Re: A crazy idea

Steve, Doug,

The second part of your question:

A CW step followed by a CCW step followed by a pause would look like
this:

100011100000000..... STEP/DIR input, also goes to the DIR input
001100111111111..... Q-not of the one-shot
--S---S------------- STEP occurs on the "S"
--0---1------------- DIR state (0=CCW, 1=CW) at the STEP edge "S"

Each "1" or "0" is say, 1 uS of time.

The maximum frequency would be 250kHz (1 / 4uS).

Mariss



--- In CAD_CAM_EDM_DRO@y..., "stephen_stallings" <stevesng@n...>
wrote:

> Hi Mariss,
>
> This sounds a bit like the encoding schemes used
> to record data on magnetic media. All that I am
> aware of have a time sensitive element that
> requires a one-shot or a PLL to recover the data.
>
> Can you describe how you would recover the data
> in the case of one step CW, pause, one step CCW,
> pause, one step CW?
>
> If time is a factor, then the software and the
> motor driver would have to agree and conform
> to a common time scale. This could be troublesome,
> as we already have problems with pulse jitter at
> high step rates.
>
> Regards,
> Steve Stallings
>
>
> --- In CAD_CAM_EDM_DRO@y..., "mariss92705" <mariss92705@y...> wrote:
> > Hi,
> >
> > Parallel port output CNC programs are limited to 3 or 4 axies
> because
> > of the limited number of port bits. Each axis requires a STEP and
> > DIRECTION bit pair. What if it could be done with a single bit

per

> > axis where STEP and DIRECTION were combined on the same line? It
> then
> > would be possible to run 6 to 8 axies.
> >
> > Here's how it could be done:
> >
> > (1) 100000000010000000001000... is CW
> > (2) 011111111101111111110111... is CCW
> >
> > In (1), a narrow positive going pulse would be interpreted as a

CW

> > motion. In (2), a narrow negative going pulse would result in CCW
> > motion at the same speed. One would simply invert (1) to generate
> (2).
> >
> > This scheme would place no additional burden on the software or

on

> > the bandwidth of the now combined STEP/DIRECTION compared to a
> > standard STEP pulse line. Decoding hardware in the drive would be
> > minimal; just a single quad gate package.
> >
> > So, what do you think, a crazy idea?
> >
> > Mariss