MQTT

We can use [pycom]'s [mqtt library][mqtt-lib].

The basic usage:

from network import WINC
from mqtt import MQTTClient
import machine
import time

def settimeout(duration):
    pass

# Init wlan module and connect to network
print("Trying to connect... (may take a while)...")
wlan = WINC()
wlan.connect(SSID, key=KEY, security=wlan.WPA_PSK)

# We should have a valid IP now via DHCP
print(wlan.ifconfig())

client = MQTTClient("demo", "broker.hivemq.com", port=1883)
client.settimeout = settimeout
client.connect()

print("Sending ON")
client.publish("/camera", "ON")

Fixes

getaddrinfo: if we pass an IP save a network call.

Alternative MQTT Clients

[umqtt.simple][umqtt-simple]:

• QoS 0 and 1 are supported for both publish and subscribe. (QoS2 isn't supported to keep code size small)
• Besides ClientID, only "clean session" parameter is supported for connect as of now.

There's a separate umqtt.robust module which builds on umqtt.simple and adds automatic reconnect support in case of network errors. Please see its documentation for further details.

msg = b'{"MsgId":%u,"Mem":%u,"Celsius":%s,"Pressure":%s,"Humidity":%s}' % (count, gc.mem_free(), v[0][:-1], v[1][:-3], v[2][:-1])
client.publish(b"home/weather", msg)

Traceback (most recent call last):
  File "<stdin>", line 48, in <module>
  File "mqtt.py", line 63, in connect
TypeError: object 'NoneType' is not a tuple or list

HTTP POST: https://github.com/micropython/micropython-lib/blob/master/urequests/urequests.py

umqtt.robust

[pycom][] [mqtt-lib]:https://github.com/pycom/pycom-libraries/blob/master/lib/mqtt/mqtt.py

umqtt-simple

samples: https://github.com/gloveboxes/ESP32-MicroPython-BME280-MQTT-Sample https://www.hackster.io/bucknalla/mqtt-micropython-044e77 (uses same)