Using SNES pads on X-Box

[Whomper]

I'm enjoying SNES emulation on the X-Box at the moment, but feel restricted by the godawful digital pad. Having read up a bit on the net, I have a few questions and a proposed project that I'd just like to run a feasibility check on.

What I'd like to do is replace one of my X-Box controller's expansion ports with a SNES port, possibly embedded in a gutted X-Box memory card (purely for looks - the memory card interface would not be used). The SNES port would come from a SNES extension cable.

A vanilla SNES pad could then be plugged into this. Either the memory card casing or the X-Box pad itself would contain a decoder chip which would convert the SNES pad serial output back into up/down/left/right etc. The output of this chip would then be wired to the reverse of the X-Box pad using the same technique described here and here.

This will leave the other X-Box buttons working for the control functions of the emulator (menus, etc), and allow me to unplug the SNES pad when it's not needed.

Questions:

1) Can the SNES serial output be decoded by off-the-shelf chip(s)?
2) Will there be any significant delay if the signal is being coded by the SNES, then decoded and recoded by the X-Box pad before being received by the X-Box?
3) Is there an easier way? I know the SNES pad can be gutted and one-wire-per-button solutions put in place, but this seems so inelegant.

I've only dabbled in digital electronics in the past, so this should be a challenge, but I'm prepared to put in the hours and break things until I get this working.

[kendrick]

Your design is interesting. As that second port on the original Xbox controller is almost never used, that's a good place for a hacked connector. You may already know that the Xbox controller contains a USB hub, but that's not useful to us since most emulators detect only that one controller. However, that hub does provide a convenient source for 5 volt power with which to power your theoretical decoder.

In youir place, I would gut the SNES controller and replace the chip with an encoder from a third-party pad. That way you're only worried about one chip and not three. Your concept is perfectly feasible, but it seems like three times as much work as you might otherwise put forth.

-KKC, cooking dinner.

[ken_cinder]

Dude.......this is so spooky! I am in the process of getting things ready to do JUST this thing. I'm going to buy the cheapest memory card I can and an SNES extension cable to cannibalize the port from and put the port in the card.

I was thinking I'd just wire direct from the memcard port pins to the appropriate pads on the Xbox controller PCB. So I WOULD be using the interface. Also wiring inside the SNES pad direct from it's buttons (Thus I would be making the SNES pad no longer viable for use on a real SNES).

I never thought of the idea of using any sort of encoder, I just wanted to go simple and direct. I also thought about gutting an SNES pad, and chopping down an Xbox controller PCB as much as possible and fitting it inside the SNES pad. Not sure how feasible that is, but removing the analog sticks etc, and maybe shaving the PCB down in uneeded areas might make it possible.

[Whomper]

I was thinking I'd just wire direct from the memcard port pins to the appropriate pads on the Xbox controller PCB. So I WOULD be using the interface. Also wiring inside the SNES pad direct from it's buttons (Thus I would be making the SNES pad no longer viable for use on a real SNES).

Hmm. According to this hack, the X-Box memcard interface is only five pins (it's USB + a pin), so if you're going for one-wire-per-button, you're going to have to encode the signal before it reaches the pad, then decode it again.

Glad to hear some encouragement - I think I'll order some breadboards from Maplin and start tinkering. Would it be feasible to pick up a dead SNES from Ebay and play with the controller decoding circuit?

[ken_cinder]

Hmm that sucks. I hadn't gotten further than the idea, and ripping my Xbox pad open to have a look-see.
What about cannibalizing an Xbox pad for it's encoder, sticking the encoder in the SNES pad and wiring an SNES extension to an Xbox controller breakaway? Or sticking the encoder somewhere in the Xbox breakway cable/SNES extension? Feasible?

[kendrick]

That's exactly the way I'd do it. Like Whomper points out, you lose analog sticks and a couple of buttons. Also, you lose the analog functions of the four main action buttons. You also need some surface-mount soldering skills, as that chip is pretty tiny. There are other methods of getting at the chip, like sawing out the part of the donor controller's board.

-KKC