internal nodes in a hierarchical page error

[daddyzaur]

KiCAD 5.1.4
Most of the internal nodes in a hierarchical page must be explicitly routed out even those used inside only

[Seth Hillbrand (sethh)]

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[daddyzaur (daddyzaur)]

Application: KiCad
Version: 5.1.4, release build
Libraries:
    wxWidgets 3.0.4
    libcurl/7.67.0 OpenSSL/1.1.1d zlib/1.2.11 libidn2/2.2.0 libpsl/0.21.0 (+libidn2/2.2.0) libssh2/1.9.0 nghttp2/1.39.2
Platform: Linux 5.3.11-1-MANJARO x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.4 (wchar_t,wx containers,compatible with 2.8) GTK+ 3.24
    Boost: 1.71.0
    OpenCASCADE Technology: 7.4.0
    Curl: 7.66.0
    Compiler: GCC 9.2.0 with C++ ABI 1013

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=ON
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=ON
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=ON
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=OFF
    KICAD_USE_OCC=ON
    KICAD_SPICE=ON

[Michael Kavanagh (michaelkavanagh)]

You need to provide more information in the bug report. What exactly is the problem? What are the steps to reproduce the issue? Can you upload example files to help recreate the issue? Maybe provide a screenshot/screen recording demonstrating the problem.

[daddyzaur (daddyzaur)]

See attached project. On the right side of the hierarchical page is a whole bunch of sheet pins routed out of the subcircuit schematic. While those nets are used inside, are totally meaningless outside the subcircuit.
Now try to remove them and the associated page pin, in the main circuit (not the internal nodes). Only the nodes A, P,G,C and error are needed here, outside, in the main page.
The simulation will crash, it will not start anymore, even if those nodes are used inside only. The bug is 100% repeatable, under all conditions.

[daddyzaur (daddyzaur)]

I was told a KiCAD project archive is not really fully contained, ready to run on any other machine. One must add all kind of extra resources. I tried to add some library files I created and used for this example. I hope it is a complete example and can be executed on other systems. I suspect some library files must be placed in the KiCAD folder somewhere. See attached project.

[Holger Vogt (h+vogt)]

Using the project file from https://forum.kicad.info/t/spice-simulation-errors/19884/6 and simply removing the sheet pins, ngspice fails.

The error message is:
Warning: singular matrix: check nodes /edc and /edc

What to do now?
Create the ngspice netlist and have a look at node /Edc.
/Edc is part of a B source
Bv2 /AVG_CM_BUCK_1/D1 /G V={V(/Edc,/G)>Dmax?Dmax:(V(/Edc,/G)<Dmin?Dmin:V(/Edc,/G))}
This one applies the voltage difference between /Edc and /G to calculate its output voltage. But there is no node /Edc in the netlist (in the circuit). So the B source cannot work, ngspice bails out. Same with /Ed2.

There is however a node /AVG_CM_BUCK_1/Edc. Maybe this one has to be used in the B source?

[daddyzaur (daddyzaur)]

How to reproduce: Open and run attached project. The simulation works without problems.
Now, delete the hierarchical pin "ccm", the wire and the netname "ccm" in the main schematic, from the sheet symbol. Now, go inside the sub-circuit schematic sheet and delete the sheet pin "ccm" only. Keep the netname inside, it is needed inside.
Now run the simulation again. You get errors:
Warning: singular matrix: check nodes /ccm and /ccm
Note: Starting dynamic gmin stepping
This is not normal, the node "ccm" is fully defined and used inside the subcircuit, is not really needed outside.
The same applies for many other nets defined and used inside only: "Gimju", "Gipc", "Ed2", e.t.c. There is no need to route them outside, but the simulation will crash if I do not bring them outside.

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/2602