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Re: DRC rules

 

Hi Jeff,

Many thanks for this - looks very powerful, and when it gets hooked in to
the PNS router will be killer. An issue I'm currently grappling with a
variety of rules considering placements around vias. Some rules require a
distance measured from the outside of the annular ring to a track (or
another annular ring outer edge), and some from the outside of a hole (i.e.
the inside of the annular ring) to the nearest other outside edge of a
hole. I suspect the former is achieved with what is currently there, but is
the latter possible? It's essentially a question of where via-to-via
measurements are made.

Thanks,
James.



On Sat, May 16, 2020 at 4:44 PM Jeff Young <jeff@xxxxxxxxx> wrote:

> I’ve just merged a possible implementation of the DRC rules.  I’d like to
> get some feedback on it, and also some testing.  (Because the rules support
> such a wide range of possibilities it’s going to need a good deal of
> testing.)
>
> For now, it picks up DRC rules from a file named “drc-rules” in the
> project directory.
>
> There’s no GUI editor at present: use a text editor.
>
> Grammar is s-expr.  It generally follows the ideas set down here:
>
>
> https://docs.google.com/document/d/1qvCH9aHwCzp5qtKTna4jJXuloNU0b96gAxAHSKPuXpU
>
> with one major exception: I found the select-a-single-rule didn’t pan
> out.  You have to duplicate too much stuff in each rule for that.
>
> Also, because the DRC engine (and zone filler) don’t currently support
> min/opt/max the prototype implements min with Seth’s “relaxed” option.
>
> Top level is a list; first expression must be (version x) followed by any
> number of (selector…) and (rule…) expressions.
>
> /*
>  * Match tokens:
>  *     match_netclass
>  *     match_type
>  *     match_layer
>  *     match_all
>  *     match_area  (not yet implemented with the exception of “$board”, which matches everything)
>  *
>  *     (selector (match_area "$board") (rule "OSHParkClass3") (priority 100))
>  *
>  *     (selector (match_netclass "HV") (rule "HV_internal"))
>  *     (selector (match_netclass "HV") (match_layer "F_Cu") (rule "HV_external"))
>  *     (selector (match_netclass "HV") (match_layer "B_Cu") (rule "HV_external"))
>  *
>  *     (selector (match_netclass "HV") (match_netclass "HV") (rule "HV2HV"))
>  *     (selector (match_netclass "HV") (match_netclass "HV") (match_layer "F_Cu") (rule "HV2HV_external"))
>  *     (selector (match_netclass "HV") (match_netclass "HV") (match_layer "B_Cu") (rule "HV2HV_external"))
>  *
>  *   TODO: pads for connector pins or wire pads have even larger required creepage clearances.  How to encode?
>  *   User attributes on parent footprint?
>  *
>  *     (selector (match_netclass "HV") (match_type "pad") (match_netclass "HV") (match_type "pad") (rule "pad2PadHV"))
>  *
>  *     (selector (match_netclass "signal") (match_area "BGA") (rule "neckdown"))
>  *
>  * Type tokens:
>  *     track
>  *     via
>  *     micro_via
>  *     blind_via
>  *     pad
>  *     zone
>  *     text
>  *     graphic
>  *     board_edge
>  *     hole
>  *     npth
>  *     pth
>  *
>  * Rule tokens:
>  *     allow  (not yet implemented)
>  *     clearance
>  *     annulus_width
>  *     track_width
>  *     hole
>  *
>  * Rule modifiers:
>  *     relaxed
>  *
>  *     (rule "HV" (clearance 200) (priority 200))
>  *     (rule "HV_external" (clearance 400) (priority 200))
>  *     (rule "HV2HV" (clearance 200) (priority 200))
>  *     (rule "HV2HV_external" (clearance 500) (priority 200))
>  *     (rule "pad2padHV" (clearance 500) (priority 200))
>  *
>  *     (rule "signal" (clearance 20))                       // implied priority of 1
>  *     (rule "neckdown" (clearance relaxed 15) (priority 2))
>  *
>  *     (rule "allowMicrovias" (allow microvia))
>  */
>
>
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