kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxx>]

On 8/23/2017 7:32 AM, Oliver Walters wrote:
> Something I have been considering for a while - instead of hard coding
> complex DRC rules into base code, what if we developed a DRC API and
> write the rules in Python?

I can see using python for complex or custom constraints but not for
general purpose constraints such as trace clearances, via stack ups, etc.

> 
> Each rule could be a separate python file (similar to how footprint
> wizards are done). Users could enable/disable each DRC and once the
> framework is in place, rather than *arguing* over DRC rules in the
> developer list, the community can create and perfect as many different
> checks as they wish. 
> 
> Each DRC should provide a pass/fail metric and also a way of providing
> formatted feedback. 
> 
> Currently there are minimal DRC checks so even if more are implemented
> in C++ I see no reason why such a framework could not be implemented
> concurrently anyway. 

This is the missing piece of the puzzle.  We would need to create a
constraints manager to handle a list of constraints which could either
be an internally defined constraint or a custom python constraint.
Without a well defined interface, this would be a mess.

> 
> Thoughts?
> 
> Oliver
> 
> On 23 Aug 2017 10:02, "Andrey Kuznetsov" <kandrey89@xxxxxxxxx
> <mailto:kandrey89@xxxxxxxxx>> wrote:
> 
>     If you're looking for good DFM manuals, check out protoexpress,
>     otherwise known as Sierra Circuits.
>     They're a professional board house in the USA with simple to complex
>     board design support including high speed interfaces, uvias, etc.
> 
> 
>     On Tue, Aug 22, 2017 at 2:33 PM, Thomas Langås
>     <thomas.langaas@xxxxxxxxx <mailto:thomas.langaas@xxxxxxxxx>> wrote:
> 
>         On Tue, Aug 22, 2017 at 9:36 PM, Wayne Stambaugh
>         <stambaughw@xxxxxxxxx <mailto:stambaughw@xxxxxxxxx>> wrote:
>         > I'm not opposed to this change.  However, there are two schools of
>         > thought when it comes to board layout: strict layout constraints and no
>         > layout constraints.  I tend to lean towards the latter but I've been
>         > doing this for 30 years so I am painfully aware of the pitfalls of no
>         > layout constraints and have a pretty good idea of what not to do.
>         > Should we choose to loosen the layout constraints for blind/buried vias,
>         > then we should be prepared for a serious tongue lashing the first time
>         > someone violates their board vendor's manufacturing limitations and ends
>         > up with a bunch of useless and likely expensive boards.  Maybe at some
>         > point in the future we will have a complete constraint system that can
>         > cover all possibilities but until then we have to walk that fine line
>         > between power users and beginners.
> 
> 
>         Is there a good reason why not to build this by rulesets, and allow
>         people to define
>         their own rulesets within KiCAD.  You can have a sensible
>         default rule
>         that covers
>         the 80-90%, and allow the people who know more about this and
>         what they need
>         just remove the default rule and add their own advanced rules?
> 
>         Of course, this would imply that without any rules at all, it's just
>         willy nilly and
>         everything allowed.  But isn't that the way design rules should
>         be?  If you want
>         to try ice skating down a mountain, it might not be smart, but
>         it's your own
>         choice  ;-)
> 
> 
>         --
>         Thomas
> 
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> 
> 
> 
>     -- 
>     Remember The Past, Live The Present, Change The Future
>     Those who look only to the past or the present are certain to miss
>     the future [JFK]
> 
>     kandrey89@xxxxxxxxx <mailto:kandrey89@xxxxxxxxx>
>     Live Long and Prosper,
>     Andrey
> 
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