simple eagle autorouter question

Community PCB Design
1

I had to manually route two wires before running the autorouter, when the autorouter completed it said it was only 98.(something)% complete. Is that not counting the two wires I routed?, When I have it show the unrouted layer only I see no yellow lines so does that mean everything is routed fine?

2

There are likely some small airwires somewhere… Often, you’ll find them to be 1 pixel wide splotches inside a pad.

As you’ve done, turn off everything but the outline and the unrouted layer, and pan around your board looking for them.

3

I found it, It was two pins next to each other on a tqfp chip, thanks for the help.

4

timgregor:
I found it, It was two pins next to each other on a tqfp chip, thanks for the help.

I'm curious, how could any autorouter not be able to connect two pins next to each other?
5

The Eagle autorouter isn’t very good.

Leon

6

leon_heller:
“The Eagle autorouter isn’t very good.”

Correct, but it would still connect them together…

7

snarflemike:

timgregor:
I found it, It was two pins next to each other on a tqfp chip, thanks for the help.

I'm curious, how could any autorouter not be able to connect two pins next to each other?

Connection points have to be on a grid for autorouter to be able to connect them. With many different pitches it’s not always possible. Sometimes it helps to route stray pin to the point on a grid, which is close.

8

Good autorouters go off-grid if necessary.

Leon

9

felis:
“Connection points have to be on a grid for autorouter to be able to connect them.”

I don’t think thats true…

It’ll just jump from a trace on a grid to it’s destination pad.

I just think the OP had the autorouter settings incorrectly setup for his board.

10

FartingMonkey92:

felis:
“Connection points have to be on a grid for autorouter to be able to connect them.”

I don’t think thats true…

In the Eagle 4x manual, it is described on page 139 ( numbered 142 ), second paragraph from the top.

11

I just made a quick board with a TQFP - with neighbouring pins connected to each other.

It wasn’t on the routing grid yet they still got connected by the autorouter.

At the moment, i’m using 5.3.0. Don’t know if they have changed the way the autorouter works since 4x…