Usermod BME280: Fix "Unit of Measurement" for temperature

[euphi]

The Unit of Measurement ("tempScale") of the MQTT message is set for each published measurement - but not for the homeassistant discovery.

Thus, openhab (and mabye other systems?) don't recognize the value as "Number" - so it uses String instead. This is somehow annoying when trying to configure the sensor channel to be linked to an existing item in OpenHAB. (Items that are created automatically or with "Add point to model" can be configured in a way that the String is transformed to Number or Number:Temperature, but existing Items cannot be linked).

When a "Unit of Measurement" is set in HomeAssistant discovery, the HA binding of OpenHAB notices that the MQTT String is a number and automatically converts it.

See also openhab/openhab-addons#6663 .

[euphi]

MQTT Message on homeassistant/sensor/WLED-Ian-Tray/Temperature/config

Before Change:

{
  "name": "WLED Ian Tray Temperature",
  "state_topic": "wled/ian-tray/temperature",
  "unique_id": "WLED-Ian-TrayTemperature",
  "device_class": "temperature",
  "expire_after": 1800,
  "device": {
    "name": "WLED Ian Tray",
    "identifiers": "wled-sensor-WLED-Ian-Tray",
    "manufacturer": "WLED",
    "model": "FOSS",
    "sw_version": "0.15.0-rc1"
  }
}

After Change:

{
  "name": "WLED Ian Tray Temperature",
  "state_topic": "wled/ian-tray/temperature",
  "unique_id": "WLED-Ian-TrayTemperature",
  "unit_of_measurement": "°C",
  "device_class": "temperature",
  "expire_after": 1800,
  "device": {
    "name": "WLED Ian Tray",
    "identifiers": "wled-sensor-WLED-Ian-Tray",
    "manufacturer": "WLED",
    "model": "FOSS",
    "sw_version": "0.15.0-rc1"
  }
}

[DedeHai]

I neither use MQTT nor the BME280 mod, but seems like a valueable addition to me.