Custom Power Pin Names

[Leandro Heck]

Hi, I see many projects with custom Power Symbols just to put a custom name on it. People just copy a power symbol, rename it and store them on his own libraries. This is not good.

Example of that is this thread:
https://forum.kicad.info/t/custom-power-pin-names/3960

It may be something dumb but, to many people, including me, it is good to have the Power Symbol with a custom name.

Also, the Kicad library has many power symbols where the differences between them are only the symbol name.

So, my question is:

Why I can't change the name/label of the Power Symbol? What is the reason behind that?

The libraries could have only a few different symbols where the difference is the shape of the symbol instead of its name and the user will be able to split the power net just renaming the power symbol.

[Leandro Heck (leoheck)]

Someone has any ideas here?

[Wayne Stambaugh (stambaughw)]

This will be addressed with the new symbol file format which is going to be part of the 6.0 development. There is limitation with the current symbol file format when defining power symbols. No changes to the current symbol file format are allowed as it will become obsolete.

[Leandro Heck (leoheck)]

Cool. That sounds good Wayne.

[Rene Poeschl (poeschlr)]

Just to make sure you have all the necessary information of the current implementation.

The symbol name is NOT what defines the netname. This is done by the pin name (Every power symbol has an invisible power input pin. That input pin has a name. This is the name of the global label.) More detailed info: https://forum.kicad.info/t/tutorial-how-to-make-a-symbol/13336/7

[Piotr Gałka (piotrgalka)]

I just got into that trap - when imported netlist to PCB I noticed all my power symbols are connected to one net.

When you save a power symbol with new name its name becomes at once its value. Then at schematic that value (haveing really no meaning) is fully protected against any change.

In my opinion the value of power symbol should be used as its net.
@Wayne - I don't know the symbol file format but I don't think that to use symbol value that format need any change. I think the only change is needed in netlist generation to use power symbol value and not its pad net value (it should be simple change, may be in only one software line).
Any KiCad power symbols need not to be changed - so no influence on libraries (power symbols in libraries have the same value as their pin net, I believe). So I think such change can be done any time with no negative influence at any past user files.
Even probably any new user gets into that trap only once I would suggest to address it to 5.1.3 (or 5.1.4) just as a care of haveing as good whole world opinion of KiCad as posiible.

When value of power symbol would be used for netlist than protecting that value from editing at schematic seems haveing no reason.
When edition will be alloved than you will be getting from library always VCC and change its value at schematic with no need to have so many power symbols in library. And it will be possible to mix that technic with old one when redesigning old schematics with no problems.

To tell you the truth I am surprised that it is not that way since KiCad 1.0.

I prefere to have 0Rs than breaking my GND. So power symbols in KiCad library don't helps me - I have only one voltage (VCC) but need symbols: VC1, VC2, VC3, VC4,...

[Leandro Heck (leoheck)]

Cool Piotr awesome idea.

So, as I understood well, we can have a fast fix or workaround with a script that parses the schematics to get the labels from the power_symbols and then update the netlist after its generation. This can be also used to test your idea easily.

[Leandro Heck (leoheck)]

Ah, the issue here is that the label 'Value' is not editable right now.

As an alternative to make the workaround working, it is possible to create a new visible field for that, let's say PWR_Value and use it instead of Value.

[Piotr Gałka (piotrgalka)]

Hi Leonardo,
Last time I used any script was a .bat files under DOS.
I don't know what is simple to do in scripts and what not.

If you assume that KiCad will allow the edition of value (or any other) field and then standard netlist will be generated then you should understand that then in netlist all that symbols will be merged as one net (as they have the same net walue of their pad.
In that one net there will be enumerated all element pins connected to any one of that power symbols.
I suppose there are no enough information in netlist to divide that one net into nets of each type power symbol (even if you find value texts of each power symbol).

I see the simplest solution by modifying the netlist generation in only one place - where it finds the power symbol it has to take its net. It takes it from its one pin (pad) one field (I do'n know its name). Instead doing it the netlist should get the power symbol value. All rest (netlist generation) should work with absolutelly no modification.
For all current made schematics the netlist generated would be the same as power symbols values are the same as their pin nets. So it would be easy to check if modification didn't generated any new error. Jast made for let us say 10 schematics the old and new netlist and compare - should be absolutelly identical.
This can be done and not noticed by any user (I assume noone uses a power symbols which at schematic has differenet text than the net they are connected to).
Then only one next step is to do - to remove the blocking of power symbol value edition.

[Leandro Heck (leoheck)]

Piotr, I am trying to create such a thing.

I was able to change the Value of the Power Symbols directly on .sch files.
- So right now, my process changed a little bit and it looks like this:

1. The user should add a new field to the power symbol (I am using "pwr_net" instead of PWR_Value now).

2. Then a simple script will replicate the current power symbol changing is power net name. It will also update the schematic with the new symbol where it should be used.

[Piotr Gałka (piotrgalka)]

Leonardo,

I don't use any script with KiCad. I think it is the task of software to work as needed and not to have to use some (in my opinion complicated) way-arounds.
If end effect of your work will be that:
- I will have in my library a new VCC symbol with pwr_net field added with value = "VCC",
- when I put that symbol at schematic I would see at schematic the value of pwr_net field (= VCC),
- when clicked that name I would have opened window allowing to edit it,
- "Update PCB from schematic" button will get everything from schematic.
Then I accept (with pain of heart) such solution.

I was never working with any serious software, but at the end of 80-years I lerned (myself) C++ and if I need something I use it. I am busy with programming may be a week or two a year so I am many years behind current.
I don't understand what is the problem to do it as I was writeing it. I am 99% sure the change is needed in only few netlist generating program lines.

Since more then year I was preparing myself to move from Protel to KiCad. I hope I will save an hour or two per PCB project, and I am designing about 10 PSBs a year. So the reason for KiCad is for me the only - "I like learning new things the best of all". I am doing the first serious project with KiCad now. I am surprised how slow is the schematic. When I select the element an noticable time passes before I have it at coursor. I have never noticed such delays in Protel we bought in 1997 even working at those time computers. I think the idea of using scripts can be the answer.

[Leandro Heck (leoheck)]

Dude, my name is Leandro, not Leonardo.
I am proposing a way to test your idea, with the current version.

Wayne said that this should be added in version 6.0

[Piotr Gałka (piotrgalka)]

Very sorry for my mistake in your name. I would not notice it myself.

Till 2004 I didn't anderstood how people can do "Czech mistake" (changing the order of two sequential letters in word). I have never done it. Then I'got to hospital and probably during operation I wos in situation of not enoug oxygenation (doctors didn't told me and I noticed consequences about two weeks later). Since then it was very hard for me to write a one line of text without such error. The most frustrating situation was when I was doing some calculation at calculator and I know that I got wrong result. During it I written one number at paper and later use it. I have repeated it about 4 times searching for mistake and I didn't notised that two digits in written by me number were switched. Each time I checked with display it looked for me as it is good (hardly to believe isn't it). The other is to do such mistake and the other if you expect and search and can't find.
After 15 years I make less such mistakes but still happens that I don't see the difference.

Once more sorry. I understand you can 'don't like' if someone mistake your name. (I wonted here a little different sentence, but I don't know how to write it in English, and dictionary don't wonts to help).

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/2203