I've put together an "interesting" shell script recently to aid in
visualizing the changes that you've made in a board (or schematic)
based on the backup files that EAGLE automatically makes as you
save new versions of your design...
More info here:
http://www.instructables.com/id/Visualizing-EAGLE-Edits-with-a-Gerber-Viewer/
Let me know if you have thoughts or suggestions for improvements.
BillW
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Intro -
The EAGLE Schematic/PCB editor keeps up to 10 backups of your board and
schematics, reflecting the board start at the last times you saved you
work. This can be very valuable if you screw something up, but I've
always been a bit frustrated that it isn't easier to look at those files
to see what changed in which revision. (EAGLE won't directly open the
backup files, so you have to rename each backup before you can look at
it. And EAGLE won't open multiple files at one time, so that you can
compare them side-by-side, either.)
Now, one way to look at a PCB is to generate gerbers (the standard
"plotter format" for PCBs), and use one of the gerber viewers to look at
those. This has the advantage of simplifying the "picture", AND most
gerber viewers will load up multiple layers of a PCB so that you can see
them all together. I realized that it would also let you display
multiple copies of the same layer, so that you could "flip" through them
and (hopefully) notice changes. In fact, the gerber viewer I use
(gerbv, an open-source utility that runs on Windows, Macs, and Linuxes),
has a display mode where the layer are displayed with their colors XORed
together. (In theory, this is an option to allow you to look at
multiple layers at once, although in reality how well it works depends
on the actual bit patterns of the colors used for each layer.)
However, if you DO pick your layer colors carefully, you can display two
(or more) layers that are almost the same, and have the differences
HIGHLIGHTED for you! This seemed close to ideal for visualizing the
changes in a PCB design. Well, for small changes, anyway. We'll have
to see how the community feels about its usefulness.
All it needed was some sort of script that would go through all the
backup files, generate appropriate gerber files, and then load up the
gerber viewer having given each file an appropriate set of color, color
mixing mode, and other display parameters. It seems to be somewhat useful.
