Some time ago I have purchased online carbon dioxide (CO2) sensor module MH-Z19b. It's a cheap and very simple sensor with the UART interface allowing concentration measurement in the range up to 5000ppm.
While working on a CO2 sensor [/2019/06/10/carbon-dioxide-sensor-mh-z19b-part-1/] I needed to manage the device without any human interface or additional connectors. Fortunately, the ESP8266 devices include the WiFi interface and it was obvious step to use it for device management.
Part 1 - Hardware design [/2019/06/10/carbon-dioxide-sensor-mh-z19b-part-1/] Prototype projects do not require complex software and I am using the Arduino framework because it has plenty of useful libraries for all possible device types. For compiling the project I am using PlatformIO framework.
Recently I have purchased one more carbon dioxide sensor module - CJMCU-811. The module is built on a chip CCS811 by company ams.
Having two different CO2 sensors it makes sense to put them together and compare reading over some period of time.
This update was delayed due to summer holidays but it brings achievement of the very important milestone. Now we have a very minimal implementation of the FIDO2 authentication protocol on the Arduino framework. The simplicity of the Arduino platform and the availability of the hardware opens the door to secure authentication to everyone interested.