I was some time since the last update on my URU Key project. However, the project did not stop, no.

Having two different CO2 sensors it makes sense to put them together and compare reading over some period of time.

Recently I have purchased one more carbon dioxide sensor module — CJMCU-811. The module is built on a chip CCS811 by company ams.

Part 1 — Hardware design [/10.06.2019/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.

I am happy to say that I'm finally done with the hardware design of the URU Key device.

After some disruption on hardware design, I have returned to writing driver for the FPC1020 fingerprint scanner [/03.12.2019/fpc1020-fingerprint-scanner/]. It's sad, but as I don't have complete documentation the process takes a significant amount of time and a lot of effort. To speed up the evaluation I started to write relevant code using C++ and Arduino Framework.

Previously [/02.02.2020/uru-key-esp32-fido2-authenticator/] I have built the single board device featuring all the main hardware components to implement FIDO2 Authenticator but without an autonomous power source. Today with the addition of a power board my project becomes a completed device.

Autonomous devices like URU Key [/category/fido2] require periodic measurement of the battery voltage. I am going to use very simple schematics and very simple algorithm to understand how much juice my battery has at the moment.