Hi everyone,

Could anyone tell me what's the difference between these types of GND? What would happen if I connect them? I am trying to connect an external board to this circuit and I am confused. Thank you in advance!

 

I think it was just carelessness on the part of whoever created the schematic and I'd connect them together.

As a matter of principle, I wouldn't use any circuits from someone who drew a ground symbol upside down. Ground should always point down.

The generally accepted symbols are:

 

I think it was just carelessness on the part of whoever created the schematic and I'd connect them together.

As a matter of principle, I wouldn't use any circuits from someone who drew a ground symbol upside down. Ground should always point down.

The generally accepted symbols are:
View attachment 209180

What about when you are in Australia?

 

What about when you are in Australia?

Nope.

Never been there and have no plans to travel by plane anywhere any time soon.

 

I was chatting with a friend from oz. I said I'd like to be his neighbor so I could play with his toys. Then he said, you could possibly seek asylum from the US. Before that sometime he said, you should live in a civilized country.

 

Then he said, you could possibly seek asylum from the US. Before that sometime he said, you should live in a civilized country.

I meant no disrespect to Australians or their country. I'm not going to take any trips by plane until they can do it safely or there's a vaccine for COVID-19.

For some reason, that's a common perception around the World these days. It has gotten seriously bad recently with talk of using active duty soldiers to quell protests, and having video of police striking foreign reporters and crew, but things are starting to look up because the secretary of defense sent the active duty troops away from DC; or at least that's what they're saying.

 

I meant no disrespect to Australians or their country. I'm not going to take any trips by plane until they can do it safely or there's a vaccine for COVID-19.

Well, AFAIK, the most stressing moment is when the plane, after crossing the Equator, starts flying upside down until destination.

 

Well, AFAIK, the most stressing moment is when the plane, after crossing the Equator, starts flying upside down until destination.

Even worse is you throw down instead of throw up when sick.

 

Hi everyone,

Could anyone tell me what's the difference between these types of GND?

Most show Earth Ground.
Max.

 

Hi everyone,

Could anyone tell me what's the difference between these types of GND? What would happen if I connect them? I am trying to connect an external board to this circuit and I am confused. Thank you in advance!

View attachment 209178

Most schematic capture tools connect global signals by name, so all of those connect to the signal named "GND". Some tools reserve the traditional ground symbol for Node 0 (but some allow you to also associate a named node with it). It's hard to say without digging into either the documentation for your schematic capture tool or examining the netlist.

But which node they are connected to is only the start of the battle -- there are many other issues that might need to be taken into consideration from a layout standpoint. It's possible that the intent of using the different symbols was to at least hint at these, such as a digital ground and an analog ground that, when all is said and done are, to first order, the same node.; but I wouldn't bet on it.

 

Most schematic capture tools connect global signals by name, so all of those connect to the signal named "GND". Some tools reserve the traditional ground symbol for Node 0 (but some allow you to also associate a named node with it). It's hard to say without digging into either the documentation for your schematic capture tool or examining the netlist.

But which node they are connected to is only the start of the battle -- there are many other issues that might need to be taken into consideration from a layout standpoint. It's possible that the intent of using the different symbols was to at least hint at these, such as a digital ground and an analog ground that, when all is said and done are, to first order, the same node.; but I wouldn't bet on it.

Thank you all for your replies! The part of the schematic I posted is from a widely used 3D printer main board called "Mini-Rambo". You can see the rest here: Complete schematic.

From a place of ignorance I think that there must be some kind of difference bewtween those two GNDs. It's really strange. The board is a 4-layer type. Could it be to differenciate between ground planes from different layers?

Thank you!

 

it looks to me like one of the grounds used a traditional gnd symbol while the other used a "power port" (see how the 12V or VCC have the same symbol as one of the GNDs. Like mentioned above, they should be tied together via net name when doing the pcb layout but it wouldn't hurt to verify. If you have this pcba in your possession, I would manually check the resistance between those two nets.

 

it looks to me like one of the grounds used a traditional gnd symbol

What is 'Traditional gnd' ?
Max.

 

What is 'Traditional gnd' ?
Max.

google is quite resourceful. i don't believe your comment is helping the OP

 

google is quite resourceful. i don't believe your comment is helping the OP

It was not a comment but a question.
Mostly the wrong symbol is generally used.
Or mis-use of the earth-GND symbol.
Max.

 

Eagle's supply1 library has the following ground symbols:

 

It was not a comment but a question.
Mostly the wrong symbol is generally used.
Or mis-use of the earth-GND symbol.
Max.

well, an earth-gnd symbol can also be referred to as a power-gnd. I referred to "traditional GND" as a GND symbol that is more commonly used. the power port "bar" symbol is normally used to identify a positive voltage source. Using that power port "bar" symbol for GND isn't the best practice (at least that is what i was tought), but as long as the net names are the same, the software tool should tie them together during layout. There are also other GNDs in the schematic which have different net names (GND1 and FGND).

 

Different names to ID separate ground planes is OK.
It is when the earth GND symbol is used in a general way, whether the plane IS actually at a earth GND reference or not, is where the confusion comes in.
IOW, IS the plane meant to be earthed or not!??
Max.,

 

it looks to me like one of the grounds used a traditional gnd symbol while the other used a "power port" (see how the 12V or VCC have the same symbol as one of the GNDs. Like mentioned above, they should be tied together via net name when doing the pcb layout but it wouldn't hurt to verify. If you have this pcba in your possession, I would manually check the resistance between those two nets.

Thank you. I am going to do the test and see then

 

I have seen several times boards which have "digital grounds" and "analog grounds". Different devices are connected to one or another depending of the type of signal they are manipulating.

Back at the power supply common, they are interconnected with an inductor.

At DC, they are essentially the same ground. But at higher frequencies, or the harmonics of those frequencies, they will be an open circuit. The idea is to prevent digital noise from corrupting sensitive analog circuitry.