Re: Shared Direction pins vs dedicated Direction pins

Mariss,

Remember what happened last time you tried a bit of "vocabulary"
humor?... <G>

Ballendo

P.S. But seriously, is <50,>50 real world acceptable?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis
<mariss92705@y...>" <mariss92705@y...> wrote:

> Ballendo,
>
> No. I try to stay calm.
>
> Mariss
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "ballendo <ballendo@y...>"
> <ballendo@y...> wrote:
> > Mariss,
> >
> > No hysteresis?
> >
> > Ballendo
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis
> > <mariss92705@y...>" <mariss92705@y...> wrote:
> > > Doug,
> > >
> > > I have a circuit worked out that is very simple that shares

step

> > and
> > > direction on a single line. If the duty cycle of the step pulse
> is
> > > less than 50% it's CW, if more than 50% it's CCW.
> > >
> > > CW = 100010001000...
> > > CCW = 11101110111...
> > >
> > > Mariss
> > >
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, Doug Fortune
> <pentam@c...>
> > > wrote:
> > > > re: dedicated Direction & Step pins need 2*N output lines
> > > > vs shared Direction & dedicated Step pins need N+1 output
> lines
> > > > (N is number of axes), thus saving output pins which are
> limited
> > > > in number on a parallel port, and hence often a constraint.
> > > >
> > > > Chris L wrote:
> > > >
> > > > > >>It would appear to be for some type of "single axis at a
> time
> > > positioning"
> > > >
> > > > Doug wrote:
> > > > > >Absolutely not!
> > > > > >This is a general scheme for lathes, mills, routers and
> > hexapods
> > > >
> > > > > Maybe by a "hand cranker".... but, On a CNC mill or
> Router ??
> > > Now I am
> > > > > lost..... Even on my simple 3 axis router, I assure you I

can

> > and
> > > do
> > > > > have more than one motor turning, and in opposite

directions

> at
> > > any
> > > > > given time, even for simple 2d profiles.
> > > >
> > > >
> > > > Hi Chris:
> > > >
> > > > Yup, lots of motors turning simultaneously at different

speeds,

> > > > accelerations and directions, thats how S&D motor drivers

work

> > > > (as you well know!).
> > > >
> > > > Yes, I think you are missing something obvious.... the Step
> > > > signals to the motor drivers are of the order of 1 uS (1
> > millionth
> > > > of a second). Apparent smooth motor motion results from
> emitting
> > > > one of these pulses (say 20,000 times/sec or once every 50
> > > millionths).
> > > >
> > > > In other words, you could have many (50 channels in this
> example)
> > > > sharing a common direction pin, and neither the motors nor

the

> > > human
> > > > would be able to detect any measurable difference. However

the

> > > Geckos
> > > > (much as I like them) have a hold-time constraint on the
> > Direction
> > > line
> > > > which precludes their use in a "shared-direction" scheme.
> > > >
> > > > <more written offline to Chris>....
> > > >
> > > > Doug Fortune
> > > > http://www.cncKITS.com