Gamecube controller, replace c-stick with c-pad.

grossaffe · Post by **grossaffe** » Fri May 30, 2008 1:00 am

I've been thinking about converting an old gamecube controller into an N64 controller FOR the gamecube/Wii. I thought maybe it would be nice to have for playing N64 emulated games on the Wii.

You see, I have an old gamecube controller that has calibration problems. The main joystick is uncalibrated for some reason. What I was considering doing was unplugging the C-stick, desoldering it and replacing the main joystick with that one. If my assumptions are correct, that would solve the calibration problems in the main joystick, at the same time, making it a single-analog controller.
Here's the problem, a gamecube controller only has 12 buttons (A,B, L, R,X,Y, Z, D-pad, Start) where an N64 has 14 buttons (A,B, L, R, Z, C-pad, D-pad, Start).

at this point in time, i am awaiting information on how the emulator deals with this issue, but until I get that info, any ideas on how I should proceed (this would be my first controller mod that involves cutting up a circuit board and requiring exact measurements to reshape, so advice on the basics would be appreciated as well).

edit: project changed, just looking to create a digital pad to replace a joystick now.

Grandmasterjimmy · Post by **Grandmasterjimmy** » Fri May 30, 2008 9:26 am

C-Stick is the C-pad, so you have more buttons on the GC pad.

heres a guide I found on the net, to make a converter for GC/wii.

http://www.raphnet.net/electronique/x2wii/index_en.php

I suggest just buying a controller adapter for the GC/Wii.

http://www.raphnetshop.com/products/n64 ... ?category=

You could wire the converter into the pad, and make the gamecube wire come from the pad. It will be way easier than stuffing the GC pad into the N64 pad.

grossaffe · Post by **grossaffe** » Fri May 30, 2008 10:36 am

Grandmasterjimmy wrote:C-Stick is the C-pad, so you have more buttons on the GC pad.

heres a guide I found on the net, to make a converter for GC/wii.

http://www.raphnet.net/electronique/x2wii/index_en.php

I suggest just buying a controller adapter for the GC/Wii.

http://www.raphnetshop.com/products/n64 ... ?category=

You could wire the converter into the pad, and make the gamecube wire come from the pad. It will be way easier than stuffing the GC pad into the N64 pad.

dang it, i kind of figured they'd probably use the c-stick in some way. I guess they convert the c-buttons into an analog signal (probably not that difficult, is it?). I guess i'll have to find another project for that controller. maybe I'll make an SNES controller out of it. how hard could that be?

Negative_Creep · Post by **Negative_Creep** » Fri May 30, 2008 10:50 am

You'll have enough buttons if you convert the C-Button analog signal.. check out the Razor X mod for the PSP, which is an analog stick but it actually points to the 4 face buttons on the PSP so techinically it's a digital signal. Yes, I know it's PSP but it's the same kind of thing you want.

grossaffe · Post by **grossaffe** » Fri May 30, 2008 11:12 am

Negative_Creep wrote:You'll have enough buttons if you convert the C-Button analog signal.. check out the Razor X mod for the PSP, which is an analog stick but it actually points to the 4 face buttons on the PSP so techinically it's a digital signal. Yes, I know it's PSP but it's the same kind of thing you want.

I think the razor mod does the exact opposite of what i'm looking to do. that takes a bunch of buttons and places a joystick on top of them. I want to be able to remove the joystick and replace is with digital buttons. not sure how i would be able to do that.

I was looking at the gamecube controller, and it appears that the c-stick is attached to the main-board via a 4-connection plug. would anyone have any idea how one could possibly create a digital setup to plug into it that outputs the correct signals?

grossaffe · Post by **grossaffe** » Fri May 30, 2008 7:18 pm

well, i've been looking over what it would take to actually cut apart the controller and put it in an n64 shell, and i'm thinking it would be much more effort than reward i would get back from it. instead, I'm thinking i'll just make a c-pad to replace the joystick and that should give me as much functionality as I need. I'll retitle the thread to fit.

Fat D · Post by **Fat D** » Sat May 31, 2008 7:08 pm

As a potentiometer used in a joystick usually is used as a voltage divider consisting of two resistors (the part between + and out and the part between - and out) for which the ratio of the resistors is the value detected, one should be able to substitute a pair of resistors with buttons to short them. However, pressing both buttons on an axis simulataneously would short-circuit the controller.

grossaffe · Post by **grossaffe** » Sat May 31, 2008 11:05 pm

Fat D wrote:As a potentiometer used in a joystick usually is used as a voltage divider consisting of two resistors (the part between + and out and the part between - and out) for which the ratio of the resistors is the value detected, one should be able to substitute a pair of resistors with buttons to short them. However, pressing both buttons on an axis simulataneously would short-circuit the controller.

ok, so when you say would short-circuit the controller, are you saying that it would fry the circuitry? i guess what really matters is that no two buttons opposite each other can be used concurrently. That can be easily solved if I use something of the d-pad variety.

I don't quite understand how a potentiometer works. I understand that as you move the joystick, it stretches and compresses resistors that change the voltage output. But how does it change the polarity of the current? What kind of resistors am I looking for, and how would they go into the circuit (there are 4 wires leading to the circuit- 5v input, x-output, y-output, ground.

Fat D · Post by **Fat D** » Sun Jun 01, 2008 7:48 am

grossaffe wrote:
Fat D wrote:As a potentiometer used in a joystick usually is used as a voltage divider consisting of two resistors (the part between + and out and the part between - and out) for which the ratio of the resistors is the value detected, one should be able to substitute a pair of resistors with buttons to short them. However, pressing both buttons on an axis simulataneously would short-circuit the controller.
ok, so when you say would short-circuit the controller, are you saying that it would fry the circuitry? i guess what really matters is that no two buttons opposite each other can be used concurrently. That can be easily solved if I use something of the d-pad variety.

I don't quite understand how a potentiometer works. I understand that as you move the joystick, it stretches and compresses resistors that change the voltage output. But how does it change the polarity of the current? What kind of resistors am I looking for, and how would they go into the circuit (there are 4 wires leading to the circuit- 5v input, x-output, y-output, ground.

It might fry the circuitry of the console if the current is not regulated, if it is, it will draw all power away from the controller, turning it off for the duration of the depression.

A potentiometer is a large resistor with an additional contact, which can be moved anywhere from one terminal to the other. If it is on the +5V side, it is directly connected to +5V and therefore signals maximum. If it is on the ground side, it signals minimum. for any position in-between, you need the rules of resistors in series: the voltage is split in the ratio of the resistance. So if you are near the center, the resistor in the potentiometer is split in half. So you have half of the voltage dropping off before the contact point and the other half behind it. The signal recieved is halfway between max and min. The voltage against ground on the terminal is +2.5V.
What resistors you use is not important, however, they should be reasonable high (for low currents) and they need to be roughly the same resistance. I have no practical experience, but I think the right resistance for a joystick potentiometer is in the range of 10k-100k, so individual resistances should be 10k-47k

grossaffe · Post by **grossaffe** » Sun Jun 01, 2008 9:02 am

Fat D wrote:
grossaffe wrote:
Fat D wrote:As a potentiometer used in a joystick usually is used as a voltage divider consisting of two resistors (the part between + and out and the part between - and out) for which the ratio of the resistors is the value detected, one should be able to substitute a pair of resistors with buttons to short them. However, pressing both buttons on an axis simulataneously would short-circuit the controller.
ok, so when you say would short-circuit the controller, are you saying that it would fry the circuitry? i guess what really matters is that no two buttons opposite each other can be used concurrently. That can be easily solved if I use something of the d-pad variety.

I don't quite understand how a potentiometer works. I understand that as you move the joystick, it stretches and compresses resistors that change the voltage output. But how does it change the polarity of the current? What kind of resistors am I looking for, and how would they go into the circuit (there are 4 wires leading to the circuit- 5v input, x-output, y-output, ground.
It might fry the circuitry of the console if the current is not regulated, if it is, it will draw all power away from the controller, turning it off for the duration of the depression.

A potentiometer is a large resistor with an additional contact, which can be moved anywhere from one terminal to the other. If it is on the +5V side, it is directly connected to +5V and therefore signals maximum. If it is on the ground side, it signals minimum. for any position in-between, you need the rules of resistors in series: the voltage is split in the ratio of the resistance. So if you are near the center, the resistor in the potentiometer is split in half. So you have half of the voltage dropping off before the contact point and the other half behind it. The signal recieved is halfway between max and min. The voltage against ground on the terminal is +2.5V.
What resistors you use is not important, however, they should be reasonable high (for low currents) and they need to be roughly the same resistance. I have no practical experience, but I think the right resistance for a joystick potentiometer is in the range of 10k-100k, so individual resistances should be 10k-47k

So would it be a good idea to build a fuse inside the circuit in the unlikely event that more than one button is pressed at the same time? if so, what kind of fuse would you suggest, and where would you build it into the circuit? would there be any harmful effects in using resistors of the wrong resistance?

as for circuit layout, what am I looking at? Am I trying to connect one button directly from the ground to the output while the opposite button is connected directly from the 5v to the output? where do the resistors fit into the circuit?

Fat D · Post by **Fat D** » Tue Jun 03, 2008 9:33 am

I'm a student, not an engineer. However, I believe the most difficult part will be positioning the buttons where the stick used to be. The actual placement of wiring is a non-issue. However, a fuse, if placed, should go between the +3.3V lane and the positive terminal of the voltage dividers. It should be for 3.3V and low-current, somewhere in the milliamps range. The current during proper operation should be about 200 microamps at worst, and a controller should have quite a few mA bufer between what it consumes and what the ports can supply. Whether it is necessary I do not know, as i do not know the exact specifications of the gamecube controller).
http://img237.imageshack.us/img237/2411 ... ticoh5.png is a crude schematic.

Remember, I have no practical experience with console modding or controllers so I can only help with theoretical knowledge. If you fry your systems, you only have yourself to blame for following some Internet weirdo who does not know what he is telling you.

grossaffe · Post by **grossaffe** » Tue Jun 03, 2008 11:19 am

Fat D wrote:I'm a student, not an engineer. However, I believe the most difficult part will be positioning the buttons where the stick used to be. The actual placement of wiring is a non-issue. However, a fuse, if placed, should go between the +3.3V lane and the positive terminal of the voltage dividers. It should be for 3.3V and low-current, somewhere in the milliamps range. The current during proper operation should be about 200 microamps at worst, and a controller should have quite a few mA bufer between what it consumes and what the ports can supply. Whether it is necessary I do not know, as i do not know the exact specifications of the gamecube controller).
http://img237.imageshack.us/img237/2411 ... ticoh5.png is a crude schematic.

Remember, I have no practical experience with console modding or controllers so I can only help with theoretical knowledge. If you fry your systems, you only have yourself to blame for following some Internet weirdo who does not know what he is telling you.

fortunately for me, the circuit that contains the joystick is detachable, it as a simple 4-wire plug that leads to the main circuit, so it probably wouldn't be that difficult just flat out replacing the circuit.

looking at your circuit design, i'm guessing the connected boxes are resistors and the disconnected boxes are buttons. at some point, the wires between the 4 buttons cross, but it looks like you made them disconnected. is that because they aren't supposed to actually connect with each other?

So my understand so far is that i need a resistor connecting an output wire to the voltage wire and a resistor connecting an output wire to the ground. then, there will be two buttons connected to the output wire. One button will also connect to the voltage line, the other button will connect to the ground line. I'm guessing whichever one is connecting to the voltage is positive and the one connecting to the ground is negative?

and the fuse, you said between the voltage wire and the positive terminal of the voltage divider. I'm not quite sure what/where the voltage divider is. where would it be placed on your little circuit you drew up?

also, being that this is basically a detatchable circuit that only has the 4 connections, I could just ignore the ground and voltage wiring that continues off the top of the picture, right?

Fat D · Post by **Fat D** » Fri Jun 06, 2008 10:56 am

that design was how they SHOULD be on the joystick. I have no idea about the sub-circuit wiring.
A voltage divider is a series of resistors that allows a fraction of the voltage to lead an input. It IS basically the whole thing I drew.
yes, the box is a resistor, it is the European symbol for one (the American is that /\/\/\-line), the hole with the T-like block is a button that is closed when depressed. where the two sensor lines cross between the buttons, they intersect without connecting.

Remember, I have no idea whether this will actually work.