Circuit Documentation

Summary

This circuit is designed for a hotel safe system that utilizes a 4x4 keypad for user input, a 16x2 I2C LCD for display, and a servo motor to control the locking mechanism. The system allows users to set a 4-digit code to lock the safe and requires the same code to unlock it. The LCD provides user feedback, and the servo transitions gradually between open and closed positions.

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Component List

4x4 Keypad

• Description: A matrix keypad consisting of 4 rows and 4 columns, used for user input.
• Purpose: To allow users to enter a 4-digit code for locking and unlocking the safe.

16x2 I2C LCD

• Description: A liquid crystal display that can show 16 characters per line and has 2 lines.
• Purpose: To provide visual feedback to the user, displaying messages related to the locking and unlocking process.

Servo

• Description: A motor that can be controlled to rotate to specific angles.
• Purpose: To physically lock and unlock the safe by moving the locking mechanism.

Arduino UNO

• Description: A microcontroller board based on the ATmega328P.
• Purpose: To control the entire system, processing inputs from the keypad and controlling the LCD and servo.

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Wiring Details

4x4 Keypad

• R1 connected to D11 on Arduino UNO
• C4 connected to D4 on Arduino UNO
• R2 connected to D10 on Arduino UNO
• C2 connected to D6 on Arduino UNO
• R3 connected to D9 on Arduino UNO
• R4 connected to D8 on Arduino UNO
• C1 connected to D7 on Arduino UNO
• C3 connected to D5 on Arduino UNO

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16x2 I2C LCD

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

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Servo

• GND connected to GND on Arduino UNO
• VCC connected to 5V on Arduino UNO
• PWM connected to D3 on Arduino UNO

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Documented Code

/*
 * Arduino Sketch for a hotel safe system using a 4x4 Keypad, 16x2 I2C LCD, 
 * and a Servo motor. The system allows the user to set a 4-digit code to 
 * lock the safe and requires the same code to unlock it. The servo motor 
 * controls the locking mechanism, and the LCD provides user feedback.
 * The servo transitions gradually between open and closed positions.
 */

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

// LCD setup
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Keypad setup
const byte ROWS = 4;
const byte COLS = 4;
char keys[ROWS][COLS] = {
  {'1', '2', '3', 'A'},
  {'4', '5', '6', 'B'},
  {'7', '8', '9', 'C'},
  {'*', '0', '#', 'D'}
};
byte rowPins[ROWS] = {11, 10, 9, 8}; // Connect to the row pinouts of the keypad
byte colPins[COLS] = {7, 6, 5, 4};   // Connect to the column pinouts of the keypad
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

// Servo setup
Servo lockServo;
const int servoPin = 3;

// Variables
String enteredCode = "";
String storedCode = "";
bool isLocked = false;

void setup() {
  // Initialize LCD
  lcd.begin(16,2);
  lcd.backlight();
  
  // Initialize Servo
  lockServo.attach(servoPin);
  lockServo.write(0); // Initial position (unlocked)
  
  // Display initial message
  lcd.setCursor(0, 0);
  lcd.print("Code to Lock:");
}

void loop() {
  char key = keypad.getKey();
  
  if (key) {
    if (key == '#') {
      if (!isLocked) {
        if (enteredCode.length() == 4) {
          storedCode = enteredCode;
          lockSafe();
        } else {
          displayError("Enter 4 digits", 0);
        }
      } else {
        if (enteredCode == storedCode) {
          unlockSafe();
        } else {
          displayError("Wrong Code", 1);
        }
      }
      enteredCode = "";
    } else if (key >= '0' && key <= '9') {
      if (enteredCode.length() < 4) {
        enteredCode += key;
        lcd.setCursor(enteredCode.length() - 1, 1);
        lcd.print('*');
      }
    }
  }
}

void lockSafe() {
  isLocked = true;
  lcd.setCursor(0, 0);
  lcd.print("Locking Safe...");

  for (int pos = 0; pos <= 180; pos += 1) { // Gradually lock
    lockServo.write(pos);
    delay(15);
  }
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Safe Locked");
  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Code to Unlock");
}

void unlockSafe() {
  isLocked = false;
  lcd.setCursor(0, 0);
  lcd.print("Unlocking Safe...");

  for (int pos = 180; pos >= 0; pos -= 1) { // Gradually unlock
    lockServo.write(pos);
    delay(15);
  }
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Safe Unlocked");
  delay(2000);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Code to Lock");
}

void displayError(String message, int code) {
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print(message);
  delay(3000);
  lcd.clear();
  lcd.setCursor(0, 0);
  if (code == 0)
    lcd.print("Code to Lock");
  else
    lcd.print("Code to Unlock");
}

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This documentation provides a comprehensive overview of the circuit, detailing each component, its wiring, and the code that drives the system.