Re: 5-axis machine controller

[Jon Elson <jmelson-at-artsci.wustl.edu>]

"D.F.S." wrote:

>  You don't need to look at the code, it outputs either step and
> > direction
> > or stepper phase signals from the parallel port.  There is a table of the bit
> > assignments somewhere on the Linuxcnc web site.
>
> The only pinouts I have been able to find are for the Step & Direction Type.
>
> I need the other one.

Anyone have this?  (It is a new feature, just in the past month, so the doc.
has not caught up, yet.)

> > > I'd like to toggle the bits on the port and drive the stepper coils directly
> > > thru FETs. I figure a 3-to-8 ttl Decoder and 3 latches along with a dozen
> > > Transistors should do it. I have all that stuff close at hand.
> >
> > Well, you really don't need that, as EMC will output the stepper phases
> > directly, as an option.
>
> Where do I find the info how to to do that?
>
> I'd like to look at that particular piece of code that sets the bits, and
> still can't find it.
>
> and... since I'm running 3 axis and 3 steppers with 4 phases Each I'll
> need 12 bits.
> How does it deal with that, without a scheme like I mentioned
> without latches, and 8255 or something?

No, there are really only 2 phases needed for full stepping.  If you want
to do half stepping, then you will want to use step & direction outputs
and a stepper driver chip.  So, you need only 2 bits / axis for step & dir.
or for full-step phase drive.

>
> Now, you guys are doing a great job, and as long as the software does what it
> should I see no reason to upgrade, but the three times I tried to go get all this
> stuff over the last year and a half, I never was able to get the "Complete" set
> of everything.
> Is any of this stuff restricted in any way that would prevent
> setting up a small archive of a complete set to address this?

I believe Red Hat has online archives of all major releases.  Yes, of course,
you don't want to download this through a 56K modem.

Jon