Restriction of autorouter?

James,

Ok, thanks for the advice. Is there literature out there that goes over

the "art of autorouting" in Eagle or anything?

What I've ended up doing so far is to route the simple digital stuff,

most of the analog measurement circuitry, and the power lines, but then

divided my board into the parts that I've routed and those that haven't

using the "restrict" layers. It seems to have worked: I ran the

autorouter and it routed the complicated digital signals that would have

taken me forever.

However, I guess I should clarify what I mean by "touching" the analog

circuitry that I've already routed. For all intents and purposes, the

circuitry that I've routed is perfect, but it wasn't to the autorouter

because it looks to end traces smack-dab in the middle of SMD pads.

Since I've got a mix of packages, it added all of these crazy angular

traces, which I have to go back and delete now. Is there any way to stop

the router from doing this?

Regards,

Brian

On 2/15/2010 1:12 PM, James Morrison wrote:

Telemachus wrote on Mon, 15 February 2010 13:04

I'm still pretty new to Eagle. I've made a few PCB's so far, and

they've turned out great, but I hadn't used the autoroute function at

all until

 

now. I need some advice.

 

I've already routed a particular area of the board since it is a

measurement circuitry area. However, now that I want to route all of

the digital signals, is there a way to restrict the autorouter such

that it

 

does not mess with my already routed measurement circuitry?

 

Hello Brian,

 

Of course, you could do your own experiments to determine this--just backup

the files first.

 

But to answer your question, the auto-router doesn't touch anything that

was routed before it starts. So if you hand-route power and critical

traces then it won't touch that stuff.

 

This is generally good but sometimes if you pushed a critical route just a

bit one way or the other you can fit one more trace through but the

auto-router needs to add a via and things get way congested very

quickly. So be careful where you put your critical routes. Your first

pass of the

auto-router may simple to figure out where congestion is going to occur and

then go back to original design (copy of design before auto-router was run)

and adjust critical traces accordingly.

 

Cheers,

 

James.

 

James,

Ok, thanks for the advice. Is there literature out there that goes over

the "art of autorouting" in Eagle or anything?

What I've ended up doing so far is to route the simple digital stuff,

most of the analog measurement circuitry, and the power lines, but then

divided my board into the parts that I've routed and those that haven't

using the "restrict" layers. It seems to have worked: I ran the

autorouter and it routed the complicated digital signals that would have

taken me forever.

However, I guess I should clarify what I mean by "touching" the analog

circuitry that I've already routed. For all intents and purposes, the

circuitry that I've routed is perfect, but it wasn't to the autorouter

because it looks to end traces smack-dab in the middle of SMD pads.

Since I've got a mix of packages, it added all of these crazy angular

traces, which I have to go back and delete now. Is there any way to stop

the router from doing this?

Regards,

Brian

On 2/15/2010 1:12 PM, James Morrison wrote:

Telemachus wrote on Mon, 15 February 2010 13:04

I'm still pretty new to Eagle. I've made a few PCB's so far, and

they've turned out great, but I hadn't used the autoroute function at

all until

 

now. I need some advice.

 

I've already routed a particular area of the board since it is a

measurement circuitry area. However, now that I want to route all of

the digital signals, is there a way to restrict the autorouter such

that it

 

does not mess with my already routed measurement circuitry?

 

Hello Brian,

 

Of course, you could do your own experiments to determine this--just backup

the files first.

 

But to answer your question, the auto-router doesn't touch anything that

was routed before it starts. So if you hand-route power and critical

traces then it won't touch that stuff.

 

This is generally good but sometimes if you pushed a critical route just a

bit one way or the other you can fit one more trace through but the

auto-router needs to add a via and things get way congested very

quickly. So be careful where you put your critical routes. Your first

pass of the

auto-router may simple to figure out where congestion is going to occur and

then go back to original design (copy of design before auto-router was run)

and adjust critical traces accordingly.

 

Cheers,

 

James.