Subject:
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Re: Flash Write Cycles
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Newsgroups:
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lugnet.robotics.nxt
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Date:
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Sun, 10 Sep 2006 00:04:14 GMT
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Viewed:
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12781 times
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In lugnet.robotics.nxt, David Wallace wrote:
> Does anyone know how the NXT firmware handles writing
> program files into flash?
I don't; John Hansen might. While Flash memory does have a limited number of
read/write cycles, it appears that the stated limit is conservative, by a large
margin... although some of us have thought about a "test to failure" trial, I've
not been willing to subject my NXT to such destruction, but I think others may
have tried, and failed, to overuse the Flash memory. So no promises, but
statisticly speaking it looks like your milage will exceed the chip
manufacturers limits.
A more important problem may be the lock bits for the bootcode, as these in some
situations need to be toggled for firmware uploads, and they "wear out" much
quicker (guarenteed for IMS 100 cycles?). But again, I know firmware developers
who have toggeled them close to that already, without problems, so perhaps those
are overspeced a good bit (byte?) too.
> Let's say that a heavy user flashes the part 200 times per week.
I've written NXT-G code that has done more than 200 writes in a single run
(using the file system to implement arrays... and yes, I've got one better way
for small arrays already, and ideas for a much better implementation... soon.).
> I also hope that the NXT firmware doesn't reprogram
> the same location.
I suspect it does. I say that for two reasons, neither iron-clad. First, keeping
track of how frequently each sector of Flash is used is probably not something
you worry about when developing compact firmware for a toy. Second, if you keep
downloading the same-named NXT-G program after editing it (again and again), it
does not fill up the memory of the NXT with a bunch of "ghost images". And for
downloading programs, I seriously doubt it matters. As far as downloading
programs, I seriously doubt even "heavy users" will come anywhere near flashing
the entire memory 200 times a week (as far as using flash as extended file
memory for program bookkeeping, you could, but not downloading programs). All I
do to try to equalize flash usage is not delete anything until the NXT has a
full memory... at which point I normally use the "delete everything" option to
clean out the entire memory at once. That way, I'm at least spreading out the
flash usage.
> Any knowledgeable people out there in this area?
Yeah, who wants to be the first to test an NXT to destruction :-) ?
--
Brian Davis
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Message is in Reply To:
 | | Flash Write Cycles
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| Does anyone know how the NXT firmware handles writing program files into flash? If you re-flash a program with the same name, does it first erase the sectors that the old program was located in and then re-flash these sectors with the new program? (...) (18 years ago, 9-Sep-06, to lugnet.robotics.nxt)
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