from machine import Pin
import time

relay_pin = Pin(12, Pin.OUT)

def relay_on():
    relay_pin.value(1)

def relay_off():
    relay_pin.value(0)

def blink():
    relay_on()
    time.sleep(0.5)
    relay_off()
    time.sleep(0.5)
    
while True:
    blink()