RASPBERRY PI | KEY PRESS CONTROL

In this guide, you'll learn how to connect three LEDs to a Raspberry Pi and write Python code to control them using keyboard input. This project is useful for understanding GPIO control and event-driven programming in Python.

SECTION 1 | MATERIAL NEEDED

• Raspberry Pi (any model with GPIO pins)
  
• 3 LEDs (red, green, blue)
  
• 3 Resistors (330Ω recommended)
  
• Breadboard and jumper wires
  

SECTION 2 | THE CONNECTIONS

Each LED has two terminals:

1. Anode (+) connects to a Raspberry Pi GPIO pin
2. Cathode (-) connects to GND through a 330Ω resistor

​Pin ConnectionsRed LED - GPIO 7 (Pin 7)
Green LED -GPIO 11 (Pin 11)
Blue LED - GPIO 13 (Pin 13)

SECTION 3 | THE CODE

Once wired, we need a Python script to read the state of the toggle switch. The script below detects when the switch is turned ON or OFF and prints a message.

In this project Tkinter is needed to capture keyboard input events in a simple GUI environment, allowing real-time interaction with the Raspberry Pi's GPIO controls.  Rather than like in the terminal where you would have to press enter after a keypress to action the command Tkinter provideds a platform to detect your keypress in real time.

• RASPBERRY PI
• GUI INTERFACE WITH TKINTER

<

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import RPi.GPIO as GPIO
import time
import sys
import tkinter as tk


GPIO.setmode(GPIO.BOARD)

# Set up LED pins as outputs
GPIO.setup(7, GPIO.OUT)
GPIO.setup(11, GPIO.OUT)
GPIO.setup(13, GPIO.OUT)

def key_input(event):
    key_press = event.char.lower()
    
    if key_press == "r":
        GPIO.output(7, True)
        print("Red LED ON")
    elif key_press == "g":
        GPIO.output(11, True)
        print("Green LED ON")
    elif key_press == "b":
        GPIO.output(13, True)
        print("Blue LED ON")
    elif key_press == "x":  # Turn off all LEDs
        GPIO.output(7, False)
        GPIO.output(11, False)
        GPIO.output(13, False)
        print("All LEDs OFF")

command = tk.Tk()
command.bind("<KeyPress>", key_input)
command.mainloop()

• Press keys to control LEDs:
  
  • Press 'r' → Red LED turns on
    
  • Press 'g' → Green LED turns on
    
  • Press 'b' → Blue LED turns on
    
  • Press 'x' → All LEDs turn off
    

SECTION 2 | TROUBLE SHOOTING

1. LEDs not turning on

• Check wiring connections and GPIO pin assignments.
  
• Ensure the correct resistor values are used to limit current.
  
• Confirm that the Raspberry Pi is providing power correctly.
  

2. Unresponsive Key Presses

• Ensure the Tkinter window is active and in focus when pressing keys.
  
• Verify that the script runs without errors.