EEPROM Page Write nonsense in avr-libc FAQ

Go To Last Post
7 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

http://www.nongnu.org/avr-libc/u...

Why is this page-write nonsense still posted after it has been well refuted?

Lee

Quote:
AVRs use a paging mechanism for doing EEPROM writes. This is almost entirely transparent to the user with one exception: When a byte is written to the EEPROM, the entire EEPROM page is also transparently erased and (re)written, which will cause wear to bytes that the programmer did not explicitly write. If it is desired to extend EEPROM write lifetimes, in an attempt not to exceed the datasheet EEPROM write endurance specification for a given byte, then writes must be in multiples of the EEPROM page size, and not sequential bytes.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Would Sir like to lodge a bug report? ;-)

https://savannah.nongnu.org/bugs...

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:

Would Sir like to lodge a bug report?

Quote:
You are not allowed to post comments on this tracker with your current authentification level.

Being authenticated is one thing, but becoming authentificated would be too painful.

I was trying to dig out the detailed discussions with the "results" so that one of you authentificated people could easily post the bug report, but must not be using the right search words. :(

bpaddock was the instigator of the wording in question:
https://www.avrfreaks.net/index.p...

But that was in 2009 and I thought someone more recently did an experiment to "prove"...
Follow up:
https://www.avrfreaks.net/index.p...
and in particular, the "proof":
https://www.avrfreaks.net/index.p...

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I would be very, very careful in formulation of the wording.

In spite of what the said experiments (both mine and Eugene's) appear to suggest - namely that the paging mentioned in datasheets is related ONLY to parallel and JTAG programming and NOT to ISP and self-programming - I still believe that there MAY be AVR models where EEPROM may be erased page-wise also during ISP and self-programming, and even that Atmel is quite free to quietly introduce new silicon revisions of already established chips where such paging may be introduced due to technology change.

Note also, that while I performed the self-programming experiment on an ATMega128 and the ISP on ATMega8, bpaddock contacted the Atmel support with a question on a CAN device.

Honestly, back then I hoped that after that report I would see other users to try the same on different devices and report back. Apparently both I am hopelessly childishly naive and people here don't find such experiments entertaining enough.

It would be nice to see somebody with true knowledge on this topic from Atmel entering with a binding explanation, but not even I am naive enough to believe that to happen.

Jan

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

No thanks for the unfriendly reminder, Lee.

How the heck would we (the avr-libc maintainers) learn of your
"nonsense" if not by a bug report? I've heard this for the first
time here.

> Being authenticated is one thing, but becoming authentificated
> would be too painful.

Lame excuse for your laziness.

Jörg Wunsch

Please don't send me PMs, use email if you want to approach me personally.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Quote:

people here don't find such experiments entertaining enough.

I found it quite entertaining. Especially my attempt at logic with the "grand conspiracy" of this page thing and the erase-only times, etc. It is obvious from the experiments that there are no page effects to cell-at-a-time operations from AVR firmware.

Especially on modern AVR generations with the erase-only operation. Re AT90S8535 or the like: Who the 'freak cares? And in any case, the dire warning in the FAQ isn't justified.

Quote:

No thanks for the unfriendly reminder, Lee.

Ouch. Re-reading, the "nonsense" word could certainly have been avoided. Re bug report: Not being a regular user of the toolchain, I have no idea how to become "authentificated" [sic]. I was in the FAQ following up on another thread and came across the quoted paragraph and was quite surprised. My recommendation would be to just pull the paragraph.

Lee

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

https://www.avrfreaks.net/index.p...
Ha! :-)

(As I said, I'd be more careful than that, but then I did not do the real work so I better shut up now...)

JW