So I just finished my first PCB layout in Eagle. It's a pretty densely packed board, with 6 motor controllers and a bunch of other stuff, packed into a shield. Based on the advice of most websites I read, I eschewed the autorouter and laid it out myself - which wasn't easy, there were about a gazillion connections to make. So I then loaded up Sparkfun's DRU file, and ran the DRU checks... And it found over 900 errors. Ugh. I'm working through them - there are a lot of clearance errors I don't understand, the clearances look ok to me.
But I wouldn't be surprised if there are some real errors in there, and I will take me forever to go through and evaluate them all. So I'm wondering if I should just start over and give the autorouter a shot. I can't imagine it woud do a worse job than my newbie first attempt. I did run it once before I started, just to see what it did, and it had 56 vias in the board, which is a lot more than I have (I think), but so what.
So any suggestions? Anyone have any issues with the autorouter?
Also, I have one of these DC barrel jacks in the board. I can't find it now, but there was something about needing to give special instructions to the PCB house about the pads needed for the jack. Can anyone explain what I need to do?
Try it, save a copy of the board files, then rip up signals (leave the power runs) setup the auto router and try.
Barrel jack connector has slots. Eagle has no slot tool, and board houses can get confused about when to run drill and cnc mill files. For example if you want a hole/slot plated that drill/mill operation needs to happen before plating, while cutouts, outlines and plain holes happen after plating. Unfortunately there is no common way to tell the PCB shop which drill or mill file is used before or after plating. I think KiCad is outputting two drill files now. If Eagle followed and added a slot tool (for before plating cnc operation). At least that pain could slowly go away as shops get use to seeing pairs of files.
When you save, make the schematic file is open at the same time. Otherwise you will have two different saves, and will get file in sync errors. Very difficult to impossible to recover from - often requiring you to delete the .brd file and recreate it from the schematic again, relaying out all the parts.
With the autorouter, try this:
View:Grid, set units to mil
Select Add via, and set Octagon and 12mil for size, press Enter. Press Escape so you don't actually place a via. Or place it, and delete it.
Add a Polygon around the outside of the board, NAME it GND. Both layers.
Select Edit:Net Classes, and make sure the trace widths are as needed. I set default to 10 mil wide, 10 mil clearance, 12 mill drill.
Add a Power class, 20 or 24 mil wide, 10 mil clearance, 24 mil drill. You may need to handroute some traces to connect power if a 20-24 mil trace can't connect to a pad without interfering with other pads. Connect up with a short 16 mil trace or as needed.
Right click the power traces, select properties, and select Power.
When you start the autorouter, set it for 1 mil or 2 mil resolution.
That should help a lot in the autorouting. If you have good parts placement (you can tell by how jumbled the unrouted lines look), then you may not have to do much more than add some Vias named GND to connect the last few grounds together. Maybe tweak placement of some traces to make room for GND areas to connect.
If you handroute anything critical first, the autorouter will work around those.
I use iteadstudio's .dru for checking clearances.
Be sure to click Rats Nest also, make sure there is "Nothing to do!", when you think it's all routed.
Run the Error check on the schematic, make sure all is connected as desired.
Run the Design Rule check on the board.
You don't want Overlap, Dimension, Clearance errors. Move stuff so those are cleared up.
I don't worry about Stop Mask errors. Smash all parts and make sure the Names are easy to read and don't have via holes or parts placement lines thru them. Once smashed you can move them around, change their size.
Run Rats Nest again, make sure you didn't accidentally delete a trace while fixing names.
I already had added ground pour polygons on the front and back.
I tried the auto router, and the DRU check still had over 300 errors. I'm away from the computer now and can't check, but I assume that there's some way to program the DRU rules into the autorouter settings so it doesn't generate errors in the routing just for the DRU file to barf on - isn't there?
I'll try iteadstudio's DRU file.
So 20-24 mil for power? Even for logic power? Does that include ground? Yikes - that's wide. I also have 24 volt power for the motors, the power supply is only 2.5 amps so shouldn't draw any more than that, and any single motor doesn't draw more than 1.2 amps max. Typical is much lower. So 24 mil is ok for that too, right?
So what should I do about the slot connectors on the barrel jacks?