kicad-developers team mailing list archive

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

For length tuning, the nicest interface I've seen is the one in Horizon
as demonstrated at the 2019 FOSDEM talk
https://archive.fosdem.org/2019/schedule/event/horizon/ at about 9
minutes in - it's not a long way between this and the hacked net
inspector dialog you describe.

Kliment

On 23.09.20 10:48, Oleg Endo wrote:
> This external spreadsheet nonsense was one reason why I converted the
> net inspector dialog to be non-modal.  And with filtering, grouping and
> sort-by-length it can be actually a very useful and productive tool. 
> I've used my own "hacked" version on several designs already. :)
> 
> Cheers,
> Oleg
> 
> On Wed, 2020-09-23 at 09:45 +0200, Nick Østergaard wrote:
>> Hi
>>
>> Slightly related to this discussion and for inspiration:
>>
>> https://twitter.com/azonenberg/status/1282188633118699520
>>
>> Nick
>>
>> On Wed, 23 Sep 2020 at 09:43, Alexander Shuklin <jasuramme@xxxxxxxxx> wrote:
>>> Hi Kliment,
>>> I think if these things you explained will be implemented, it will make high speed design very much easier.
>>> And the problem is much worse if you have a lot of differential pairs. When I see design and the only thing which I can do with differential pairs is to tune length or redraw, I feel stressed.
>>> Is it right that diffpairs are always treated as just single tracks now? If I want to write a script or piece of code to change diffpair width or gap, what idea should I use?
>>> I think about finding all coupled lengths of some differential pair and changing the gap on all of coupled lengths and don't touch it if it is uncoupled... Or maybe shift a bit (by gap/2 difference for each side)
>>>
>>> On Tue, 22 Sep 2020 at 22:23, Kliment (Future Bits) <kliment@xxxxxxxx> wrote:
>>>> 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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>>>>
>>>>
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