MQTT

MQTT is a lightweight messaging protocol that is ideal for sending small packets of data to and from IoT devices via WiFi.

The broker used in this example is the IO Adafruit](https://io.adafruit.com) platform, which is free and allows for tinkering with MQTT.

Visit IO Adafruit and create an account. You'll need to get hold of an API Key as well as your credentials. Visit this guide for more information about MQTT and how to use it with Adafruit's Broker.

from mqtt import MQTTClient
import machine
import time

def sub_cb(topic, msg):
   print(msg)

wlan = WLAN(mode=WLAN.STA)
wlan.antenna(WLAN.EXT_ANT)
wlan.connect("yourwifinetwork", auth=(WLAN.WPA2, "wifipassword"), timeout=5000)

while not wlan.isconnected():  
    machine.idle()
print("Connected to Wifi\n")

client = MQTTClient("device_id", "io.adafruit.com",user="your_username", password="your_api_key", port=1883)

client.set_callback(sub_cb)
client.connect()
client.subscribe(topic="youraccount/feeds/lights")

while True:
    print("Sending ON")
    client.publish(topic="youraccount/feeds/lights", msg="ON")
    time.sleep(1)
    print("Sending OFF")
    client.publish(topic="youraccount/feeds/lights", msg="OFF")

    time.sleep(1)