Simple MQTT Tutorial

[gertjanvanhethof]

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

[gertjanvanhethof]

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

[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?

[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]

@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]

@vruizvil
For Windows, I use MQTTFX Client. Here the link
http://www.jensd.de/apps/mqttfx/

[vruizvil]

@MainSheet said in Simple MQTT Tutorial:

broker.hivemq.com

Try client.disconnect(), then client.connect(). Try on firefox, it works fine in my tests, and try another topic (without slash), ie.: "mylopytopic"

[MainSheet]

Dummy question,

I have the code on my LoPy working :

from simple import MQTTClient
import  time
def settimeout(duration): pass
client = MQTTClient("MainSheet", "broker.hivemq.com", port=8000)
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)

output is this

connected with goofy, channel 1
Sending ON
Sending OFF
Sending ON
Sending OFF
Sending ON
Sending OFF
Sending ON
Sending OFF
Sending ON
Sending OFF

Connecting to http://www.hivemq.com/demos/websocket-client/? with Chrome
Host = broker.hivemq.com
ClientID = MainSheet
Port = 8000. ( I tried setting the port to 1883 but then I can't connect to hivemq. I also tried to set the code above to connect to port 8000, however, got an out of range error)
subscribed to /lights

however, the messages never get through to HiveMQ

Steve

[vruizvil]

Well, thanks a lot for the comments.
After uppgrade recent firmware, the code works fine connecting mosquitto broker.
But, I can't connect two differents sockets with two differentes brokers at same time.
It needs run .disconnect() function to be abel to use the other one broker.
I don't know the reason....., well, I'am not a python expert.

# Initialize MQTT Client
def settimeout(duration): pass


def t3_publication(topic, msg):
	print (topic, ';', msg)
	pycom.rgbled(0xff00)


UNIQUE_ID = machine.unique_id()
MQTT_BROKER = "192.168.2.220"
MQTT_PORT = 1883
mqtt_client = MQTTClient(UNIQUE_ID, MQTT_BROKER, port=MQTT_PORT)
mqtt_client.settimeout = settimeout
mqtt_client.set_callback(t3_publication)
mqtt_client.connect()

MQTT_BROKER_2 = "test.mosquitto.org"
#MQTT_PORT = 1883
mqtt_client2 = MQTTClient(UNIQUE_ID, MQTT_BROKER_2, port=MQTT_PORT)
mqtt_client2.settimeout = settimeout
mqtt_client2.set_callback(t3_publication)
mqtt_client2.connect()

[MrPy]

@thibault My apologies, I was replying to vruizil below.

[thibault]

Sorry i don't speak very well english, so i hav'nt really understand what you says exactly. But i mean you want data about the different version
I have use the pycom_update_0.9.3.b2 on the lopy. And for the mosquitto the version is 1.3.4-2. I'm begin in the IoT world, and maybe i have too few knowledge in it for understand you. If i have not answer that you wait, feel good about explain another way.

[MrPy]

Hmmm, do you have your Mosquito broker details to hand to i can test?

I usually have a node-red instance running that connects to my broker so i can quickly test if the broker is up or down. A few of these public test brokers are not that stable so 9/10 it's the broker being down that causes my issues.

[thibault]

My try was successful with this on debian:
https://pallavichaurasia94.wordpress.com/2014/10/14/mosquitto-in-debian/
for install MQTT brockers.

On the lopy i use this initialisation:

from umqtt import MQTTClient
def settimeout(duration): pass

client = MQTTClient("joe", "192.168.4.2", port=1883)
client.settimeout = settimeout
client.connect()

that give me the possibility to publish fine on my brockers with the command:

client.publish("hello/world", "My publication")

I have make some try to basic read brocker's data from lopy, We need to define a function who have been called if message are find:

import pycom
def t3_publication(topic, msg):
    print (topic, ':', msg)
    pycom.rgbled(0xff00)

and assign it:

client.set_callback(t3_publication)

now we can subscribe to the desired channel:

client.subscribe("hello/world", qos=1)

I put data to the MQTT brockers from another terminal (localhost from brocker's server) mosquitto_pub -d -t hello/world -m "Hello, MQTT. This is my first message.", and i launch the check of the brocker's message from lopy by:

client.check_msg()

That's print message in channel, and set led to green (who's been reset by the heartbeat).

I hope that will help you.

[vruizvil]

The code works fine on my lopy (release 0.9.1.b1) to connect broker.hivemq.com, but it doesn't work to connect test.mosquitto.org. I have a mosquitto broker on local machine, but...... not working. Please, help about this issue. Thanks.