[sdiy] RE: RE: [sdiy] DIY Heaven

[harrybissell]

ratsnests are for wussies ???   :^P

(I have not used ratsnests or found them useful... I can work from a GOOD
schematic and do a good initial placement. That said I have never had a TOOL
with a good ratnest program. Mostly the thing looks like... a rat's nest :^)

We use a tool at work (Mentor Graphics something...) that I hate.  It takes the
netlist and then FORCES you to follow it, or go back and change the schematic.
I like to change the board layout on the fly, then fix the schematic later.  I
could understand if the engineer did the schematic and a flunky does the
layout... it would
prevent dumb errors.  In my case the engineer does the schematic AND the
layout...
i guess you might call that 'empowerment'. OTOH you might say therfore, the
engineer IS a flunky :^)     I see it as one more chance to finesse the design.

I'm using Hiwire II from Wintek. I wish I had a dollar of every person who isn't
using
that program.  (I could probably fill my tank if-you-know-what-I-mean :^)

anyway... wouldn't "clarify a ratsnest" be an oxymoron ???

H^) harry

Tom Arnold wrote:

> On Fri, Sep 02, 2005 at 12:56:06AM +0300, Samppa Tolvanen wrote:
> > On 9/2/05, Tom Arnold <xyzzy at sysabend.org> wrote:
> > >
> > > Most of the sharing now is in Eagle format files.  Problem with the free
> > > software that several of the PCBfabs are passing out is they dont do
> > > schematic capture and have limited support for netlist import and things
> > > like ratsnests that I depend on.
> > >
> >
> > Please clarify. I didn't understand a bit.
>
> Board layout, at least for me, is easy.  I used to use PADS and I could
> churn out a mixed digital/analog board for the CAMAC crates we used in about
> 2 days ( without sleep ).  These were multilayer boards.  Very ugly stuff.
>
> I think schematic entry is where the mistakes are made.
>
> IMHO to properly lay out a board, you should take a working schematic, enter
> it into schematic capture, generate your netlist, then go to PCB layout.  In
> PCB Layout you basically have your list of componants, connectors, LEDs,
> whatever, and the netlist that shows how they are all connected.  You place
> the components and then turn on the rats nest.  It shows, in straight lines,
> where everything connects.  As you connect pins on the board itself, each
> ratsnest connection goes away.  When you have no ratsnest left, you can be
> fairly confident that everything is connected on the board.  Then start
> looking at ways to optimize the board for layout, noise, etc.  If you move
> something and break the connections, the ratsnest reappears for you to fix.
>
> Probably a bad description of it but I tried.
>
> The only company I know that at least discounts a full featured PCB Layout
> and schematic capture is Douglas, which heavily discounts DouglasCAD when
> you use them to make the board.  Also discounts on Designworks which is the
> schematic capture side of things.  All the other packages I've played with
> have been just PCB layout, I cant think of any off the top of my head that
> had even netlist import.
>
> Hrm.  Actually, I just looked again at http://www.pcb123.com and they do in
> fact have schematic capture now so maybe things are changing.
>
> --
>  ------------------------------------------------------------------------
>  - Tom Arnold -       When I was small, I was in love,                  -
>  - Sysabend   -       In love with everything.                          -
>  - CareTaker  -       And now there's only you...                       -
>  --------------         -- Thomas Dolby, "Cloudburst At Shingle Street" -