Only able to publish 1 message with umqtt.simple

[Stubbs]

I'm trying to send config info to Home Assistant from a Pico W with the following code:

import time
import config
from network import WLAN,STA_IF
import ubinascii
# import gc
# import micropython

from machine import Pin, UART
from pimoroni import RGBLED, Button
# from pms5003 import PMS5003
from pimoroni_i2c import PimoroniI2C
from breakout_bme68x import BreakoutBME68X, STATUS_HEATER_STABLE
from breakout_ltr559 import BreakoutLTR559

from umqtt.simple import MQTTException, MQTTClient

# set up the LED
led = RGBLED(6, 7, 10, invert=True)
led.set_rgb(200,100,0)

# micropython.mem_info()
# Connect to the wifi
wlan = WLAN(STA_IF)
wlan.active(True)
wlan.connect(config.SSID, config.PASSWORD)
unique_id = ubinascii.hexlify(wlan.config('mac')).decode().upper()

# Connect to the MQTT Server
mqtt_connected = False;
try:
    mqtt = MQTTClient("enviro_plus", config.MQTT_SERVER, config.MQTT_PORT, config.MQTT_USER, config.MQTT_PASSWORD)
    mqtt.DEBUG = True
    mqtt.connect()
    mqtt_connected = True;
except MQTTException as e:
    print(f"Unable to connect to MQTT: {e}")
except OSError as e:
    print(f"Unable to connect to MQTT: {e}")

# Initialise Home Assistant.
if mqtt_connected:
    # print('Initial free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))
    mqtt.publish(f"homeassistant/sensor/enviroplus_{unique_id}_gas/config1", f'{{ "name":  "Gas resistance",   "state_topic": "homeassistant/sensor/enviroplus_{unique_id}/state",  "value_template": "{{{{ value_json.temperature }}}}",  "unique_id": "enviroplus_{unique_id}_temp", "unit_of_measurement": "Ω",  "device": {{"identifiers": ["enviroplus_{unique_id}"], "name": "Workshop Environment"}}}}   ')
    mqtt.publish(f"homeassistant/sensor/enviroplus_{unique_id}_pm1/config1", f'{{ "name": "PM1", "device_class": "pm1", "stat_t": "homeassistant/sensor/enviroplus_{unique_id}/state", "value_template": "{{{{ value_json.pm1 }}}}", "unique_id": "enviroplus_{unique_id}_pm1", "unit_of_measurement": "µg/m³","device": {{ "identifiers": "enviroplus_{unique_id}", "name": "Workshop Environment"}}}}   ')
    mqtt.publish(f"homeassistant/sensor/enviroplus_{unique_id}_pm25/config1", f'{{ "name": "PM2.5", "device_class": "pm25", "stat_t": "homeassistant/sensor/enviroplus_{unique_id}/state", "value_template": "{{{{ value_json.pm25 }}}}", "unique_id": "enviroplus_{unique_id}_pm25", "unit_of_measurement": "µg/m³","device": {{ "identifiers": "enviroplus_{unique_id}", "name": "Workshop Environment"}}}}   ')
    mqtt.publish(f"homeassistant/sensor/enviroplus_{unique_id}_pm10/config1", f'{{ "name":  "PM10",  "device_class": "pm10",  "state_topic": "homeassistant/sensor/enviroplus_{unique_id}/state",  "value_template": "{{{{ value_json.pm10 }}}}",  "unique_id": "enviroplus_{unique_id}_pm10", "unit_of_measurement": "µg/m³",  "device": {{"identifiers": ["enviroplus_{unique_id}"], "name": "Workshop Environment"}}}}   ')
    mqtt.publish(f"homeassistant/sensor/enviroplus_{unique_id}_T/config1", f'{{ "name":  "Temperature",  "device_class": "temperature",  "state_topic": "homeassistant/sensor/enviroplus_{unique_id}/state",  "value_template": "{{{{ value_json.temperature }}}}",  "unique_id": "enviroplus_{unique_id}_temperature", "unit_of_measurement": "°C",  "device": {{"identifiers": ["enviroplus_{unique_id}"], "name": "Workshop Environment"}}}}   ')
    mqtt.publish(f"homeassistant/sensor/enviroplus_{unique_id}_H/config1", f'{{ "name":  "Humidity",  "device_class": "humidity",  "state_topic": "homeassistant/sensor/enviroplus_{unique_id}/state",  "value_template": "{{{{ value_json.humidity }}}}",  "unique_id": "enviroplus_{unique_id}_humidity", "unit_of_measurement": "%",  "device": {{"identifiers": ["enviroplus_{unique_id}"], "name": "Workshop Environment"}}}}   ')
    mqtt.disconnect()
    # print('Initial free: {} allocated: {}'.format(gc.mem_free(), gc.mem_alloc()))
else:
    print("MWTT not connected.")

There are a couple of issues, firstly I have to pad the paylod with 3 extra characters or the json that's sent in missing it's terminating brackets.

The other issue is that it only seems to send the first message, I have MQTT Explorer watching what's published and I only ever see the first of those published messages, no matter what order I put them in.

[Stubbs]

A little more on this, from the mqtt logs themselves:

mqtt                        | 1697055632: New connection from 192.168.1.62:50051 on port 1883.
mqtt                        | 1697055632: New client connected from 192.168.1.62:50051 as enviro_plus (p2, c1, k0, u'ha').
mqtt                        | 1697055632: Client enviro_plus disconnected due to malformed packet.

That's without the padding on the payload, with the padding it's a different error:

mqtt                        | 1697055412: New connection from 192.168.1.62:50046 on port 1883.
mqtt                        | 1697055413: New client connected from 192.168.1.62:50046 as enviro_plus (p2, c1, k0, u'ha').
mqtt                        | 1697055413: Client enviro_plus disconnected due to protocol error.

[Stubbs]

The issue is caused by "unit_of_measurement" where some of the values are UTF-8, even when I encode the strings with .encode() it still causes the protocol error.

The padding is a red herring.

[hmaerki]

Hi Stubbs

I assume that you have to many '{{' around "{{{{ value_json.temperature }}}}".

Suggestion A

Before passing the strings to mqtt.publish(), you could verify it using this code:

json_string =f'{{ "name":  "Gas resistance"...'
print(json.loads(json_string))
mqtt.publish(..., json_string)

Looking at the print output, you will quickly see, which variables have not been expanded.

Suggestion B

Write a python dictionary and let json.dumps() do the job for you.

dict_json = { "name":  "Gas resistance",   "state_topic": "..."}
mqtt.publish(..., json.dumps(dict_json))

[rnlgreen]

For info, I just stumbled across this same problem. I had working code until I tried to publish a temperature and included the ° (degree) symbol. I haven't the patience to figure out how to solve this, so I've just dropped that symbol!

[kdpuvvadi]

With json.dumps(), there's still issue with some charectors such as °.

payload = { "name": "Temprature",   "value_template": "{{ value_json.temp }}", "unit_of_measurement": "°C"  }
mqtt.publish(TOPIC, json.dumps(payload))

Just crashes and thows ECONNRESET. If I remove degree charector, It goes through.