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.. _4.1.14_py_pi5:

4.1.11 Password Lock
================================

Introduction
-------------

In this project, we will use a keypad and a LCD to make a combination
lock. The LCD will display a corresponding prompt for you to type your
password on the Keypad. If the password is input correctly, “Correct”
will be displayed.

On the basis of this project, we can add additional electronic
components, such as buzzer, LED and so on, to add different experimental
phenomena for password input.

Required Components
------------------------------

In this project, we need the following components.

.. image:: ../python_pi5/img/4.1.14_password_lock_list.png
    :width: 800
    :align: center

It's definitely convenient to buy a whole kit, here's the link: 

.. list-table::
    :widths: 20 20 20
    :header-rows: 1

    *   - Name	
        - ITEMS IN THIS KIT
        - LINK
    *   - Raphael Kit
        - 337
        - |link_Raphael_kit|

You can also buy them separately from the links below.

.. list-table::
    :widths: 30 20
    :header-rows: 1

    *   - COMPONENT INTRODUCTION
        - PURCHASE LINK

    *   - :ref:`cpn_gpio_board`
        - |link_gpio_board_buy|
    *   - :ref:`cpn_breadboard`
        - |link_breadboard_buy|
    *   - :ref:`cpn_wires`
        - |link_wires_buy|
    *   - :ref:`cpn_resistor`
        - |link_resistor_buy|
    *   - :ref:`cpn_i2c_lcd`
        - |link_i2clcd1602_buy|
    *   - :ref:`cpn_keypad`
        - \-

Schematic Diagram
------------------

============ ======== ======== ===
T-Board Name physical wiringPi BCM
GPIO18       Pin 12   1        18
GPIO23       Pin 16   4        23
GPIO24       Pin 18   5        24
GPIO25       Pin 22   6        25
GPIO17       Pin 11   0        17
GPIO27       Pin 13   2        27
GPIO22       Pin 15   3        22
SPIMOSI      Pin 19   12       10
SDA1         Pin 3             
SCL1         Pin 5             
============ ======== ======== ===

.. image:: ../python_pi5/img/4.1.14_password_lock_schematic.png
   :align: center

Experimental Procedures
-------------------------

**Step 1:** Build the circuit.

.. image:: ../python_pi5/img/4.1.14_password_lock_circuit.png

**Step 2:** Change directory.

.. raw:: html

   <run></run>

.. code-block:: 

    cd ~/raphael-kit/python-pi5

**Step 3:** Run.

.. raw:: html

   <run></run>

.. code-block:: 

    sudo python3 4.1.14_PasswordLock_zero.py

After the code runs, keypad is used to input password: 1984. If the
“CORRECT” appears on LCD1602, there is no wrong with the password;
otherwise, “WRONG KEY” will appear.

.. note::

    * If you get the error ``FileNotFoundError: [Errno 2] No such file or directory: '/dev/i2c-1'``, you need to refer to :ref:`i2c_config` to enable the I2C.
    * If you get ``ModuleNotFoundError: No module named 'smbus2'`` error, please run ``sudo apt install python3-smbus2``.
    * If the error ``OSError: [Errno 121] Remote I/O error`` appears, it means the module is miswired or the module is broken.
    * If the code and wiring are fine, but the LCD still does not display content, you can turn the potentiometer on the back to increase the contrast.


.. warning::

    If there is an error prompt  ``RuntimeError: Cannot determine SOC peripheral base address``, please refer to :ref:`faq_soc` 

**Code**

.. note::
    You can **Modify/Reset/Copy/Run/Stop** the code below. But before that, you need to go to source code path like ``raphael-kit/python-pi5``. After modifying the code, you can run it directly to see the effect.

.. raw:: html

    <run></run>

.. code-block:: python

   #!/usr/bin/env python3

   from gpiozero import DigitalOutputDevice, Button
   from time import sleep
   import LCD1602

   class Keypad:
       def __init__(self, rows_pins, cols_pins, keys):
           """
           Initialize the Keypad with specified row and column pins and keys.
           :param rows_pins: List of GPIO pins for the rows.
           :param cols_pins: List of GPIO pins for the columns.
           :param keys: List of keys in the keypad layout.
           """
           self.rows = [DigitalOutputDevice(pin) for pin in rows_pins]  # Row pins setup
           self.cols = [Button(pin, pull_up=False) for pin in cols_pins]  # Column pins setup
           self.keys = keys  # Keypad key layout

       def read(self):
           """
           Read and return a list of keys that are currently pressed.
           :return: List of pressed keys.
           """
           pressed_keys = []
           for i, row in enumerate(self.rows):
               row.on()  # Activate current row
               for j, col in enumerate(self.cols):
                   if col.is_pressed:
                       index = i * len(self.cols) + j
                       pressed_keys.append(self.keys[index])
               row.off()  # Deactivate row after checking
           return pressed_keys

   # Password verification setup
   LENS = 4
   password = ['1', '9', '8', '4']  # Preset password
   testword = ['0', '0', '0', '0']  # User input storage
   keyIndex = 0  # Index for input keys

   def check():
       """
       Check if the entered password matches the preset password.
       :return: 1 if match, 0 otherwise.
       """
       for i in range(LENS):
           if password[i] != testword[i]:
               return 0
       return 1

   def setup():
       """
       Setup the keypad and LCD display.
       """
       global keypad, last_key_pressed
       # Pin configuration for keypad
       rows_pins = [18, 23, 24, 25]
       cols_pins = [10, 22, 27, 17]
       keys = ["1", "2", "3", "A",
               "4", "5", "6", "B",
               "7", "8", "9", "C",
               "*", "0", "#", "D"]

       # Initialize keypad and LCD
       keypad = Keypad(rows_pins, cols_pins, keys)
       last_key_pressed = []
       LCD1602.init(0x27, 1)  # Initialize LCD
       LCD1602.clear()
       LCD1602.write(0, 0, 'WELCOME!')
       LCD1602.write(2, 1, 'Enter password')
       sleep(2)

   def loop():
       """
       Main loop for handling keypad input and password verification.
       """
       global keyIndex, LENS, keypad, last_key_pressed
       while True:
           pressed_keys = keypad.read()
           if pressed_keys and pressed_keys != last_key_pressed:
               if keyIndex < LENS:
                   LCD1602.clear()
                   LCD1602.write(0, 0, "Enter password:")
                   LCD1602.write(15 - keyIndex, 1, pressed_keys[0])
                   testword[keyIndex] = pressed_keys[0]
                   keyIndex += 1

               if keyIndex == LENS:
                   if check() == 0:
                       LCD1602.clear()
                       LCD1602.write(3, 0, "WRONG KEY!")
                       LCD1602.write(0, 1, "please try again")
                   else:
                       LCD1602.clear()
                       LCD1602.write(4, 0, "CORRECT!")
                       LCD1602.write(2, 1, "welcome back")
                   keyIndex = 0  # Reset key index after checking

           last_key_pressed = pressed_keys
           sleep(0.1)

   try:
       setup()
       loop()
   except KeyboardInterrupt:
       LCD1602.clear()  # Clear LCD display on interrupt


**Code Explanation**

#. The script imports classes for managing digital output devices and buttons from the gpiozero library. It also imports the sleep function from the time module, enabling the addition of delays in the script's execution. Additionally, the LCD1602 library is imported for controlling the LCD1602 display.

   .. code-block:: python

       #!/usr/bin/env python3
       from gpiozero import DigitalOutputDevice, Button
       from time import sleep
       import LCD1602

#. Defines a custom class for managing the keypad. It initializes the keypad with specified row and column pins and provides a ``read`` method to detect pressed keys.

   .. code-block:: python

       class Keypad:
           def __init__(self, rows_pins, cols_pins, keys):
               """
               Initialize the Keypad with specified row and column pins and keys.
               :param rows_pins: List of GPIO pins for the rows.
               :param cols_pins: List of GPIO pins for the columns.
               :param keys: List of keys in the keypad layout.
               """
               self.rows = [DigitalOutputDevice(pin) for pin in rows_pins]  # Row pins setup
               self.cols = [Button(pin, pull_up=False) for pin in cols_pins]  # Column pins setup
               self.keys = keys  # Keypad key layout

           def read(self):
               """
               Read and return a list of keys that are currently pressed.
               :return: List of pressed keys.
               """
               pressed_keys = []
               for i, row in enumerate(self.rows):
                   row.on()  # Activate current row
                   for j, col in enumerate(self.cols):
                       if col.is_pressed:
                           index = i * len(self.cols) + j
                           pressed_keys.append(self.keys[index])
                   row.off()  # Deactivate row after checking
               return pressed_keys

#. Sets up the password verification system. ``LENS`` defines the length of the password. ``password`` is the preset correct password, while ``testword`` is used to store the user's input. ``keyIndex`` tracks the current position in the user's input.

   .. code-block:: python

       # Password verification setup
       LENS = 4
       password = ['1', '9', '8', '4']  # Preset password
       testword = ['0', '0', '0', '0']  # User input storage
       keyIndex = 0  # Index for input keys

#. Function to compare the entered password (``testword``) with the preset password (``password``) and return the result.

   .. code-block:: python

       def check():
           """
           Check if the entered password matches the preset password.
           :return: 1 if match, 0 otherwise.
           """
           for i in range(LENS):
               if password[i] != testword[i]:
                   return 0
           return 1

#. Initializes the keypad and LCD display. Displays a welcome message and instructions for entering the password.

   .. code-block:: python

       def setup():
           """
           Setup the keypad and LCD display.
           """
           global keypad, last_key_pressed
           # Pin configuration for keypad
           rows_pins = [18, 23, 24, 25]
           cols_pins = [10, 22, 27, 17]
           keys = ["1", "2", "3", "A",
                   "4", "5", "6", "B",
                   "7", "8", "9", "C",
                   "*", "0", "#", "D"]

           # Initialize keypad and LCD
           keypad = Keypad(rows_pins, cols_pins, keys)
           last_key_pressed = []
           LCD1602.init(0x27, 1)  # Initialize LCD
           LCD1602.clear()
           LCD1602.write(0, 0, 'WELCOME!')
           LCD1602.write(2, 1, 'Enter password')
           sleep(2)

#. The main loop for handling keypad input and password verification. It updates the LCD display based on the entered password and provides feedback if the password is correct or incorrect.

   .. code-block:: python

       def loop():
           """
           Main loop for handling keypad input and password verification.
           """
           global keyIndex, LENS, keypad, last_key_pressed
           while True:
               pressed_keys = keypad.read()
               if pressed_keys and pressed_keys != last_key_pressed:
                   if keyIndex < LENS:
                       LCD1602.clear()
                       LCD1602.write(0, 0, "Enter password:")
                       LCD1602.write(15 - keyIndex, 1, pressed_keys[0])
                       testword[keyIndex] = pressed_keys[0]
                       keyIndex += 1

                   if keyIndex == LENS:
                       if check() == 0:
                           LCD1602.clear()
                           LCD1602.write(3, 0, "WRONG KEY!")
                           LCD1602.write(0, 1, "please try again")
                       else:
                           LCD1602.clear()
                           LCD1602.write(4, 0, "CORRECT!")
                           LCD1602.write(2, 1, "welcome back")
                       keyIndex = 0  # Reset key index after checking

               last_key_pressed = pressed_keys
               sleep(0.1)

#. Runs the setup and enters the main loop. Allows for a clean exit from the program using a keyboard interrupt (Ctrl+C), clearing the LCD display.

   .. code-block:: python

       try:
           setup()
           loop()
       except KeyboardInterrupt:
           LCD1602.clear()  # Clear LCD display on interrupt