• Owner: Lomanic
• Participants: none
• Status: deployed at Lomanic's office
• Project created on Sun 14-11-21 by Lomanic

• Implement Operame, a project from the Dutch hackerspace Revspace using a CO2 sensor coupled to a TTGO T-Display to tell people in a room that they should open the windows to limit Covid-19 aerial spread indoors
• Document it in English
• Maybe extend it in some way (automatic ventilation system?)

• LILYGO® TTGO T-Display, 16MB CH340K Chip variant
• Winsen MH-Z19C NDIR CO2 Sensor, 400-2000ppm-Pin Ver. variant, difficulty was to buy a genuine version as mentioned on the Hardware page, the tip is to buy from Winsen official store even if costlier
• through-hole female header pins (bought years ago, look around for cheaper options)
• perfboard (bought years ago, look around for cheaper options)
• solid core wire (left overs from other projects)

As I won't order PCBs online (and specific SMD sockets as shown in soldering instructions video) and just use what I have at hand, it will be assembled on a perfboard I had in my drawer for years.

Pinout:

TTGO T-Display      MH-Z19C
   5V                 VCC
   GND                GND
   D26                RX
   D27                TX

D12 on the TTGO has to be grounded but it's not obvious why

https://github.com/revspace/operame unmodified, had to install vscode (vscodium doesn't have platformio in its openvsx store) and the appropriate driver on Windows so platformio could flash the TTGO T-Display onboard ESP32

Initial proof of concept with breadboard, everything works perfectly.

Then perfboard implementation. A first for me, quite the hassle, I probably didn't go the easiest way with the solder traces and then the cables on the back. A multimeter with continuity mode is a must have to ensure there's no short between traces.

Next time, solder traces are not worth the time and headache and cables should just be soldered through holes with a single solder joint to the next hole.

• maybe build another one for the hackerspace, but not convinced at all seeing the general attitude of just being maskless in a basement
• automatic ventilation system at Fuz? (PID controller, "industry-level library" according to some dude on the Internet), bang-bang)
• statistics?