#include <LiquidCrystal.h>
LiquidCrystal Lcd(12,11,10,9,8,7);
void setup(){
  Lcd.begin(16,2);
  Lcd.print("Hello World!");
}
void loop (){

}

electronic-safe.ino

This project implements an electronic safe, powered by an Arduino Uno.

The safe has three main components:
An [16x02 LCD Monitor](https://wokwi.com/playground/lcd1602)
and a [Membrane Keypad](https://wokwi.com/playground/keypad) for the
user interface, and a Servo motor that powers the lock mechanism.

The state of the safe (locked/unlocked), as well as the secret code
are stored in the Arduino's [EEPROM](https://wokwi.com/playground/eeprom), so
the code isn't wiped even when the power goes off.


README.md

/**
   Arduino Electronic Safe

   Copyright (C) 2020, Uri Shaked.
   Released under the MIT License.
*/

#ifndef ICONS_H
#define ICONS_H

#include <LiquidCrystal.h>

// Our custom icon numbers
#define ICON_LOCKED_CHAR   (byte)0
#define ICON_UNLOCKED_CHAR (byte)1

// This is a standard icon on the LCD1602 character set
#define ICON_RIGHT_ARROW   (byte)126

void init_icons(LiquidCrystal &lcd);

#endif /* ICONS_H */


icons.h

/**
   Arduino Electronic Safe

   Copyright (C) 2020, Uri Shaked.
   Released under the MIT License.
*/

#ifndef SAFESTATE_H
#define SAFESTATE_H

class SafeState {
  public:
    SafeState();
    void lock();
    bool unlock(String code);
    bool locked();
    bool hasCode();
    void setCode(String newCode);

  private:
    void setLock(bool locked);
    bool _locked;
};

#endif /* SAFESTATE_H */


SafeState.h

/**
   Arduino Electronic Safe

   Copyright (C) 2020, Uri Shaked.
   Released under the MIT License.
*/

#include <Arduino.h>
#include "icons.h"

const byte iconLocked[8] PROGMEM = {
  0b01110,
  0b10001,
  0b10001,
  0b11111,
  0b11011,
  0b11011,
  0b11111,
};

const byte iconUnlocked[8] PROGMEM = {
  0b01110,
  0b10000,
  0b10000,
  0b11111,
  0b11011,
  0b11011,
  0b11111,
};

void init_icons(LiquidCrystal &lcd) {
  byte icon[8];
  memcpy_P(icon, iconLocked, sizeof(icon));
  lcd.createChar(ICON_LOCKED_CHAR, icon);
  memcpy_P(icon, iconUnlocked, sizeof(icon));
  lcd.createChar(ICON_UNLOCKED_CHAR, icon);
}


icons.cpp

/**
   Arduino Electronic Safe

   Copyright (C) 2020, Uri Shaked.
   Released under the MIT License.
*/

#include <Arduino.h>
#include <EEPROM.h>
#include "SafeState.h"

/* Safe state */
#define EEPROM_ADDR_LOCKED   0
#define EEPROM_ADDR_CODE_LEN 1
#define EEPROM_ADDR_CODE     2
#define EEPROM_EMPTY         0xff

#define SAFE_STATE_OPEN (char)0
#define SAFE_STATE_LOCKED (char)1

SafeState::SafeState() {
  this->_locked = EEPROM.read(EEPROM_ADDR_LOCKED) == SAFE_STATE_LOCKED;
}

void SafeState::lock() {
  this->setLock(true);
}

bool SafeState::locked() {
  return this->_locked;
}

bool SafeState::hasCode() {
  auto codeLength = EEPROM.read(EEPROM_ADDR_CODE_LEN);
  return codeLength != EEPROM_EMPTY;
}

void SafeState::setCode(String newCode) {
  EEPROM.write(EEPROM_ADDR_CODE_LEN, newCode.length());
  for (byte i = 0; i < newCode.length(); i++) {
    EEPROM.write(EEPROM_ADDR_CODE + i, newCode[i]);
  }
}

bool SafeState::unlock(String code) {
  auto codeLength = EEPROM.read(EEPROM_ADDR_CODE_LEN);
  if (codeLength == EEPROM_EMPTY) {
    // There was no code, so unlock always succeeds
    this->setLock(false);
    return true;
  }
  if (code.length() != codeLength) {
    return false;
  }
  for (byte i = 0; i < code.length(); i++) {
    auto digit = EEPROM.read(EEPROM_ADDR_CODE + i);
    if (digit != code[i]) {
      return false;
    }
  }
  this->setLock(false);
  return true;
}

void SafeState::setLock(bool locked) {
  this->_locked = locked;
  EEPROM.write(EEPROM_ADDR_LOCKED, locked ? SAFE_STATE_LOCKED : SAFE_STATE_OPEN);
}



SafeState.cpp

diagram.json

# Wokwi Library List
# See https://docs.wokwi.com/guides/libraries

Keypad
LiquidCrystal
Servo
