Re: [CAD_CAM_EDM_DRO] Geckodrive asking for user input

My vote is for making the common terminal common signal ground. While I really like the option of having it be a drop in replacement using +5 common,option 2 eliminates the need for the seperate +5 supply from the pc using the gameport, usb, or floppy drive connectors and eliminates the seperate cable that provides the +5.
Additionally, the G203s could be used with existing G201's with the simple elimination of the +5 connection and adding the signal ground connection.
Mariss, let me know when you have some of the new drivers in stock. I would like to buy some.
Dan Mauch
low cost stepper and servo motors.
cases for Gecko drives
kits and assembled 3-4 axis drives
www.camtronics-cnc.com
www.seanet.com/~dmauch

----- 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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