This is just sharing the project from https://github.com/CRG-Glen/CD32-to-A500-gamepad, and all design credit goes to the original author, CRG-Glen. The board is a drop-in replacement PCB for the Amiga A500 gamepad that turns it into a true CD32 pad, based on Commodore’s CD32 gamepad schematics.

A 74LS165 shift register and a 74LS125 buffer implement the CD32 serial button protocol, reading all seven CD32 buttons including Play and the two shoulder switches. The D-pad and face buttons use the original rubber domes pressing on copper contact pads, so an ENIG finish is recommended.

The SMD parts are 0402 and best left to the assembly house. The 47µF capacitor is hand-fitted and folded flat, and the shoulder switches can be reused from the original PCB. A cut DB9 extension cable is soldered directly to the 1.27 mm-pitch holes. The design is released under CERN-OHL-P v2 with KiCad 8 sources included, and a YouTube video covers the design, assembly and testing.