Python + GPIO: Blink an LED and Read a Button

gpiozero comes pre-installed on Raspberry Pi OS and is the friendliest way to control hardware. Pins are numbered by their GPIO (BCM) number, not their physical position.

Video tutorial

▶ Robotics Back-EndWatch on YouTube ↗

Video by Robotics Back-End, embedded from YouTube. The written steps below are our own and match the parts list.

Mission steps

1. Create the script

   SSH into the Pi and run nano blink.py, then paste the first example.

2. Run it

   python3 blink.py — your LED blinks. Press Ctrl+C to stop.

3. Add a button

   Wire a push button between GPIO27 (pin 13) and GND (pin 14). gpiozero enables the internal pull-up resistor for you.

4. Use events

   The second example turns the LED on only while the button is held — no loops needed.

5. Experiment

   Try led.blink(on_time=0.1, off_time=0.9), or use PWMLED to fade brightness.

Code

# blink.py
from gpiozero import LED
from time import sleep

led = LED(17)
while True:
    led.on()
    sleep(0.5)
    led.off()
    sleep(0.5)

# button.py
from gpiozero import LED, Button
from signal import pause

led = LED(17)
button = Button(27)

button.when_pressed = led.on
button.when_released = led.off
pause()

Tip: test every script on the bench before installing it in a moving machine.

Questions