Re: [CAD_CAM_EDM_DRO] Re: Black box again

Dave,

Wouldn't it be wise to be able to buffer a few moves? Maybe the handshaking
could provide for a fixed number of moves being buffered. Maybe they could
be numbered, so that if there were an interruption of a move the black box
could inform the control of which move was interrupted etc. I think a
software control could keep track of the last few moves sent out. I would
think the goal of any black box/ software solution designed today should be
to provide smooth transitions between moves as well as a smooth pulse train
based upon changes in slope and feed rate of the move. The command sent over
to the black box could include feed rate, and whether there should be
acceleration and /or deceleration. This may appear to be getting more
complicated, but it seems to me that it should be pretty doable. In my
control software loop, to achieve smooth transitions between moves, I do all
of those considerations then send over the move to a software loop dedicated
to only making the linear interpolation move. It works pretty good, but I
have not yet made the feed rates as accurate as I would like, thus I have
never talked about it much on this forum. Others have mastered that aspect
however.


I intend to use Jon Elsons black box this year, but I think an assortment of
approaches, serial/USB are reasonable, and fun to develop.

Just my 2cents,

Tom Eldredge

----- Original Message -----
From: <dkowalcz@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Thursday, June 28, 2001 8:39 AM
Subject: [CAD_CAM_EDM_DRO] Re: Black box again


> Hi Alan,
>
> Here's the chip I'm helping with:
>
> http://www.public.iastate.edu/~dkowalcz/rt900_1.pdf
>
> And here it is again on a proto-board with connectors, etc.., as it
> might look to the consumer:
>
> http://www.public.iastate.edu/~dkowalcz/900000_1.pdf
>
> It's a "dumb box" type device, based on a PIC16C74, 3 axes and 16
> bits digital I/O. Tentatively named StepEx.
>
> My role on this project is to adjust TurboCNC to be able to drive
> this device as a user option, so right now I'm a little short on the
> fine details. Have a look at http://rutex.com to see what the
> hardware guy is up to.
>
> Haven't got source yet, I should be getting a couple chips in the
> mail any day now to play with on my workbench.
>
> I'm also working on a "smart box" personally, since a chip that
> accepts just a motion command like "MOVE(params)" via COM/USB port
> and lets the computer know when it gets there seems a bit more
> flexible on the software side. But that hasn't gotten much farther
> than just some rudimentary specs and picking up a handful of PICs and
> a "burner".
>
> BTW, thanks Ballendo for explaining "fire and forget" in this
> context...!
>
> Dave Kowalczyk
> Seattle WA
>
> --- In CAD_CAM_EDM_DRO@y..., Alan Marconett KM6VV <KM6VV@a...> wrote:
> > Hi Dave,
> >
> > "fire and forget"? USB's are getting easier to play with on the
> device
> > end, anyhow. The PC side? Well, I'm not anxious to write a special
> > windoz driver! If a std. driver can be used (must need something
> like a
> > printer dump, right?), then that will simplify the task. Then you'd
> > have to write the application in windoz too! I think ActiveWire
> (was
> > mentioned the other day) has some type of driver for DOS.
> >
> > http://www.activewireinc.com/
> >
> > I don't think I'd put all the smarts of a controller down in the USB
> > (8051), probably just generate the pulses.
> >
> > Open source for PIC code to run 3 axis? Can I see? ;>)
> >
> > Timed updates. Yup, there is a USB xfer mode (isochronous) that I
> think
> > does that within the 1ms frames.
> >
> > Talk about re-inventing the wheel. Saw a model of "Ezekiel's
> Wheel" the
> > other night on one of the "robot wars" type of show (I only watch
> for
> > the technology). Also saw a tube with wheels in it at right angles
> used
> > for steering. Clever, but I didn't get a good enough look to
> figure out
> > how it worked. The tube was rotated to steer somehow.
> >
> > Alan KM6VV
> >
> >
> > dkowalcz@i... wrote:
> > >
> > > To list,
> > >
> > > Well, I'm currently co-developing a dumb box with another semi-
> > > commercial hobbyist. It's an open source, PIC based device that
> > > handles 3 axes via serial port. Drawback is that it requires
> more or
> > > less timed updates still, just fewer and farther between. Still
> in
> > > development - I'll let the list know when it's done, if it flies
> that
> > > is.
> > >
> > > I think a good "fire and forget" USB smart controller on one
> chip
> > > is long overdue in this hobby. Commercial ones are around, sure,
> but
> > > they start at about a G-note and typically aren't scalable. So I
> got
> > > some PIC's to engineer one the other month.... That's still
> cooking
> > > too, but *way* on the back burner.
> > >
> > > Dave Kowalczyk
> > > Seattle WA
> > > not a huge fan of wheel re-invention either!
>
>
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