Re: gEDA-user: PCB: Connecting Nets by hand

[sdb@xxxxxxxxxx (Stuart Brorson)]

If your nets are connected in the netlist file, another common problem
occurs when you try running a track between two pins, and the pins are
too close to each other.  

PCB automatically enforces DRCs while you are routing.  If your track
width + trace separation spacing DRC is larger than the distance
between two pins or pads, then you can't route between them.  PCB
won't let you route through.

You can always find out if your are allowed to connect two bits of
metal by hitting <shift>-O to turn on the rats and see what is
connected.  You can do this even while drawing a trace.  If you see a
brown rat line connecting two bits of metal, then they are connected
in the netlist.  If you can't route between them, then the problems is
likely that you would violate a DRC by routing between the two.

Finally, sometimes PCB itself is confused & won't let you connect two
traces which *do* belong together.  You can update PCB's knowledge
about your design's connections by updating the rats.  Accordingly,
you are best advised to  hit <shift>-O early and often while routing.
That way, PCB's knowledge about your design's connectivitity is
continually updated. 

Stuart


> 
> The pins that you are going to connect must be connected in the
> netlist file, otherwise the software won't allow you to connect them.
> A way out is to disable the 'auto DRC clearance' in the settings manu.
> 
> vax, 9000
> 
> On 6/23/05, Samuel A. Falvo II <sam.falvo@xxxxxxxxx> wrote:
> > I'm attempting to connect some nets by hand in a PCB layout that I
> > have, but the thing won't let me!  For example, after I get done
> > drawing the vias and the actual lines, I end up with the following
> > situation (please excuse the use of ASCII art, but a picture is more
> > succinct than words here):
> >=20
> > o------ *
> > |       *
> > |       *
> > |       *
> > |
> > |
> > o-- *
> >     *
> >=20
> > Note that there are unavoidable *gaps* between the pins of the ICs and
> > the lines that join to them.
> >=20
> > I so far have not found *any* way to circumvent this.  What am I doing
> > wrong?  I find it excruciatingly hard to believe that auto-routing and
> > direct, point-to-point connections are the *only* way to join nets.
> > :(
> >=20
> > Thanks.
> >=20
> > --
> > Samuel A. Falvo II
> >
>