[CAD_CAM_EDM_DRO] Programmable deviced (was: Setup for stepping on revolution counter)

I think is on-topic, because it relates directly to building hardware to
control machines.

Sometimes, what is needed to solve a motion control problem isn't a
microprocessor, but rather some counters and gates. Also the answers to
some problems are more easily stated as logic gates than as computer code.

For those solutions which benefit from direct logic solutions, you might
consider using a programmable logic device (PLD) rather than a
microprocessor. Although several vendors offer appropriate parts, I have
found that Atmel offers several parts are quite nice, as well as the
support structure needed to use them.

Atmel gives you a compiler that translates from a flip-flop and gate
description language to the final fuse maps. The compiler does a good job
of packing logic into the FPGA.

The compiler is free, and includes a simple (but useful) simulator.

The simulator lets you check the logic before you put in into a part. Of
course, the parts are reprogrammable, so if the logic isn't right, you can
try again.

The Atmel parts are programmed (as well as erased and reprogrammed) through
a simple 5 volt-only interface. I program them through a parallel
port. Source code for the programmer is available -- I had to port it to
Linux, which turned out to be very simple.

The FPGAs come in several packages, with quite a variety of complexity
levels. The RS232 interfaced motor drivers I've built use the Atmel for
the UART (send and receive), as well as decoding, clock generation, and
protocol functions. If you're curious,
see
http://www.foxkid.net/cgi-bin/notebookpage.pl?pdp=/home/httpd/html/&name=/cmm/platform/fb-15.page&imagedir=/Processed/Carl%27s%20Projects
for details about the motor drivers.

Atmel FPGAs are available from DigiKey, so getting them is easy.

-- Carl