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 | × | LCD I2C | |
| 1 | × | Keypad 3x4 and 4x4 Kit | |
| 1 | × | Breadboard | |
| 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
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
- Prior to utilizing the LCD I2C with a Raspberry Pi, we need to enable I2C interface on Raspberry Pi. See How to enable I2C interface on Raspberry Pi
- Install the LCD I2C library by running the following command:
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!