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SQMeter

ESP32 Dark Sky Quality Monitor

SQMeter is an open-source sky quality meter built on the ESP32. It measures light pollution in real time and gives you Bortle class, SQM magnitude, and naked-eye limiting magnitude — accessible from any browser on your local network.

Try the Live Demo View on GitHub

Features

  • Sky Quality Measurements

    SQM (mag/arcsec²), NELM, and Bortle Scale 1–9 calculated from raw lux.

  • Web Interface

    Real-time dashboard over WebSocket. No polling. No app required.

  • Environmental Sensors

    Temperature, humidity, and pressure via BME280.

  • MQTT Publishing

    Push readings to Home Assistant, Grafana, or any MQTT broker.

  • OTA Updates

    Flash new firmware from the browser — no USB cable needed after first flash.

  • Open Hardware

    Standard I2C sensors. Runs on any ESP32 dev board.

Sensors

Sensor Measures Interface
TSL2591 Lux (full / visible / IR) I2C 0x29
BME280 Temperature, humidity, pressure I2C 0x76
MLX90614 IR cloud temperature I2C 0x5A
GPS (optional) Location & time UART
RG-15 (optional) Rain detection UART

Quick Start

New device? Go to Flashing Your Device — you only need a USB cable and the release binaries.

Already flashed? Go to First Boot to configure WiFi.