"""
MicroPython IoT Ejemplo en Wokwi

Para ver los datos recibidos:

1. Ir a http://www.hivemq.com/demos/websocket-client/
2. Pulsar "Connect"
3. En el botón Subscriptions, pulsar "Add New Topic Subscription"
4. In el campo Topic, teclear "wokwi-TEC_DEMO" y luego "Subscribe"

Pulsando en el sensor DHT22 en la simulación 
podemos cambiar la temperatura y humedad, y ver aparecer  
el mensaje en el Broker MQTT, en el panel "Messages".
Realizado a partir de un Script de Uri Shaked (agradecimientos)
Script original:
https://wokwi.com/arduino/projects/322577683855704658

Este script está disponible en:
https://wokwi.com/projects/384079126639491073

"""

import network
import time
from machine import Pin
import dht
import ujson
from umqtt.simple import MQTTClient

# MQTT Server Parameters
MQTT_CLIENT_ID = "TEC_Board1"
MQTT_BROKER    = "broker.mqttdashboard.com"
MQTT_USER      = ""
MQTT_PASSWORD  = ""
MQTT_TOPIC     = "wokwi-TEC_DEMO"

sensor = dht.DHT22(Pin(15))

print("Connecting to WiFi", end="")
sta_if = network.WLAN(network.STA_IF)
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() 
  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)