TeHyBug CO2 Mini Sensor

This is a smaller version of the https://blog.tehybug.com/index.php/2022/02/20/tehybug-senseair-co2-sensor/ its smaller because it uses a different sensor SCD4x which has a smaller size. The new board also has an OLED Display connector, the senseair s8 board was upgraded too and also supports a display connection.

Size comparison TeHyBug CO2 with S8 Senseair Sensor and with SCD4X Sensor

Here is a demonstration video of the new mini board in a 3d printed enclosure. https://youtu.be/aRd_TyuY4yc

I have also released firmware for OLED Display support and HomeAssistant autodiscovery, which is available on GitHub: https://github.com/gumslone/tehybug/tree/master/tehybug_co2_firmware

An enclosure for 3D Printing is available on Thingiverse for download: https://www.thingiverse.com/thing:5494215


  • I have just received my CO2 sensor thanks. I want to use it standalone for CO2/ temp display as in your photos. Not with a network. I cant find any doco on how to get into this mode. From the firmware I can see the mode button is configured for click, long click & double click handlers – is there are doco other than reading the code? Are the left & right buttons in the code just for debugging? Thanks!

    • Hi,

      most handlers are not used, the documentation is available in the readme.

      i.e. to turn off the Network mode and use the offline mode, hold the IO_5 (it’s located on the device’s back) Button and hit reset, then when you see a purple light release the IO_5 Button.
      The latest firmware release remembers the state online/online, so after the device restart, it boots to the previously set state. Older firmware versions always boot in network mode.

      The left side button is mode and the right side button is reset.
      If you hold the mode button for 15 Seconds it will do a factory reset and reboot the device.

      I will also extend the documentation at GitHub and add a photo with a button description.

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