While it's a good idea to have air quality measuring devices deployed in occupied portions of a home or office, sometimes you want a portable, self-contained CO2 monitor you can take with you to meetings, events, and when traveling. This project provides a simple verison of such a device using a Sensirion SCD40 to measure carbon dioxide, temperature and humidity and a built-in TFT display to show ongoing readings.
Several different screens of information can be shown, including all current sensor readings, an easily glanceable red/yellow/green CO2 air quality indication, screen-saver style CO2-only status, and a cumulative table of max, min, and average values. A single push-button allows sequencing through the screens.
The current version supports a combination of Adafruit ESP32 V2 Feather and Adafruit 240x135 Color TFT Display, with the separate components well suited for incorporation in an enclosure. Work is under way to add support for the Adafruit ESP32-S3 Reverse TFT Feather, which provides all needed hardware components in a single board for simpler development and greater portability. By design the sketch properly configures itself using information provided by the Arduino IDE along with a few special settings documented in the config.h configuration file.