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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Tue, 12 Sep 2006 03:57:59 GMT
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Viewed:
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13816 times
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In lugnet.robotics.nxt, Ralph Hempel wrote:
> David Wallace wrote:
> >
> > Does the NXT firmware have a bootloader that is locked in the first couple
> > of sectors? And if so, why would it be required to be unlocked?
>
> As I understand it, the lock bits are only touched if SAMBA mode
> is entered, which is done when the reset button is pressed for more
> than about three seconds.
>
> At that point, the ARM erases the bottom two sectors and installs
> the SAMBA firmware into FLASH and locks the lock bits. Argh.
>
> The LEGO firmware can then be loaded, and I believe it contains
> a SAMBA compatible firmware downloader too, but it leaves
> the lock bits open.
Whether you reset the brick or just run the download firmware routine in the
LEGO Mindstorms NXT software or in RobotC or in NBC/BricxCC you've put the brick
in SAMBA mode (clicking brick mode) and the lock bits have been cycled. But I
have heard from a very reliable source that ATMEL has measured lock bit
read/write cycles at up to 7500 under normal temperature conditions (they just
don't guarantee that many under all conditions).
I could write a little test program which would repeatedly boot the brick into
firmware download mode, download the firmware, then repeat if anyone would like
to see how many times it can go through that cycle before the lock bits quit
working.
John Hansen
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Message has 1 Reply:
 | | RE: Flash Write Cycles
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| (...) I guess it depends on which way they fail? Do they fail in locked mode or in unlocked mode? If, as would be good design, they fail to permanently locked, I'd guess nobody is interested in trying. What nobody has mentioned yet is the (...) (18 years ago, 12-Sep-06, to lugnet.robotics.nxt)
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Message is in Reply To:
| | Re: Flash Write Cycles
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| (...) As I understand it, the lock bits are only touched if SAMBA mode is entered, which is done when the reset button is pressed for more than about three seconds. At that point, the ARM erases the bottom two sectors and installs the SAMBA firmware (...) (18 years ago, 11-Sep-06, to lugnet.robotics.nxt)
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