Subject:
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Re: Why do it? Was: multi-device output controller
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Newsgroups:
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lugnet.robotics
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Date:
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Fri, 26 Mar 1999 23:15:45 GMT
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Original-From:
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Joel Shafer <joel@connect.(saynotospam)net>
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Viewed:
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1167 times
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I think that the solution should also be flexible enough to allow the power
to be plugged into either an RCX output port or a battery pack. That way
if you didn't want to lug around another battery pack, or if you didn't
want to use up another individual output port, no problem, just switch the
plug to the appropriate device.
At 11:05 PM 3/26/99 +0000, you wrote:
> Ralph, Thanks for reigning in the rabbit chase!
>
> As the originator of this thread I'd like to respond to the 'why'...
>
> I keep running out of ports on my creations. I see 5 or 6 as a practical
> limit. My criteria for a
> solution:
>
> 1. Entirely compliant with RCX firmware.
> 2. Clean programmability. My initial idea: control is accomplished by
> setting the power level of a
> port to select which device, and by setting the second port for actual
> device performance (on/off,
> fwd/rev, pwr level). This means it would be usable by the RIS software.
> 3. Reasonable cost (In my mind this means < $50).
> 4. Leave at least 1 port for normal, direct RCX control.
>
> The directions this thread has taken are not attaining this goal. Instead
> of blue-sky ideas about the
> theoretical possibilities I'd like to see possibilities/critisisms towards
> an attainable project. Am I
> way off base on the ability to create a simple circuit that measures various
> PWM to enable a set of
> ports? If this is am expensive undertaking then say so now so more time
> isn't wasted on this topic.
>
> If someone has a simpler idea for attainment of more than 3 outputs then I
> am all ears.
>
> -Wes
>
> Ralph Hempel wrote:
>
> > Lou Sortman wrote:
> >
> > > Thanks for checking this out. This is important to know. I assume, • then, that the duty cycles
> > > are 1/8 through 8/8 as well as off, which would be 0/8. Can anybody • verify this (with a scope or
> > > something)? I have long wondered whether the duty cycles were linear or • followed some nonlinear
> > > curve.
> >
> > I have checked this out, and if you use the standard RCX firmware (or • other firmware
> > that uses the RCX ROM, then you get the waveforms you are talking about at • 125Hz
> > 1/(1ms x 8). You also get polarity information - oh no, I've said too much.
> >
> > > I thought that NQC used the same firmware as the RIS software, and, • therefore drove the ports the
> > > same way. I guess either the documentation is wrong, or the highest or • lowest power level is
> > > missing.
> >
> > Dave Baum, correct me if I am wrong, but I use the internal RCX ROM code to
> > do the motor driving for pbFORTH, and I'm pretty sure NQC does the same • thing.
> >
> > In other words, NQC and RIS use the SAME code to drive the ports.
> >
> > Seems to me that all of this talk about multi-device control assumes:
> >
> > 1. That you REALLY need to do this
> > 2. That the RCX using standard firmware can process information for you
> > 3. That you use non-LEGO software to do the work (legOS,NQC,pbFORTH)
> > 4. That you want to spend a lot of time and money getting it to work
> >
> > With all of the talk about RS232 converters, and PWM decoders, why not buy a
> > single board computer and do everything from your PC?
> >
> > I've been with the group for a couple of years now, and in my early • emergence
> > from the Dark Ages though it would be neat to make a single board computer
> > for LEGO control. Then I thought about it a bit (I'm an embedded systems
> > designer with 15 years exp) and decided it wasn't worth the effort, and • then TLG
> > came out with Mindstorms. I have always maintained that "neat to do" was fun
> > until it became a mishmash of technology that was hard to get working. I had
> > fun doing pbFORTH for the RCX because it did not cost me much except some • time
> > over the holidays. Now I can focus on BUILDING stuff, instead of • fiddling and
> > wishing for things to build.
> >
> > If you still want to do this, go ahead, we'll support you as much as • possible.
> >
> > Cheers,
> >
> > Ralph Hempel - P.Eng
> >
> > --------------------------------------------------------
> > Check out pbFORTH for LEGO Mindstorms at:
> > <http://www.bmts.com/~rhempel/lego/pbFORTH/default.html>
> > --------------------------------------------------------
> > Reply to: rhempel at bmts dot com
> > --------------------------------------------------------
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
Joel Shafer joel@connect.net
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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