In my professional life, I sometimes need to create timing diagrams for protocols: UART, SPI, etc. However, I can't find any good programs available. What programs can be recommended for this and what is the experience using them?
Electronic – Software to create timing diagrams
communicationdrawingspitiminguart
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I was suspecting that maybe I was activating the SPI mode automatically, so I've putted the SPI associated pins at a state that will shut it down for this device (CS high, everything else low).
The problem was, indeed, the SPI module being activated, but not by the microcontroller's doings, but by some noise that was being generated in this. Sorry about asking a question with such a dumb mistake in hands. Thanks for all the comments.
To make this question (and answer) more useful, I can answer to @mng comment: it is possible to use SPI with the RN-171 module, but there is no documentation in their site yet. If you ask their engineers, they will send you some docs for you to use it, but you are not allowed to redistribute them.
I've had the same problem in the past. It looks like there is no public spec available. Instead Motorola (SPI's originator) had timing diagrams in datasheets for controllers supporting SPI. For instance the 68HC11 datasheet has SPI timing information in section 10.17, on page 171. General SPI description on page 119 ff.
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"The SPI bus is broadly accepted because it has little or no patent issues. This is partly because Motorola, its creator, provides no specification or central support. Those applying SPI can create hardware and software solutions without patent issues, but also without support or definition of supporting protocols." (source)
Best Answer
A quick web search turns up Drawtiming. Never used it, but it looks like it would work very well for brief examples of a few dozen clock cycles.
If you want to do your drawings in an Office-like toolset, try OpenOffice.org, specifically the Draw program. If you want to generate the best graphics (And don't mind if it takes a while), try Inkscape as suggested by digikata. Professional datasheets will probably be best served by the tikz-timing package an as suggested by jluciani, or the older (but less complex) timing.sty, both with (La)TeX (Try Lyx for a shorter learning curve, if you're new to TeX. Be warned that it's a steep curve no matter what, but it's worth it!)
You could also try simulating in GTKWave (or any other circuit simulator with a logic analyzer):
(source: bec-systems.com)
but that's oriented more towards simulation of Verilog/VHDL/schematics, rather than just drawing waveforms.