RE: [CAD_CAM_EDM_DRO] step dir inputs on Gecko Bridgeport saga

But, unless he switches it to ground, the optocoupler will never light(+5V
is the "common")

Andy

-----Original Message-----
From: Jon Elson
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: 9/7/2004 1:10 AM
Subject: Re: [CAD_CAM_EDM_DRO] step dir inputs on Gecko Bridgeport saga

JanRwl@... wrote:

>In a message dated 9/6/2004 8:07:29 PM Central Standard Time,
>mail@... writes:
>Any suggestions?
>Yes. The "logic level" must go "hard" to ground. Just opening the +5

VDC

>source doesn't do it, as the "internal stuff" in the IC where the gate

involved

>connects will often "pull up" the input line (though not ideally).
>
>Suggest you connect the +5 to this DIR input via a 1K resistor, and

then that

>same point to GND via the switch. The switch, then, will make this a

"hard

>LOW" when closed, and a "pulled-up +ve" when open.
>
>

No, not needed with the Gecko drives. They have optocouplers of the
2531 variety
that require about 15 mA to turn on. So, opening the connection will
guarantee
the LED is off. What you say is totally correct for a logic gate,
especially a
CMOS gate, which can stay charged for days.

Jon



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