Terms and disclaimers

CYGM is firmware I write in my spare time and give away under the MIT licence. You buy ordinary parts from ordinary retailers, you put them together yourself, and you flash the firmware yourself. I sell nothing: no hardware, no software, no subscription, no paid tier, no account. Money you spend on this build goes to the shops you bought the parts from, and none of it comes to me.

Because nothing is sold, there is nothing bought, and nothing is owed. There is no support contract, no guaranteed response time and no service level. I answer what I can, in the Discord and the issue tracker and by email, when I have time. I may change how any of this works, stop publishing updates, take the site down, or stop the project altogether, at any time and without notice. The source stays under the MIT licence either way, which is the practical protection here: if I stop, the code is still yours to carry on with.

Using this site, or building and running the firmware, means you accept these terms. If you do not accept them, do not build one.

The device shows readings by asking a service you already use: Dexcom Share for a Dexcom sensor, LibreLinkUp for a FreeStyle Libre sensor, or your own Nightscout site. Weather comes from a public forecast service. None of those are mine, none of them are involved in this project, and none of them have agreed to anything with me.

Any one of them can change an interface, add a check, rate-limit a request, or simply stop, at any time and without warning, and the day that happens the device stops showing what it showed the day before. I may or may not be able to fix it. You have no remedy against me if that happens, and no claim on me for the cost of the parts.

Your relationship with your CGM provider is between you and them. Their terms of service, and whether using a third party display sits comfortably with them, is yours to read and decide on. I cannot make that call for you.

On credentials, the rule is short: use your own, and nobody else's. Your login details are stored on your own device and sent only to that provider's own servers, never to me and never to this website. Putting somebody else's credentials into a device is not something I can stop and not something I will defend. Where your provider supports it, a separate follower account rather than your main login is the sensible thing to use.

This is a do-it-yourself build with no certification of any kind behind it. You choose the parts, you assemble them, you flash the firmware, and you decide where it lives in your house. Everything that follows from that is yours: a bricked board, a part that arrives faulty, a case that does not fit, a device that stops working in the middle of the night.

The optional battery deserves its own sentence. A lithium cell can catch fire or vent if it is the wrong type, wired the wrong way round, damaged, swollen, or charged unattended. The build page carries the handling rules and they are not decoration. If you are not comfortable with that, build it without the battery and run it from USB, which is how the simplest version works anyway.

You assume the whole of that risk, including any risk to your property and to people in your home.

The firmware, this website and everything on it are provided as is, without warranty of any kind, express or implied, including but not limited to the warranties of merchantability, fitness for a particular purpose and non-infringement. That is the MIT licence the firmware ships under, and it is meant literally rather than as a formality.

I do not warrant that any of it will work, that it will keep working, that it is free of defects, or that anything it shows you is correct or current.

To the fullest extent the law allows, I am not liable for any indirect, incidental, special, consequential or punitive damages, or for any loss of data, property or profits, arising out of or connected with this project, the firmware, this website, or any device you build. This applies however the claim arises, whether in contract, in tort including negligence, or otherwise, and it applies even if I have been told such damages were possible.

To the fullest extent the law allows, my total liability for any claim connected with this project is limited to fifty United States dollars, which is more than I have ever received for it.

Some states do not allow the exclusion or limitation of certain damages, or the exclusion of implied warranties, so some of the above may not apply to you. Nothing here excludes or limits liability that cannot lawfully be excluded or limited, and in that case my liability is limited to the smallest amount the law permits.

Sending a story is voluntary and nothing is paid for one. What you send stays yours: you keep the copyright in your words and your pictures. By sending them you give me a non-exclusive, worldwide, royalty-free licence to publish them on this website, to edit them for length, clarity and formatting without changing their meaning, and to remove them at any time. That licence lasts only as long as the story is published, and it ends when you ask for it to come down.

By sending something you confirm that it is yours to send: that the words are yours, that any photographs are yours, and that everyone appearing in a photograph, or named or identifiable in the story, has agreed to it. If that person is a child, you are their parent or guardian. You have to be eighteen or older to submit.

I read every submission before anything is published, and I can decline or remove any of it for any reason. Removal on request is covered on the consumer health data page, along with exactly what is stored.

You agree to indemnify me against any claim, loss or cost arising from something you sent me, or from your use of this project in a way these terms do not permit.

Dexcom and Dexcom Share are trademarks of Dexcom, Inc. FreeStyle Libre and LibreLinkUp are trademarks of Abbott. Nightscout is a project of the Nightscout Foundation. All other marks belong to their owners.

CYGM is an independent project. It is not affiliated with, endorsed, sponsored or approved by any of them. Those names appear on this site only to say which service a device can read from, which is information you need in order to know whether this is any use to you.

The firmware source is released under the MIT licence and is at https://github.com/decibelkaos/CYGM. The licence text in that repository governs the code, and it permits use, modification and redistribution, commercial included, as long as the copyright notice and the licence travel with it.

The text, photographs and design of this website are mine, copyright Carl Brothers, all rights reserved, except where something says otherwise. Stories and photographs sent in by readers belong to the people who wrote and took them. Quote a paragraph with a link back and I will not mind at all; republishing a page wholesale is a different thing, so ask first.

If you believe something here infringes your copyright, email decibelkaos@gmail.com with the subject line DMCA. Identify the work, point me at the exact page, tell me how to reach you, and include the statements the Digital Millennium Copyright Act asks for: that you believe in good faith the use is not authorised, and that your notice is accurate and you are the owner or authorised to act for them, under penalty of perjury. I read that address myself and I will act on a valid notice quickly.

Law and venue. These terms are governed by the laws of the State of Washington, United States, without regard to its conflict of law rules. Any dispute goes to the state or federal courts sitting in King County, Washington, and you and I both agree to that venue.

Severability. If any part of these terms turns out to be unenforceable, that part is trimmed to the least extent needed to make it enforceable, or removed, and everything else stands.

The whole agreement. This page, together with the privacy page and the consumer health data page, is the whole of what is agreed between us about this project, and it replaces anything I have said elsewhere about it.

Changes. I may update this page. The date below moves when I do, and continuing to use the site or the firmware after that means you accept the revision. There is no mailing list to announce it on, so the date is the honest signal.

Contact. Carl Brothers, Washington state, United States, decibelkaos@gmail.com.

Effective 10 September 2026.