MiniMon

MiniMon 1.1 released! MiniMon can now also be used as a device under GeigerLog:
https://sourceforge.net/projects/geigerlog/

CO2 Monitor is a small, low-cost (~65€) device, which is advertised as a 'bad-air' monitor for home and office, which it indicates by green, yellow, and red LEDs, and a small numeric LCD display.

MiniMon is a simple Python3 program, which can read the data from this device via a USB connection, show them on the computer screen, and log them to disk, including a timestamp.

MiniMon in its current form runs on Linux, using the default HIDRAW driver, but can be adapted to other operating systems, where such a driver is available.

Example output in a normal office setting:
CO2: 501 ppm, T: 26.29 °C
CO2: 502 ppm, T: 26.29 °C

After exhaling towards the device, you may find this output, while the display on the device itself (limited to 3000ppm) only shows 'Hi' with the red LED on:
CO2: 9723 ppm, T: 26.85 °C
CO2: 7824 ppm, T: 26.85