Subject:
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Re: lego and steppers
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 17 Jun 1999 21:51:03 GMT
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Viewed:
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1201 times
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Jeffrey Weil <jeffw@shadow.net> wrote:
> I need to know the max speed that a touch sensor can advance the
> counter. I would like to control a stepper motor with the rcx and use a
> touch sensor input to count the steps.
Which counter are you referring to?
If believe that if you are using the standard Lego firmware, e.g. by using
NQC, and you are using the "pulse/edge" counting modes, you can detect an
edge only once every 300 ms or so, which is fairly slow. I'm not 100%
positive on this, though - it is just my interpretation based on an
analysis of the firmware/ROM. I do not use NQC.
One edge every 300 ms means that you can count at most 10 press/release
cycles every 6 seconds.
If you do not use the edge counting modes but implement counting on your
own (by using the boolean mode, not the pulse or edge modes, and polling
the sensor constantly looking for changes in value), then you can sense
changes that happen every 3 ms or so, which means you can count 1000
press/release cycles in 6 seconds, or 166 press/release cycles per second.
If, instead of using NQC, you write native code like e.g LegOS/librcx, and
if additionally you are willing to write some assembly, you can probably
increase the sensor speed to many 1000s of cycles per second, but this is
probably faster than you can physically move the sensor in the first place...
(Along this line of reasoning - that moving the sensor will limit the
practical speed at which you can sample - 166 is pretty fast too.)
-Kekoa
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Message is in Reply To:
 | | lego and steppers
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| I need to know the max speed that a touch sensor can advance the counter. I would like to control a stepper motor with the rcx and use a touch sensor input to count the steps. I am not going to actually use the touch sensor itself, just the sensor (...) (25 years ago, 17-Jun-99, to lugnet.robotics)
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