Splitting a Wired GC Controller's Data Line

[I3lackR0se]

Hey everyone, doing my first modding project for a GC, and I've ran into a bit of a snag.

I'm working on a project to split the bidirectional data line of a Gamecube controller. Part of split will continue back down the wire to the plug where it can connect to the console as normal. The other end is going to an Arduino micro-controller that will interface with a computer. Other than the data line, no other wires / parts of the controller will be modified or messed with.

Basically, I am making the GC wire version of this: http://www.compuphase.com/electronics/rs232split.htm

After copious amounts of research, I believe the best way to go about this task is to run the data line through an optocoupler. This seems like it would be the simplest way to transmit the data to another line without the circuit getting too complicated.

The 4N35 optocouplers I have in stock (the data sheet here http://www.avagotech.com/docs/AV02-0773EN) have a forward voltage of 1.2v. That will drop the 3.43V high of the data line to 2.23V, at which point I assume the console will no longer recognize the signal.

My problems/questions are thus:
1) Is the approach I am taking valid/the simplest method, or I am completely off-base in my approach?
2) If the approach is good, is finding a way to boost the high signal back to 3.43V the only thing I need to do to have the controller able to communicate with the console again?
3) If all I need to do is boost the signal, what would be the cheapest/simplest circuit part to do this?

 

[zack]

Well.. the simplest method would be to use a slide switch or similar SPDT switch. But I imagine you're going through all this trouble because you don't want to switch anything manually?

 

[I3lackR0se]

Indeed, I wish my plans were that simple : /

My end goal is to create a program that records the inputs of the controller with time stamps into a file on my computer while still playing the game on the console. Then I can do fancy things with them (input playback in discrete games, create controller input gui's to superimpose on captured gameplay, etc). At least the programming part I have covered easily enough, as my background is Computer Science, with some dabbling in Computer Engineering (and hence my somewhat able but still very limited circuit knowledge).

 

[public-pervert]

RDC figured out the GC controller protocol, if it helps you.
viewtopic.php?f=36&t=11386

 

[I3lackR0se]

Yea I saw that. I actually plan to reference it often for the programming portion. Unfortunately he doesn't have much info on what the circuit for the data line looks like outside of the wire/controller.

 

[Blargaman91]

I can't say I know a thing about what you're doing, but can you not connect the controller to two devices at the same time?

 

[I3lackR0se]

That is in essence what I am trying to do, I just need to figure out the exact circuit setup to make it happen.

If you're asking if I can just split the wire and connect half of the split directly into the Arduino micro-controller, no I don't believe I can do that. Perceivably there would be some sort of voltage drop for powering the pin on the Arduino, and then the voltage for the line going into the Gamecube would be less than the 3.43V required for the console to detect the signal.

 

[Theodote25]

I have a really silly way of solving this. You need one wave bird controller and two receivers, set to the same frequency. That way the signal won't drop.