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In lugnet.robotics.rcx, Steve Hassenplug wrote:
>
> While in theory, this sounds very cool, in pratice, I doubt it
> will work quite that well.
It works very well for me, with the variation that I use home-made
touch sensors that are actually microswitches embedded into 2x2
blocks. That does mean you might need to debounce in software, but
normally I don't bother since the inertia of the mechanicals is such
that a bit of contact bounce doesn't matter.
Everything uses the normal lego wires with 2x2 connectors on teh end.
The multiplexer is a 10x2 piece 2 plates thick, with teh resistors
embedded within it. This means that with the wires attached it's four
plates thick, and therefore neatly fits within the 'standard' 5 plate
vertical grid. I actually used a network of eight resistors in there
to get teh ratios closer to teh ideal 1:2:4:8.
Although it's homebrew, it _looks_ purist in every respect except teh
contact point of the touch sensors, which are obviously microswitches.
Built into something, all parts look like they could be genuine. I
could post photos somewhere if they would be of interest to anyone -
I'm very pleased with the compactness of teh multiplexer.
I have pbforth code that unmultiplexes teh contacts, but tend not to
program in anything else. Shouldn't be hard in anything else
though. Works a treat every time I've used it.
regards, Ian SMith
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> Although it's homebrew, it _looks_ purist in every respect except teh
> contact point of the touch sensors, which are obviously microswitches.
> Built into something, all parts look like they could be genuine. I
> could post photos somewhere if they would be of interest to anyone -
> I'm very pleased with the compactness of teh multiplexer.
>
> I have pbforth code that unmultiplexes teh contacts, but tend not to
> program in anything else. Shouldn't be hard in anything else
> though. Works a treat every time I've used it.
Ian,
Great to see that you are having success with pbForth! I have
a couple of questoins:
1. Which version are you using?
2. Are there any features you REALLY wish were available?
3. Do you have any stories or code to share?
Ralph
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Check out pbFORTH for LEGO Mindstorms at:
<http://www.hempeldesigngroup.com/lego/pbForth>
Buy "Extreme Mindstorms: an Advanced Guide to Lego Mindstorms"
<http://www.amazon.com/exec/obidos/ASIN/1893115844/hempeldesigngrou>
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Reply to: rhempel at bmts dot com
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On Wed, 10 Sep 2003 22:56:24 GMT, Ralph Hempel <rhempel@bmts.com> wrote:
> > I have pbforth code that unmultiplexes teh contacts, but tend not to
> > program in anything else. Shouldn't be hard in anything else
> > though. Works a treat every time I've used it.
(apologies for delay - my server decided to stop talking to lugnet for
some reason, hopefully now fixed)
> Great to see that you are having success with pbForth! I have
> a couple of questoins:
>
> 1. Which version are you using?
Errm, probably 2.1.0 (but I don't have it immediately to hand at the
moment - that's the name of the directory on my computer with teh srec
file of teh firmware I use, however).
> 2. Are there any features you REALLY wish were available?
I did think I'd like something on getting 2 RCXs to talk to each
other, and a few more example scripts, but a peruse of your web site
reveals that these have been addressed even before I asked for them!
> 3. Do you have any stories or code to share?
Not really. The reason I use pbforth is because I'm no good at it!
I earn some of my money programming in (order of favour) perl, C,
visual basic (spit), and have dabbled (also for money) in postscript,
tcl/tk and nearly language things like sed and awk and so on.
On the RCX, I didn't want to use anything I was familiar with (much
rather learn something new - where's teh fun in doing something you
know how to do?), and in my distant past I nearly bought a home
computer which spoke forth (though I can't remember what it was - 80s
sometime). Hence, pbForth seemed ideal.
My learning materials have been a printout of powerpoint 'introduction
to pbforth' which is 31 slides copyright you 1999, a file
'rcxWordlist.html' that I seem to have downloaded in Feb 2002, and a
copy of ANSI X3.215-1994. As such, my code is probably not something
which ought to be inflicted on teh world at large (though it works).
I also tend to dismantle everything I build and lose everything I code
as soon as it's working - I have to document, QA, save, store,
evaluate, optimise, develop etc at work and for fun I'd rather hack it
operational and then start on a new challenge!
My current project is a two RCX, three drive holonomic platform (a
killough) with a 'commander' RCX and an 'engine room' RCX. The idea
is that the commander says something like "drive 1 stationary, drive 2
reverse to rotation x, drive 3 advance to rotation y", and teh engine
room does the motors while monitoring the rotation sensors.
Meanwhile the commander is monitoring some other sensors (probably via
the multiplexer) and might at any moment instruct "all stop" while it
does something else. At present rate of progress, you can look
forward to this sometime in 2007.
So, I'm probably not a great advocate or example of pbforth use.
I'm really glad you wrote it, however
regards, Ian SMith
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