How hard would it be to build an adapter so I could plug a Saturn controller into my Dreamcast? What kind of parts would I need?
Alternately, does anyone have a couple they'd be willing to sell? I've looked around, but have had very little luck finding any since Lik-Sang closed up shop.
You can get a Total Control 3 from Play-Asia.com (http://www.play-asia.com/SOap-23-83-lss-71-h5-49-en-84-j-70-46.html)
for a do it your self..
There is only one know tut on DC's
http://mc.pp.se/dc/dchid.html
this will get you to usb, and will contain the information to convert to saturn. You will need c coding experience and know how of an oscilloscope.
or
here is a away to interface with the DC ( if you can get the saturn to send neo-geo style out put )
http://www.instructables.com/id/How-to-Piggyback-a-Dreamcast-Controller-on-a-Unive/
How hard , I dont know how to answer this as I dont know what your familiar with. For me from 1 to 10 1 being snes -> nes 10 being DC -> usb I would say a 7.
i dont know what encoder the saturn uses, but you likely just need to build a box that decodes the data then feeds it to a dc encoder which you can scavenge from an aftermarket dc controller. if you just want to use the dreamcast dpad then it should be fairly straight forward, otherwise therelll be a bit more to it.. analogue inputs are more difficult to turn digital, but by no means impossible.
youre looking at a box with at least two ic's and probably a crystal oscillator, unless a clock signal from the dreamcast can be used. for analogue buttons (l, r, analogue stick) theres probably a bunch of ways to do it, personally i'd measure the resistance of the minimum and maximum (and neutral for the stick) resistance values (assuming your after market controller uses pots and not a hall effect like the official controller) and rig something up to switch between those amounts depending on the state of the saturn buttons.
hopefuly i've given you something to look into.