Hello.
Just wanted to make sure my understanding of connections on the schem and on the PCB is correct. Just hoping someone can give me confirmation!
If you have a simple circuit, one page, then hierarchical, global, net label, are essentially all the same thing. They tell the PCB, “hey, make sure all these points are connected as long as they have the same name.”
Power connections: These are the same. As long as you keep the name the same, they will connect.
Ground: name doesn’t matter. use the same ground symbol, they connect.
Why would it be no for number one? I realize global does more than connect traces, but after opening up in PCBnew, it does ultimately do that function as well, right?
I’ve got some memory holes and never seem to be able to remember which labels connect to which. Does a hierarchical or local label connect to a global label with the same name on the same sheet?
My solution is usually to either read the manual again, or just create a simple schematic with some connectors and labels, [F8] it to the PCB editor and see which ratsnest lines turn up.
I don’t know how in V6, but in V5 the answer is not so simple. Important is what name you have in mind. If you place many times the same power symbol and then rename some of them to another name than even you see different names at schematic they will be connected together.
Ground is simply another power symbol.
They key problem is that hidden names decides about connection.
The concept (power symbol assigns net-name according to hidden pin-name) is the same as in v5. But in v6 it’s nearly impossible to change the power-symbol name in the schematic - all name/value-dialogs are disabled (I suppose to prevent exactly this case of misnaming the power-symbol).
So for standard usage I would also answer “yes” to question 2.
The invisible power input pin’s name sets the net name. The symbol value is irrelevant to the name of the net, although typically it should be set the same as the desired net name in order to minimize confusion because it is displayed on the schematic.
KiCad prevents you from editing the value field once a power symbol has been placed in the schematic so that users don’t change the value field and think that changes the associated net.
When designing my first schematic using KiCad 4.0.7 I used to edit power symbol value fields (as I always done with Protel). When I went to PCB I was surprised that KiCad wants me to short all my power lines together. So I designed separate symbols for power values I use (I sometimes use 0Rs in VCC line so I need more symbols that I know they are really VCC - so I have VC, VC1, VC2 symbols).
I just now tried how it is in V5 and I see that editing power symbol value seems being impossible (I didn’t tried it before my previous post just thinking that what I remember happened with V5).
As I read here in V6 it is the same.
To check what decides of net the power symbol is connected to define power symbol with different value and Pin name then you will see (didn’t checked it now, but believe that it is pin-name).
The name “global” is chosen for a reason.
You can use global labels inside a sheet, eg, to avoid a connection from the lower left corner to the upper right.
It’s not good practice and disturbs readability of the schematic. If this is necessary for your design, reconsidering component placement is a better way to go.
Remember, both schematic and PCB layouts are called “Artwork”, not “tedious chore”.
Readability is priority #1, perhaps not now, but if you want to revisit and understand your design 5 years from now.