Why is there more than one ground on Pin-outs?

Musturd · Post by **Musturd** » Wed Dec 10, 2008 12:08 pm

Why is there more than one ground on Pin-outs?
And more importantly does a specific ground associate with certain other pins?
And if that doesn't make sense, which it probably won't, I made a picture.

bacteria · Post by **bacteria** » Wed Dec 10, 2008 3:15 pm

Ground it ground is ground.

They all connect to each other as all are ground; however it is a good idea to ground audio and video to different grounds on a board rather than the same place.

Post by **Skyone** » Wed Dec 10, 2008 3:41 pm

Righto; all grounds will be connected. Like bacteria said and for organization's sake, you'll want to sort out the grounds neatly.

Musturd · Post by **Musturd** » Wed Dec 10, 2008 3:44 pm

OK, thanks

deviouskoopa · Post by **deviouskoopa** » Tue Dec 30, 2008 2:43 pm

Is it a bad idea to simply connect the ground pins (for audio and video) together? Why?

It seems like ground is eventually connected to each other anyways... although there could be distortion or something I'm not thinking of.

Kyo · Post by **Kyo** » Tue Dec 30, 2008 3:31 pm

No, it is not a bad idea. It would do absolutely nothing. Ground is ground is ground, as bacteria said.

bacteria · Post by **bacteria** » Tue Dec 30, 2008 4:03 pm

There is an exception to the rule with ground I have found - sometimes, for example on plug'n'play boards, there are more than one ground and you can't connect one to the other, they are independent. Bit of a head scratcher as to why.

Kyo · Post by **Kyo** » Tue Dec 30, 2008 4:08 pm

that does not make sense. Are you sure they both were ground? Maybe it was just mislabeled? There can't be 2 grounds unless there are two power supplies, and even then there should only be one

palmertech · Post by **palmertech** » Tue Dec 30, 2008 5:49 pm

Some 360 controllers have multiple grounds, too. Sucks, and makes no sense.

Post by **Skyone** » Tue Dec 30, 2008 6:23 pm

Depends what type of ground you're talking about I suppose. Sometimes, analog signal connections (audio/video) have what a manufacture may tag as ground, but might fit the definition of reference voltage better.

Also: http://en.wikipedia.org/wiki/Electrical_potential

superdeformed · Post by **superdeformed** » Tue Dec 30, 2008 7:01 pm

For most electronics, the term ground in itself just implies that it's the reference point (as opposed to being earth ground). It's not uncommon to have multiple grounds in a circuit, such as a ground for digital and a separate ground for analog signals, in order to prevent noise from one part of the circuit interfering with another. Another reason for doing it is if you have an external component to plug in with its own supply (which may or may not be at the same potential), then you can avoid blowing things up by isolating the part of your circuit that interfaces with the outside world. You don't necessarily need to have two separate power supplies to do this (in the sense of things you plug into the wall), but you would need a way to generate an isolated supply such as a transformer. There are a few companies that make small-footprint isolated DC/DC converters for this purpose.

For the same reason as having multiple grounds (noise), there may also be multiple ground connections for different signals even if they all go to the same place. If you're connecting an audio input, for example, and you connect the ground on the opposite side of the board from where the audio processing is done, you're more likely to pick up (or cause) extra noise than if you connected it to ground closer to where the input is. This also keeps the line impedance more closely matched but that really isn't an issue here, and in the case of the PSone screens and older consoles, which ground you use probably isn't anything to worry about as long as they all go to the same place.

Kyo · Post by **Kyo** » Wed Dec 31, 2008 4:06 am

but that's bullcrap. They should call it something else then

bacteria · Post by **bacteria** » Wed Dec 31, 2008 4:55 am

Ground is a common connection; it doesn't necessarily mean it is common to all only a group, I suppose. For example, on some plug'n'plays, one ground works on one side of the board, a different one on the other side; one voltage throughout.

deviouskoopa · Post by **deviouskoopa** » Wed Dec 31, 2008 2:03 pm

Seems like it would make more sense to label the pins GND1 and GND2 just to show that they shouldn't be connected (in audio/video applications). One GND works fine for the N64 as superdeformed pointed out.

Kyo · Post by **Kyo** » Wed Dec 31, 2008 2:26 pm

buuuut ground is the place where the electrons are getting the hell out of the circuit. There shouldn't be two places. Think about the electron families that would get seperated. This is madness!