From owner-freebsd-hackers Tue Jan 30 13:49:52 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.3/8.7.3) id NAA02848 for hackers-outgoing; Tue, 30 Jan 1996 13:49:52 -0800 (PST) Received: from phaeton.artisoft.com (phaeton.Artisoft.COM [198.17.250.211]) by freefall.freebsd.org (8.7.3/8.7.3) with SMTP id NAA02822 for ; Tue, 30 Jan 1996 13:49:42 -0800 (PST) Received: (from terry@localhost) by phaeton.artisoft.com (8.6.11/8.6.9) id OAA07490; Tue, 30 Jan 1996 14:43:47 -0700 From: Terry Lambert Message-Id: <199601302143.OAA07490@phaeton.artisoft.com> Subject: Re: Watchdog timers (was: Re: Multi-Port Async Cards) To: jgreco@brasil.moneng.mei.com (Joe Greco) Date: Tue, 30 Jan 1996 14:43:47 -0700 (MST) Cc: terry@lambert.org, msmith@atrad.adelaide.edu.au, hsu@clinet.fi, hm@altona.hamburg.com, freebsd-hackers@freebsd.org, brian@MediaCity.com In-Reply-To: <199601301914.NAA05659@brasil.moneng.mei.com> from "Joe Greco" at Jan 30, 96 01:14:38 pm X-Mailer: ELM [version 2.4 PL24] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org Precedence: bulk > I was thinking about tackling the problem myself by putting an 8751-class > microcontroller on a PC card and writing a quick'n'stupid bit of timer code > for the 8751 that would do all the dirty work (mainly because I would hate > trying to wire all the digital logic for a traditional watchdog counter, > and I'm not familiar with any of the Maxim-type monolithic watchdog chips). > I don't have PC board facilities available to me and the prototyping cards > are expensive$$$$$. Go down to Radio shack and buy a copper dot-pad prototype board; they are about $10. Then solder a ribbon connector on it, and run a ribbon cable off to a bread board. Put optoisolators on the breadboard before connecting anything else. Alternately, if you can afford 2 prototype boards, put the isolators on the prototype board and save yourself some breadboard space. Run the chips off the local (not the bus) supply. Drop your motherboard clock frequency to 8MHz on your test box so you don't screw yourself from going over the ribbon cable at too high a frequency. Voila, prototype card heaven. In case anyone gets confused about my EE/Programmer comments from the above, I don't claim to be an EE, I claim to be a solid state physicist. So it's OK for me to use a soldering iron, since I still burn my fingers occasionally. 8-). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers.