X-Authentication-Warning: delorie.com: mail set sender to geda-user-bounces using -f X-Recipient: geda-user AT delorie DOT com Date: Wed, 18 Feb 2015 10:26:39 +0100 (CET) X-X-Sender: igor2 AT igor2priv To: geda-user AT delorie DOT com X-Debug: to=geda-user AT delorie DOT com from="gedau AT igor2 DOT repo DOT hu" From: gedau AT igor2 DOT repo DOT hu Subject: Re: [geda-user] Star connection points in PCB? In-Reply-To: Message-ID: References: <1502170242 DOT AA18887 AT ivan DOT Harhan DOT ORG> <54E354D4 DOT 3040509 AT ecosensory DOT com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Reply-To: geda-user AT delorie DOT com Errors-To: nobody AT delorie DOT com X-Mailing-List: geda-user AT delorie DOT com X-Unsubscribes-To: listserv AT delorie DOT com Precedence: bulk On Wed, 18 Feb 2015, Kai-Martin Knaak wrote: >>> Drawbacks: >>> >>> - the same pin numbering and back-annotation problem that you >>> have with connectors > > @Igor2: Would you mind to elaborate? > > >>> - the star symbol/footprint will have explicit number of pins, >>> you may end up unused pins or will have to replace with the next >>> bigger if more nets are to be connected > > The pads of the star symbol can be 100% overlapping in the footprint. > So a replacement won't break the layout. If there's 100% overlap of all pads, and you connect a trace to it, you connect it to all pads, not just the one you wanted to. This would require another exception. The simplicity of my proposal 3 works only if you have a section of the pad which does overlap and a section which doesn't and the trace is connected to the non-overlapping section only. This means find.c figures the trace is connected to that given pad, pad number N, and this is what the netlist wants too, so all fine. The only exception to be added is that it should stop checking whether this pad is galvanically connected to other pads as well. Another problem with 100% overlap is that once you connect two traces of two different nets to it, the two traces may (under the pad, sort of invisible to the user in some cases) also touch. This way find.c would detect both traces are connected to the pad(s) but they are also shorted together in the same point. My proposal makes this more explicit because the non-overlapping parts of the pads would be sticking out, like bristles of a hedgehog and there is an 1:1, visible connection between a pad and nets. Just like with connectors now. Hence the pin-numbering/back-annotation problem I mentioned: when drawing the schematics, it's hard to predict what pin number of the star should be used for a net. When you do the PCB, you already see swapping two pads makes routing easier, but then there's no easy mechanism (that I know of) to get this swap back-annotated to the schematics. Regards, Igor2