Creating a PDK from scratch

[svenboulanger]

I'm trying to set up a minimal PDK that OpenLane can work with. I've decided to start with only the synthesis step to not complicate matters. I've found the following links from this discussion:

• Porting a PDK
• PDK Configuration Variables

Right from the start I'm confronted with the following errors:

[11:19:50] ERROR    Errors have occurred while loading the PDK configuration.                            __main__.py:124
[11:19:50] ERROR    The PDK mypdk was not found.                                                         __main__.py:126
[11:19:50] ERROR    OpenLane will now quit. Please check your configuration.                             __main__.py:128

No matter what I fill in for PDK_ROOT and PDK, I get the same errors. So I'm left with a lot of questions:

• Is my path wrong? I'm currently specifying "PDK_ROOT": "~/pdks/mypdk" and "PDK": "mypdk".
• Am I missing anything in the TCL scripts (they're empty now)? Is there a "minimum set of parameters" that need to be present before it will recognize my PDK?
• Am I missing any files that make my PDK not recognized as one? I'm only interested in synthesis right now, but will OpenLane even try to run it if I'm missing LEF/DEF/tech/etc. files?

I have the PDKs from sky130 as a reference, but it made it even more confusing to me because the folder structure doesn't follow the given documentation.

[svenboulanger]

I was specifying PDK_ROOT and PDK inside the project config.json file, but it couldn't use it. I then tried just defining the environment variable directly from the shell and that appeared to change things.

I also figured out eventually that I didn't fully follow the folder structure (I forgot the openlane subfolder).

Specifies the folder path of the PDK. It searches for a config.tcl in $::env(PDK_ROOT)/$::env(PDK)/libs.tech/openlane/ directory and at least have one standard cell library config defined in $::env(PDK_ROOT)/$::env(PDK)/libs.tech/openlane/$::env(STD_CELL_LIBRARY).