Turn your EAGLE schematic into a PCB

Step 11 Try the autorouter

Now we'll see if the autorouter can do some of the work for us. The EAGLE autorouter isn't the best in the world, but even when it does a "bad" job, it will give us some general hints on how things need to look, or where the trouble spots are.

Clcik the AUTOROUTE icon, and a dialog box will pop up. The default parameters will produce a double sided board, and we want to at least TRY to make a single-sided board, so the first thing to do is set the preferred direction for the TOP layer to NA (Not Applicable.)

The other thing you may need to change is the routing grid. This defaults to the same default grid as the board layout editor in general: 0.05 inches (1.27mm, since I have my editor set up in metric.) Since this particular board has big parts, and we haven't moved any off the default grid, we're ok with that value. If you have SMT components or have moved things around on a finer grid, you might have pads that are not on the touing grid, which the autorouter doesn't like much ("unreachable pad", etc) You can make the grid very small, but it will take longer. IMO, it's better to start with a coarse grid and halve it each time it looks like routes fail because the grid is too large.

Also note that the autorouter obeys the board dimension lines, so if you haven't moved them close to your components, you might have traces travel all over the board. Or if you've moved the outline too close to the pads, you may have prevented traces from going places they need to go.

Comments

[thypnotist]

Your a Ledgend.
This is exactly what I needed to know from start to finish.
Thanks heaps.....
David

[abraxas2]

Now that the autoroute has destroyed my hours of work, how do I undo it ? Undo doesn't work !!!

[computurwizard]

You can undo the autorouter. Click the ripup icon, then on the top toolbar click the little traffic light icon. A window will pop up asking if you are sure. Hit Yes.

[westfw]

You can't undo the autorouter. It's a good idea to save your work often, especially before large changes like autorouting. The autorouter should not have destroyed any of the manual routing you did; it just added a bunch of "other" traces. You can get rid of individual traces, or sections, or everything, with "ripup", but there isn't specifically a "ripup the bits you just autorouted."