Subject:
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Re: Gray code vs. Binary
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Newsgroups:
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lugnet.technic
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Date:
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Thu, 20 Oct 2005 23:36:38 GMT
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Viewed:
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3998 times
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In lugnet.technic, Kevin L. Clague wrote:
> In lugnet.technic, Mark Bellis wrote:
> > In lugnet.technic, Kevin L. Clague wrote:
> > > To all those pneumatic gurus.....
> > >
> > > The classic pneumatic timing circuit made with one switch per piston changes
> > > state following gray code (i.e. only one piston changes at a time). This means
> > > that a two piston timer goes through these states:
> > >
> > > 00-10-11-10 vs. a binary sequence of:
> > > 00-01-10-11
> > >
> > > For three pistons we get
> > >
> > > 000-100-110-111-011-001 a sequence length of 6 vs. binary that gets this:
> > > 000-001-010-011-100-101-110-111 a seqeunce of length 8.
> > >
> > > To get a gray code of length 8 takes four pistons:
> > >
> > > 0000-1000-1100-1110-1111-0111-0011-0001
> > >
> > > Has anyone spent time creating a binary sequencer for two or more pistons? I
> > > have not, and could use one if it was cheaper than gray code, either in time or
> > > in parts.
> > >
> > > Kevin
> >
> > Hi Kev,
> >
> > I think the cheapest way to do 3 or 4-bit binary with pneumatics would be to use
> > gray code and convert it. Gray code always changes the least significant bit
> > possible in order to achieve a change to a new state, so there will always be
> > 2^n states, just like binary.
>
> Hi Mark,
>
> You are right. I've had the wrong term in my head all this time. Gray code
> is not what I was thinking about I guess...... I'll have to go study Gray code
> better, and then study your descriptions. Man I wish you had a scanner and
> could share drawings.
>
> I hate perceiving circuits through netlists :^)
>
> I'm going to see if I can make my problem work with Gray and skip the binary
> part. I was looking for a mechanism of using three piston to get 8 states,
> instead of six. Interesting ponderance.
>
> Thanks!
>
> Kev
Haha! I've found a better way to do it, and a better drawing :-)
Take my Pick and Place robot circuit:
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1106191
Cut out the Elbow pistons and switch and connect the Elbow piston inputs to the
Wrist piston instead (effectively draw the horozontal lines top right across the
top). Cut out the small grab pistons too and you should have exactly what you
want, a circuit with 3 variables, 8 states and gray code, where the arm
extension is the least significant bit because it changes twice as often as the
other two).
This has 4 pistons (need 2 to drive 5 switches in one bank) and 8 switches. The
small piston on the right is a compressor.
Mark
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Message is in Reply To:
 | | Re: Gray code vs. Binary
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| (...) Hi Mark, You are right. I've had the wrong term in my head all this time. Gray code is not what I was thinking about I guess...... I'll have to go study Gray code better, and then study your descriptions. Man I wish you had a scanner and could (...) (19 years ago, 20-Oct-05, to lugnet.technic)
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