EEPROM "refresh"

[Luciano]

Hello,

I was wondering if anybody has had any experience with the
EEPROM refresh mentioned in the data sheet of the PIC18FXX2.

What about other families of PIC MCUs?

Please stay on topic EEPROM. (Built-in or external EEPROM).

Please do not talk in this thread about other type of memory like FRAMs.

Best regards,

Luciano


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PIC18FXX2 Data Sheet:
http://ww1.microchip.com/downloads/e...Doc/39564b.pdf

* * * *
PDF Page 70

6.8 Using the Data EEPROM

The data EEPROM is a high endurance, byte addressable
array that has been optimized for the storage of
frequently changing information (e.g., program variables
or other data that are updated often). Frequently
changing values will typically be updated more often
than specification D124. If this is not the case, an array
refresh must be performed. For this reason, variables
that change infrequently (such as constants, IDs, calibration,etc.)
should be stored in FLASH program memory.

Note: If data EEPROM is only used to store constants
and/or data that changes rarely, an
array refresh is likely not required. See
specification D124.

A simple data EEPROM refresh routine is shown in
Example 6-3.

* * * *
PDF Page 270

Data EEPROM Memory

D120 ED Cell Endurance
Min=100K Typ=1M

D124 TREF Number of Total Erase/Write Cycles before Refresh
Min=1M Typ=10M

* * * *

(The link below is about the specification D124 of Microchip).

EEprom endurance/specification D124:
http://oase.uci.kun.nl/~mientki/pic/..._problems.html

================================================== ========
Microchip Application Note AN537
Everything a System Engineer Needs to
Know About Serial EEPROM Endurance
http://ww1.microchip.com/downloads/e...otes/00537.pdf

Microchip Application Note AN601
EEPROM Endurance Tutorial
http://ww1.microchip.com/downloads/e...otes/00601.pdf

Data EEPROM (Section 7 of the Mid-Range Reference Manual)
http://ww1.microchip.com/downloads/e...Doc/31007a.pdf
================================================== ========

[NavMicroSystems]

Luciano,

what I can tell is: Refreshing an EEPROM is no Problem.

what I can't tell is: what would have happened to the Memory Cells that were supposed to be static if they wouldn't have been refreshed.

I personally wouldn't store "static" data together with "dynamic" data on physically the same chip.
(I wouldn't use an EEPROM for frequently changing data either)
(OK, it all depends on the definition of "frequently")

You could run a simple test to find out where the limits are,
but bear in mind that this test will wear out your EEPROM (sooner or later).

Write some "static" data to some EEPROM locations.
Run un a loop overwriting some other locations with "dynamic" data.
with every cycle of the loop read back the "static" locations and compare them to the initial values.
When the first mistmatch occurs your loop counter will tell you the number of cycles.