On 9/14/05, Jesse Lackey <jsl-ml@celestialaudio.com> wrote:
> I agree, the autorouter is a good tool for determining overall
> complexity of a design ... if it is having major problems, one is likely
> to have problems doing it by hand as well.
> 
> Marvellous to watch it run... now that is a good tough CS algorithm
> problem to tackle, kind of amazing.
> 
> Earlier on in my career I used the autorouter a lot, and set up class
> attributes, etc.  But as I and projects got more sophisticated it became
> increasingly useless.  Boards with multiple different grounds, traces
> from one section to another that can't go over various ground planes,
> differential pairs that must stay together, etc. etc.
> 
> Everything is done by hand now, unfortunately.  Takes up a lot of my
> time... but its hard to say if a far more sophisticated autorouter would
> be much of a time saver, balancing the time it would take to tag signals
> and board areas with all the constraints and rules it would need to do a
> usable job vs. just doing it myself.
> 
> Anyway, FWIW, my process now is:
> 1. move parts into functional groups, by looking at a printout of the
> schematic and typing "move <whatever>" and dropping it, then checking
> that part off on the printout.  Repeat for everything.
> 
> 2. for each functional group, now that the ratsnest is more sane, do the
> placement.  This takes longer to do as I get better at it, ironically,
> but in the end routing is easy - its clear what has to go where, and
> very few vias wind up being needed (usually).
> 
> 3. run the autorouter to see what it does with the placement I did.
> maybe change the placements a little, etc.
> 
> 4. rip up all autorouter work and now move functional groups around to
> make it tight and have connectors on the board edges where they need to
> be, etc.
> 
> 5. run autorouter again, see if it seems impossibly tight, and decide
> 4-layer vs. 2-layer if it is still a question.
> 
> 6. rip it all up - or most of it anyway - and route route route by hand...

 We have a senior designer here, right ? How old are you please ?

thx,
Vasile

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