Circuit Documentation

Summary

This circuit is a door lock system that uses an Arduino UNO microcontroller to control a servo motor, a 16x2 I2C LCD, a 4x4 membrane matrix keypad, and a buzzer. The system allows users to enter a password via the keypad, which is then evaluated by the Arduino. If the password is correct, the servo motor unlocks the door, and the LCD displays a message. If the password is incorrect, the buzzer sounds an alert, and the LCD prompts the user to try again.

Component List

1. Arduino UNO

   • Description: A microcontroller board based on the ATmega328P.
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

2. 4x4 Membrane Matrix Keypad

   • Description: A keypad with 4 rows and 4 columns.
   • Pins: R1, R2, R3, R4, C1, C2, C3, C4

3. Servo

   • Description: A servo motor used to lock and unlock the door.
   • Pins: gnd, vcc, pulse

4. 16x2 I2C LCD

   • Description: A 16x2 character LCD with I2C interface.
   • Pins: GND, VCC, SDA, SCL

5. Buzzer

   • Description: A piezoelectric buzzer used for audio alerts.
   • Pins: PIN, GND

Wiring Details

Arduino UNO

• 3.3V connected to Servo vcc
• 5V connected to 16x2 I2C LCD VCC
• GND connected to:
  • 16x2 I2C LCD GND
  • Servo gnd
  • Buzzer GND
• A4 connected to 16x2 I2C LCD SDA
• A5 connected to 16x2 I2C LCD SCL
• D11 connected to Buzzer PIN
• D10 connected to Servo pulse
• D9 connected to 4x4 Membrane Matrix Keypad R1
• D8 connected to 4x4 Membrane Matrix Keypad R2
• D7 connected to 4x4 Membrane Matrix Keypad R3
• D6 connected to 4x4 Membrane Matrix Keypad R4
• D5 connected to 4x4 Membrane Matrix Keypad C1
• D4 connected to 4x4 Membrane Matrix Keypad C2
• D3 connected to 4x4 Membrane Matrix Keypad C3
• D2 connected to 4x4 Membrane Matrix Keypad C4

4x4 Membrane Matrix Keypad

• R1 connected to Arduino UNO D9
• R2 connected to Arduino UNO D8
• R3 connected to Arduino UNO D7
• R4 connected to Arduino UNO D6
• C1 connected to Arduino UNO D5
• C2 connected to Arduino UNO D4
• C3 connected to Arduino UNO D3
• C4 connected to Arduino UNO D2

Servo

• vcc connected to Arduino UNO 3.3V
• gnd connected to Arduino UNO GND
• pulse connected to Arduino UNO D10

16x2 I2C LCD

• VCC connected to Arduino UNO 5V
• GND connected to Arduino UNO GND
• SDA connected to Arduino UNO A4
• SCL connected to Arduino UNO A5

Buzzer

• PIN connected to Arduino UNO D11
• GND connected to Arduino UNO GND

Code Documentation

#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 {
    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);
    digitalWrite(buzzer, HIGH);
    delay(200);
    digitalWrite(buzzer, LOW);
    delay(200);
    lcd.setCursor(0, 0);
    lcd.print("WRONG PASSWORD!");
    lcd.setCursor(0, 1);
    lcd.print