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Topic: EEPROM ? (Read 906 times) previous topic - next topic

Udo Klein

I have also covered this issue in my blog together with some rudimentary wear leveling code: http://blog.blinkenlight.net/experiments/counting-resets/wear-leveling/.
Check out my experiments http://blog.blinkenlight.net

Krupski


I have also covered this issue in my blog together with some rudimentary wear leveling code: http://blog.blinkenlight.net/experiments/counting-resets/wear-leveling/.


Well, I thought that it would be good to present the info in an easy to understand form. Too many times a student is drowned in arcane mathematics and unexplained things like "Fowler-Nordheim electron tunneling" and comes away from the lesson with nothing but a headache.

Way too many "teachers" and professors know the material, but are awful TEACHERS. A good TEACHER does whatever it takes to get the idea UNDERSTOOD by the student.

I like to teach in a way that is easy to understand, then when the basic idea is understood, THEN present the math and "higher level" facts that go along with it.

I didn't mention wear leveling simply because I didn't want to over-complicate what I wrote. New concepts are hard enough for some to grasp without making it even more confusing.

AFTER the student grasps the idea of trapped charges and the deterioration of the gate insulator, THEN the need for wear leveling can be introduced.


On another note... I once had an OTP (one time programmable) 68HC11 MCU that I screwed up (burned the wrong code into). So I figured I would test the EEPROM to destruction and wrote a little loop that just kept writing 0x55 and 0xAA to each byte, then switching the pattern (with a full erase after each write).

After running for WEEKS straight and many tens of millions of cycles, the EEPROM was still good!

I don't know if the EEPROM was damaged (and may have leaked away in a few days or weeks), but the programming time for a byte never changed and there was never a read-back error.

I think manufacturers are way conservative when they publish EEPROM cell write life numbers......
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CrossRoads

#7
Nov 23, 2012, 03:43 am Last Edit: Nov 23, 2012, 03:45 am by CrossRoads Reason: 1
If its really a concern, adding an external FRAM can provide a lot more nonvolatile storage space, is fast to write to like an SRAM, has EEPROM dataholding capability, and "High Endurance 100 Trillion (1014) Read/Writes"!
http://www.mouser.com/ProductDetail/Ramtron/FM25W256-G/?qs=sGAEpiMZZMtsPi73Z94q0IidxlBy6KhxDctIlbo1eg0%3d

Can operate fom 5V also, not just 3.3V.
http://www.ramtron.com/files/datasheets/FM25W256_ds.pdf
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
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dkallergis

Amazing, 256kb of fast and long lasting non-volatile memory! It is the first time I hear about FRAM (or FeRAM) and I am very impressed!

Is there an FRAM shield commercially available? and if not why do we not see such products offered?

Udo Klein

Quote
On another note... I once had an OTP (one time programmable) 68HC11 MCU that I screwed up (burned the wrong code into). So I figured I would test the EEPROM to destruction and wrote a little loop that just kept writing 0x55 and 0xAA to each byte, then switching the pattern (with a full erase after each write).

After running for WEEKS straight and many tens of millions of cycles, the EEPROM was still good!

I don't know if the EEPROM was damaged (and may have leaked away in a few days or weeks), but the programming time for a byte never changed and there was never a read-back error.


Obviously you did not read my blog. Otherwise you would know that your experiment was pointless. EEPROM damage shows up in decreased retention time. Typically a cell is considered damaged if the threshhold (usually something in the range of years) can not be guaranteed anymore. You tested for retention times in the seconds / minutes range. This does not provide any insights whatsoever into remaining retention capabilities.
Check out my experiments http://blog.blinkenlight.net

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