Raspberry Pi - Keypad - LCD

This tutorial instructs you how to use Raspberry Pi to display the input from keypad on LCD display.

Hardware Preparation

1×Raspberry Pi 4 Model B
1×Keypad 3x4 and 4x4 Kit
1×Jumper Wires
1×(Optional) Screw Terminal Adapter for Raspberry Pi

Or you can buy the following sensor kits:

1×DIYables Sensor Kit (30 sensors/displays)
1×DIYables Sensor Kit (18 sensors/displays)
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Overview of Keypad and LCD

If you are unfamiliar with keypad and LCD (including pinout, functionality, programming, etc.), the following tutorials can help:

Wiring Diagram

The wiring diagram between Raspberry Pi and Keypad LCD

This image is created using Fritzing. Click to enlarge image

Raspberry Pi Code

Detailed Instructions

  • Make sure you have Raspbian or any other Raspberry Pi compatible operating system installed on your Pi.
  • Make sure your Raspberry Pi is connected to the same local network as your PC.
  • Make sure your Raspberry Pi is connected to the internet if you need to install some libraries.
  • If this is the first time you use Raspberry Pi, See how to set up the Raspberry Pi
  • Connect your PC to the Raspberry Pi via SSH using the built-in SSH client on Linux and macOS or PuTTY on Windows. See to how connect your PC to Raspberry Pi via SSH.
  • Make sure you have the RPi.GPIO library installed. If not, install it using the following command:
sudo apt-get update sudo apt-get install python3-rpi.gpio
pip install lcddriver
  • Create a Python script file keypad_lcd.py and add the following code:
# This Raspberry Pi code was developed by newbiely.com # This Raspberry Pi code is made available for public use without any restriction # For comprehensive instructions and wiring diagrams, please visit: # https://newbiely.com/tutorials/raspberry-pi/raspberry-pi-keypad-lcd import RPi.GPIO as GPIO from lcddriver import lcd from time import sleep # GPIO pins for the keypad rows and columns ROW_PINS = [17, 27, 22, 24] COL_PINS = [25, 8, 7] # I2C address 0x27, 16 columns, 2 rows LCD = lcd() # Mapping of keys on the keypad keys = [ ['1', '2', '3'], ['4', '5', '6'], ['7', '8', '9'], ['*', '0', '#'] ] def setup_gpio(): GPIO.setmode(GPIO.BCM) for row_pin in ROW_PINS: GPIO.setup(row_pin, GPIO.IN, pull_up_down=GPIO.PUD_UP) for col_pin in COL_PINS: GPIO.setup(col_pin, GPIO.OUT) def read_key(): for col_num, col_pin in enumerate(COL_PINS): GPIO.output(col_pin, GPIO.LOW) for row_num, row_pin in enumerate(ROW_PINS): if GPIO.input(row_pin) == GPIO.LOW: return keys[row_num][col_num] GPIO.output(col_pin, GPIO.HIGH) return None def display_key(key): LCD.lcd_clear() LCD.lcd_display_string(f"Key Pressed:", 1) LCD.lcd_display_string(f"{key}", 2) try: setup_gpio() while True: key = read_key() if key is not None: display_key(key) sleep(0.1) # Adjust the sleep duration as needed except KeyboardInterrupt: pass finally: GPIO.cleanup() LCD.lcd_clear()
  • Save the file and run the Python script by executing the following command in the terminal:
python3 keypad_lcd.py

The script runs in an infinite loop continuously until you press Ctrl + C in the terminal.

  • Press certain keys on the keypad
  • Check out the outcome on the LCD display

If the LCD display is not showing anything, check out Troubleshooting on LCD I2C . for assistance.

Code Explanation

Check out the line-by-line explanation contained in the comments of the source code!

Video Tutorial


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