kicad-developers team mailing list archive

[Tomasz Wlostowski <tomasz.wlostowski@xxxxxxx>]

On 20.01.2015 17:58, Wayne Stambaugh wrote:
> On 1/20/2015 10:51 AM, Tomasz Wlostowski wrote:
>> On 20.01.2015 16:19, Wayne Stambaugh wrote:
>>> On 1/20/2015 12:44 AM, LordBlick wrote:
>>>> In response to a message written on 13.01.2015, 19:20, from Tomasz
>>>> Wlostowski:
>>>>> Hi all,
>>>>>
>>>>> During my work on diff pairs/matched length tools, I've encountered a
>>>>> rather tricky problem: as the diff pair gap specific to a particular
>>>>> pair of traces is stored nowhere, the shove algorithm will mess up DP
>>>>> coupling after saving and re-loading the board. Ergo: the DP gaps (and
>>>>> possibly other settings) need to be stored somewhere in .kicad_pcb
>>>>> files. Perhaps in a yet another s-expr token.
>>>>>
>>>>> The problem is that adding any new token to the file format causes all
>>>>> precedent versions of pcbnew to drop an error attempting to load the
>>>>> file. I would propose two solutions to overcome this:
>>>>> - (a dumb one) if the version in the file header is newer than the
>>>>> version supported by the running application, issue warnings instead of
>>>>> fatal errors on unknown tokens,
>>>>> - (a bit smarter) enclose all optional tokens in a "minimum" version
>>>>> block ( min_version version_number ( optional_token ( ... ) ) ) that
>>>>> would be ignored if the application version < version_number.
>>>>>
>>>>> I consider this modification quite important from the point of view of
>>>>> adding future features and the upcoming stable version: if we keep
>>>>> things as they are, adding any new feature will either make the files
>>>>> unreadable to the stable version or force us to support saving in
>>>>> multiple format versions.
>>>>>
>>>>> Looking forward to your feedback,
>>>>> Tom
>>>> I think that may be sufficient to add section [gal] to .pro file as
>>>> usual project setting. In this way you can avoid the next .kicad_pcb
>>>> format version change.
>>>>
>>>
>>> I'm not terribly thrilled about that idea.  One of the things we have
>>> changed over the years is to move board specific settings out of the
>>> project file and into the board file.  This makes the board file more
>>> portable. 
>>
>> Hi Wayne,
>>
>> Fully agree here. What I meant when I started this thread was defining a
>> way to store more complex DRC constraints than simple clearance/track
>> width. The current model can't handle differential pair and constrained
>> trace length. Such parameters surely belong to a PCB design, so their
>> place is IMHO in the .kicad_pcb file.
>>
>> Anyway, for the first release of the new P&S features, I'm not going to
>> modify the file format.
>>
>> Cheers,
>> Tom
>>
> 
> Hey Tom,
> 
> If it is important to save the design settings, now would be the time to
> make any file changes rather than after the stable release.  We know we
> are already going to have issues with users who upgrade from the current
> stable release due to layer name translations and the 32 to 64 layer
> transition.  I would rather get it over with now than drag it out over
> the next development cycle.

Hi Wayne,

I meant the merge of diff pairs into product branch, so that people
could already test and profit from the new features. I hope we'll have
the time to define and implement file format upgrades before the stable
release goes out.

Cheers,
Tom