test_inv.sch references $::SKYWATER_MODEL but when you run a NGSPICE simulation it does not exist

[stefanschippers]

test_inv.sch references $::SKYWATER_MODEL but when you run a NGSPICE simulation it does not exist

[StefanSchippers]

I assume you installed open_pdks, then, make sure you copy the xschemrc into the directory where you start xschem:
something like:
cp .../share/pdk/sky130A/libs.tech/xschem/xschemrc .
Before starting xschem set the PDK_ROOT variable:
export PDK_ROOT=.../share/pdk
In above examples replace the '...' with the actual path where your open_pdks is installed.

[armleo]

Can this be documented somewhere? A lot of people ask the following questions: How to install XSCHEM, How to make a XSCHEM project directory (as they need to copy the .spiceinit and from your suggestion xschemrc), How to install XSCHEM sky130 library.

Maybe it's documented somewhere, but I couldn't navigate there from README.md of the Open PDKs.

[StefanSchippers]

The process is explained in this video (at 5:40) which is linked in the pinned posts in the #xschem slack channel of skywater-pdk.
There is one recent addition: if you installed open_pdks in an unusual place you have to setup a PDK_ROOT variable that tells xschem where open_pdks is installed.

[armleo]

I just wish this was documented in the text form, so I could refer to it when people asked.