timing diagram software

Look at the combination of latex + tikz-timing:

This will give you publishable-quality results with almost no effort. And learning this tools is an investment that pays back quickly -not what you get when trying to learn other tools...

Pere

That doesn't appear to be able to draw "cause+effect" arrows between signals. Am I missing something?

Step 8 of:

I can't help with details as I haven't used it extensively, but I found a complex diagram showing cause+effect arrows here

Also have a look at page 14 in the documentation of the package

[The relevant points to be used seem to be "Timing Shape Anchors" (page 4 of the pdf)]

Pere

You write something like

CLK25=tick. CLK25 -20ns> CLK25=tick.

and it spits out a .png with two periods of a square wave, annotated with timing.

I use wavedrom.com

I find it simple and powerful enough. I also use pen and paper but I suspect that it's not what are you looking for.

That looks like a keeper! Thanks!