Re: digitizer debouncing

Roman,

I have to disagree here. 555 timers are lousy anyway, there are better
"timer" parts. What may be needed is a schmitt trigger, something like
the old 74LS14 I've mentioned before. No caps across the contacts. Run
5-20 ma. (1K pull-up) through the contacts.

The real "debounce" is in the software! If you sample the line
periodically (between steps), and take action on the 1ST one (and only
the 1ST one), you have all the debounce you need.

Did it this last weekend. No GATES/TIMERS! Last night I got the
position latched, and decelerated afterwards to a stop. Did this
repeatedly, with good results. Which raises a question. How much OVER
TRAVEL do we have with the Renishaw "model" we are building? My little
micro switch got a little "up tight" with a longer deceleration!

Alan KM6VV

Roman Black wrote:

>
> --- In CAD_CAM_EDM_DRO@egroups.com, Jon Anderson <janders@n...> wrote:
> > ballendo@y... wrote:
> >
> > > I know what i'm about to say is 'arthroscopic' as well, but
> debounce
> > > in s/w is easy and effective.
> >
> > Not for a non-programmer. For me, it would be a decent project to
> write
> > a probing routine in Ahha's macro language. If Alan goes through
> with
> > his software, that would be a good place to do it. For me, it's
> gotta be
> > a simple and easy bench project.
> >
> > Jon
>
> I would suggest some type of electrical debouncing,
> like the 555 timer chip i mentioned. It only costs
> a few cents for the extra parts.
>
> A mechanical switch this sensitive will jitter
> and create micro arcing, and should NOT be
> coupled straight into a logic input. It's not
> a proper high-speed silver contact switch,
> remember?
>
> At the very least it will need a cap or something
> across the contacts, but that can encourage
> arcing in some instances. Simple electrical
> de-bounce, then put it into your parallel port
> or other logic input. When you are going to
> a number of hours on the mech construction why
> not do the job properly and make a nice
> reliable product? :o)
> -Roman
>
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