Add mqtt example

mqtt/main.py

@@ -0,0 +1,38 @@
+from machine import Pin
+from time import sleep
+import machine
+import dht
+from umqtt.robust import MQTTClient
+import json
+import gc
+
+with open("config.json", 'r') as f:
+    config = json.load(f)
+    
+print(config)
+
+led = Pin(2, Pin.OUT)
+d = dht.DHT11(Pin(12))
+adc = machine.ADC(0)
+
+c = MQTTClient("umqtt_client", config["mqtt"]["server"],ssl=True, user=config["mqtt"]["user"], password=config["mqtt"]["password"])
+gc.enable()
+
+while True:
+    led(0)
+    d.measure()
+    data = {'temp': d.temperature(), 'humid': d.humidity(),'light': adc.read(), 'id': config["id"]}
+    print(data)
+    led(1)
+    try:
+        c.connect()
+        c.publish(b"sensors", json.dumps(data))
+    finally:
+        c.disconnect()
+    gc.collect()
+    
+    
+
+
+
+