Re: Interface. Gauging interest.

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Codesuidae <codesuidae@...> wrote:

>
> Mariss Freimanis wrote:
> > Why the persistent mindset that step pulses be sent
> > over the serial interface be it USB or ethernet?
> > That's like trying to use a hammer as a screwdriver.
> >
> > The other end of the cable has to have a box.
>
> I agree with this, to some extent. While it's possible to
> do it without the box to clean up the step pulses the
> resulting performance is less than what is possible with
> a little more effort and not much more cost.
>
> However, I don't have any issue with the PC doing the work
> of generating step pulse timing information, packaging that
> and shipping it off to a piece of hardware that can do the
> work of turning the pre-calculated timing information into
> precisely timed pulses. This keeps all of the details of
> figuring out stepping and timing in the big, fast hardware,
> uses the high-bandwidth data channels that are available
> (usb, ethernet) and relies on the microcontroller only as
> a precision timer of pulses.
>
> This approach keeps the hardware to an absolute minimum and
> allows maximum flexibility and control for the software on
> the PC.

Dave:

What you describe is exactly the way I designed my Axis4
controller board. The Axis4 board can drive up to 4 bipolar
stepper motors in 1/8 step microstepping mode (2A per coil.)
It also has a dedicated microcontroller and memory buffer
for buffering up pulse timing information. Here's a URL
for the Axis4:

<http://gramlich.net/projects/cnc/axis4/rev_a/index.html>

The software that does all of the step pulse timing is
run on the PC. Again, here's the URL for the software:

<http://gramlich.net/projects/steps/index.html>

The system runs just fine off of my laptop using a
USB to RS232 serial converter.

While there are still a number of software and firmware
enhancements in the queue, I am able to successfully and
reliably make parts using the technology.

I'm unlikely to win the IPM rapid bragging rights that
many people on this list seems are fixated on, but in
terms of running a table top mill and getting the job
done, it works just fine off of a standard USB port.

-Wayne