Re: [CAD_CAM_EDM_DRO] Geckodrive asking for user input

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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