METEO_P4 — Home Assistant Integration via MQTT

1.Requirements

MQTT broker — e.g. Mosquitto, reachable by both METEO_P4 and Home Assistant.
Same network — METEO_P4 and the broker must be able to reach each other.
MQTT integration in Home Assistant — installed and configured to use the same broker.

Tip Mosquitto as an HA add-on

If Home Assistant is installed as Home Assistant OS or Supervised, the easiest option is to install the official Mosquitto broker add-on from the HA add-on store. The broker and HA will already share the same network.

2.How it works

After connecting to Wi-Fi, METEO_P4 automatically:

Connects to the MQTT broker with the configured credentials.
Publishes MQTT Discovery configuration to topics homeassistant/<тип>/<MAC>/<id>/config.
Starts publishing measurements periodically to meteo_p4/<MAC>/state.
Publishes availability status to meteo_p4/<MAC>/status.

Thanks to Discovery, you do not need to create entities in YAML manually — Home Assistant detects the device and adds all sensors automatically.

Auto MQTT Discovery

Make sure Enable MQTT Discovery is turned on in Home Assistant (it is on by default). Entities will appear within seconds after the device first connects.

3.MQTT Topics

<MAC> — the device Wi-Fi MAC address in lowercase without separators, e.g. a1b2c3d4e5f6.

Status and state

meteo_p4/<MAC>/status

Availability: online / offline (LWT)

meteo_p4/<MAC>/state

JSON with all current sensor values

Keys in JSON payload (`state`)

Ключ	Description	Unit
`indoor_temperature`	Indoor temperature	°C
`outdoor_temperature`	Outdoor temperature	°C
`humidity`	Indoor humidity	%
`outdoor_humidity`	Outdoor humidity	%
`pressure`	Atmospheric pressure	hPa
`co2`	CO₂	ppm
`voc`	VOC index (SGP41)	—
`wind`	Wind speed	м/с
`forecast_temp_now`	Forecast temperature	°C
`wifi_rssi`	Wi-Fi signal level	dBm
`free_heap`	Free RAM	bytes
`free_psram`	Free PSRAM	bytes
`uptime`	Uptime since boot	с
`fw_version`	Firmware version	string

Discovery topics

Published once at startup. Example for the temperature sensor:

topichomeassistant/sensor/<MAC>/indoor_temperature/config

4.Sensors in Home Assistant

Once discovered, the device appears in HA as a single METEO P4 integration with the following entities:

Climate

Indoor temperature и на улице
Indoor humidity и на улице
Atmospheric pressure
CO₂ (ppm)
VOC index

Weather

Wind speed
Forecast temperature

Diagnostics

Wi-Fi RSSI
Free RAM и PSRAM
Uptime
Firmware version

5.Connection Setup

On the device open: Settings → Server → MQTT.

Field	Value
Host	IP address of the MQTT broker, e.g. `192.168.100.40`
Port	`1883` (no TLS) or `8883` (TLS)
User	Login (if authentication is enabled)
Password	MQTT password
Interval	Publish interval, at least `10` seconds

Press SAVE, then ENABLE MQTT. The device will connect and start publishing data.

Important Security

Do not use allow_anonymous true in a production network. Never publish your MQTT password, home-network IP address or server credentials publicly.

6.Connection Check

Verify that the device is publishing data by subscribing to all its topics:

Docker (Mosquitto in a container)

bashdocker exec -it meteo_mosquitto mosquitto_sub \
  -h localhost -u USER -P PASSWORD \
  -t "meteo_p4/#" -v

Windows (Mosquitto installed locally)

powershellcd "C:\Program Files\mosquitto"
.\mosquitto_sub.exe -h 127.0.0.1 -p 1883 `
  -u METEO_P4 -P your_password `
  -t "meteo_p4/#" -v

When the connection works, messages like these will appear in the console:

outputmeteo_p4/a1b2c3d4e5f6/status online
meteo_p4/a1b2c3d4e5f6/state {"indoor_temperature":22.4,"humidity":48,...}

Check port reachability from another PC

powershellTest-NetConnection -ComputerName IP_СЕРВЕРА -Port 1883

7.Troubleshooting

Symptom	Cause / solution
Device does not appear in Home Assistant	Check that the MQTT integration is enabled in HA and that MQTT Discovery is on. Make sure the broker matches the one configured in METEO_P4.
Entities appeared but values show `unavailable`	The device is not connected or status is `offline`. Check Wi-Fi and MQTT settings on the device.
`Connection refused: not authorised`	Wrong login or password, or `allow_anonymous false` is set but no credentials are provided in the client.
No data arriving but status is `online`	Publish interval is too long, or the sensor is not physically connected. Reduce the interval in settings.
METEO_P4 cannot connect via TLS (port 8883)	A CA certificate must be installed on the device or a trust-bundle enabled. The certificate `CN` must match the broker hostname or IP.
Duplicate entities in HA	Delete the old device in HA (Settings → Devices & Services → MQTT) and wait for re-discovery.