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Subject: 
Re: Weird RCX electrical ideas
Newsgroups: 
lugnet.robotics
Date: 
Mon, 15 Sep 2003 22:12:32 GMT
Viewed: 
934 times
  
I certainly don't see a reason why the whole motor-to-sensor thing wouldn't
work.  Actually, it's really a good idea, I don't know how much has been
done with it before, but it sounds like it could be a great little serial
interface - if programmed in bickOS, I'd imagine it could be a very powerful
serial interface.  Plus, you wouldn't necessarily have to give up the sensor
port, it could function like normal when no data was being sent.

Dan


"Jordan Bradford" <jordan_bradfordREMOVE_THIS_SPAM_THINGY@hotmail.com> wrote
in message news:HKIG7G.1t9L@lugnet.com...
I'd like to share two thoughts with you all. They involve the RCX and • doing
things with it that I'm sure the designers never intended (or thought • possible).

Oh, if you're reading this in the .trains newsgroup, you can skip over the • first
thought because it doesn't involve trains. But the second one does.

1.
--

Last year I was thinking about the fact that the motor outputs send pulses • of
current. So, I was wondering if the {input} ports were polled fast enough • to
sense this. The idea was you could hook up a motor output from one RCX to • an
input port of a second RCX, creating a physical link between them for
communication. This would be advantagous in situations where the two RCXs' • IR
ports can't "see" each other.

I took my RCX to the electronics lab at school and hooked it up to an
oscilloscope. I really wish I had written down what my professor and I • saw, but
the pulses were very fast; I believe they were 20ms each. If that number • is
incorrect, it's due to my failing memory, but I know for sure they were in • the
millisecond range. I also remember that the pulse that's on for 7 ticks • and off
for 1 didn't look much different than the pulse that's on for the full 8 • ticks.
Anyway, I don't think the input ports can sense stuff that fast, so that • was my
first question for you all: How often are the input ports polled?

I wasn't a LUGNET member back then, otherwise I would have asked this • sooner.

Oh yeah, one other thing. I'm not sure how much voltage or current the • inputs
can handle. There might have to be some kind of load in between the two • RCXs. I
was thinking of using a bunch of 9V lights connected in series (that's • actually
hard to do -- try it sometime.)

2.
--

The second idea came to me yesterday as I was reading
<http://news.lugnet.com/org/ca/rtltoronto/?n=7281 this thread>. I wondered • if
instead of building a contraption involving magnets and a light sensor, • could I
instead simply induce current in a wire as a LEGO train and its coupling • magnets
passed above it? That would tell the RCX the train passed that point.

The answer was no. I put the end of a LEGO wire on a baseplate between two • 9V
track ties (in between the rails, too). Then I attached a multimeter to • the
other end. I waved my LEGO magnets over the end in the track, but no • current. I
drove a train car with its magnets over it, and still no current. Hmmmm.

I then put a 2x4 electric plate on top of the wire's end, thinking that a • larger
area would work. Nope, it didn't.

Neither did a 2x8 electric plate.

It's been a long while since I took physics, so I think I need a {coil} of • wire,
not just a wire/electric plate. And a much bigger magnet.

Oh well. Thanks for reading.



Message is in Reply To:
  Weird RCX electrical ideas
 
I'd like to share two thoughts with you all. They involve the RCX and doing things with it that I'm sure the designers never intended (or thought possible). Oh, if you're reading this in the .trains newsgroup, you can skip over the first thought (...) (21 years ago, 1-Sep-03, to lugnet.robotics, lugnet.trains, FTX)

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