Controlling GPIO Outputs with Python — LED, Relay, and Buzzer

The Raspberry Pi GPIO lets you control real-world hardware from Python. Three essential output patterns.

Setup

pip install gpiozero  # usually pre-installed

Blink an LED

Wiring: Pin 17 > 330 ohm resistor > LED > GND

from gpiozero import LED
from time import sleep

led = LED(17)
while True:
    led.on()
    sleep(1)
    led.off()
    sleep(1)

Control a Relay

from gpiozero import OutputDevice
from time import sleep

relay = OutputDevice(18, active_high=False)  # most relay modules are active-low

relay.on()   # closes relay
sleep(5)
relay.off()  # opens relay

Caution: Relays switch mains voltage. Use proper housing and fusing.

Piezo Buzzer

Wiring: Pin 20 > Buzzer positive, GND > Buzzer negative

from gpiozero import Buzzer
from time import sleep

buzzer = Buzzer(20)
for _ in range(3):
    buzzer.on()
    sleep(0.2)
    buzzer.off()
    sleep(0.1)

Running at Boot

Create a systemd service in /etc/systemd/system/myscript.service to auto-start GPIO scripts on boot.