I’ve been really getting into making homebrew games. I got my game engine running on the Wii last year and I thought why not give the GameCube a shot. It’s a similar architecture, Broadway (Wii) is pretty much a faster Gekko (GC).
Open-Source to the rescue
I remembered reading about how the more popular modchips (or drivechips) for the GC and Wii worked, so I started looking into making my own. After some digging I found that the Xeno-GC modchip had been open-sourced a couple of years back, so I only needed to compile it and build some compatible hardware.
This little guy is the final result. I want to keep tweaking the firmware, so I made the board be just the right size to fit a small gap in the back of the GC; This would make it easy to flash and test on the actual hardware. I also made it big enough to allow for easier circuit board population.
I wired the bottom of the drive unit and ran a few tests. Everything checked out fine so I soldered in the modchip and crossed my fingers. :)
I proceeded to flash the modchip and it immediately came to life! I then popped in a homebrew game I burned earlier and it worked without a hitch, no laser adjustments needed or anything!
I cut of a tab in the back of the console cover, this is where the modchip will be placed.
You can see it here, snug and tight.
That’s pretty much it! Now I move on to porting my game engine and making a demo.
I noticed that the modchip would sometimes fail to boot up correctly, I changed the fuses on the AVR so that the modchip would start 64ms after powering up, giving the drive unit some time to setup. I used the following fuse values: 0xE4 0xD9
Make your own!
The modchip firmware can be found in here.
I also made a smaller version of the modchip, you can also order it from OSH Park.