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EEPROM Memory Burn-Out — Parallax Forums

EEPROM Memory Burn-Out

George SuttonGeorge Sutton Posts: 180
edited 2006-10-22 08:11 in BASIC Stamp
I frequently read posts here that suggest the EEPROM memory can be eventually "burned out" by writes to the various memory location(s).· Has this ever actually happened to anyone with a BS2?· If so, did it render the entire memory useless, or was it just a location or two?· Thanks for any replies.


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Comments

  • allanlane5allanlane5 Posts: 3,815
    edited 2006-10-20 13:21
    Yes, this can, and has happened. And my understanding is only the location written to is 'broken' -- meaning it always reads zero, no matter what byte was written to it.

    There do exist 24LC640 eeproms, which can be written to using SHIFTOUT/SHIFTIN instructions, which are easily replaced.

    Note you have about 1 million writes to the eeprom before anything goes wrong. If you write to it every millisecond, that would take about 16 hours to 'wear out'. If you write to it every 10 minutes (for programming, or logging purposes), it would wear out in about 19 years.

    So with some care, it can be used.· Note also, it's only "write" that counts toward that 1 million writes.· Once written, you can read it an infinite number of times with no effect on the wear-out of the eeprom.

    Post Edited (allanlane5) : 10/20/2006 4:33:20 PM GMT
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-10-20 14:15
    George,
    ·
    ·· I have seen where someone has written to the EEPROM updating a value every pass through a loop.· As Allen pointed out, it doesn’t take long to wear out a location doing that.· We have a few projects that update EEPROM locations when certain events happen, but only when the specified event happens, therefore it is not being written to constantly.· Just don’t try to use the EEPROM as if it was NVRAM and you should be okay.

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    Chris Savage
    Parallax Tech Support
  • Sutton MurraySutton Murray Posts: 88
    edited 2006-10-22 08:11
    My understanding is also, that you have the 1 million writes per each bit of location. So laying out your program so that every write will be to a different new location will extend the life span tremendeus. Write every minute to a different location, this will probably keep on going long beyond your own life.
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