This is just sharing the project from https://github.com/trickydee/ultrausbt-amiga. All credit goes to the original author, trickydee, and to the upstream amigahid-pico project by borb.

The adapter uses a Raspberry Pi Pico (a Pico 2 W for Bluetooth) to connect modern USB and Bluetooth keyboards, mice and gamepads to classic Amiga computers. The Amiga itself needs no USB stack. It plugs into the Amiga’s 5-pin DIN keyboard port and both DB9 joystick ports with standard straight-through cables.

Many controllers are supported, including PlayStation 3/4/5, Xbox, Switch Pro, Stadia and generic HID pads. There is also CD32 seven-button pad emulation and a twin-stick Llamatron mode. A small OLED with three buttons handles port modes, Bluetooth pairing and settings.

The adapter also works in reverse (Host Mode), turning a real Amiga keyboard, mouse and Atari-style joystick into USB devices for a modern PC. The board is a simple two-layer, all-through-hole design, so it is easy to hand-solder.