Re: [CAD_CAM_EDM_DRO] DeskNC Windows version

Hi Larry,

It's not the stepper DRIVER we're trying to do (we LOVE Geckos), it's
the controller, with it's ability to generate step/direction for
MULTIPLE motors, in INTERPOLATED moves! Once you need to create varying
ratios of pulses for multiple axis (circular and helical interpolation),
on top of acceleration and deceleration, it gets a little more
complicated!

Microstepping? just think of outputting sin/cos "microsteps", where the
two phase analog signals follow the sin/cos curves to drive the motor
coils (OK, something like that)! Yeah, I can do that... (that wasn't
me). ;>)

Alan KM6VV
(We want GECKO, not Geico!)


Larry Edington wrote:

>
> It is rather trivial to build a stepper motor controller. Any PIC or other
> good microcontroller can become a stepper controller with the addition of
> just a little software. Somewhere I've got the code in C for one I did about
> 3 years ago to run an embedded printer motor with a PIC16C77. It would need
> current limiting added to it and microstepping if you wanted to do that.
>
> It wouldn't be very difficult to add ramping to the micro either.
>
> Microstepping, I have no idea how to do. But if someone would explain it, I
> could code it <g>.
>
> But then comes the question of why. With the price of Gecko drives, it's
> really not worth the trouble to build your own drivers.
>
> later,
> Larry E.
>
> ----- Original Message -----
> From: "Carol & Jerry Jankura" <jerry.jankura@...>
> To: <CAD_CAM_EDM_DRO@yahoogroups.com>
> Sent: Wednesday, April 18, 2001 7:01 PM
> Subject: RE: [CAD_CAM_EDM_DRO] DeskNC Windows version
>
> > Has anyone looked into some of the stepper motor controller chips that
> used
> > to be available. It's been several years now, but I've used a Cybernetics
> > Microsystems chip that was a self contained stepper controller. You simply
> > added the driver transistors. That was at least 10-15 years ago, so I'd
> bet
> > that there are better chips out there today. It shouldn't be all that
> > difficult to put a few of these on a board to drive your steppers.
> >
> > -- Carol & Jerry Jankura
> > Strongsville, Ohio
> > So many toys, so little time
> >
> >
> >
> > -----Original Message-----
> > From: Larry Edington [mailto:ledington@...]
> > Sent: Wednesday, April 18, 2001 7:13 PM
> > To: CAD_CAM_EDM_DRO@yahoogroups.com
> > Subject: Re: [CAD_CAM_EDM_DRO] DeskNC Windows version
> >
> >
> > High speed I/O on the parallel port under Windows is not impossible. But
> it
> > is difficult to do a lot of calculations, timing and pump the data out
> under
> > Windows. The parallel port is just 3, 8 bit ports. You have hundreds of
> > other 8 bit ports in your PC screaming along at very high speeds under
> > Windows software control all the time.
> >
> > The best way I know of to do this in Windows is by using a .vxd ( or wdm
> or
> > whatever it'll be called in the next versions of Windows ). The
> application
> > program reads the G codes and calculates the step commands. These commands
> > are handed off to the .vxd which runs at Ring 0 and has access to all
> ports
> > of the system without the usual restrictions of Windows. The .vxd handles
> > the timing and step / dir outputs.