Re: [CAD_CAM_EDM_DRO] Re: Lost Steps => time for microprocessors!

Ron Ginger wrote:

> Ah well, we dont disagree that a dedicated box of electronics should
> do
> the hard real time stuff. If its a microprocessor or a gate array, the
>
> effect is a special box of hardware.
>
> I assume your box needs to be told how many steps to move, and how
> fast
> to make them. How do you handle the acceleration, let the PC program
> it
> in a series of short moves until it reaches speed?

No, it is essentially only told velocity and direction (and an on/off
bit, too.)
That is all it needs. The decoupling of the velocity output from the
computer
needs a position counter to be added, but I am already working on that.

> If your box has a nice clean interfce so I can poke values to it by a
> simple driver, or even the BASIC equivalents of PEEK and POKE, then it
>
> shuold satisfy my needs jsut fine.

Well, you could generally do that. It will use the EPP signals on the
parallel
port. There would be 3 addresses per counter x 4 channels, so that
would
come out to be 12 bytes to load. Those could be sent with a burst of
DataStrobes in less than 24 uS using the EPP protocol. I've done
stuff like this for the quad DAC board, it is just a couple of lines of
code
in Turbo Pascal (my language of choice for this sort of stuff).
Of course, I'll be writing a driver (real time module) for EMC under
RT-Linux.

> I am very anxious to hear the specs of your box and know when it will
> be
> real.

I have to build and test the encoder counter board, next. The DAC is
done, and
the biggest hurdle was getting the fast EPP transfer modes to work, by
far.
But, now I know how to do that! The emcoder counter is a pretty complex

device, about 4 pages of VERY tight schematics on one chip. It will
probably need a little tinkering to get it to run just right. Anyway,
the
program for the FPGA is written and compiled, and the board is etched
and drilled.
So, it will take a couple of weeks to get it fully operational. Then, I
have taken
on a project to make the 'wonderboard', a parallel-port opto-isolated
input and
power output board. That will take a couple of weeks. Then, I can
look into the timing generator. Since I'm going to have boards made for
the
encoder counter, I can probably hack one of those to convert it to a
timing generator prototype board. (Actually, it might be possible to
just
put a different program in the chip, leave out the differential
converters
and use the board as is!)

Jon