Introduction

The relay is the interface between your Raspberry Pi and high-voltage components. It enables you to control the lighting of a component requiring high power, such as a light bulb, from the Raspberry Pi. It is widely used in home automation to control roller shutters, coffee machines and heaters from a Raspberry Pi.

The relay consists of two parts: the control part (on the Raspberry Pi side) and the power part. These two parts are separated by galvanic isolation. To supply the energy needed to light a lamp, for example, you’ll need an external power supply delivering the power required for what you want to light.

Here are the relay pins:

  • Ground: connects to the ground of the Raspberry board
  • Vcc: connects to 5V on the Raspberry board
  • Signal: connects to a GPIO on the Raspberry board

 

The relay can be operated on 230V, which can be dangerous. Be careful what you do. Arduino Factory is not responsible for any problems.

 

Buy a 3.3V relay!

The Raspberry Pi’s GPIOS operate at +3.3V. This means you need a relay operating at +3.3V. A relay with a higher operating voltage won’t be able to open and close its switch.

Here’s the diagram to connect the relay to the Raspberry Pi:

Programming

In the diagram, you can replace the lamp with the object you wish to control.

Here’s the program that opens and closes the relay:

import RPi.GPIO as GPIO
import time

# Pin configuration
relay_pin = 17

# Initial GPIO configuration
GPIO.setmode(GPIO.BCM)
GPIO.setup(relay_pin, GPIO.OUT)

try:
    while True:
        print(“Relay activated”)
        GPIO.output(relay_pin, GPIO.HIGH) # Activate relay
        time.sleep(2) # Keep relay activated for 2 seconds

        print(“Relay deactivated”)
        GPIO.output(relay_pin, GPIO.LOW) # Deactivate relay
        time.sleep(2) # Wait 2 seconds before next activation

except KeyboardInterrupt:
    pass

finally:
    # Clean GPIO resources
    GPIO.cleanup()