RE: [CAD_CAM_EDM_DRO] Re: Interface. Gauging interest.

Hi Dave,

Yes, I agree, if we're going to go to USB, then might as well kick the
interface up a notch and let a uP handle part of it.

Actually to answer my own question a little, I just remembered I DO have a
USB dongle I bought with my new IBM because I thought I was loosing the
on-board serial and parallel ports. Still in the box, as the computer HAS
them. I might just get it out and play with it, but I'll bet that it just
simulates a PRINTER port, not one that we could really use; as you've said
(wouldn't it be nice if I were WRONG about this!).

> Alan Marconett wrote:
> > There are drivers to make USB look like serial, but I haven't heard of
> one
> > for making them look like a parallel. Are they out there?
>
> There are USB-attached devices that have a parallel port suitable for
> connecting a printer under Windows. However, the Windows drivers for
> them do not map them into IO space like a standard parallel port, so
> they are not suitable for bit-banging in the way that CNC systems use a
> standard parallel port. If someone wanted to write a VxD to connect the
> IO space to the device then it could be used that way, although there is
> still the issue of timing precision. Since its a virtual device writing
> to the IO port with precise timing doesn't guarantee that the pins on
> the output will reflect that timing.
>
> IMO if one is going to the trouble of doing a USB attached device one
> should just go ahead and make it a microcontroller and feed it the
> information it needs to produce precisely timed step/direction signals.
> If necessary backwards compatibility can then be provided by writing a
> device driver that presents the device as a parallel port, but this
> would be a secondary mode of operation. Best performance would be
> provided by using the devices native command language.
>

I fully agree!

> > Dave,
> >
> > CNC dude z (?) has a free USB app and PIC project on their website that
> may
> > be what you need to control 3 axis via USB. (No source code) ;>(
> >

>
> Cool, I'll check it out. I want to make something similar, mostly
> because I like to make stuff :)

I thought I would as well. They have said that they'd change some port
address around if desired. I have the PICDEM FS USB demo board, uses the
18F4550 PIC, should work on it. I also have some DIP parts. With a few
slight differences, it can work on my '452 demo board too, I think.

>
> > I want a simple 4 axis USB PIC interface! Lets talk!
> >
>
> I'm interested in using an Atmel ATMega chip with integrated USB to read
> commands similar (if not identical) to what the G100 reads, and then
> converts those into step/direction commands. Essentially a device that
> can handle 4 axis coordinated moves, but not as smart as the G100. It
> would translate short 4 dimensional vectors into step and direction
> commands.

That could be the better way to go, but I'm trying (until the company I work
for shifts) stay with PICs and the development tools I have ('ole learning
curve).

Perhaps we can ask Mariss if we can also use the G100 commands! I like that
Idea.

Mariss wrote:

"

>Say I'm at X,Y,Z = 0 and I want to trace a 3-D line from there to:
>X = 1000, Y = 2000 and Z = 3000
>
>I would send to the G-Rex:
>x1000y2000z3000<CR>
>
>What if I wanted all 6-axis to start and stop simultaneously, each at
>their new locations?
>
>I would send to the G-Rex:
>x123y456z789a321b654c987<CR> where the numbers are the end points.
>
>How would you write this in g-code?

"

I'd be happy with " x1000y2000z3000<CR>" That's ALMOST GCODE! Add a G1 in
front of it...

Seems to me that " x123y456z789a321b654c987<CR>" would just be
"G1x123y456z789a321b654c987<CR>", am I missing something?

OK, These are PROBABLY in machine steps (?), but that's no big deal.

>
> I've got one other RC motor control project ahead of this one that I
> need to finish, and I need to scrounge up something to read step-dir
> commands (I sold my mill and HCNC board, so I don't have real hardware
> any more). So I'll be doing some experiments in this direction in the
> next couple of weeks.
>
>
> Dave K
>

Funny you should mention R/C motor controller projects, I've ALSO got a 32
channel R/C motor controller project in the queue, behind my current Baby
PCB Router project. Source code is available for the Mega8, I'm (again)
wanting to port it over to a PIC (and USB).

Get a $10 Miccrostep bare board from EAS, add a few parts...

http://www.embeddedtronics.com/

Alan KM6VV