Hi Mike,

It's really important how experienced is a person to
use the autorouter.
As you said the fanout should be done manually. The
placement is also manual work. The routing depends on
how clever the placement and fanout were done.
I have a friend who uses Specctra and had to autoroute
a PCB with 4 BGAs and I don't know how many other
components. He spent about two months autorouting just
this board and even went to work at night to check the
results and run another session.
Even if I had to work at night, I'd do it manually
much faster.

My $0.02

Mira


--- edsi <[EMAIL PROTECTED]> wrote:
> Tony
> 
> > But do you spend 'days' each time you do a board?
> I rather just route the
> > board by hand for 'days' and have it look the way
> I want it to look.
>  Tony,  I spend day on what would otherwise might be
> months.  You shouldnt manually route 2000
> components.  Because there is no smart fannout
> algorithim in Spectra or Electra,  I used prefanned
> patterns.  I have posted this a while ago.  The
> pattern are also rule driven to allow for routing
> channels.  I have tried some do file for fan out but
> the results are not as good.  I get close to 100 
> percent routing in very little CPU time
> 
> > I've tried using autorouters and after a while I
> just say f**k it, and route
> > by hand. They always look 'auto routed', busses
> seem to not stay together,
> This is major misconception, that busses should
> follow each other..... Maintaining the same
> topography and wire lengths are important.  Routing
> and Wrapping  busses togehter invites crosstalk  I
> see this all of the time...on noisey boards/  
> > etc.
> > 
> > I am about a week into my Electra trial, and it
> got a current board to 100%> with no violations, but
> it looks like hell.  
> 
> It looks like hell because, you have to understand
> the how an autorouter behaves.    The shortest path
> for any route is  a straight line, the autorouter's
> algorithm is a manhattan path.  If you can get the
> the router to run diagonal then horizontal, then the
> router is working properly.   If you get all of your
> lines on each layer running in the same direction,
> you are routing correctly.  I call it my "stick"
> theory.  Drop some sticks on the floor,  at random
> they occupy the most space.   Placed adjacent to
> each other, they occupy the least amount of space.
> If your routes are running in the same direction, it
> should be very efficient  
> 
> 
>  >I would have so much clean up, 
> 
> I rarely have any clean up except for reviewing high
> speed and signal integrity issues.   ie mentioned
> last posting,  I review lenghts, and via counts. 
> The via count also tells me if the the manhattan
> path was followed.   On any two nodes I expect 3
> vias max.  Start, turn and terminate. 
> 
> 
> > rather just route the board by hand...again. I am
> trying different
> > instructions in the DO file, and maybe that will
> help.
> 
> 
> It gets more complicated than that,  you may have to
> place boards on a router several times.  For
> instance I have a design right now that I can see
> very strong sets of Horiz and Vertical ratsnest.  I
> am selecting busses to route Horz,  reviewing it
> then I select only Vertical routing.  Rotuting 
> begins at placement, isuring that routing channels
> are always open
> 
> There is a misconception in this industry that
> autorouters are not up to the task.  If you want to
> route every thing on the top layer,  specify the top
> layer, with no vias.  You might be surprized at the
> results.
> 
> 
> Mike Reagan
> EDSI
> ---------- Original Message
> ----------------------------------
> From: "Tony Karavidas" <[EMAIL PROTECTED]>
> Reply-To: "Protel EDA Forum"
> <[EMAIL PROTECTED]>
> Date:  Thu, 20 May 2004 23:41:32 -0700
> 
> >But do you spend 'days' each time you do a board? I
> rather just route the
> >board by hand for 'days' and have it look the way I
> want it to look.
> >
> >I've tried using autorouters and after a while I
> just say f**k it, and route
> >by hand. They always look 'auto routed', busses
> seem to not stay together,
> >etc.
> >
> >I am about a week into my Electra trial, and it got
> a current board to 100%
> >with no violations, but it looks like hell. I would
> have so much clean up, I
> >rather just route the board by hand...again. I am
> trying different
> >instructions in the DO file, and maybe that will
> help.
> >
> >Tony
> >
> >
> >-----Original Message-----
> >From: edsi [mailto:[EMAIL PROTECTED] 
> >Sent: Wednesday, May 19, 2004 2:44 PM
> >To: Protel EDA Forum
> >Subject: Re: [PEDA] Router comparison
> >
> >Good question Joe
> >
> >I plan to phase out my usage with Spectra, Since I
> have an older version,
> >with not quite all the bells and whistles.  Alot of
> the "bells" in Spectra
> >dont work any way.  What I have found is ...SPECTRA
> like all the other
> >routers were written 20 years ago. Spectra has not
> kept  up with the latest
> >footprint technology. Spectra has a difficult time
> keeping bundled busses
> >together.  Has problems fanning out ( Advantage
> goes to ELECTRA for fanout,
> >but I use pre fanned parts)    Dont get me wrong
> SPECTRA  is ....the best
> >router on the market at any price.
> >ELECTRA is a newcomer. I have been using it with
> great success and the
> >enginnering department at ELECTRA is in tune with
> its users.  They are
> >receptive to inputs and will turn a suggetion
> around fairly quickly.  Give
> >this company time,  they will be a major player in
> the CAE market.
> >
> >You guys need to plunk 3 K down and purchase the
> ELECTRA router. Then  learn
> >to use it. I never like to hear "WE ALWAYS ROUTE BY
> HAND". That  tells me
> >you are designing small boards, or dont know how to
> use a router.  or you
> >are simply farming out a design that should take
> you about half the time.
> >Dont just hit GO and expect a rotuer to work.  I
> might spend days thinking
> >about routing stategies.   I  spend days tuning
> parts to open channels.  I
> >might make several passes, and adjust my rules.   
> Rules driven routing can
> >control vias, number of vias, line lengths,
> pairing, layers line widths, and
> >spacing.  Routers work!
> >
> >
> >And yes I am finally becoming an expert at
> something....it may be auto
> >routing
> >
> >Mike Reagan
> >
> >---------- Original Message
> ----------------------------------
> >From: "Joe Sapienza" <[EMAIL PROTECTED]>
> >Reply-To: "Protel EDA Forum"
> <[EMAIL PROTECTED]>
> >Date:  Wed, 19 May 2004 13:05:07 -0400
> >
> >>Mike,
> >>
> >>Maybe my response came across wrong, What I was
> getting at why both
> >routers,
> >>I had no problems justifying the Specctra router,
> but I don't see me
> >>spending for the Electra. Agreed that Protel with
> a less than spectacular
> >>router may benefit from partnering with someone
> else for their bundled
> >offer
> >>or just ommiting it altogether. Like you I'm doing
> this full time, but with
> >>the economy having been down loads have been too
> rollercoatery to spend
> >much
> >>when I'm getting by.
> >>
> >>Sounds like you have spent some time with the
> Electra router, care to
> >>expound some virtues since I was working and my
> demo expired long before I
> >>had any real time to spend on it.
> >>
> >>Joe
> >>
> 
=== message truncated ===



        
                
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