Safe Project Description

This project involves designing an electronic safe using an ATmega32 microcontroller, a keypad for input, an LCD for feedback, and a DC motor to control the locking mechanism. The microcontroller interfaces with external EEPROM to store and verify a user-set password for accessing the safe.

Components Used:

1. ATmega32 Microcontroller:

   • Central control unit that manages input from the keypad, interacts with the EEPROM, updates the LCD, and controls the DC motor.

2. Keypad:

   • A numeric keypad used to input passwords for setting and verifying the code to open the safe.

3. LCD Display (LM016L):

   • A 16x2 character display used to provide user feedback, such as entering and verifying passwords, or indicating if the password is correct or incorrect.

4. DC Motor:

   • Used to simulate the locking and unlocking mechanism of the safe. The motor turns when the correct password is entered, unlocking the safe.

5. EEPROM (External Memory):

   • Stores the password securely. The EEPROM ensures that the password is retained even when power is turned off.

Key Functionalities:

1. Initialization:

   • On startup, the system initializes the LCD, keypad, and motor.
   • The system checks if a password has been set by reading a specific EEPROM address. If not set, it prompts the user to set a new password.

2. Password Setting:

   • The user is prompted to enter a 4-digit password using the keypad.
   • The entered password is displayed as asterisks (*) on the LCD to maintain confidentiality.
   • The password is stored in four consecutive addresses in the EEPROM.

3. Password Verification:

   • When the user attempts to open the safe, they must enter the 4-digit password.
   • The entered password is compared with the stored password in the EEPROM.
   • If the password matches, the safe unlocks, and the DC motor rotates to open the lock.
   • The LCDs a success message: "correct password" and "the safe opened".

4. Changing the Password:

   • After unlocking, the user has an option to change the password.
   • The user is prompted to enter the current password again to confirm identity, and then a new password can be set following the same procedure as the initial setup.

5. Wrong Password Handling:

   • The user has a maximum of three attempts to enter the correct password.
   • If a wrong password is entered, the system decrements the remaining attempts and displays "wrong password" and the number of remaining attempts.
   • After three failed attempts, the system locks out the user for some time (e.g., 60 minutes), displaying a countdown on the LCD.

6. EEPROM Usage:

   • EEPROM_status_address (0x20): Indicates if a password has been set. Initialized to 0xFF (default) if no password is set.
   • EEPROM_first_address_of_password (0x21) to EEPROM_fourth_address_of_password (0x24): Stores each digit of the 4-digit password.

Code Walkthrough:

1. Main Function:

   • Initializes peripherals (LCD, keypad, motor).
   • Checks if a password has been set by reading EEPROM_status_address.
   • If no password is set, calls set_password() to initialize a new password.
   • Continuously loops to check if the entered password matches the stored password, allowing access and further options if correct.

2. Set Password (set_password function):

   • Clears the LCD screen and prompts the user to set a new password.
   • Reads each digit from the keypad, displays it briefly on the LCD before replacing it with an asterisk, and stores it in EEPROM.
   • Updates the EEPROM_status_address to indicate that a password has been set.

3. Check Password (check_password function):

   • Clears the LCD and prompts the user to enter the password.
   • Reads each entered digit, displays it temporarily, and compares it against the stored password.
   • Stores the entered digits in the password_array for further comparison.

Operational Flow:

1. User Starts the System:

   • System checks if a password is set. If not, it prompts to set a new one.
   • If a password exists, the user is prompted to enter it.

2. User Enters the Password:

   • The system verifies the entered password against the stored password.
   • If correct, it unlocks the safe, and the user is given options to change the password or keep it.

3. Wrong Password Handling:

   • If the entered password is incorrect, the user is notified and asked to try again.
   • After three incorrect attempts, the user is locked out for a specified duration.

This safe project demonstrates a secure, user-interactive embedded system using an ATmega32 microcontroller to handle digital input, provide feedback, and control an electromechanical device.