Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

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?

Thanks in advance
David