On 13.02.2017 17:26, Jon Evans wrote: > I verified using Novak's test case on the Launchpad bug report. DRC > error is generated if the distance between the tracks is exactly equal > to the clearance. > If you increase the spacing by the minimum distance recognized by the > software's precision, the DRC passes. > So, I think it's an issue of DRC specification -- The code currently > requires that the clearance be *larger* than the minimum in the design > rules. > The diff pair router is setting the spacing to the minimum (exactly) > which causes this bug. > > IMHO, the DRC code should be changed to "larger or equal to", but I am > not sure if there is some subtle reason why it is implemented this way. > If you tell KiCad that you can go down to 2mm clearance, you should be > able to design something with *exactly* 2mm clearance :-)
Hi guys, The issue is a bit more complex: it's a mix of DRC's floating point inaccuracies as well as ill-defined (rounding-error-wise) fixed point calculations in the 'gateway' computation part of the diff pair code. I'll fix it when my time permits (certainly before v5.0). Cheers, Tom > > -Jon > > On Mon, Feb 13, 2017 at 11:15 AM, Andy Peters <de...@latke.net > <mailto:de...@latke.net>> wrote: > > > > On Feb 13, 2017, at 2:06 AM, Clemens Koller <c...@embeon.de > <mailto:c...@embeon.de>> wrote: > > > > Hello! > > > > If the global minimum mandatory clearance/spacing (pitch) of a design > (due to manufacturing limitations) is set (& activated) it should complain > when some other settings are violating that. > > I purposely set the differential gap and trace width to something > higher than the global minimum to see if that would have an effect, > and it didn’t. > > > It could be assisting if the user gets a clear warning when the > differential pair dimensions violate the design limitations and then give > options to > > a) reset the differential pair dimenstion to the global minumum, which > is x. > > b) create an exception for the differential pairs (the DRC need to > handle that). > > c) adjust the global design limitations accordingly. > > > > If b) or c) is selected, the Ok button should be labelled with "Ok, I > really know what I do..." ;-). > > Differential routing in the GAL canvas with “shove” as the default > routing mode should result in never having a DRC clearance failure. > Let’s expand on that — all routing in that mode should never result > in a DRC clearance (or width) fail. I remember the first time I > tried differential routing and it wouldn’t let me draw any traces > because the default diff width/gap violated my global minimums. > > So the question is: what is the real source of the error? Is it in > the routing algorithm that allows the user to place differential > traces that violate the design rules, or is it, as Jon Evans wrote, > an error in the post-routing DRC code? > > -a > > > On 2017-02-13 03:15, Jon Evans wrote: > >> I took a quick look at the DRC code, and it looks like it is > doing an exclusive check on the minimum distances for clearance -- > i.e. it is requiring the clearance be greater than the minimum, not > greater or equal. > >> I'm not familiar enough with this part of the code to want to > submit a patch for this now, but maybe someone who is familiar can > comment on whether there is a reason that it is done this way. > >> > >> -Jon > >> > >> On Sun, Feb 12, 2017 at 8:08 PM, Andy Peters <de...@latke.net > <mailto:de...@latke.net> <mailto:de...@latke.net > <mailto:de...@latke.net>>> wrote: > >> > >> > >>> On Feb 12, 2017, at 5:59 PM, Andy Peters <de...@latke.net > <mailto:de...@latke.net> <mailto:de...@latke.net > <mailto:de...@latke.net>>> wrote: > >>> > >>> I am using a nightly build from 26 January 2017 on a Mac. > >>> > >>> The design has a handful of differential pairs. I have set up > design rules for most nets in the design as 1.6 mm trace width and > 1.6 mm clearance. I created a net class for the pairs with those > clearances and widths and made that the “diff pair width” and “diff > pair gap” too. > >>> > >>> Then I set the “Differential Pair Dimensions” in the Dimensions > menu to that same width and gap. Aside: why is this step necessary? > Why doesn’t the differential routing use the net classes set up by > default? > >>> > >>> I route the signals and run the DRC, and for every corner in the > trace pairs, I get an ErrType(x): “Two Track Ends Too Close” > complaint. Sometimes it’s ErrType(16), sometimes it’s ErrType(17), > the rest ErrType(18), but they are for all corners. See the picture. > This doesn’t make any sense. > >> > >> This was reported as a bug over a year ago: > https://bugs.launchpad.net/kicad/+bug/1533551 > <https://bugs.launchpad.net/kicad/+bug/1533551> > <https://bugs.launchpad.net/kicad/+bug/1533551 > <https://bugs.launchpad.net/kicad/+bug/1533551>> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > <https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers>> > >> Post to : kicad-developers@lists.launchpad.net > <mailto:kicad-developers@lists.launchpad.net> > <mailto:kicad-developers@lists.launchpad.net > <mailto:kicad-developers@lists.launchpad.net>> > >> Unsubscribe : https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > <https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers>> > >> More help : https://help.launchpad.net/ListHelp > <https://help.launchpad.net/ListHelp> > <https://help.launchpad.net/ListHelp > <https://help.launchpad.net/ListHelp>> > >> > >> > >> > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > >> Post to : kicad-developers@lists.launchpad.net > <mailto:kicad-developers@lists.launchpad.net> > >> Unsubscribe : https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > >> More help : https://help.launchpad.net/ListHelp > <https://help.launchpad.net/ListHelp> > >> > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > > Post to : kicad-developers@lists.launchpad.net > <mailto:kicad-developers@lists.launchpad.net> > > Unsubscribe : https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > > More help : https://help.launchpad.net/ListHelp > <https://help.launchpad.net/ListHelp> > > Andy Peters > 5511 E Rosewood St > Tucson, AZ 85711 > 520-907-2262 <tel:520-907-2262> > de...@latke.net <mailto:de...@latke.net> > > > > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > Post to : kicad-developers@lists.launchpad.net > <mailto:kicad-developers@lists.launchpad.net> > Unsubscribe : https://launchpad.net/~kicad-developers > <https://launchpad.net/~kicad-developers> > More help : https://help.launchpad.net/ListHelp > <https://help.launchpad.net/ListHelp> > > > > > _______________________________________________ > Mailing list: https://launchpad.net/~kicad-developers > Post to : kicad-developers@lists.launchpad.net > Unsubscribe : https://launchpad.net/~kicad-developers > More help : https://help.launchpad.net/ListHelp > _______________________________________________ Mailing list: https://launchpad.net/~kicad-developers Post to : kicad-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~kicad-developers More help : https://help.launchpad.net/ListHelp
