Re: Using "delay until" in real-time

[Marin David Condic <mcondic.nospam@acm.org>]

Its not uncommon to have that sort of limitation, but depending on the
system, you can usually reason your way around it. The box gets turned on
and run for N hours at most, so we'll never overflow the counter." I had a
similar problem once with a control that used EEPROM and there was a major
concern about limiting the number of times it would be rewritten. The
estimate was that you had about 10,000 writes before the EEPROM would
potentially burn out. We were concerned with minimizing the writes to it
until I started investigating the probable number of updates. The best guess
was that a given control might need the EEPROM reloaded not more than 5..10
times in its production life. In the lab, it might experience 50..100
updates. That left plenty of margin, so we stopped worrying about it.

Of course we had to make sure we didn't accidentally get into some sort of
loop that might repetitively write a single address - it happened once on
another project so people got nervous about it.

You always need to look at the real world and sometimes say "Good Enough is
Good Enough!"

MDC

Ted Dennison wrote:

> Something pretty much like that has been suggested. My problem with it
> is that "n" is a counter that has to be monotonically increasing. That
> means that it will eventually hit an archetectural limit. Of course on
> my 32-bit machine at 240Hz that limit won't happen until the machine has
> been running for about 1/3 of a year, but the limit is there.

--
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Marin David Condic - Quadrus Corporation - http://www.quadruscorp.com/
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