Modder turns original Game Boy Advance into a Nintendo Switch controller using GBA Link Cable

Tinkerer and modder Robert Dale Smith has figured out how to use a classic Game Boy Advance, its old proprietary link cable, and a bit of jerry-rigging to turn it into a controller for the Nintendo Switch.

He announced this modding feat on X just a few days ago and showcased a demo of himself playing Nintendo Switch Online while using the original GBA as a controller to play emulated GBA games, as well as the recently released physical copies of Pokémon FireRed and LeafGreen.

Smith looked back at his early youth and his love for the GameCube and the GBA, which served as the driving motivation behind his project. It’s cleverly put together. He stated on X:

“Yeah, as far as the console knows, it’s a generic Switch controller. But I do have two-way communication with the GBA on the Pico adapter in the middle. More would be possible if software for the Switch were to be written. The way it works is that the GBA link cable can sideload a small multiboot ROM into memory and run it.”

Smith further explained, “Then it can be configured to send and receive messages over the link cable to trigger actions. In this case, the adapter just signals that it is in Switch USB mode when the Switch powers it.”

He continued later, “If Nintendo ever wants to talk, then my DMs are open. We can easily make this happen. The open-source firmware is done. The hardware costs just a few bucks. Switch games just need a small software patch to bridge the gap.”

The project itself harkens back to the wild couch co-op vibes of games like The Legend of Zelda: The Wind Waker, where players could use the GBA as a second screen or let friends join in the fun.

But this isn’t just nostalgia; it’s reality, as this mod makes the link-cable-connected GBA feel right at home with the Switch, even though there are a few wires and a microcontroller dangling off to the side.

Smith created the mod using his open-source Joypad OS firmware, which allows the GBA to act as a USB controller compatible with virtually any console or hardware, including PC, PS3, Xbox 360, and many more.