Subject:
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Re: microcontroller
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 1 Jul 1998 02:34:31 GMT
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Original-From:
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David Kott <dakott@STOPSPAMalpha.delta.edu>
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Viewed:
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3395 times
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On Mon, 29 Jun 1998 brian-c@technologist.com wrote:
> -I'd like to say thanks to all the folks who replied
> to my question on the microcontroller speeds.
>
> Here's another general question about them though.
> Should any unused pins be left open or should they
> be grounded?
Eeeeeeeeeeek! Outputs left floating, CMOS inputs taken to ground with a
4.7K resistor... presuming, of course, that a Logic 0 on that input won't
generate adverse effects, e.g. a grounded active low interrupt line
might be a problem. Such inputs should be taken to +5 with a 4.7K
resistor.
Floating CMOS inputs have a tendency to oscillate with the merest whisper
of a voltage.
TTL inputs may be left floating.
Driving an output externally will just heat up your CPU.. or worse.
-d
The box said "Requires Windows 95/NT or better"...
So I got Unix.
Free the Source. Free your Computer... http://www.FreeBSD.org
http://www.NetBSD.org
http://www.OpenBSD.org
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