Improve SpiceLibComp device

[ra3xdh]

SpiceLibComp device was intended for usage of the unmodified SPICE libraries with Qucs-S https://qucs-s-help.readthedocs.io/en/latest/SubLib.html#usage-of-unmodified-spice-libraries The current implementation has many issues that prevents its usage for circuit design. The following improvements must be done:

• Provide more symbol file patterns in share/qucs-s/symbols
• Define the syntax of *.sym files. Probably a common XML schematic header need to be added to these files
• Provide a simple way for symbol editing: Add editor for symbol *.sym files #147 Add symbol editor #700
• Recreate 4 existing SYM files in share/qucs-s/symbols subdirectory using new format. See Add symbol editor #700
• Provide a simple way to assign the SUBCKT pins and symbol pins without wrapping symbol in Qucs subcircuit
• Fix the nested subciruit warning that appears with Ngspice and may cause simulation convergence issues

Help is appreciated here.

[wawuwo]

@ra3xdh I've made a small patch enabling Qucs-S to save only a subcircuit symbol of a schematic to a file and to load back symbols from such files. Patch reuses Schematic object and resulting "symbol files" are in effect stripped usual schematic files (no components, no properties etc.)

Workflow to create a symbol:

1. Create new schematic
2. Add the required number of ports
3. Switch to symbol editing mode
4. Draw symbol
5. Save symbol by going to File->Save as and selecting "Symbol only" type of file

After that one can load this symbol back using usual "File->Open" dialog, where "Symbol only" type of file has to be selected.

Unfortunately with this patch symbols from share/qucs-s/symbols can't be loaded — they lack <Qucs Schematc … > tag on first line.

Please check out branch https://github.com/wawuwo/qucs_s/tree/feature-export-symbol in my repo if it sounds interesting, I think it's not worth of opening a PR yet.

[wawuwo]

I forgot to mention that SpiceLibComp can use symbol files made this way, but you have to manually put them into share/qucs-s/symbols

[ra3xdh]

I've made a small patch enabling Qucs-S to save only a subcircuit symbol of a schematic to a file

Yes, this may help to resolve #147 I was thinking about the similar way. The main problem was how to add/remove ports for symbol without schematic. I will try to evaluate your patch in the next week.

Unfortunately with this patch symbols from share/qucs-s/symbols can't be loaded

It is not a big problem, because only 4 symbols are shipped with Qucs-S now. These four symbols could be easily recreated using new format.

[wawuwo]

how to add/remove ports for symbol without schematic

Maybe a solution is to show "port" tool in paintings alongside with arrow, line, ellipse, etc. when in symbol editing mode, so a user would be able to go straight to symbol editing, skipping the "add required number of ports" part. I'll look into it

[ra3xdh]

@wawuwo

I've made a small patch enabling Qucs-S to save only a subcircuit symbol

I have tested your patch. I have found this a good solution for #145 The following things should be fixed if possible:

• Ports are shown without numbers when opening *.sym files This makes difficult to identify ports
  
• The four existing symbol files must be replaced with files having a new format. It is not a bug deal because we have only 4 of them.
• It's need to provide a mechanic to add/remove symbol ports
• Ideally add a New symbol action in File menu

I propose the following logic of adding symbol ports. It could be done using the Add port button on the toolbar

• If normal schematic is opened it add subcircuit ports
• If normal schematic (SCH file) is opened in symbol mode (F9) the button is disabled, because the ports are assigned automatically
• If symbol (SYM) is opened the button inserts a symbol port

I am not sure if proposed workflow could be implemented. Alternative solution is also welcome.

[wawuwo]

@ra3xdh

Ports are shown without numbers when opening *.sym files This makes difficult to identify ports

I need some clarification here… Where should these numbers come from? I see you've added the symbol to SpiceLibComp component and I guess then the port numbers should be the numbers from .SUBCKT entry? I mean, if it's .SUBCKT Thyristor 99 88 77, then you expect to see 99, 88 and 77 somewhere around the ports on schematic picture? Or do you mean something like 555 timer has? (I'm sorry if my questions sound stupid, I don't have a lot of experience with it)

[ra3xdh]

Normally the port number comes from subcircuit ports (Port device inserted from button on the toolbar) property like Num=1. I am not sure how the application derives symbol port number from subcircuit port number. But if the symbol opened without attached schematic, the port is drawn without numbers.

[wawuwo]

Oh god, it clicked, I finally see what port numbers you mean. Will look into it; I guess that's because adjustPortNumbers applies some "magic" to symbols and it's not called for "*.sym" files

[wawuwo]

I've added a commit with patch to display port numbers, but unfortunately has huge disadvantage.

Symbol files store ports like this:

  <.PortSym -30 -30 1 0>
  <.PortSym 30 -30 2 0>
  <.PortSym -30 30 3 0>
  <.PortSym 30 30 4 0>

where numbers are: x coordinate, y coordinate, auto assigned index number, rotation angle. So for *.sym files the only port label we can obtain is its index number plus some static string, there is no more info in file. In contrast, ports in subcircuit symbols (i.e. usual schematics, not *.sym) derive their labels from names of corresponding ports on schematic, so their labels can be of any form.

The only way to circumvent this I think is to change the format in which symbols are stored, to put "freeform" port numbers into files too.

[wawuwo]

But to make "freeform" port numbers in symbol mode when there is no corresponding schematic ports it's required to allow somehow editing of port texts 🤔

[ra3xdh]

It would be sufficient to show the automatically assigned port index number. No need to change the port format.

[wawuwo]

@ra3xdh
Please, try the same branch with recent commit. I was able to patch here and there to allow adding ports when in symbol edit mode.

• it's based on your idea of reusing "insert port" tool
• the format in which ports are stored in a file is unchanged
• in symbol edit mode left mouse button click with "insert port" tool activated spawns a dialog asking for port name, then inserts a port
• in symbol edit mode double click on existing port spawns a dialog asking for new port name. This shouldn't work for usual "subcircuit + subcircuit symbol" files.

"insert port" tool works in symbol edit mode for usual "subcircuit + subcircuit symbol" files too. But ports added this way are automatically removed when file is saved. In other words, if one adds ports in symbol edit mode and then saves the document as *.sym, the all ports end up in a file. But if the document is saved as *.sch, then only the ports with a corresponding port in schematic end up in the file, "dangling" ports are removed from symbol.

[ra3xdh]

@wawuwo

Please, try the same branch with recent commit.

Yes, the recent improvements on this branch makes the new feature acceptable. I have found two minor issues:

• Delete port doesn't work in *.sym files. The port deletion is not needed for SCH.
• The port name dialog allows to enter duplicate port names. This may be a problem when attaching symbol to SpiceLibComp.

"insert port" tool works in symbol edit mode for usual "subcircuit + subcircuit symbol" files too. But ports added this way are automatically removed when file is saved.

This behavior is correct. The symbol ports and SCH ports must be synchronized. The manual ports edition should be allowed only for detached symbols (SYM). Furthermore the port add button may be disabled when SCH file enters symbol editing mode (F9).

[ra3xdh]

@wawuwo You may open a PR on symbol editor and link it to the #147

[ra3xdh]

The merging #700 makes possible converting subcircuit symbols to symbol patterns *.sym files. The next step is to implement a custom dialog window for SpiceLibComp device that will allow to assign symbol pin and device pin. The extension of SpiceLibComp will be required.

[ra3xdh]

I propose to implement a custom dialog for SpiceLibComp containing symbol pins assignment table like in KiCAD. It's need to add something like this for SpiceLibComp: