import network 
import time 
from machine import Pin 
import dht 
import ujson 
from umqtt.simple import MQTTClient 
 
# MQTT Server Parameters 
MQTT_CLIENT_ID = "micropython-weather-demo" #HiveMQ is the client receiving the messages (temp and Humidity) 
MQTT_BROKER    = "broker.mqttdashboard.com" 
MQTT_USER      = "" 
MQTT_PASSWORD  = "" 
MQTT_TOPIC     = "wokwi-weather" 
 
sensor = dht.DHT22(Pin(15)) 
 
print("Connecting to WiFi", end="") 
sta_if = network.WLAN(network.STA_IF) 
#The Station mode (STA) is used to connect the ESP32 module to a WiFi access point.  
#The ESP32 behaves like a computer that is connected to our router.  
#If the router is connected to the Internet, then the ESP32 can access the Internet 
#STA_IF is the WiFI interface for the station (when ESP connects to a router) 
 
sta_if.active(True) 
sta_if.connect('Wokwi-GUEST', '') 
while not sta_if.isconnected(): 
  print(".", end="") 
  time.sleep(0.1) 
print(" Connected!") 
 
print("Connecting to MQTT server... ", end="") 
client = MQTTClient(MQTT_CLIENT_ID, MQTT_BROKER, user=MQTT_USER, 
password=MQTT_PASSWORD) 
client.connect() 
 
print("Connected!") 
 
prev_weather = "" 
while True: 
  print("Measuring weather conditions... ", end="") 
  sensor.measure() #obtain the data from sensor 
  # ujson.dump(obj, stream) 
  #   Take obj serialize to JSON string, Write it to the given stream . 
 
  message = ujson.dumps({ 
    "temp": sensor.temperature(), 
    "humidity": sensor.humidity(), 
  }) 
  if message != prev_weather: 
    print("Updated!") 
    print("Reporting to MQTT topic {}: {}".format(MQTT_TOPIC, message)) 
    client.publish(MQTT_TOPIC, message) 
    prev_weather = message 
  else: 
    print("No change") 
  time.sleep(1)