From dakott@alpha.delta.edu Wed Jul 1 05:33:51 1998 Received: from aleve.media.mit.edu by hub.media.mit.edu; (5.65v3.2/1.1/06Jun95-8.2MPM) id AA20653; Wed, 1 Jul 1998 05:33:51 -0400 Received: from alpha.delta.edu (alpha.delta.edu [161.133.129.3]) by aleve.media.mit.edu (8.8.7/ML970927) with SMTP id EAA12514 for ; Wed, 1 Jul 1998 04:41:22 -0400 (EDT) Received: from pm295-18.dialip.mich.net by alpha.delta.edu; (5.65v3.0/1.1.8.2/06Jan97-0932AM) id AA31111; Wed, 1 Jul 1998 04:44:45 -0400 Received: from kott.my.domain (dakott@kott.my.domain [192.168.0.1]) by kott.my.domain (8.8.8/8.8.5) with SMTP id WAA20239; Tue, 30 Jun 1998 22:34:32 -0400 (EDT) Date: Tue, 30 Jun 1998 22:34:31 -0400 (EDT) From: David Kott Sender: dakott@kott.my.domain To: brian-c@technologist.com Cc: handyboard@media.mit.edu Subject: Re: microcontroller In-Reply-To: <199806291430.KAA07909@web01.globecomm.net> Message-Id: Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII 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