It might be good to have a FAQ entry for: https://gitlab.com/kicad/code/kicad/-/issues/9257
I’m happy to help write it from the software perspective, but the design domain is outside my knowledge.
Did you have something in mind related to differential pairs, or more / only to the custom rules?
As far as I know there is no cohesive documentation yet on how these rules work, but only bits and pieces spread around.
The original FAQ is in WIKI format and anyone with enough ‘cred’ can edit it. Write what you want and someone can help with the insertion.
Did you have something in mind related to differential pairs, or more / only to the custom rules?
Yeah, I don’t even know enough about it to know what the common cases are. Does impedance-controlled imply diff pairs?
(I last did hardware for a living when a data bus was 8 bits and they were laid with tape on mylar.)
Not necessarily. You can create a single-ended impedance-controlled track by knowing the distance of the track above a ground plane (microstrip) or between two ground planes (stripline), the permittivity of the PCB material, and managing the width of the track. The KiCad PCB calculator does a pretty good job of handling the math. 
Oh, right. I remember updating the PCBCalculator graphics for those…
1 Like
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.