Shallow Thoughts : tags : circuitpython

Akkana's Musings on Open Source Computing and Technology, Science, and Nature.

Fri, 19 Dec 2025

A Homebuilt CO2 Meter as a Virus Risk Proxy

[A sensor and small microcontroller, connected by a cable, sitting on pink anti-static bubblewrap. The microcontroller is also plugged in to a USB cable and a battery; it has a built-in display that reads: CO2: 470 ppm, Temp: 77F, Hum: 18%, BAT 65%] Despite most of the world deciding that COVID is over, I continue to be cautious about it. (My one bout of COVID resulted in congestive heart failure which I'm still dealing with, so I'm fairly anxious not to get it again.)

That means that I'm cautious about indoor gatherings. Some places say they've upgraded their ventilation, but can you believe them? I've long read about people using CO2 meters as a proxy, to tell you how well the air is circulating and how high the virus load might be in a crowd, and I've wanted to get one of my own.

You can buy CO2 meters, of course. But making a custom one sounds so much more fun! Reading Wired's story about New Zealand's Kawaiicon cybersecurity convention that provided CO2 trackers inspired me to finally order some parts.

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[ 18:06 Dec 19, 2025    More hardware | permalink to this entry | ]

Tue, 09 Dec 2025

Installing CircuitPython on a Gemma M0

(On Linux.)

[a microcontroller the size of a qyarter, plugged in to a light string wound through a blue knit cap] I wrote previously about my difficulties installing CircuitPython on an ESP32 Feather.

When I ordered the Feather, I ordered a bunch of other stuff too, including a tiny wearable microcontroller that's sold specifically for MicroPython: a Gemma M0.

Again, I had trouble getting MicroPython working, but the Gemma's problem was quite different.

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[ 18:13 Dec 09, 2025    More hardware | permalink to this entry | ]

Thu, 04 Dec 2025

Installing CircuitPython on an ESP32 Reverse Feather TFT

[A small microcontroller with a built-in display reading CO2: 470ppm and some other stuff, plugged into a USB-C cable] (On Linux, natch.)

I've been wanting to play around with CircuitPython for ages. I like Python, I like microcontrollers, what's not to like? Quite a while back, I even ordered a Feather M0 for that — but I didn't do my research, ordered the wi-fi version and it turned out that's the one Feather M0 that can't run CircuitPython.

This time I checked more carefully before ordering, and got a processor that for sure claimed to run CircuitPython.

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[ 13:58 Dec 04, 2025    More hardware | permalink to this entry | ]