Re: [CAD_CAM_EDM_DRO] NAMES and EMC

alex wrote:

>SWMBO - yes, exactly, I have to put forward a strong case on why I have
>to substitute Saturday's/Sunday's: "walk in the
>park, bike ride, helping at home..." for a "meaningless" trip to Detroit
>and back.
>Jon, can you please explain, what exact command do I write into parport,
>connected to the USC , to move, say,
>X axis at a certain speed for a certain distance.
>

You don't put position limits on it. It acts as a velocity servo
system. The
computer reads position, computes, and outputs velocity. So, the program
has to do all the acceleration and distance calculations, and decide when to
begin ramping the speed back down.

> Can I do it in Basic
>or C?
>

Sure, but a real time environment with timer interrupts at 1000 Hz or so
would
be the best way to go. Actually, the USC has an interval timer that can
send
interrupts through the parallel port at 1, 2.5, 5 or 10 KHz (and other
rates, too).

>I browsed your web site but had a
>hard time getting a relevant info.
>

See http://jelinux.pico-systems.com/univstep.html at the bottom of the page
click on register definitions. Also, you can see the drivers that I
wrote for
EMC at SourceForge, see http://sourceforge.net/projects/emc then click on
CVS, then "browse CVS tree", then click on emc/, then click on src/, then
click on emcmot/ and you will see a directory of all the motion interface
drivers. The most important for the USC board are ppmc_encoder.c,
ppmc_rate.c, ppmc_dio.c, ppmc_internal.c, and ppmc.h
These files are used to control more than one type of interface, so the
symbol UNIV_STEP should be defined to select all the right code and
consants.

> Also sending/getting some I/Os. Do
>you have a Yahoo group for USC?
>
>

This gets more complex. All reasonably current PC motherboards support
the IEEE-1284 protocol in hardware, if the parallel port is set up for EPP
mode. There are additional I/O ports added to the basic parallel port set
to activate these functions, which perform handshaked data transfers to
up to 256 individually addressed I/O device registers through one single
I/O instruction. ppmc_internal.c has a bunch of C functions to perform
simple transfers, such as to read the contents of a register or write to
a specific register. I have an address counter in the USC, so if you
select an
address and then write 4 times, you have written to 4 consecutive addresses.

No, I don't have a Yahoo group for the USC or PPMC products. Maybe
it is getting to be time for my own group, though. Especially when I
bring out the universal PWM controller and PWM servo amps, this may
be necessary.

Jon