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Internal EEPROM endurance?

 
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Tom-H-PIC



Joined: 08 Sep 2003
Posts: 105
Location: New Castle, DE

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Internal EEPROM endurance?
PostPosted: Mon Jul 03, 2006 7:24 am     Reply with quote

Hello All
I'm working with a 16F916 with 256K internal EEPROM.
My question is the EEPROM endurance with respect to read.
The data sheet list the endurance at TYP 1M.
This is not clear if this is read and write or just write.
My tough is that this is just write and not read.

What I would like to do is write some cal numbers to the EEPROM.
The cal numbers would be written to the EEPORM a limed number of times in the life of the part maybe 20 times.
In normal execution the cal numbers would be read at startup to RAM then I would like to reread the EEPROM about every 5 minuets to refresh the RAM locations.

Thanks All Tom
newguy



Joined: 24 Jun 2004
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PostPosted: Mon Jul 03, 2006 9:31 am     Reply with quote

The endurance specs refer to writes. Reading the EEPROM doesn't damage it and/or shorten its life.
Ttelmah
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PostPosted: Mon Jul 03, 2006 10:24 am     Reply with quote

It is worth perhaps saying how we 'know' this. If you look at the data sheet, and the column for 'units', it gives 'E/W'. This stands for 'erase/write', and tells you what cycles the value relates to. So the 'life', is in 'erase/write' cycles.
Also though, though the main memory is 'flash', rather than EEPROM', the 'cycle life' for which is generally even lower, and if it applied to 'reads', think how long the program memory would last!...

Best Wishes
Tom-H-PIC



Joined: 08 Sep 2003
Posts: 105
Location: New Castle, DE

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PostPosted: Mon Jul 03, 2006 11:09 am     Reply with quote

Thanks for all the info.
This was also my though I just wanted to make sure that I was on the right track.
Although I did not see the E/W in the units column thanks for pointing that out Ttelmah.
Tom
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