Flashing

Web flasher

The web flasher is the fastest route onto the board. Open it in a browser that supports web serial, select your board and version and click “Flash”.

Tip

You see in the web flasher itself if your browser supports web serial. If it does, you can flash the firmware without installing any tools via USB. If you don’t have a browser that supports web serial, you can use the command line flasher below.

First flash

Without firmware on the board nothing handles the auto-reset handshake, so enter the ROM bootloader manually: hold BOOT, press RESET, release BOOT, then start the flash (web flasher or inv flash). This is the only manual button sequence; every later flash auto-resets without buttons (the firmware drives the DTR/RTS handshake esptool expects).

Danger

Always flash a merged image, never a bare app binary: a bare image has no bootloader or partition table and the board silently never boots.

Command line

During development you flash from the repo:

nix develop
inv flash        # build (if needed) → convert → flash via esptool