Eagle trace length balancing

[Zangetsu57]

Hello everyone,

I'm working on a design in eagle that requires the trace lengths to be equal for several outputs. Is there a function that can automatically calculate the trace length? The method I've been using is the info command, then adding all of the individual lengths, but this doesn't account for overlapping on the edges of the trace segments, so it is inaccurate.

Any ideas? Thank you for any help!

 

[spiffed]

In the default Eagle 5.x install (maybe 4.x too?) is a ULP called "length.ulp" which calculates the length of select nets and can save .csv files for better analysis. It may however just add up their combined lengths.

There's also "length-freq-ri.ulp"

 

[Zangetsu57]

Thanks for the information!

I'm still relatively new to Eagle, and am not exactly sure how to utilize .ulp files. I'm at the point where I've fabricated boards using Gerber files on a LPKF milling machine (doing manual routing). I've also added my own parts to libraries.

Could you please explain how I would go about doing this?

Thank you,

Paul

 

[wanton789]

I'm still relatively new to Eagle, and am not exactly sure how to utilize .ulp files.
Could you please explain how I would go about doing this?

You just go to File... Run (all the way at the bottom)

You cannot do this from the main menu, only from a Schematic window or Board Layout window.

 

[FvM]

but this doesn't account for overlapping on the edges of the trace segments, so it is inaccurate.

You can assume, that most CAD tools, even high end autorouters are measuring the center line length of a trace when calculating electrical length. This seems reasonable from a geometrical viewpoint. If you are targetting to signal delay (you didn't tell), most of the inaccuracy will be caused the transmision line effects of sharp bends, so you'll primarly want to go for round edges, although they further complicate length calculation.