.. note:: Hello, welcome to the SunFounder Raspberry Pi & Arduino & ESP32 Enthusiasts Community on Facebook! Dive deeper into Raspberry Pi, Arduino, and ESP32 with fellow enthusiasts. **Why Join?** - **Expert Support**: Solve post-sale issues and technical challenges with help from our community and team. - **Learn & Share**: Exchange tips and tutorials to enhance your skills. - **Exclusive Previews**: Get early access to new product announcements and sneak peeks. - **Special Discounts**: Enjoy exclusive discounts on our newest products. - **Festive Promotions and Giveaways**: Take part in giveaways and holiday promotions. 👉 Ready to explore and create with us? Click [|link_sf_facebook|] and join today! .. _2.1.8_py_pi5: 2.1.8 Keypad ============ Introduction ------------ A keypad is a rectangular array of buttons. In this project, We will use it input characters. Required Components ------------------------------ In this project, we need the following components. .. image:: ../python_pi5/img/2.1.8_keypad_list.png 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_keypad` - \- Schematic Diagram ----------------- .. image:: ../python_pi5/img/2.1.8_keypad_chematic_1.png .. image:: ../python_pi5/img/2.1.8_keypad_chematic_2.png Experimental Procedures ----------------------- **Step 1:** Build the circuit. .. image:: ../python_pi5/img/2.1.8_keypad_circuit.png **Step 2:** Open the code file. .. raw:: html .. code-block:: cd ~/raphael-kit/python-pi5 **Step 3:** Run. .. raw:: html .. code-block:: sudo python3 2.1.8_Keypad_zero.py After the code runs, the values of pressed buttons on keypad (button Value) will be printed on the screen. .. 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 .. code-block:: python #!/usr/bin/env python3 from gpiozero import DigitalOutputDevice, Button from time import sleep class Keypad: def __init__(self, rows_pins, cols_pins, keys): """ Initialize the Keypad with specified row and column pins and keypad layout. :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. """ # Initialize row pins as DigitalOutputDevice self.rows = [DigitalOutputDevice(pin) for pin in rows_pins] # Initialize column pins as Buttons self.cols = [Button(pin, pull_up=False) for pin in cols_pins] self.keys = keys # Set the keypad layout def read(self): """ Read the currently pressed keys on the keypad. :return: A list of pressed keys. """ pressed_keys = [] # Scan each row and column to identify pressed keys for i, row in enumerate(self.rows): row.on() # Enable the current row for j, col in enumerate(self.cols): if col.is_pressed: # Check if the column button is pressed # Calculate the key index based on row and column index = i * len(self.cols) + j pressed_keys.append(self.keys[index]) row.off() # Disable the current row return pressed_keys try: # Configure rows, columns, and keypad layout 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"] # Create an instance of the Keypad class keypad = Keypad(rows_pins, cols_pins, keys) last_key_pressed = [] # Continuously read the keypad and print newly pressed keys while True: pressed_keys = keypad.read() if pressed_keys and pressed_keys != last_key_pressed: print(pressed_keys) # Print the list of pressed keys last_key_pressed = pressed_keys sleep(0.1) # Short delay to reduce CPU load except KeyboardInterrupt: # Handle a keyboard interrupt (Ctrl+C) for a clean exit pass **Code Explanation** #. Imports the ``DigitalOutputDevice`` and ``Button`` classes from the ``gpiozero`` library, and the ``sleep`` function for delays. .. code-block:: python #!/usr/bin/env python3 from gpiozero import DigitalOutputDevice, Button from time import sleep #. Defines the ``Keypad`` class. The ``__init__`` method initializes the keypad with given row and column pins and keys. The ``read`` method scans the keypad and returns a list of 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 keypad layout. :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. """ # Initialize row pins as DigitalOutputDevice self.rows = [DigitalOutputDevice(pin) for pin in rows_pins] # Initialize column pins as Buttons self.cols = [Button(pin, pull_up=False) for pin in cols_pins] self.keys = keys # Set the keypad layout def read(self): """ Read the currently pressed keys on the keypad. :return: A list of pressed keys. """ pressed_keys = [] # Scan each row and column to identify pressed keys for i, row in enumerate(self.rows): row.on() # Enable the current row for j, col in enumerate(self.cols): if col.is_pressed: # Check if the column button is pressed # Calculate the key index based on row and column index = i * len(self.cols) + j pressed_keys.append(self.keys[index]) row.off() # Disable the current row return pressed_keys #. Sets up the GPIO pins for rows and columns and defines the keypad layout. .. code-block:: python try: # Configure rows, columns, and keypad layout 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"] #. Creates an instance of the ``Keypad`` class with the specified configuration. .. code-block:: python try: ... # Create an instance of the Keypad class keypad = Keypad(rows_pins, cols_pins, keys) last_key_pressed = [] #. Continuously reads the keypad for pressed keys, prints any changes in the key state, and introduces a short delay to reduce CPU load. Catches a KeyboardInterrupt (like Ctrl+C) to allow for a graceful exit from the script. .. code-block:: python try: ... # Continuously read the keypad and print newly pressed keys while True: pressed_keys = keypad.read() if pressed_keys and pressed_keys != last_key_pressed: print(pressed_keys) # Print the list of pressed keys last_key_pressed = pressed_keys sleep(0.1) # Short delay to reduce CPU load except KeyboardInterrupt: # Handle a keyboard interrupt (Ctrl+C) for a clean exit pass