4dapter Firmware Flasher
Flash official 4dapter firmware over USB — no Arduino IDE required.
1 Choose your firmware
Don't see a release build, or want to test a firmware you built yourself? .
2 Connect
Click below and pick your 4dapter. If a second button appears here right after, click it fast — it means your browser needs one more click to finish connecting, and the board only waits a few seconds before giving up.
This firmware doesn't show up as a serial port on its own — press and release the small reset button on the 4dapter PCB first, then click below.
Why does it sometimes need a second click?
Flashing needs the board in a special "bootloader" mode. If it isn't already, we reset it automatically — but browsers only allow a device picker to open once per click, so picking the board again afterward needs a fresh click the first time you flash it here. The device may also take a couple of seconds to reappear in the picker under a different name than before. Once a board's been through this once, later flashes should reconnect automatically with no extra click.
3 Flashing
Progress shows here once connected. You can also click below to retry without reconnecting, if needed.
4 Done
Once flashing finishes above, your 4dapter is running the new firmware. Unplug and replug it if it doesn't show up right away.
5 Test it
Press any button on your 4dapter to confirm it's working.
This build has more than one gamepad wired to it, but browsers only ever show one of them here — that's a Chrome/Edge limitation, not a problem with your board. Any response above means it's working; see Advanced diagnostics if you want to confirm each port individually.