Re: A crazy idea

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