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in article NEBBIHKHBKAFAGKCCILOAEGCCAAA.rmeenaks@olf.com, Ram
Meenakshisundaram at rmeenaks@olf.com wrote on 7/7/00 9:58 AM:
> Hi,
>
> With only 3 input and 3 output ports, the RCX becomes quite limiting after a
> while. There are several different solutions to this at various sites.
> Does anyone know which one is the best out of all of them. I basically
> looking for good functionality and ease of use. Thanks....
I am a Lego purist, so I don't want to modify my pieces. Of course, if Lego
ever creates an official multiplexer, I'll probably get it. On the other
hand, I originally promised myself I wouldn't buy a Mindstorms set until
Lego released it for the Mac, but when RobotBooks put it on sale, well,
let's just say I downloaded MacNQC shortly thereafter. I may be unable to
wait for Lego to release an official multiplexer.
In the meantime, I find ways to "multiplex" mechanically, or I do without.
Clever design can overcome lots of problems.
Example: limit switches. If you have a touch sensor to detect when (say) a
robot leg has reached its limit, you can reverse the motor when you hit the
switch, until the switch opens again. Now you can use that sensor port to
detect when some other part (powered by a different motor) has reached its
limit.
Example: directional transmissions. See
http://www.sonic.net/~rci/transmission.htm for one example. I built a
Scout-based tank using directional transmissions (of my own design -
pictures on my site someday). I could use the Lego remote to make the tank
go forward, turn clockwise, raise and lower the gun, and fire the dart. The
Scout only has two motor outputs.
Example: regular transmissions. Use one motor to "shift" the output of
another motor to several different places. I found a page once with
pictures of several ways to do this - sorry, I can't find it any more. The
robot I'm working on now (and have been for over a year, grr) has a
turntable in the middle that directs power to four different outputs.
Example: use the Lego polarity switches. See
http://prelude.PSY.UMontreal.CA/~cousined/lego/1-Varia/arm-v3/ for one way
to use these things to multiplex. This one is needlessly complicated - I
recall seeing a different one mentioned on LugNet earlier this year. Oh,
here it is. http://www.brickshelf.com/cgi-bin/gallery.cgi?i=2651
And so on.
>
>
> Ram
--
Doug Weathers, http://www.rdrop.com/~dougw
Portland, Oregon, USA
Don't spam me - I know how to use http://www.spamcop.net
"On a clear disk you can seek forever"
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