Windows: one-time USB driver setup

macOS and Linux: skip this — nothing to install.

The first time you flash a C100 from Windows, the browser cannot reach the board's ROM bootloader until Windows has a driver bound to it. You assign the generic WinUSB driver once, with a small free tool called Zadig. Every flash after that just works.

1. Get Zadig

Download from zadig.akeo.ie — a single executable, no installation.

2. Enter the C100 into bootloader mode

Hold the top-left corner key while plugging in the USB cable. Windows detects a new device — it appears as DFU in FS Mode (USB ID 2E3C:DF11) with no driver yet.

USB cable at the top — hold the highlighted top-left key.

3. Run Zadig

Start zadig-2.9.exe and accept the admin (UAC) prompt.
In the dropdown, select DFU in FS Mode. If it is not listed, tick Options → List All Devices.
Check the USB ID field reads 2E3C / DF11 and Driver shows (NONE) — do not pick a mouse, hub, or your other keyboard.
In the driver box right of the green arrow, choose WinUSB.
Click Install Driver. It takes ~10–30 seconds.
When it reports success, close Zadig.

4. Flash

Unplug and re-plug the C100, open the WebEditor, and click UPDATE on the Firmware page. Pick the C100 bootloader in the browser's device dialog.

Undo

Device Manager → right-click the entry → Uninstall device → tick Delete the driver software for this device. Or run Zadig again.

Troubleshooting

Symptom	Fix
`2E3C DF11` not in the list	Tick Options → List All Devices; make sure the board is really in bootloader mode.
Install fails / "cannot find the file specified"	Re-run Zadig as administrator, try Replace Driver again.
WebEditor still can't find the device	Unplug/replug, fully close and reopen the browser.
Changed the driver on the wrong device	Device Manager → that device → Uninstall device (delete driver) → unplug/replug.