⚡

GMRS Bridge — Web Flasher

Flash a field-bridge board over USB, from any Chrome / Edge / Brave — no toolchain.

This is a full flash — the wired bootstrap / recovery path. It writes bootloader, partition table, and app at once, resetting the board to a known firmware and clearing its saved settings (bridge password + Wi-Fi return to defaults). Use it for a brand-new board, to migrate a pre-1.4.0 board onto over-the-air updates, or to rescue one. For a routine update on an already-1.4.x board, prefer the bridge's own ⚙ panel (over Wi-Fi) — it keeps your settings.

1Firmware image

Published image? loading… Choose a .bin file? A merged full-flash image the admin sent you (writes at 0x0).

2Options

Flashing speed

Erase entire flash first Also wipes everything beyond the firmware image (e.g. crash logs). A full flash already resets the bridge password and saved Wi-Fi to defaults either way — this just clears the rest. Usually leave it off.

3Connect & flash

Plug the board into this computer's USB, then click below and pick the board's USB-serial port? in the chooser. Keep it plugged in and the page open until it finishes.

Troubleshooting & notes

Which port to pick: the board's WCH USB-serial chip (vendor 1a86). It's named wchusbserial… on a Mac and USB Single Serial (ttyACM0) on a Chromebook — there, ignore the ttyS0–ttyS3 entries (the computer's own internal ports). On Windows it's a CH34x USB-serial COM port. Always use the board's USB-to-serial port ②, not the Direct/OTG port ①.

Where the firmware comes from: Published image downloads the latest admin-published build straight from the server — you normally never handle a file. It needs this computer online (the flasher page and image aren't cached for offline use). Fully offline, use Choose a .bin file with a build saved earlier (AirDrop / email / USB). A brand-new firmware becomes the Published image once the admin deploys it.

No port appears / can't connect: some boards need download mode — hold BOOT, tap RST, release BOOT, then click Connect. The flasher resets the board automatically at the end.

Fails partway or "packet content transfer stopped": drop the speed to 115200 and try again; a cheap USB cable or hub is the usual cause.

Chromebook: works in the built-in Chrome — no Linux, no flags.

After flashing: the board reboots on its own. A full flash resets the bridge password to gmrsfield and clears saved Wi-Fi, so join GMRS-Bridge with that default, then open the ⚙ panel to set your password and save Wi-Fi. From then on use the ⚙ panel's over-the-air update — it keeps those settings.

GMRS-Bridge doesn't appear after flashing? The flasher resets the board automatically when it finishes, but on these boards that auto-reset doesn't always start the app cleanly — it can be left idle in the bootloader with no Wi-Fi. Just tap the board's RST button once and GMRS-Bridge shows up right away. This is normal and harmless.