Sean Breheny wrote:
> Bob,
>
> Do you have more information about this? My reading of the Mchip docs
> suggests that the problem is not reads but writes to one cell
> affecting other cells in the array, so that writing address 0 and then
> writing address 1 10,000 times, if I try to then read address 0, I may
> get garbled data - so I need to make sure the refresh address 0 after
> every N writes to any cell in the array. In other words, if I simply
> write data once, I should then be able to read it indefinitely with no
> further refreshes.
>
> Sean
>
>   
I thought this was settled years ago; the PICforum and the PIClist 
should all have archives on it.
Trust me, if you did nothing but read EEPROM data repeatedly, in a few 
days, the data will be
corrupted, regardless of where it is in the array. And yes, there  is 
interaction with other data
in close proximity.  The read process, like the write process, slowly 
erodes the data, as does
other lesser-occurring effects, such as radiation, cosmic rays, heat, etc.

In years past, PICs were made with thicker interconnections and better 
isolation for the EEPROM
arrays, and errors in EEPROM data was almost unheard of. But as the 
devices have become smaller
and the protection less, the "dark side" of smaller die sizes begins to 
show up.

Refresh it en masse as Microchip recommends, or use my "best of" 
algorithm and refresh it as needed.
My algorithm just increases cell life.

--Bob
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