MQTT Integration

SQMeter can publish sensor readings to any MQTT broker — Home Assistant, Grafana, or your own pipeline.

---

Enabling MQTT

In the Settings page (or via API), enable MQTT and set your broker details:

{
  "mqtt": {
    "enabled": true,
    "broker": "192.168.1.10",
    "port": 1883,
    "username": "mqttuser",
    "password": "mqttpass",
    "topic": "sqm/backyard",
    "publishIntervalMs": 60000
  }
}

The device will start publishing once it reconnects.

Current MQTT limitations

The current firmware uses the publish topic as the MQTT client ID, publishes timestamp as device uptime milliseconds rather than Unix epoch time, and does not publish an availability/LWT topic. Avoid using MQTT as a sole safety signal until those firmware gaps are fixed.

---

Payload Format

Published to {topic} every publishIntervalMs milliseconds:

{
  "timestamp": 1234567,
  "light": {
    "lux": 0.0234,
    "visible": 123,
    "infrared": 45
  },
  "sky": {
    "sqm": 21.5,
    "nelm": 6.2,
    "bortle": 2.0
  },
  "environment": {
    "temperature": 12.4,
    "humidity": 72.1,
    "pressure": 1013.25
  },
  "infrared": {
    "skyTemp": -15.2,
    "ambientTemp": 12.4
  },
  "clouds": {
    "temperatureDelta": -27.6,
    "correctedDelta": -24.1,
    "coverPercent": 5.0,
    "condition": 0,
    "description": "Clear"
  },
  "location": {
    "latitude": 51.5074,
    "longitude": -0.1278,
    "altitude": 42.0,
    "satellites": 8,
    "hdop": 1.2
  },
  "rain": {
    "isRaining": false,
    "acc": 0.0,
    "eventAcc": 0.0,
    "totalAcc": 12.34,
    "rInt": 0.0
  }
}

infrared and clouds are omitted if the MLX90614 reading is unavailable. location is omitted unless GPS has a valid fix. rain is omitted unless the RG-15 is enabled, initialised, and has an OK reading.

---

Home Assistant

Add to your configuration.yaml:

mqtt:
  sensor:
    - name: "Sky Quality (SQM)"
      state_topic: "sqm/backyard"
      value_template: "{{ value_json.sky.sqm }}"
      unit_of_measurement: "mag/arcsec²"

    - name: "Bortle Class"
      state_topic: "sqm/backyard"
      value_template: "{{ value_json.sky.bortle }}"

    - name: "NELM"
      state_topic: "sqm/backyard"
      value_template: "{{ value_json.sky.nelm }}"

    - name: "Sky Temperature"
      state_topic: "sqm/backyard"
      value_template: "{{ value_json.infrared.skyTemp }}"
      unit_of_measurement: "°C"

    - name: "Rain Intensity"
      state_topic: "sqm/backyard"
      value_template: "{{ value_json.rain.rInt | default(0) }}"
      unit_of_measurement: "mm/h"

---

Mosquitto Test

Verify data is publishing:

mosquitto_sub -h 192.168.1.10 -t "sqm/#" -v