00 About v1.1.10 Release
2026-10-15
One person, one reason
CYGM isn't a company. I wrote the firmware for my own house, then gave it away because plenty of other houses need the same thing.
01 Who makes it
Carl Brothers
I work in live entertainment as a sound engineer, a lighting tech and a stage manager. Developing is the hobby, not the trade. When my step-daughter was diagnosed with type 1 diabetes I knew I had to do something, and with my wife Stefanie behind it, this is what it turned into.
I'm in Auburn, Washington. The belief behind the whole thing is one line: if I can make someone's life easier, I should.
02 Why it exists
The number was always on a phone that was somewhere else
After the diagnosis, the reading we needed most was the one hardest to see. It lived in an app, on a phone charging in another room. We didn't need more data. We needed a screen you could glance at.
The screens I could buy were expensive, closed, and usually wanted a subscription, so I went the other way: about $40 in parts you buy yourself, source anyone can read, and no account with me. That puts this in #WeAreNotWaiting, families building their own diabetes tools. I'm in that community, not selling to it.
03 How it is made
Written by one person, tested on real hardware
No team, no QA department, no release board. A bench with devices on it, a version number on every build, and a public history.
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Open from the first commit
The firmware is on GitHub under an MIT licence. Read exactly what the device does with your credentials, or build your own version.
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Every build is numbered, and it is still beta
I bump the version on every build that reaches a device, so two units can't report the same version and behave differently. The published history lists twenty-six releases between March and September 2026, and the current firmware is v1.1.10 Release, and I print the stage on the device's own About screen too.
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Tested on the real board
I flash changes to physical units and drive them over the serial console before releasing anything. The hardware is cheap enough that I keep several running.
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Updates arrive over WiFi
After the first flash, new firmware is offered on the device and installs over the air. No cable, no computer.
04 How it is funded
It is not a business
I sell nothing. No subscription, no paid tier, no account, and the firmware and its updates are free. I don't sell the hardware either: the parts are ordinary items from ordinary retailers, and that money goes to the sellers.
I buy my own development hardware out of pocket. That's the whole arrangement, and it explains what not to expect from me: no support contract, no guaranteed response time, no obligation either way.
05 Contact
Reaching a real person
All three land with me. The choice mostly decides how quickly somebody else can get to you before I do.
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Discord
Best for setup trouble. Other builders are in there, so it is usually fastest.
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Issue tracker
Best for a bug you can reproduce, or a feature request. It's public, I can't lose it, and the logs stay attached.
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Email
Best for anything you'd rather not post in public. I'm the only one reading it, so a reply can take a while.
06 The code
Where it all lives
The firmware source is at https://github.com/decibelkaos/CYGM, released under the MIT licence. Use it, change it, redistribute it, commercially included, as long as the copyright notice and licence text travel with it. It comes with no warranty. I mean that part too.
Tagged builds and their notes are on the releases page, and flashing instructions are on the build page. The current firmware is v1.1.10 Release, released 2026-10-15.
CYGM is an open-source, experimental secondary CGM display. It is not FDA-cleared or FDA-approved, and it has not been clinically validated. It shows readings that have already travelled through your own CGM's app and cloud service, so it can lag, gap or fail independently of them.
Never use it as the sole basis for a treatment decision, and never rely on it as your only alarm. Always confirm on your prescribed CGM receiver or app before dosing or treating.