Just remember that.....your current eeprom address holds the latest data,
while the address+1 holds the earliest data point you are keeping.  Unless
address=9 then the earliest is 0, but all very easy to keep track of once
you read it out eventually.

>From: "Mccauley, Daniel H" <daniel.h.mccauley@LMCO.COM>
>Reply-To: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
>To: PICLIST@MITVMA.MIT.EDU
>Subject: Re: [PIC]: Storing 10 Sets of Data to EEPROM and performing revol
>     ving updates ? ? ?
>Date: Fri, 16 May 2003 11:33:45 -0400
>
>Yes, that makes perfect sense.  I think with a scheme like this you could
>easily implement up to 1000's of stored datapoints very easily (with the
>proper EEPROM of course).
>
>Thanks again.
>
>Dan
>
>
> > > Does the newest datapoint *have* to be in location 10? If
> > not, then you
> > could just keep an index that pointed to the current memory
> > location, and
> > have it wrap back to 0. something like:
> >
> >         index = 0;
> >         while (recording)
> >         {
> >                 WriteMemory(index, measurement)
> >                 (index^9)?index++:index=0;
> > //increment index,
> > but wrap to zero if index==9
> >         }
> >
> >
> >         where WriteMemory() is whatever function you use to
> > store your data
> > that specifies address and measurement to store. I guess you
> > get the idea.
> > You can re-read the data newest to oldest just by knowing the value of
> > <index>, since that was the last address you stored. when
> > re-reading, you
> > would just have to decrement the index, and wrap from 0 to 9. Same
> > principle, though.
> >
> > hope that makes sense
> >
> > > -----Original Message-----
> > > From: Mccauley, Daniel H [mailto:daniel.h.mccauley@LMCO.COM]
> > > Sent: Friday, May 16, 2003 10:22 AM
> > > To: PICLIST@MITVMA.MIT.EDU
> > > Subject: [PIC]: Storing 10 Sets of Data to EEPROM and performing
> > > revolving updates ? ? ?
> > >
> > >
> > > For my project I wish to do the following:
> > >
> > > For each measurement I take with this electronic timing
> > device (my PIC
> > > controlled device), I want to store the result as following:
> > >
> > > Measurement 1 - Result 1
> > >
> > > For the next measurement, the data would be stored in:
> > >
> > > Measurement 2 - Result 2
> > >
> > > This would go so on until 10 Results are stored.  Since I am
> > > only storing 10
> > > results, for the 11th measurement, I want to discard the oldest
> > > datapoint and store the new datapoint at location Result 10.
> > >
> > > So basically I'm only storing the last 10 Results and always
> > > dropping the
> > > oldest to allow room for the newest result.
> > >
> > > My question is, what is the best way to code this??? (I'm
> > using CCS C
> > > compiler)  Do I move actual data through EEPROM everytime
> > > the 11th, 12th, so on results are being stored, or is it
> > > better to change
> > > the actual EEPROM storage address.
> > >
> > > Any help appreciated!!!
> > >
> > > D
> > >
> > > --
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> > >
> >
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