPUT);
    pinMode(buzzer, OUTPUT);
    pinMode(m11, OUTPUT);
    pinMode(m12, OUTPUT);
    whta sholud be here it is constatntly giving me errors plzzz help me plzzzzzzzzzzzzzzzzz

    Jan 01, 2017
  • Lebrome's picture
    Lebrome

    it shows error: 'EEPROM' was not declared in this scope. but i already import that library in these code but still it appears an error? how can i fix it ?

    Feb 01, 2017
  • Dylan's picture
    Dylan

    Hi Saddam!

    Thanks for the tip. This is a great help. I will try to use EEPROM.h instead of Password.h

    Thank you!

    Feb 07, 2017
  • shreya's picture
    shreya

    it is showing error dat" led is not declared".....wat shud i do now?????

    Mar 12, 2017
  • kuldeep's picture
    kuldeep

    nice bro,thanks

    Mar 29, 2017
  • abdelwahab's picture
    abdelwahab

    the right code after modification

    #include <Keypad.h>
    #include<LiquidCrystal.h>
    #include<EEPROM.h>
    #define buzzer 15
    LiquidCrystal lcd(13,12,11,10,9,8);
    char password[4];
    char pass[4],pass1[4];
    int i=0;

    char customKey=0;
    const byte ROWS = 4; //four rows
    const byte COLS = 4; //four columns
    char hexaKeys[ROWS][COLS] = {
    {'1','2','3','A'},
    {'4','5','6','B'},
    {'7','8','9','C'},
    {'*','0','#','D'}
    };
    byte rowPins[ROWS] = {3, 2, 1, 0}; //connect to the row pinouts of the keypad
    byte colPins[COLS] = {4, 5, 6, 7}; //connect to the column pinouts of the keypad
    //initialize an instance of class NewKeypad
    Keypad customKeypad = Keypad( makeKeymap(hexaKeys), rowPins, colPins, ROWS, COLS);
    void setup()
    {
    lcd.begin(16,2);

    pinMode(buzzer, OUTPUT);

    lcd.print(" Electronic ");
    lcd.setCursor(0,1);
    lcd.print(" Keypad Lock ");
    delay(2000);
    lcd.clear();
    lcd.print("Enter Ur Passkey:");
    lcd.setCursor(0,1);
    for(int j=0;j<4;j++)
    EEPROM.write(j, j+49);
    for(int j=0;j<4;j++)
    pass[j]=EEPROM.read(j);
    }

    void loop()
    {
    customKey = customKeypad.getKey();
    if(customKey=='#')
    change();
    if (customKey)
    {
    password[i++]=customKey;
    lcd.print(customKey);
    beep();
    }
    if(i==4)
    {
    delay(200);
    for(int j=0;j<4;j++)
    pass[j]=EEPROM.read(j);
    if(!(strncmp(password, pass,4)))
    {

    beep();
    lcd.clear();
    lcd.print("Passkey Accepted");
    delay(2000);
    lcd.setCursor(0,1);
    lcd.print("#.Change Passkey");
    delay(2000);
    lcd.clear();
    lcd.print("Enter Passkey:");
    lcd.setCursor(0,1);
    i=0;

    }

    else
    {
    digitalWrite(buzzer, HIGH);
    lcd.clear();
    lcd.print("Access Denied...");
    lcd.setCursor(0,1);
    lcd.print("#.Change Passkey");
    delay(2000);
    lcd.clear();
    lcd.print("Enter Passkey:");
    lcd.setCursor(0,1);
    i=0;
    digitalWrite(buzzer, LOW);
    }
    }
    }
    void change()
    {
    int j=0;
    lcd.clear();
    lcd.print("UR Current Passk");
    lcd.setCursor(0,1);
    while(j<4)
    {
    char key=customKeypad.getKey();
    if(key)
    {
    pass1[j++]=key;
    lcd.print(key);
    beep();
    }
    key=0;
    }
    delay(500);

    if((strncmp(pass1, pass, 4)))
    {
    lcd.clear();
    lcd.print("Wrong Passkey...");
    lcd.setCursor(0,1);
    lcd.print("Better Luck Again");
    delay(1000);
    }
    else
    {
    j=0;

    lcd.clear();
    lcd.print("Enter New Passk:");
    lcd.setCursor(0,1);
    while(j<4)
    {
    char key=customKeypad.getKey();
    if(key)
    {
    pass[j]=key;
    lcd.print(key);
    EEPROM.write(j,key);
    j++;
    beep();
    }
    }
    lcd.print(" Done......");
    delay(1000);
    }
    lcd.clear();
    lcd.print("Enter Ur Passk:");
    lcd.setCursor(0,1);
    customKey=0;
    }
    void beep()
    {
    digitalWrite(buzzer, HIGH);
    delay(20);
    digitalWrite(buzzer, LOW);
    }

    May 06, 2017
  • surya rama's picture
    surya rama

    thank you very much..

    Oct 12, 2017
  • attari's picture
    attari

    Excellent sujet , merci pour les explications///
    Bonne continuation....

    May 27, 2017
  • Abdifitah mohamoud's picture
    Abdifitah mohamoud

    i am from somalia i want to design this project so can you help me i don't have any data about this project but i like to make this project thanx sir.

    Jun 03, 2017
  • ArdPi_Tinkerer's picture
    ArdPi_Tinkerer

    Thanks for posting this project.  I've just completed it myself!

    Jun 07, 2017
  • sathwik's picture
    sathwik

    sir i need full code including library files code

    Jun 21, 2017
  • venkat's picture
    venkat

    compilation terminated.

    exit status 1
    Error compiling for board Arduino/Genuino Uno.

    how can i solve this error

    Jul 01, 2017
  • Abhishek's picture
    Abhishek

    Please the previous comment before posting, your question/issue might have answered already.

    Jul 05, 2017
  • Mel's picture
    Mel

    EEPROM.write(j, j+49);

    may I know what value is j+49 is?
    you write it in address "j" right??
    ty for reply

    Jul 31, 2017
  • Sheryar Hanif Baig's picture
    Sheryar Hanif Baig

    I want to make this project can you give me the actual code with no errors ,and plz also tell it's some applications . Thank you

    Oct 15, 2017
  • Abdul Zelani's picture
    Abdul Zelani

    Anyone knows how to program pic16f877a my program is working on simulation mode but not on hardware any help plz...

    Jan 23, 2018
  • VES VEGAS's picture
    VES VEGAS

    Hello, Dear
    I am new and beginner in electronics. I want to build the above circuit, my proteus is not having the keypad shown here. I can only find the one with seven pins not eight. How can I get it?
    Please help me!
    Thank you!

    Mar 20, 2018
  • R.HIMA JYOTHI's picture
    R.HIMA JYOTHI

    what is use of transistor??? can't we connect buzzer without transistor???

    Mar 22, 2018
  • Pooja Karamchandani's picture
    Pooja Karamchandani

    Awesome work :)

    Jun 20, 2018

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