Nintendo's idea of implementing support for NES, SNES and N64 games in their new console, the Wii, is in my opinion one of their greatest ideas. As soon as I learned that it would be possible to use Gamecube controllers to play those games, I started thinking about designing an Snes/Nes controllers to Gamecube adapter which would be compatible with the Wii.
As soon as I got access to a Wii (I still dont have mine), I started testing my code which I had prepared in advance. I started by doing the NES and SNES adapter. Later, since a friend kept insisting that I should also design a N64 to Gamecube/Wii adapter, I implemented such an adapter.
Because of the complexity of the Gamecube's controller protocol, it's not possible to build a simple conversion circuit without using programmable components. For this project, I used an atmel Atmega8 microcontroller. Maybe it's a little overkill, but using this chip allowed me to use my Multiuse tiny 1 PCB. Given the small size of this circuit, it's possible to fit it inside an original controller.