Questions about Gamecube controller circuitry - wiring LED to button press

[Sixfortyfive]

I need to wire a small LED to a controller so that it lights up at the exact moment when a specific button (either X or Y, preferably) is pressed or held. However, I'm a noob at electrical circuits. Can anyone help me with babby's first soldering project?

So, here's the controller's circuit board. Standard 1st party GCN pad:

I've marked the only points I know in red, and I've confirmed ground, 5v, and 3.3v with a multimeter, at least. The rest is a mystery, though.

I currently have this LED on hand. I'm not sure if it'll work, as the packaging indicates that it's designed for 12V circuits. (From what I've read, the input signals on a GCN pad are 3.3V and rumble is 5V, but I'm not positive about any of that myself.) What points on the controller would I need to connect something like this to in order for this to work? Do I need a different LED? Do I need a resistor? If so, what type?

Any help would be appreciated. It's not necessary that the controller is fully put back together. I only need this for testing, so I can leave the circuit board exposed if need be. Here are bigger shots of the front and back of the controller, if needed.

 

[SinsOfApathy]

http://www.int03.co.uk/crema/hardware/gamecube/gc-control.html

You'll probably want a 100 - 470 Ohm resister. With the 5V line, you're looking at about a 220.

 

[Yeroc]

First, yes. You'll need a different LED. Second, this is a fairly difficult mod to do if you've never soldered before.

Some basic info about attaching an LED to the rumble power supply that will be of some informative use to you:
http://smashboards.com/threads/the-new-guide-to-spray-painting-your-gamecube-controller.265922/
(you have to scroll down to my LED guide)

There are two ways that I know of to attach an LED to a specific button. One I have tried and verified, one I have not but I see no reason it shouldn't work. For the first, you connect the input of a logic inverter to the positive wire for the button, and the LED connects between the inverter output and ground (in series with a 100ohm resistor). The logic inverter needs to be connected to a supply voltage (either the 3.3V or the 5V will work) and to ground. What this does is when you press the button, the inverter does as it's name suggests and drives it's output high, triggering the LED.

The second method is directly wiring the LED from the 3.3V source to the positive lead of the button, again in series with a resistor. Again I have never done this personally, but I don't see why it wouldn't work.

To do these mods, you will need to attach leads to the supply voltage pins on the header, and attach very fine wires to the pins on the core IC of the controller. This page has info on which pins those are:
http://forums.modretro.com/viewtopic.php?f=36&t=8517
This is not the easiest task. It takes a very steady hand and high degree of comfortableness with soldering.

 

[Sixfortyfive]

After discussing this with a friend, I think I'll go with the following approach:

I'll wire a button/switch in place of the X button, with the LED connected like so. If I can't get a LED to match the voltage exactly, I'll wire the necessary resistor on the + line.

Going to have to sacrifice the controller for this, but it's for a worthy cause.

Thanks for the tips though.

 

[SinsOfApathy]

Going to have to sacrifice the controller for this, but it's for a worthy cause.

I feel your pain. I need to take the cable from one of my controllers, so I can use it to send inputs over a TCP server to my RPi. I really wish I could've gotten the SI registers to pan out, but I'm just too damn lazy to get all the interrupt registers and such in proper form.

 

[Kadano]

Hey, I’m just curious, do you need this so you can sync the button input registered by the game with a visual cue that is recorded by a camera for lag-testing? If not, what is its use?

Will the X button still register and output inputs if it’s connected to the 3.3v line?

 

[Sixfortyfive]

Hey, I’m just curious, do you need this so you can sync the button input registered by the game with a visual cue that is recorded by a camera for lag-testing? If not, what is its use?

Will the X button still register and output inputs if it’s connected to the 3.3v line?

Yes, the idea is to test a Gamecube against a Wii U running a GCN game loader, plus a few other things I have in mind.

As for your second question, I guess I'll find out.