how to create a custom constraint group for Layout XL connectivity

Thank you for the link. I have learned how to write and load the Incremental Techfile into an existing design library; here I want to summarize it for any other 'Techfile beginner'.

The content of the new Incremental Techfile below directs Virtuoso XL to ignore connectivity for the "exclude" purpose for all metal/poly/RX layers. This should logically be true since "exclude" purpose is an indicator layer not a physical one.

;********************************
; CONSTRAINT GROUPS
;********************************
constraintGroups(

;( group [override] [definition] [operator] )
;( ----- ---------- ------------ ---------- )
( "newExtractorSetup" nil

interconnect(
( validLayers ( RX PC M1 M2 M3 M4 M5 M6 MQ LM V1 V2 V3 V4 V5 VL VQ CA ) )
( validPurposes 'exclude ("exclude") )

) ;interconnect

) ;newExtractorSetup

) ;constraintGroups

This is how I load this new Incremental Techfile into the design library (I merge it with the PDK techfile, already attached to the library):

1. (should have been done already) Attach or compile the standard PDK Techfile into the design library upon creation

2. CIW -> Technology File Manager -> Load -> select my Incremental Techfile text file -> Classes: Select All -> Merge (!! not Replace)

3. Open Layout XL, in layout window: Options -> Layout XL -> Connectivity -> Verification Controls -> ... from constraint group (drop down menu) -> "newExtractorSetup"

Note: Diagnostics Report can be used to show the connectivity rules loaded by Virtuoso XL from the combined new techfile code.

You can compile the incremental part of the ITDB into the design library or create a separate ITDB techlib. I recommend the latter. To do this..

  Create the new library e.g. 'myITDBtechLib'.

  Select "Reference existing technology libraries'.

  On the next form select the PDK techlib and push over to the right as the refTechLib.

  OK and create the library.

  Now from the 'Technology File Manager' dump the ascii techfile for myITDBtechLib

  Edit the file. It will start with something like this...  

; Technology File gpdk045_ITDB
; Generated on Apr 24 17:15:42 2020
; with @(#)$CDS: virtuoso version 6.1.8-64b 03/10/2020 22:02 (cpgbld01) $

;********************************
; CONTROLS
;********************************
controls(
techVersion("1.0")

refTechLibs(
; techLibName
; -----------
"gpdk045"
) ;refTechLibs

) ;controls

See how it references the pdk techlib.

Now add any customisation (your constraint group) to this file.

Then load use the 'Technology File Manager' to load the modified file into the new 'myITDBtechLib'.

Save it.

For a sanity check you can dump it out again to check it has loaded correctly.

N.B. Once you are familiar with how 'refTechLibs' is used you can just write this from scratch and avoid the dump/edit part. I just included that so you understood some detail.

Finally you need to attach or reference the new  'myITDBtechLib' from your design library. Use the 'Technology File Manager' again for this. I recommend 'Reference'. It offers more flexibility. The design lib can include ITDB elements if you wish.

You can also use 'Graph' to view the ITDB hierarchy in detail. FYI: Also available from the Layout window Tools -> Technology Database Graph.

Rob.

Rob, thank you! I now understand to Attach (or 'Reference' <- unrelated to refTechLibs directive) a techfile lib to the design lib, rather than Load or compile the techfile ASCII into the design lib like I did above.

And I see that we use refTechLibs( "tech_lib_name" ) to reference the pdk/main tech lib, and then write our code, and thus make the new code additive.

Finally, I used Load for new itdb file b/c I am replacing a techfile already attached or compiled in the existing design lib, not starting with a brand new design lib.

If I want to attach the itdb_lib to an existing design lib which already has a complied techlib in it, I found I need to delete tech.db (and/or data.dm?) files first in that design lib directory, and only then I am able to Attach the new itdb_lib. I don't know if this last approach has any downsides, but seems to work so far.

You cannot "attach" an itdb_lib to a (pre-compiled) techlib. The itdb_lib must "reference" the techlib. The reference is handled by 'refTechLibs(...' in the itdb_lib techfile. Using the gui to "attach" is the equivalent. Deleting the techlib techfile is not correct. Without a techfile I wouldn't expect you to be able to attach or reference.

You cannot "attach" an itdb_lib to a (pre-compiled) techlib. The itdb_lib must "reference" the techlib. The reference is handled by 'refTechLibs(...' in the itdb_lib techfile. Using the gui to "attach" is the equivalent. Deleting the techlib techfile is not correct. Without a techfile I wouldn't expect you to be able to attach or reference.