Simple MQTT Tutorial

[gertjanvanhethof]

@MainSheet I'am not able to connect.
What do I wrong?

In my main.py I setup the wifi connection successfully.
I checked that by doing an http get call and I was able to get HTML data from a website. So internet connection is working.

I went to: http://www.hivemq.com/demos/websocket-client/

And created a connection with the following details:

Host: broker.hivemq.com
Port: 8000
ClientID: MyLoPy

I created a subscription and tested some messages. All works.

Then I typed the following commands on my LoPy:

MicroPython v1.8.6-40-gd10463e on 2016-11-25; LoPy with ESP32
Type "help()" for more information.

from umqtt import MQTTClient
def settimeout(duration): pass
...
client = MQTTClient("MyLoPy", "broker.hivemq.com", port=8000)
client.settimeout = settimeout
client.connect()
0xc b'10:12:00:04:4d:51:54:54:04:02:00:00'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "umqtt.py", line 86, in connect
IndexError: bytes index out of range

[vruizvil]

@gertjanvanhethof Hi!, try with machine.reset(), then try your code one more time, you need only one client socket, when you try few times the code, I think the socket doesn't work fine. That is the way to solve the same problem in my tests, but I don't know the reason.

[gertjanvanhethof]

@vruizvil

My code is as following:

import time
import machine
from umqtt import MQTTClient

def settimeout(duration): pass

def connect():
if machine.reset_cause() != machine.SOFT_RESET:
client = MQTTClient("MyLoPy", "broker.mqttdashboard.com", port=8000)
client.settimeout = settimeout
client.connect()
print('Connected MQTT Broker.')
return client

def send(client):
while True:
print("Sending ON")
client.publish("/lopy", "ON")
time.sleep(1)
print("Sending OFF")
client.publish("/lopy", "OFF")
time.sleep(1)

I do a connect() and the result is as following:

client.connect()
0xc b'10:12:00:04:4d:51:54:54:04:02:00:00'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "umqtt.py", line 86, in connect
IndexError: bytes index out of range

Still going wrong. What could be the solution?

[gertjanvanhethof]

@MrPy Are you sure those are you messages? I checked and somebody else was publishing these messages.

[gertjanvanhethof]

I found the error. The port is wrong.
It should be: 1883.
Then connect is working.

[gas]

@vruizvil Hi
I started a mosquitto on my laptop (vm debian) and it is working with the code as it is i updated it a little to make it configurable via config param file (wifi and mqtt)
what error you are getting ?

[gertjanvanhethof]

@gas It's working now. The used port was wrong. Thxs for your help.

[RSK]

MQTTClient is missing in the latest firmware, using the image release on 02/Dec/2016.

Could someone confirm this.

[sakis]

@RSK umqtt is not part of Pycom's firmware or standard micropython. It is an external Python library, so to be able to use it you need to upload it to your device.

The easiest way to do that is using Pymakr. Another way is using plain FTP (https://docs.pycom.io/pycom_esp32/pycom_esp32/general.html#local-file-system-and-ftp-access).

Please read step 2 again and try to follow the instructions. If you have any problems let us know.

[RSK]

@sakis Thanks!

I have downloaded umqtt.simple.py from https://github.com/micropython/micropython-lib and placed it in /flash/simple.py of the LoPy using FTP.

And trying to connect from my LoPy application:

With Hive settings:

But connect fails with error "bytes index out of range":

Please help to resolve.

Thanks & Regards,
Satish Kumar. R.

[RSK]

Sorry the link i provided is incorrect, downloaded from the below link:
https://pypi.python.org/pypi/micropython-umqtt.simple

And the changes done to line number 57 "self.sock.settimeout(self.timeout)"

Thanks & Regards,
Satish Kumar. R.

[sakis]

@RSK Have you tried using port 1883 instead of 8000?

[RSK]

I am trying in Windows, by default http://www.hivemq.com/demos/websocket-client/
give port number 8000.

If i try to change in the browser to 1883 then socket connection fails in websocket client.

[MrPy]

@RSK , Pretty sure you have a port issue. 1883 should work. For some reason Hive MQ isn't accepting requests on 1883 currently. I will search for another public test broker..

[RSK]

@MrPy Thanks!

Adjusting the timeout period in simple.py is helping to make the setup work consistent.

This might help.

Thanks & Regards,
Satish Kumar. R.

[lcgeldenhuys]

What version of the micropython-umqtt.simple library are you using? I'm trying the latest 1.3.2. It doesn't have the same bug on line 57 anymore, in fact it doesn't seem to use the same timeout mechanism.

I'm not able to connect successfully to the HiveMQ public broker:

Traceback (most recent call last):
File "main.py", line 10, in <module>
File "/flash/lib/umqtt.py", line 74, in connect
OSError: [Errno 113] EHOSTUNREACH

Using:

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

I can pub / sub using the MQTT.fx client on my laptop, and the WiPy is on the same network (I can ping and ftp to WiPy from laptop).

Any ideas?

[pwest]

I'm also using the same apparently current 1.3.2 simple.py file, and having the exact issue described by lcgeldenhuys 3 months ago. Any suggestions on how to get past this?

-Phil

[bucknall]

Hi @pwest,

It might be work checking out https://youtu.be/3NDPSbr5J14?list=PLS09TA19umCOavPeP_FoMHoCuCzjJUWQk, where I talk about MQTT and how to get set up with it.

Currently, the documentation on MQTT that we have online is out of date and I am re-writing it as we speak. I'll post back once it has been published!

Thanks,

Alex

[achide]

Hi,

I'm new with pycom. Maybe it's a stupid question, I would like to know how to import umqtt library.
I've put it in lib folder of sys.path, but when I import this module, it told me no module named 'umqtt'?

[bucknall]

@achide How are you uploading code to your device? Are you using the Pymakr Plugin?