Subject:
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Flash Write Cycles
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Newsgroups:
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lugnet.robotics.nxt
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Date:
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Sat, 9 Sep 2006 18:40:39 GMT
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Viewed:
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13837 times
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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? Or, does it write the new program (with the same name), to a different
set of sectors and then erase the old program?
The flash used in the NXT which is internal to the AT91SAM7256 microcontroller
can be re-programmed 10,000 times according to the spec.
Let's say that a heavy user flashes the part 200 times per week. I know that
some people will exceed this while others will be lower. If the NXT firmware
erases and re-writes the same area, this user would exceed the number of cycles
in 1 year. Probably, most people will be OK, but the heavy users who may even
exceed 200/week will be very disappointed.
I'm hoping that Atmel's 10,000 number is conservative. I also hope that the NXT
firmware doesn't reprogram the same location. If I'm working on a program and
reflashing it many times, I think I'm going to keep changing the name so it gets
stored at a different location until the flash is full, and then erase and start
over.
Any knowledgeable people out there in this area?
David Wallace
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Message has 4 Replies:
 | | Re: Flash Write Cycles
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| (...) 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 (...) (18 years ago, 10-Sep-06, to lugnet.robotics.nxt)
| | | Re: Flash Write Cycles
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| (...) When downloading a program to the NXT using NBC if there is a file with the same name on the NXT already it is first deleted. Then a new file is created and written using the same filename. I don't know whether that means the firmware will (...) (18 years ago, 10-Sep-06, to lugnet.robotics.nxt)
| | | Re: Flash Write Cycles
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| In article <J5C97r.BBF@lugnet.com>, David <dww.robotics@gmail.com> writes (...) This is the guaranteed minimum number, with higher voltages and at higher temperatures than you are likely to use the NXT at. FLASH memory is a pretty mature technology (...) (18 years ago, 10-Sep-06, to lugnet.robotics.nxt)
| | | Re: Flash Write Cycles
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| (...) One probable reason that the NXT does not do any wear leveling is that it executes instructions directly from flash (the instructions in the firmware itself), which is memory mapped. This requires that these instructions are contiguous, which (...) (18 years ago, 10-Sep-06, to lugnet.robotics.nxt)
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