Subject:
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68HC11's inputs
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Wed, 27 Aug 1997 00:03:10 GMT
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Original-From:
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Randy Sargent <rsargent@newtonlabs.com+spamcake+>
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Viewed:
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1250 times
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John,
Thanks for the excerpt. Ouch.
On first read, it looked like the 6811's input pin was beefier than I had
originally thought. On my second reading, I realized that my hack probably
is in fact outside the specs for the chip, so if you're trying my hack, be
sure that you're hooking up to a Handyboard digital input to the 74HC244,
rather than one of the digital inputs that connects directly to a 6811
timer pin.
The excerpt John provided stated both that 1) the 6811 protection circuitry
didn't tend to conduct until 20v (!), and 2) that the 6811 input gates
aren't designed to withstand over 7v for significant periods of time. The
protection circuitry seems to be quite beefy for dealing with transients,
but can't be co-opted to truncate your everyday 10v signals.
-- Randy
----------------------------------------------------------------
Randy Sargent Newton Research Labs
Senior Design Engineer Robotic Systems and Software
rsargent@newtonlabs.com http://www.newtonlabs.com/
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