This repo contains the slides for two workshops I recently held at CETI Institute in Portland, Oregon. It also includes code for a demo.
The first workshop - SensorTech - covers broad concepts in sensors - kinds of sensors, things you need to think about, how to prioritize. And ends with a discussions of a sensor I dislike (eCO2 - "equivalent CO2", which guesses how much CO2 there might be in a space) and a sensor I do like ("Nuclear Event Detector").
The second workshop - Assisted Assisted Living covers a project for monitoring an asissted living space using Home Assistant and Zigbee-based sensors.
The demo is written in CircuitPython. Run it by copying the files to a CircuitPython device and restarting it (or use circremote.
You'll want to connect a true CO2 sensor - the SCD40 or SCD41 - and an "equivalent CO2" sensor - CCS811 or ENS160. The code will show live graph of both sensors. Try exposing them to various gasses - especially actual pure CO2 (a SodaStream CO2 cartridge is useful for this) or alcohol - and you'll see how wildly the eCO2 sensor can vary from a true CO2 sensor.
Presentations are licensed CC BY-NC 4.0, Creative Commons Attribution-NonCommercial 4.0 International by John Romkey, 2025.
The code is licensed under the MIT License.
Datasheets are owned and licensed by the companies that published them.