I’ll be giving a short presentation for the Squidwrench meeting at /root in New Paltz this evening:
Arduino Survival Guide for Squidwrench – 2012-06-12
The general idea is to mention the things you need to know so you don’t kill your Arduino while fiddling around with the software side of the project.
It’s a rather dense collection of facts & figures and I expect a whole bunch of Q&A activity… which should result in a better Survival Guide the next time around.
#1 by madbodger on 15-June-2012 - 11:52
I assume in the picture of the MOSFET tester, the thin little flying wire-wrap wire is the high-current ground shared with digital ground?
#2 by Ed on 15-June-2012 - 14:27
Got it in one! [grin]
Actually, that’s an “internal layer” wire; I route hand-connected flying leads on the two internal layers (one power, one signal) so I don’t lose forget them. It’s easier to add few jumpers for non-critical signals & low-current supply voltages & suchlike, than to waste a day trying to jam the board into two layers…
#3 by smellsofbikes on 15-June-2012 - 12:12
I dunno if I mentioned this earlier, but when I was building the counts-per-second back end for the Geiger tube, using an Arduino, I found that its analog input pins can handle -600 VDC and survive the experience. Not recommended, but still quite impressive. (They don’t do so hot on +9VDC, though. Or more to the point, they do very, very hot, but not for long.)
#4 by Ed on 15-June-2012 - 14:37
Yeah, but surely that was from some candy-ass supply good for a few mA at most: it’d kill you stone cold dead, but not a well-protected chip!
Actually, tell me true: it was a kilo-amp beam tube brick that you just happened to have lying around, right?
Likewise, a casual swipe of the +12 V external supply across an Arduino doesn’t do it the least bit of good.
Better that than the goof pulled many, many years ago by a guy I was working with, which involved brushing a hot 120 VAC lead across a TTL circuit board with a top-surface Vcc plane. That’s where I first learned just how bad burned tantalum caps smell, plus marveling at how bypass caps cast interesting overlapping shadows in carbonized spatter…
#5 by smellsofbikes on 15-June-2012 - 20:21
A reel of tantalum caps loaded backwards in a pick-and-place makes final test/burn in like the fourth of july.
(why oh why is someone dragging a 120v line across things?)
#6 by Ed on 15-June-2012 - 22:00
He used to design mag-amp gun laying equipment for the Navy, so he hewed +5 V from transformers and diodes in a manly manner …
IIRC, after that incident he developed an unnatural attraction to brick power supplies.
#7 by Aki on 16-June-2012 - 03:31
The smell of gunpowder will be replaced by the odor of ozone…
http://en.wikipedia.org/wiki/Railgun
#8 by Ed on 16-June-2012 - 07:01
For those guns located within a bus-bar distance of a power plant, anyway…
#9 by Aki on 16-June-2012 - 14:18
No Sweat, Dude…
http://en.wikipedia.org/wiki/Olkiluoto_Nuclear_Power_Plant#Unit_4
#10 by hexley ball on 16-June-2012 - 22:05
A little late to the party here, Ed; sorry to weigh in after the presentation has already happened. Two suggestions come to mind:
1. One common theme I have seen with novice users of Arduino-like modules is a need to manipulate analog source voltages to match the chip’s input range. So perhaps a slide showing an op-amp level shifter/gain adjuster would be helpful in the next revision of the slide show.
2. Serial I/O levels also seem to puzzle new users; you might consider pointing out that driving an Arduino input from a +/- 12volt RS-232 device isn’t a good idea. For that matter, driving an RS-232 device with a TTL signal is also frowned on, though it’s less likely to cause damage :-)
#11 by Ed on 17-June-2012 - 14:41
A single-supply op amp shifter with “pick these resistors” info should be do-able for analog input. Negative voltages and wide output ranges, though, get tricky, because then you’re into dual supply op amps and suchlike. Gotta mull that over a bit…
Does anybody use serial any more? It’s all USB these days; the Arduino Leonardo can even look like a mouse / keyboard. Maybe I should just provide a pointer to a serial interfacing guide and leave the details for the interested reader.