A while ago I built a PSX saturn pad, then traded it, then found myself wanting one again. Since I don't want to go through the horrible wiring crap again, I figured it would be easiest to build a converter, since both PSX and Saturn protocols seem fairly simple. I'm using an Atmel AVR, and I've got it talking to a PSX adapter using the USI interface. The thing is, it only talks to one specific converter, a "3 in 1 PC Joy Box". On my other converters and a real PSX, nothing happens - the PSX won't acknowledge it's connected. I've messed with the timing of the ACK signal, but that hasn't helped. All the PSX wires are connected straight to the IO pins of the chip - is there something else I need to add?
Oh, something else that came to mind. According to the various pages on the controller protocol, the lines that the controller uses to send data are meant to be pulled up on the console side. I was poking around with a multimeter and there seemed to be capacitors between those lines and Vcc. Is there a reason for this?