Tour
See what this page does first
A walk through the charts and the summaries with example readings already in them, if you would rather look before you go and fetch your card.
00 Tools v1.1.10 Release
2026-10-15
See your readings
Your display quietly saves every reading onto a little memory card. Open them here and look at your days. Nothing is uploaded.
Which one have you got?
The little memory card
Out of the display, in a card reader.
What is on the card, further down, says what each file holds.
The card is still in the display
- Unplug the display, then push the card in gently until it clicks and pops back out.
- Slide it into a card reader on this computer.
- You will see files named
GYYMMDD.CSV, one for each day.G260907.CSVis the 7th of September 2026. - Select them all and press Choose the files. On a computer you can drag them onto this box instead, if that is easier.
Take the lot. Anything that is not a day gets skipped, so you do not have to work out which files matter. Copying them changes nothing on the card: put it back and the display carries on where it left off.
The display itself, on a cable
Leave the card where it is, plug the display into this computer or into an Android phone, and the page copies your days across for you. It then keeps showing the reading the display has right now.
Some computers and phones keep the cable to themselves, so the display never turns up in the list they offer. The button above talks to the cable directly instead.
This browser cannot open a USB port, so it cannot reach the display.
Take the card out of the display and use The little memory card
instead — that way works in every browser.
What happens when you press it, and what to do if nothing does
- Use a USB cable that carries data. A charging cable looks identical and will never work; there is a tester at the foot of this page if you are not sure which one you have.
- Press Connect the display, then pick the display when your browser asks. That permission is yours to give, and you can take it back at any time from the icon in the address bar.
- Opening the connection restarts the display, so it waits a few seconds, then lists your days and copies them across, checking each one.
- However it ends, the display stays connected and a bar along the bottom of the page shows what it is showing right now: the reading, how old it is, the battery and the signal. It stops when you press Disconnect or unplug the cable.
- If the list your browser offers comes up empty, a second button appears above. Some systems hold on to the cable themselves, and that button talks to it directly.
- On an Android phone the first button already takes that direct route, because Android never offers the cable in the list. If the phone will not let go of it, unplug the cable, plug it back in and press the button again.
- A display with no card in it still connects. There are no days to copy, but its reading appears along the bottom of the page and keeps itself up to date.
Nothing is uploaded. Your readings stay on this computer.
Your readings will show up here
Pick one of the two boxes above and this part of the page fills in.
- One day at a time. That day drawn hour by hour, with the gaps left as gaps rather than drawn over.
- How much of the day was in the green. Your five zones as plain percentages, with what each one means underneath.
- Everything else, under More detail. All your days at once, a typical day, every single reading, and a report you can print or hand to your clinic.
Want a look before you dig the card out?
Your days
Pick a day
Newest first. The little bar under each day shows how much of it sat in the green zone.
The day, hour by hour
What these numbers mean
Timeline
Drag across the chart to zoom in, scroll to zoom, double-click to zoom out.
The numbers
Every figure here follows the days set at the top of this view.
A typical day
Every day shown, stacked on top of each other. The line is the middle value at that time of day; the bands hold the middle half and the middle four-fifths of readings.
Time in range
Overall first, then day by day.
About the display
What the display itself recorded alongside each reading. Newer cards only.
Every reading
| When | Reading | Heading |
|---|
Your readings stay on this computer
- Nothing is uploaded. No account, no server, nothing counting visits. Turn the network off and this page still works.
- The card and the cable are the only sources. Your days and the reading on the display come straight into this tab.
- None of it identifies you. Readings, the times they arrived, and how the display was doing. No name, no location.
- Files you save are saved by your browser, onto this computer, like any other download.
- Only this page came from the internet. From then on it works on its own.
Every claim here can be checked in the source of this page, which is the point: as a promise it would be worth nothing.
What is on the card
The files on it
GYYMMDD.CSV— one day of readings. This is what the page opens.SYYMMDD.LOG— the display's own diary of what it was doing. It stays off unless you switch it on, so most cards never have one. Useful if something goes wrong, and ignored here.
Each line starts with the time, the reading, and which way it was heading. After that the display records how it was doing itself at that moment: where the reading came from, how old it was, the battery, whether it was charging, the Wi-Fi signal, free memory, how long it had been running, and any alarm it raised. Files from an older release hold just the first three and open exactly the same. Nothing on the card identifies you.
Gaps are normal
A reading arrives about every five minutes, so a full day holds around 288 of them. Fewer is completely ordinary: a new sensor warming up, the display out of reach of the Wi-Fi, or simply switched off. The page shows you where the gaps are rather than quietly drawing a line through them.
The other tools
Cable
Find out if a cable carries data
A charge-only cable looks exactly like one that talks. This tells you which of the two you are holding, in a few seconds, before you start suspecting the board.
Flash
Put the firmware on a board
Connect a board to this computer and the current release is written straight onto it from the browser. Nothing to install, and it is the same page whether the board is brand new or already running.
Beta
Try a build before everyone else
Each new firmware goes to a handful of people before it goes to everyone. There is room for you if you would like a turn.
A second screen, not your source of truth
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.