RE fpga black boxes

> I am basically just a lurker that has been following this thread. I have
> NO CNC experience whatsoever. So maybe this comment is totally off the
> wall, but ...
>
> What about using FPGAs as a compromise between dedicated fast but
> inflexible HW and flexible but slow SW?

Dennis,

That is an excellent idea, and one that several of us have been
thinking about on and off the list for a while. FPGA's are "field
programmable gate arrays" which is to say chips that can be configured
in the field to support various logic functions. That means it should
be possible to 'download' a new hardware design to ones 'black box'
from the host PC.

The only problem I see in all of this right now is that the tools to
'compile' the design and target it to a particular chip tend to be
proprietary and often quite expensive (Although sometimes
complexity-limited versions are free or inexpensive). So while
someone who has the tools can make the updates to the resulting
configuration file freely available for download to go along with an
open source control program, the community as a whole is not very free
to make their own modifications to the control box.

I'd like to see a "gfpga" tool for building fpga designs to go along
with the "gcc" compiler used to build things like linux and EMC. Alas
creating such a tool would be a very, very big software project - and
may require details about how the chips work which their makers are
not willing to release.

I know that only a few of the people here have actually modified
programs like EMC, but the same thing could be said about modifying
machine tools - those who do it are a small minority of those who use
them. Its nice to have the option of learning to do it, or making
friends with someone who knows how.

Chris

-------------------------------------------------
Christopher C. Stratton
Engineer, Instrument Maker, and Horn Player
ccs@... 617 628 1062
http://web.mit.edu/~stratton/www/brassbuild.html