Homebrew PCBs

----- Original Message ----- 
From: "David McNab" <david@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Sunday, June 05, 2005 4:57 AM
Subject: [Homebrew_PCBs] eagle autorouting - got any tips?


> Hi all,
>
> I'm having some weird times with CadSoft Eagle's autorouter.
>
> The project is based on a 28-pin PIC device, on a single sided board,
> with a moderate number of peripheral devices and passive components.
>
> Eagle's autorouter is an absolute god-send, but is incomplete in the
> sense that it can't automatically change component placement (within
> user criteria) to achieve greater success.
>
> I'm trying to autoroute the bottom side of the board to minimise the
> number of unrouted connections. This is challenging, because due to
> physical requirements, several components have to stay in fixed
> positions on the board. At best, I'm getting down to 4 or 5 unrouted
> connections, which I could solve with manual vias and top-side wires,
> but I'd really like to get it down to 0 unrouted.
>
> I tried 2-side autorouting, and setting high costs for vias, as well as
> maximum numbers of vias. But the autorouter seems to ignore these, and I
> end up with 30 vias or more.
>
> My experiences with the autorouter have been weird to say the least. It
> feels like I could get more scientific certainty from inspecting chicken
> entrails to predict movements in the NASDAQ.
>
> If anyone here has got Eagle autorouting down to a fine art, would you
> care to share your tips to help myself and others learn from your
> experience?

Most autorouters are a waste of time, especially on single-sided boards. The 
Eagle autorouter is crap, anyway.

If you want a decent autorouter have a look at Electra, it's available for 
Eagle. I use Pulsonix for PCB layout and it comes with Electra as an option.

Leon
--
Leon Heller, G1HSM
http://www.geocities.com/leon_heller