Re: motion control chips

> From: "Elliot Burke" <elliot@...>
> Subject: motion control chips
>
> Forgive me if this has already been mentioned. There has been a little talk
> about motion control boards, conparing the low priced spread with Galil
> boards. Well, while browsing the HP optoelectronic catalog (really, I don't
> have much time to waste), I came across the HCTL-1100 General Purpose Motion
> Control IC.
> It has lots of features, is intended to control stepper , DC, or DC
> brushless motors, has encoder inputs. It does all the motion control
> calculations, and can be synchronized with other HCTL-1100's.
> It has a 24 bit counter, which beats most of the decoders I've looked at.
>
> This may be the right chip for a motion control board.
>
> Has anyone looked at this part?

There are a number of companies producing such chips, with PMD ( Performance
Motion Devices ) being perhaps the leader in this field. They are all close
to magic devices, methinks, IF A PERSON DOES NOT HAVE A MODERN PC.

The real tipoff here is in the HP datasheets, where interfacing to small
8-bit uControllers is documented. These parts are designed for factory
floor use, and other similar single-purpose devices, wherein a task is
programmed into the uC and sent to run.

If we wish to use such a device as part of a CNC setup, we would still
need some hardware and software to read our CNC files. The best choice
for such hardware is a PC running some OS, so even if we chose to use these
devices, we would still need a PC. And since we already have a PC, if only
to read the files, we may as well get the PC to generate the step pulses as
well.

Remember, these chips only replace a small part of the CNC program, the part
that takes a direction/velocity instruction and produces step pulses. The
only hardware they replace is a parallel port and one channel of a DRO board.
( i.e., 1/4 of Tom's design/Dan's board ), while requiring a PCB of their
own.

At $45.00/chip ( Newark's price ) with one chip driving one motor only, this
starts to get pricy, just to replace a bit of code .. code that HAS been
written .. while requiring more code that HASN'T.

Now, if we were still all using 8088 based XTs, these chips would look pretty
good. Since Pentiums are almost free, they're not as pretty .

Alan

--

Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta