Please HELP!!!!!!! - Page 1
Forum section: electronics / general

author: olsenn
author_rank: Frequent Contributor
timestamp: December 03, 2011, 12:17:39 am
content: I am trying to build my very first PCB using Eagle, and I have been largely following the SparkFun tutorials; however, one thing is not working out for me, and that is when I create the board file from my schematic, none of the wires/nets going from my SMD part are appearing in the board. Furthermore, I cannot seem to manually connect them in the board itself.I am under the belief that the wires/nets aren't actually making proper contact in the schematic but I can't figure out what to do. I think those wires are appearing as being just floating, even though they look perfect to the eye.Here's a photo of the schematic:jpg image hosting...and the board so far:gif image hostingThe TPA6120A2 part (surface mount) doesn't have anything connected to it in the pcb??? I didn't create the part, but instead downloaded it fromhttp://tendolla.com/designgallery/main.php/v/Eaglelibs/TPA6120A2_lbr.html.I did check it out though, and as far as I can tell it looks to be done properly (if anyone can confirm/deny this I'd be grateful).If anyone has any ideas or needs more info, please let me know. I really want to get this finished so I can send it away for fabrication.

author: Joshua
author_rank: Regular Contributor
timestamp: December 03, 2011, 12:53:44 am
content: You have air wires on the board which signifies connections to be made, but haven't been routed yet. (The air wires are the sickly yellow thin lines making everything look like a mess. ) The first thing you should do before you try and route the board is place your 'constants' - connectors, buttons, LEDs, basically anything that you KNOW where you want or it has to go.Then move and rotate components to make as little overlap between the air wires. Also you'll want to put things like bypass caps as close the the relevant part as you can.Then, for me sometimes eagle is a little finicky for me when routing. If you are using sparkfuns keyboard shortcuts, press F9. This puts you in 'route' mode. Then make sure that you are routing on top or bottom copper. Probably bottom for through hole and top for SMD. Then click one of the air wires. It should attach a track to one of the pads. Begin routing. You can also click on a pad to start the route.Hope this helps! If you have anymore questions don't hesitate to ask. (FYI, however that using all caps and multitudes of explanation points in your title is not exactly smiled upon.try and use something more specific. You generally attract those you are more experts in that particular field)Joshua

author: olsenn
author_rank: Frequent Contributor
timestamp: December 03, 2011, 01:53:09 am
content: Thanks, and sorry about the title, haha. Unfortunately though, I don't think you understood my problem. I know the thin yellow wires mean there is supposed to be a connection but it hasn't been routed yet (actual traces aren't there), but if you take a look at the SMD part in the board, you will see that no thin yellow wires are going to it... there should be connections from resistors et cera to that part, but it's just sitting there doing nothing. Actually, one connection did go through fine which was the grounded thermal pad on the back of the chip; however, none of the actual pins are making a connection even though I'm drawing nets in the schematic.As a second note, I did try pressing F9 to draw a new wire, but it doesn't line up with the pins. The grid is (I believe) on a 0.05" spacing, which the casing of the part lines up with, but the pins are in between the points which I can access (if i click on pin 1 to draw a wire, the wire starts in between pin 1 and pin 2).

author: 8086
author_rank: Super Contributor
timestamp: December 03, 2011, 01:58:04 am
content: You can still draw a signal on the pcb if you zoom in enough that you can get an accurate placement on the pad.

author: ivan747
author_rank: Super Contributor
timestamp: December 03, 2011, 01:59:28 am
content: Did you use the Net tool instead of the wire tool? The Net tool guarantees an electrical connection; the wire tool is for graphical purposes. I recommend you take an EAGLE webinar on Element14, they can give you some useful tips.Good luck,Ivan

author: olsenn
author_rank: Frequent Contributor
timestamp: December 03, 2011, 02:25:35 am
content: Yes I have tried connecting the pins with nets as well as wires; it makes no difference in my case

author: Balaur
author_rank: Unknown
timestamp: December 03, 2011, 02:52:20 am
content: Could it be that the schematic and pcb became inconsistent (i.e. you closed the pcb view at some point, and modified the schematic?)Does it complains about that at some point (by example when starting the pcb or when performing ERC)?If yes, then you will have to remove the pcb and create a new one from the schematic.Cheers,Dan

author: olsenn
author_rank: Frequent Contributor
timestamp: December 03, 2011, 02:57:49 am
content: No, unfortunately it isn't that simple. I didn't create the board until the schematic was finished and I didn't make any changes to the schematic since then. Also I don't get any error messages

author: Balaur
author_rank: Unknown
timestamp: December 03, 2011, 03:20:44 am
content: Hey, I checked the library and it looks like the symbol was created using a smaller grid.Most of the schematic wires looks normal but miss the actual pins by just a little (by not snapping to the correct grid)Set a finer grid in the View>Grid.Ex: 0.05 inches Size / 0.005 inches Alt (i.e. two times finer that the default).Then, zoom a bit on the opamp connection and you will be able to redo the connections.Check that everything is connected by moving the part and see that the wires follows it. Use the alt grid if needed.Good luck

author: olsenn
author_rank: Frequent Contributor
timestamp: December 03, 2011, 03:33:17 am
content: Excellent! That worked like a charm. Thank you very much!

author: ivan747
author_rank: Super Contributor
timestamp: December 03, 2011, 04:23:32 pm
content: Quote from: olsenn on December 03, 2011, 02:25:35 amIf you use the Net commands, Eagle will add a dot to the nets that need one automatically. Also, it is the only way to cconnect nets to buses.

author: Ellis64
author_rank: Newbie
timestamp: December 04, 2011, 07:59:43 pm
content: Quote from: ivan747 on December 03, 2011, 04:23:32 pmWhat Ivan noted is very importand my friend. When you have problems like this again delete all suspicious signals in schematic and reroute 'em using NET command. Also at the start of each project set the grid, units and snap and do not play with it till you finish the project. Good luck to your first attempt for a good pcb.

author: ivan747
author_rank: Super Contributor
timestamp: December 07, 2011, 07:14:21 pm
content: Quote from: Ellis64 on December 04, 2011, 07:59:43 pmIt is best to use the default grid and don't ever change it. Parts not sticking to this grid are very uncommon and they are not acceptable because they don't follow this convention.It is OK to change the grid when working with PCBs but it is best to let the PCB trace snap to the IC pin. If you ever change the grid in the PCB, I recommend to use a multiple of the grid you were using before, for example, you can go from a 0.1" grid to a 0.05" one without too many problems.

author: Unknown
author_rank: Unknown
timestamp: December 07, 2011, 11:31:23 pm
content: Quote from: ivan747 on December 07, 2011, 07:14:21 pmGood luck with mixing imperial and metric pitches, eg. 50 mil and 0.8 or 0.5 mm. What grid do you use so both 1.275 mm and 0.8 mm match, 0.025mm? Doesn't Eagle have a feature similar to Altium's electrical grid, where it will just snap to pads if it comes within a certain distance?

author: olsenn
author_rank: Frequent Contributor
timestamp: December 08, 2011, 07:53:02 pm
content: It seems to have all worked well, and my pcb is being made by BatchPCB as we type. One thing that frightens me is ground planes. I've added a plane to both sides of the board, but when I open the pcb file in Eagle, it doesn't show by default (just has a perforated outline). Once I click the Auto button everything fills in nicely. Does anyone know if that will be a problem with my gerber files (will they include the ground lanes as I had intended)?

author: bfritz
author_rank: Regular Contributor
timestamp: February 13, 2012, 02:16:42 am
content: The ground planes are done by adding a Polygon if I remember correctly. (I don't use Eagle all the time, just when people want that tool.) I remember the default for "filling" the polygon to be off. I think you can edit the parameters of the polygon and turn fill on. Take a look at the documentation, and I'm sure you'll find the parameter for turning them on.I would suggest that before sending your board files for manufacture, that you view the gerber files with one of the many free gerber viewing utilities available. PCB Layout software isn't supposed to make things look different in the Gerbers, but I've seen enough instances of software doing strange things, to take the time to review the Gerber files before I send them out for Fab. Looking at the Gerber files will make it very clear if your ground planes are working as you expect!

author: ivan747
author_rank: Super Contributor
timestamp: February 13, 2012, 08:27:38 pm
content: Quote from: alm on December 07, 2011, 11:31:23 pmYes, there's a similar feature.