Flash the firmware in your browser

A board, a cable that carries data, and Chrome or Edge on a computer. The browser talks to the board directly, so there is nothing to install on your machine and nothing to compile.

Start flashing Build one

01 Firmware

Putting the software on it v1.1.10 Release

You do this once, from a computer, over the USB cable. After that new firmware arrives over WiFi, and you should never need the cable again.

Before you start

A computer, not a phone Running Chrome or Edge. Not Safari, not Firefox, and not a phone or tablet.

A USB-C cable that carries data Plenty of cables only carry power, and that is the most common reason this goes wrong. If no port appears, change the cable before you blame the board.

Maybe a driver If no port appears in the list, install the CH340 driver and try again.

Six steps, about a minute

Plug the board into your computer with the USB cable.
Find the two small buttons on the board. Press and hold BOOT and RESET together. Tip: they are not labelled well. BOOT is the inner one, closest to the centre of the board. RESET is the one nearer the edge.
Let go of RESET. Keep holding BOOT.
Start the install, and pick the port when the browser asks you which one. An empty list is the cable or the driver. Go back to the boxes above.
Keep holding BOOT until the progress bar reaches about five per cent, then let go.
Wait about a minute. The device restarts on its own and walks you through WiFi, your location and your CGM.

Install it

Standing by

Standing by.

Finding the current firmware.

Pre-flight

The cable carries data, not just power.
The board is plugged in and holding BOOT.
Nothing else has the port: close any serial monitor or IDE.

Flashing erases everything stored on the device

WiFi credentials, your CGM login, alarm thresholds, preferences: all of it goes, and I have no option that preserves them. A microSD card is left alone, so wipe that yourself if it holds logged readings.

Where updates come from, and what the device can check

After the first flash, new firmware arrives over WiFi. The device keeps two application slots and only switches to a new one once the update has been written in full, so an interrupted update falls back to the firmware you were already running.

The download happens over an encrypted connection whose certificate the device verifies, and the address it will accept is pinned to this site. The images themselves are not separately signed, though, which means the device has no signature to check before it installs one. Install from a source you trust, which for now means me.

Read the quick start Release history

Current firmware v1.1.10 Release · released 2026-10-15

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.