Simple MQTT Guide



  • Hi All,

    Posted in the WiPy section but the same applies for the LoPy.

    Figured this code may help those relatively new to Pycom/Micropython/MQTT. It's a simple way to quickly get Mqtt publishing on your WiPy or LoPy board. I used the Hive Mq broker for demo purposes:

    http://www.hivemq.com/demos/websocket-client/

    1. Make sure the WiPy is connected over serial to Pymakr ( sometimes restarting Pymakr gets things going if it can't detect it).

    2. Download the UMQTT Library that is available here: https://pypi.python.org/pypi/micropython-umqtt.simple and open simply.py

    The library on the whole is pretty good, but there is a bug on line 57. Make sure to change:

       self.settimeout(self.timeout)
    

    To

       self.sock.settimeout(self.timeout)
    

    Go ahead and save the Library but rename it so umqtt instead of simple.py

    1. Open Pymakr to start building your main script. Create a new project (Mqtttest or whatever)

                            from network import WLAN
                            from umqtt import MQTTClient
                            import machine, time
      
                           def settimeout(duration): pass
      
                         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("joe", "broker.hivemq.com", port=1883)
                         client.settimeout = settimeout
                         client.connect()
                         while True:
                          print("Sending ON")
                          client.publish("/lights", "ON")
                          time.sleep(1)
                          print("Sending OFF")
                          client.publish("/lights", "OFF")
                          time.sleep(1)
      

    After inputting your WIFI and broker details, go ahead and choose a publish topic of your choice, along with a message

    1. Almost ready to give it a try! Next connect to your WiPy over WIFI and FTP into the /lib folder. I use Fillezilla for this. Upload our renamed library umqtt to the /lib folder on the board.

    2. Make sure the WiPy is connected over serial to Pymakr ( again a restart may help this). Then hit the play button to upload your script to the board . You should see the Wifi connected printed in the console, and then the while loop commence.

    alt text

    Go back to http://www.hivemq.com/demos/websocket-client/ and subscribe to your topic, and you should see the messages start coming in on the broker.

    alt text

    Bit of a dummies guide but hope this helps some people!


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