You can find the D-spec's in the datasheet, "DC Characteristics"...
in the 18F242 datasheet anyway.
Rick wrote:
--
I'm thinking about using the Data EEPROM in an 18F8620, and can't
figure out what the datasheet is trying to say. I hope someone
can clarify.Section 7.8 says, in part "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 ... should be stored in Flash program
memory."But here's the catch: there is no specification D124 anywhere to be
found in the data sheet, therefore no frame of reference for fuzzy
relative terms "frequently" and "infrequently".Then, perversely, they go on to say "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."And again, since there is no "specification D124", there is no frame
of reference for the relative term "rarely". Also notice fuzzy words
"likely not required".And then they proceed to give sample code for a refresh routine that
is obviously going to consume a significant amount of processing time,
so not something I would want in my main loop, but they give no
guidelines.Near as I can gather, it must be fine if you change it constantly or
never, but there is some window between milliseconds and centuries
where problems can occur, the datasheet author did not understand the
situation, and the engineers didn't deem it worthy to supply any
usable information.Can anyone shed light on this?