DIP pins shorted

On 11/18/2011 8:42 AM, Robert Scott Jr wrote:

Hello All. This is my first attempt at using Eagle software to develop a printed circuit board. This project is for the purpose of jumping into the program to gain a foothold on learning it's ways. I've come accross something that I don't understand so I've come asking for some help. As seen in the board image, IC1 (L297) is a DIP. It looks to me that pins on both sides of the chip are shorted to adjacent pins. Anyone have an idea of what's going on? Thanks. - Scotty

 

  Image:L297 board.jpg  Image:L297 schematic.jpg

 

The images are of pretty poor resolution so its hard to tell.    Some of

the (non- adjacent) pins are shorted together but it appears that the

schematic has the same connections.

I do not see a case where "adjacent" pins are shorted.    You do

understand that editor is showing you multiple layers?   The blue traces

are on a different layer of the board than the red traces.   Although

these traces do cross each other they are not electrically connected

unless there is a via or pin also connecting the board layers.

Why not use the "show" command to display the nets on your board.   This

will quickly tell you if there are connections between adjacent pins.

Jim

On 11/18/2011 8:42 AM, Robert Scott Jr wrote:

Hello All. This is my first attempt at using Eagle software to develop a printed circuit board. This project is for the purpose of jumping into the program to gain a foothold on learning it's ways. I've come accross something that I don't understand so I've come asking for some help. As seen in the board image, IC1 (L297) is a DIP. It looks to me that pins on both sides of the chip are shorted to adjacent pins. Anyone have an idea of what's going on? Thanks. - Scotty

 

  Image:L297 board.jpg  Image:L297 schematic.jpg

 

The images are of pretty poor resolution so its hard to tell.    Some of

the (non- adjacent) pins are shorted together but it appears that the

schematic has the same connections.

I do not see a case where "adjacent" pins are shorted.    You do

understand that editor is showing you multiple layers?   The blue traces

are on a different layer of the board than the red traces.   Although

these traces do cross each other they are not electrically connected

unless there is a via or pin also connecting the board layers.

Why not use the "show" command to display the nets on your board.   This

will quickly tell you if there are connections between adjacent pins.

Jim

Thanks for responding Jim. I inserted some new images. They are readable now. Yes, I do understand about trace colors and board sides. When I use the Show tool on a selected 'problem' trace, the trace and only the intended component pins of the selected trace illuminate. However, that trace has a path right along the drill holes of adjacent pins of IC1.

Hi robert,

First which version do you use and can you put in the sch and brd files so we can check for you.

On 11/18/2011 11:24 AM, Robert Scott Jr wrote:

Thanks for responding Jim. I inserted some new images. They are readable now. Yes, I do understand about trace colors and board sides. When I use the Show tool on a selected 'problem' trace, the trace and only the intended component pins of the selected trace illuminate. However, that trace has a path right along the drill holes of adjacent pins of IC1.

 

Ok..I see it now and it does look wrong.   How did the traces get routed

this way ....manually perhaps?   Try running DRC and see if the problems

are picked up in the check.   I think the suggestion to post your sch

and brd files makes sense.

Jim

Gentlemen, I am using Eagle light version 5.11.0. Attached are the files. I did run DRC and there are about 60 errors. Most have to do with IC1. The others I created when trying to reposition the resistors, leds and the switch. I was working on them when I realized the problem with the traces of IC1. I haven't done any manual routing on this board. It almost seems that the source of this problem may be the L297 file in the library. Thanks agian for responding. - Scotty

Well, I tried attaching the files. I went to their location in the folder and chose the .brd and .sch files. When tried to post, I got an error message; 'The content type of this attachment is not allowed.' ???

On 11/18/2011 6:19 PM, Robert Scott Jr wrote:

Gentlemen, I am using Eagle light version 5.11.0. Attached are the files. I did run DRC and there are about 60 errors. Most have to do with IC1. The others I created when trying to reposition the resistors, leds and the switch. I was working on them when I realized the problem with the traces of IC1. I haven't done any manual routing on this board. It almost seems that the source of this problem may be the L297 file in the library. Thanks agian for responding. - Scotty

 

Well, I tried attaching the files. I went to their location in the folder and chose the .brd and .sch files. When tried to post, I got an error message; 'The content type of this attachment is not allowed.' ???

 

Try zipping the files and posting the zip?

Ok. I'll try the zipped files. - Scotty

Hi Robert,

I looked at your files and I see some things that are beginners failures.

I would advice you to first look at the tutorials to see how things are working.

Use the ERC/DRC to check for consistency and errors in schematic / PCB layout.

Keep your hands of the Design rules as long as you don't really know what you are doing and look if you can find DRU files at your boardhouse for eagle.

Use VCC instead of 5V for digital power this because when you look at IC2 in the PCB you'll see that power is not connected.

Also for GND instead of AGND (AGND is analog ground and not Digital GND).

Also check trace sizes, the traces at the 24V is way to thin when looking at the maximum current the MOSFETs can drive.

Advices you to define extra NETCLASSES for power and 24V with wider traces and use a polygon for GND.

Did you route the board by hand or autorouter? If you can use the autorouter you better try these will respect the design rules.

Whe you have more wuestions don't hesitate to ask.

On 11/20/2011 3:54 AM, Marco de Grauw wrote:

Hi Robert,

 

I looked at your files and I see some things that are beginners failures.

I would advice you to first look at the tutorials to see how things are working.

Use the ERC/DRC to check for consistency and errors in schematic / PCB layout.

Keep your hands of the Design rules as long as you don't really know what you are doing and look if you can find DRU files at your boardhouse for eagle.

Use VCC instead of 5V for digital power this because when you look at IC2 in the PCB you'll see that power is not connected.

Also for GND instead of AGND (AGND is analog ground and not Digital GND).

Also check trace sizes, the traces at the 24V is way to thin when looking at the maximum current the MOSFETs can drive.

Advices you to define extra NETCLASSES for power and 24V with wider traces and use a polygon for GND.

Did you route the board by hand or autorouter? If you can use the autorouter you better try these will respect the design rules.

 

Whe you have more wuestions don't hesitate to ask.

 

Hi Robert,

I also looked at your files and agree with Marco's suggestions.   I

tested the layout by running DRC and there were many reported overlap

errors ..some of which you had pointed out.   I then ripped up all the

traces and auto-routed the board and it did not re-create the overlaps

in your original design.    From these results it appears likely that

the original layout errors were created during a manual routing procedure.

You may have been expecting that Eagle would automatically avoid other

traces/nets/pads/vias but in the manual routing mode it does not.   If

you have a version of Eagle that supports the "follow-me" routing modes

you get something like the behavior I think you were looking for so

maybe you want to experiment/read up on that feature (added around

version 5.10 I think).

Regards,

Jim

Thank You Gentleman for your time and advice. Your comments are exactly the leads I (and other beginners) need to go off and learn how to more successfully use Eagle. I will take all your suggestions and start over. The ground and supply I chose from the library as the best I could find. I'm gonna have to do some poking around and see if there is a way to take certain common, frequently used, frequently used by me, etc. components and create my own library from them to avoid spending so much time trying to figure out where components are in th default library. - Scotty

On 11/20/2011 12:44 PM, Robert Scott Jr wrote:

Thank You Gentleman for your time and advice. Your comments are exactly the leads I (and other beginners) need to go off and learn how to more successfully use Eagle. I will take all your suggestions and start over. The ground and supply I chose from the library as the best I could find. I'm gonna have to do some poking around and see if there is a way to take certain common, frequently used, frequently used by me, etc. components and create my own library from them to avoid spending so much time trying to figure out where components are in th default library. - Scotty

 

Yes...finding parts it the libraries can be puzzling at first.

Different people have different methods but I find the following steps

will often get me to what I need or close...

- First search on a portion of the device name.   Try to use wildcards

to make the search term reasonable specific but not exact.   Eg use

"LS04  instead of "SN74LS04".   This will avoid the case where two

manufacturers add a different prefix code to what is essentially the

same part.   If you find what you need then use it....but definitely

verify the pinout and package footprint against the datasheet to be sure

that its right.   ( You could also check on download section of the

cadsoft website to see if there are some libraries there that might have

what you want).

- If you can't find something close then search for the package in an

existing library.   Again use the wildcards in the search term, "SOIC

to find all the SOIC packages.    If you find something with the right

package then copy that package to a custom library of your own.   This

way you have 1/2 the work done and all you need to do is create the

symbol and device.   Again...check to make sure that the package

footprint you found is exactly what the datasheet recommends....if not

you can edit it to agree.

- If neither of the previous steps fails then its time to create your

own part.    This can be daunting the first time or two but after you've

created a few devices it becomes pretty routine and it doesn't take that

long unless your part has lots of pins/pads.   There are some excellent

video tutorials on-line about how to use the library editor.

Have fun w/ Eagle

Jim