Re: Geckodrive asking for user input

The 3.3V thing with new PCs has been a real headache. Some of our
drives "sort of work" at 3.3V, others flat-out do not. Both working
and non-working drives are being operated completely out of spec.

The typical support exchange for this begins with "I got 3 of your
drives. One works, the other 2 don't. What's wrong with them?". Well,
what's wrong is they are not designed to work with 3.3V signals.

Normally I stick with 100% backwards compatibility with any new
design but this 3.3V/5V thing is a real and growing headache. It's
very tempting to make it all go completely away using option 2.

I don't normally design by poll but I do need to know who if anyone
would be negatively impacted by the proposed change. It's a real
tossup.

Mariss


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Bob Muse" <mtebob1@...>
wrote:

>
> Hi Mariss
>
> Just judging by the debate that comes up every so often with

regards to the confusion generated by having the common terminal tied
to +5 volts, I think I would opt for #2. It would simplify things
for a lot of people. Just my 2 cents.

>
> Bob Muse
> Machine-Tech Engineering
>
>
> ----- Original Message -----
> From: Mariss Freimanis
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Sent: Wednesday, July 05, 2006 8:12 PM
> Subject: [CAD_CAM_EDM_DRO] Geckodrive asking for user input
>
>
> Hi,
>
> I'm cross-posting this everywhere because I need a lot of replies
> fast.
>
> I'm nearly done with a G201/G210/G202/G212 replacement design

called

> the G203 for right now. It is a complete, clean-sheet CPLD based

new

> circuit. Same size and pinout as the G201 drive but a whole lot

of

> new features.
>
> Here's where I need input. The G203 uses 3.3V logic which makes

the

> step/direction opto-solator interface require much lower current.

The

> quandry:
>
> 1) Be 100% backwards compatible with the existing drives. That

means

> supplying +5VDC to the COMMON terminal and require 5VDC
> step/direction signal levels. The G203 would keep an unplug and
> replace compatibility with our current drives.
>
> 2) Change the COMMON terminal spec from +5VDC to GND. The G203
> requires only 2mA max to operate step/direction optos instead of
> 16mA. The G203 has a max step pulse frequency of 350kHz (>10,000

RPM

> on a 1.8-degree motor) without any funny G201 step/direction

timing

> restrictions.
>
> The result is supply step, direction and PC ground to the G203

and it

> will run. It will work now with 3.3V or 5V logic; no level-

shifting

> breakout boards are required, no +5VDC supplies.
>
> Please let me know: Option (1) or option (2). The first 1,000

boards

> must go to the PCB fabrification house Monday.
>
> Mariss
>
>
>
>
>
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