Re: joystick control two axis stage (More)

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ibewgypsie"
<ibewgypsie@h...> wrote:

> Looks pretty indepth. A Basic stamp using the "pot" command, calling
> the step pulses "Low" and setting direction pins on Gecko drives.

I'd

> of course use tried and proven drives like geckos if you are
> unfamiliar "start with a proven product".
>
> Pretty simple stuff. One chip replaces a whole breadboard of them.
> Software is the hard part. I too have thought of this to replace the
> Joystick program I have for Windows 98. Then I would not have to

boot

> the computer on the cnc. You are welcome to a copy of that program,
> that with computer, a hex inverter to change positive logic on the
> parallel port to negative logic and you'd be set to hook up Geckos.
>
> I have a board I have put together, predrilled for geckos wired with
> hex inverter chip, and opto-22. I can send you a drawing if you

like.

>
> My cnc machine runs with 8 amp Larken drives. Ran for a year with

geckos.

>
> My cnc program to drill backplane, would that be a help to others to
> post it here?
>
> David
>
>
>Interesting. How do you develop the direction off the pot to the

AtoD section of the micro? One other thing is you need a "dead zone"
in the middle of the control. A point below where you get zero pulses
so the unit doesn't creep on you. You cannot depend on the joystick
to be precisely centered. The pulse range needs to be in the range
of a 1000:1 for it to be usable and you need to provide for ramp up
and down,or the steppers will never reach close to their upper RPM.
Like you say the devil is in the programming.

If I were going to be the circuit commercially I would consider the
PIC or STAMP (maybe even 68HCXX series) but for one, the time to
right, troubleshoot and build an embedded micro solution cancels any
advantage in parts count and board size.