Why can't you simply connect all GNDs together? (eg. when using multiple GNDs)

[sofakng]

If you're trying to hack a dreamcast controller to arcade controls and the dreamcast controller has multiple GNDs (eg. each button has it's own GND or whatever), then why can't you just connect all the GNDs together?

I really don't understand electronics at all, but I've read that GND is really just a point with zero voltage.

So couldn't you in theory stick a nail into a piece of plastic and use that as your GND?

EDIT: Also, can I hook the Perfect 360 GND to the Dreamcast controller button's GND?  (eg. all the Dreamcast controller buttons and the P360 GND would connect to the same place on the Dreamcast controller)

Thanks for any help

[northerngames]

dreamcast do have a common ground so all the grounds can be connected together I do 1&2 player with there own seperate grounds but all the buttons and joys for each player all can run on a single ground line sure.

[fjl]

I really don't understand electronics at all, but I've read that GND is really just a point with zero voltage.

So couldn't you in theory stick a nail into a piece of plastic and use that as your GND?

No. Depending on which theory of electronics you want to go by, either electrons flow from positive to negative or negative to positive. But without delving deep into the whole electron flow theories Ground(GND) is not neccessarily a point without voltage. GND is usually the opposite of the side with voltage. Basically its where the voltage wants to go. One way to put it, its the negative side of the battery. And the voltage from the positive side is looking for a path to reach the negative side(the ground). So simply sticking a nail into a piece of plastic does not qualify as a ground since that nail is not in contact with the negative side of the battery.

In short, GND is not a point with zero voltage but usually the negative side of the battery/power supply etc.
In some instances not all grounds are the same so they cannot be connected together. I found this to be true on the Logitech Precision gamepad for the PC.

Also, can I hook the Perfect 360 GND to the Dreamcast controller button's GND?  (eg. all the Dreamcast controller buttons and the P360 GND would connect to the same place on the Dreamcast controller)

Like I said before not all grounds are usually the same, and this is even more so for separate devices. There is a possibility they are the same and it will work. But in the instance that they do not share the same ground, and you connect them together its possible you can damage some electronic components rendering them useless.

[sofakng]

Thanks for the explanation...

I'm still a little confused, but let me ask you this...

If an X-Box controller uses a common ground for all it's buttons, would it safe to take +5V from the controller and use the same GND as the buttons?  (eg. I'm hooking up my Perfect 360's to an X-Box controller but the P360's require +5V)...

[versapak]

Thanks for the explanation...

I'm still a little confused, but let me ask you this...

If an X-Box controller uses a common ground for all it's buttons, would it safe to take +5V from the controller and use the same GND as the buttons?  (eg. I'm hooking up my Perfect 360's to an X-Box controller but the P360's require +5V)...

Yep.

That is how mine have been connected, and working perfectly for a few years.


I should note that I am not using 1st party controllers. I am using the boards from Pelican Real Arcade sticks.


To be sure you want to test with a multimeter that the ground for the controller's power is indeed common with the buttons.

If so, then see the first part of my reply.

[HaRuMaN]

dreamcast do have a common ground so all the grounds can be connected together I do 1&2 player with there own seperate grounds but all the buttons and joys for each player all can run on a single ground line sure.

Not all Dreamcast controllers...  the officials and the MadKatz do, but the Astro pads do not...

[sofakng]

Thanks for the explanation...

I'm still a little confused, but let me ask you this...

If an X-Box controller uses a common ground for all it's buttons, would it safe to take +5V from the controller and use the same GND as the buttons?  (eg. I'm hooking up my Perfect 360's to an X-Box controller but the P360's require +5V)...

Yep.

That is how mine have been connected, and working perfectly for a few years.


I should note that I am not using 1st party controllers. I am using the boards from Pelican Real Arcade sticks.


To be sure you want to test with a multimeter that the ground for the controller's power is indeed common with the buttons.

If so, then see the first part of my reply.

EDIT: Actually... how do I know which GND is for the +5V power?

Thanks again for the help.

Suppose they are not common but they each use a seperate 0V GND?  Would it be safe to share them?

I understand what you're saying that "GND" can be any voltage so it's not safe to connect different GNDs together, but if they both read the same voltage (with respect to earth GND?) then I would assume that it's safe to connect them?

[fjl]

GND is common or the same in the first and next device/gamepad ONLY if they are physically connected together. This means they would have been made to share the same ground all the way back to the power supply and that power supply shares the ground back to the outlet.

You can use a multimeter to find out. Set it to check for voltage and touch the GND on both gamepads. If you see a voltage amount, then they are not shared. If you do see not voltage then they might be shared. Next do a continuity test. If you get 0 ohms, then they are indeed common and connected to each other. At that point you can then share the grounds. If they are not connected, then I wouldn't share the GND cause they are not common. And it is very likely they are not since the Dreamcast goes through an insulating transformer that most likely makes up its own ground. But perhaps not. test it and see. Then tell us your results.

[sofakng]

Are you talking about two controllers sharing the same GND?

I'm definitely going to seperate GNDs between controllers, but I'm wondering how to figure out which GND to use when I find a +5V line on a controller.

I was just going to use the same GND as the buttons, but then you said the +5V might not use the same GND, but I'm trying to figure out how to find which GND is used with the +5V...

[fjl]

Yes you should separate grounds between controllers. No sure what you mean by +5 volts.

Each button has what usually looks like forks meshed together on the circuit board. Although they never touch each other. The button lies on top of the forks and when pressed, causes a path to connect the forks. One of the forks will be the positive side and the other ground. Find out which is GND and simply follow the path they take and see if they all connect together at some point. If not, then they will have to be separated.

[northerngames]

dreamcast do have a common ground so all the grounds can be connected together I do 1&2 player with there own seperate grounds but all the buttons and joys for each player all can run on a single ground line sure.

Not all Dreamcast controllers...  the officials and the MadKatz do, but the Astro pads do not...

I only use name branded products and never modded any third party things becuase all the one's I have ever bought broke on their own in less then a month so after getting junk after junk and them dying on their after being bought new I never bother with any 3rd party stuff anymore since then.

3rd party controllers memory cards and the screw on type a/v cables have all failed me everytime I tried one.

[sofakng]

Yes you should separate grounds between controllers. No sure what you mean by +5 volts.

I'm talking about powering my Perfect 360 joystick which requires +5V and a GND connection of it's own.

What I'm wondering is if I can use the same GND for buttons and the Perfect 360 joystick's power.

I really do appriciate your help!

[versapak]

Yes you should separate grounds between controllers. No sure what you mean by +5 volts.

I'm talking about powering my Perfect 360 joystick which requires +5V and a GND connection of it's own.

What I'm wondering is if I can use the same GND for buttons and the Perfect 360 joystick's power.

I really do appriciate your help!

I don't know enough about electronics or electricity to answer that, but I have often wondered myself why there isn't always a common ground in the first place.

Some controllers do have it, while others don't, but then when all is said and done there is only one + and one - going to/from the controller, so in the end isn't it all part of the same loop? I just don't know.

[fjl]

Yes you should separate grounds between controllers. No sure what you mean by +5 volts.

I'm talking about powering my Perfect 360 joystick which requires +5V and a GND connection of it's own.

What I'm wondering is if I can use the same GND for buttons and the Perfect 360 joystick's power.

I really do appriciate your help!

Where is the Perfect360 supposed to get the +5 volts from originally? A wall wart, PC power supply, batteries?

I suppose you can use a +5 volt supply from the Dreamcast(DC) if it has one. I don't know if the DC controller works on +5 volts or not. But even if it did, I wouldn't use it. The controller isn't meant to handle any extra loads like the Perfect360, you can end up overloading the circuits on the controller or worse the Dreamcast and either blow a fuse or damage the console. I would suggest using a separate power supply for the perfect360. This just means an extra wire coming from a power supply and leading to the control panel.

[sofakng]

Ok, thanks for the help.

Normally the Perfect 360 gets it's +5V from my Opti-Pac (when using the PC).

After all this discussion I might just scrap the idea of connecting my Dreamcast/X-Box to my control panel.  I've only found a handful of games that would be good to play on the Dreamcast and the X-Box is not very well suited for digital controls (most games _require_ analog controls).

[versapak]

Ok, thanks for the help.

Normally the Perfect 360 gets it's +5V from my Opti-Pac (when using the PC).

After all this discussion I might just scrap the idea of connecting my Dreamcast/X-Box to my control panel.  I've only found a handful of games that would be good to play on the Dreamcast and the X-Box is not very well suited for digital controls (most games _require_ analog controls).

Again...

I do have Perfect 360's in my Xbox arcade cab.

They work excellently. Have you checked with a multimeter yet?

If you are looking for a place to wire to for power, check the expansion ports (memory card slots). They are simply USB with a different shape.

Check the negative on that, and see if it is common with the d-pad.