CO2 Gadget — Advanced Air Quality Monitor with Companion App
An advanced CO2 monitoring firmware for ESP32 display boards with BLE/WiFi/MQTT/ESP-Now connectivity, real-time Android/iOS companion app for charting, and support for SCD4x, SCD30, and MH-Z19 sensors.
Overview
CO2 Gadget (100+ GitHub stars) is a comprehensive air quality monitoring firmware that goes far beyond a simple sensor display. It features a companion mobile app for Android and iOS with real-time charting, multiple communication protocols (BLE, WiFi, MQTT, ESP-Now), and support for a wide range of CO2 sensors — making it a complete indoor air quality monitoring ecosystem.
Key Features
- Companion App: Android and iOS apps for real-time CO2 visualization, historical charts, and alerts
- Multiple Sensors: Supports Sensirion SCD4x, SCD30, SenseAir S8, Winsen MH-Z19, and CM1106 CO2 sensors
- Multi-Protocol: BLE for mobile app, WiFi for web dashboard, MQTT for Home Assistant, ESP-Now for sensor mesh
- Color Display: Real-time CO2 levels with traffic-light color coding on the T-Display S3's screen
- Data Logging: Log readings to SD card for long-term analysis
- Alerts: Configurable CO2 threshold alerts via buzzer and app notifications
- Captive Portal: WiFi configuration via web browser — no serial console needed
Getting Started
Flash CO2 Gadget via PlatformIO. Connect a CO2 sensor (SCD41 recommended) via I2C to the T-Display S3. Power on and configure WiFi through the captive portal. Install the companion app on your phone for charts and remote monitoring.
Why This Project
Most ESP32 CO2 projects are basic sensor-to-display sketches. CO2 Gadget is a complete ecosystem — the mobile companion app alone sets it apart, providing real-time charting and historical data without needing Home Assistant or any server infrastructure. It's a genuinely useful daily tool for offices, classrooms, and bedrooms.
