Raspberry Pi GPIO: Control LEDs with Python

Introduction

The Raspberry Pi's GPIO (General Purpose Input/Output) pins let you interact with the physical world using Python. In this tutorial, you'll learn to control LEDs — the foundational skill for all Pi hardware projects.

What You'll Need

• Raspberry Pi (any model with GPIO header)
• 1× LED
• 1× 330Ω resistor
• Breadboard and jumper wires
• Raspberry Pi OS installed

GPIO Pin Layout

The Raspberry Pi has 40 GPIO pins. We'll use GPIO 17 (physical pin 11) for this tutorial.

Wiring

1. Connect GPIO 17 → 330Ω resistor → LED anode (long leg)
2. Connect LED cathode (short leg) → GND (physical pin 6)

Python Code: Blink

import RPi.GPIO as GPIO
import time

LED_PIN = 17

GPIO.setmode(GPIO.BCM)
GPIO.setup(LED_PIN, GPIO.OUT)

try:
    while True:
        GPIO.output(LED_PIN, GPIO.HIGH)
        print("LED ON")
        time.sleep(1)
        GPIO.output(LED_PIN, GPIO.LOW)
        print("LED OFF")
        time.sleep(1)
except KeyboardInterrupt:
    pass
finally:
    GPIO.cleanup()

Run with: python3 blink.py

Python Code: Button-Controlled LED

Add a push button connected to GPIO 27 with a pull-down resistor.

import RPi.GPIO as GPIO

LED_PIN = 17
BUTTON_PIN = 27

GPIO.setmode(GPIO.BCM)
GPIO.setup(LED_PIN, GPIO.OUT)
GPIO.setup(BUTTON_PIN, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

try:
    while True:
        if GPIO.input(BUTTON_PIN):
            GPIO.output(LED_PIN, GPIO.HIGH)
        else:
            GPIO.output(LED_PIN, GPIO.LOW)
except KeyboardInterrupt:
    pass
finally:
    GPIO.cleanup()

Important Notes

• Always use a resistor with LEDs to prevent burning them out
• GPIO pins output 3.3V (not 5V like Arduino)
• Always call GPIO.cleanup() when done to reset pin states
• The BCM numbering refers to the Broadcom chip pin numbers