rp-webusb-picoflash

A single-file WebUSB UF2 flasher for RP2040 and RP2350 devices in BOOTSEL mode.

This project runs fully in the browser (Chromium-based only) and uses the ROM vendor protocol (picotool-style), not the mass-storage UF2 drag & drop path.

Features

• Load UF2 in the browser (no helper app).
• Optional erase before write.
• Progress feedback with color phases: load (blue), erase (red), write (green).
• Simple UI and plain JavaScript (no build step).

Requirements

• A Chromium-based browser: Chrome, Edge, or Brave.
• A RP2040 or RP2350 device in BOOTSEL mode.
• WebUSB enabled (default on desktop Chromium).

Usage

1. Open sidecartridge-firmware-installer.html in a Chromium-based browser.
2. Click Select UF2 and choose your file.
3. Put the device into BOOTSEL mode and plug it in.
4. Click Flash and select the device in the WebUSB dialog.
5. Watch the progress log and bar.

Notes

• BOOTSEL mode is required for ROM flashing.
• The flasher uses the ROM vendor interface (not MSC), so it streams commands directly.
• If reboot fails at the end, unplug/replug the device.

Development

Everything is in a single file:

• sidecartridge-firmware-installer.html

No build or dependencies required.

License

See LICENSE.