Mistakes were made, but I learned a lot about PCB design with this and the subsequent projects that I have worked on (like don't bother trying to use the autorouter), and I have since produced a much more refined PCB for this project. One of the frustrations that I have run into with this project is the lack of a decent quality Saturn socket. The only current production socket I know of comes from those cheap Saturn controller extension cables you find on Aliexpress, and they do not fit tightly and do not make reliable contact with the controller plug. I really didn't have a solution for the problem until a couple of days ago it occurred to me that my main reason for doing this project in the first place was to connect my MC Cthulhu to my JAMMA PCBs, not necessarily to connect Saturn pads (although I did like having the option), so I decided to directly wire an ethernet cable to my converter PCB skipping the Saturn plug all together and thus creating what is effectively an RJ45 to DB15 cable.
This works wonderfully, but after using it for a little while a new frustration crept in. The fact that the Saturn controller doesn't have a select button means that there isn't an easy way to map a coin button to my arcade stick. Since I ditched the Saturn plug I decided that there was really no reason to keep using the Saturn controller protocol for communicating with the MC Cthulhu, so I started working on alternatives. First I tried to work on SNES code since it has 6 available buttons as well as Start and Select. I got a sketch working pretty well, but there are some bugs with certain button combinations causing the board to freak out and press all buttons simultaniously. I have not yet been able to figure that problem out, so I then tried an existing arduino library for capturing PSX controller inputs, which appears to be completely bug free as far as I have been able to test.
So here is the current status of the mod:
*PSX mode firmware is the most feature complete version and can be downloaded from my Github
*Lag appears to be under 1 frame compared to a directly wired button based on high speed camera captures that I did.
*PCB V0.8 is very refined, and fits comfortably inside Norcomp's 956-015-010R031 Backshell. PCB is on OSHPark
*BOM is also on OSHPark.
*You can use this as an RJ45 to DB15 adapter, or you could use it to adapt actual Saturn, SNES or Playstation controllers to DB15 by soldering the appropriate plug to the adapter.
*Everything is open source so feel free to build your own/play with my code. I may offer assembled cables in the future, but my projects are always free for anyone to use.
Future plans for the mod
*Switchable button maps for NEO-GEO or normal 6 button operation.
*On the fly user configurable buttons (this feature is probably not happening any time soon.)
*Possible support for other controller types. Genesis maybe?
*If Retro Bit ever releases officially licensed Saturn controller extensions maybe they will create a source for high quality Saturn controller sockets, in which case the original concept of a Saturn pad adapter can be realized.
I have tested this with the MC Cthulhu and got great results, however I don't have a Brook Retro board or a PS360+, If you have one of these boards and would like to volunteer to do some testing, PM me and I can see about sending a prototype your way.
