kicad-developers team mailing list archive

["Kliment (Future Bits)" <kliment@xxxxxxxx>]

Having just routed a board with 56 diffpairs I have an idea about number 4:

I think we should treat diffpairs as single traces when routing and when
using the pns functionality to move them around. The trace should have
the thickness of 2x dpair trace width + 1x dpair trace gap, and have a
clearance of dpair clearance. It should behave as such a trace to the
pns and revert back to being a diffpair when shoving/pns manipulation is
done. This way dragging, rerouting, and shoving diffpairs works as
expected - it maintains the diffpairness of the pair. Length adjustment
works just as well on a single trace, and places where the pair splits
up or has a skew tune can remain locked while the trace is being
manipulated. This requires minimal change to the pns (we just feed it
different data) to work, and would dramatically improve the usability of
diffpairs because all the lovely stuff we can do to traces now will be
available to diffpairs without breakage. We still need the diffpair
routing logic for vias and for starting/ending pairs, but we have that now.

On 22.09.20 21:11, Tomasz Wlostowski wrote:
> My 5 quick cents:
> 
>>     1) tool to visualize nets lengths (similar to
>>     https://github.com/MitjaNemec/Kicad_action_plugins#length-stats ). I
>>     want to make a gui where you can define what nets you want to see
>>     altogether. And it should show you length on each layer and summary.
>>     And vias as well.
> 
>       2) Same stuff for length between 2 objects (for example via and pad
>>     for T-topology) similar to
>>     https://github.com/MitjaNemec/Kicad_action_plugins#pad2pad-track-distance.
> New DRC will take care of that (checking length between arbitrary
> endpoints as well as reporting constrained length traces/diff pairs).
> 
> 
>>     3) some tool to define and automatically change tracks length on
>>     different layers (to match target impedance)
> Did you mean per-layer width/gap constraints? abs(Impedance) is not
> related (at least not so simply) to trace lengths. We already have
> length tuner tool, with the V6 design rule system it will be able to
> pick length constraints from board design rules instead of hand-typed
> values.
> 
>>     4) Tool to work with differential pairs. 
> We didn't plan implementing such a tool. Beware that even if it happens,
> applying more than cosmetic changes to the routing globally will likely
> ruin your board so badly you'll spend rest of the day cleaning it up...
> 
> Tom
> 
> 
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