N STEENKAMP [M.ING E&E] wrote:
>
> Hi,
>
> > Another problem with periodic saving is that if power fails during a save
> > the data may be garbled.  One solution to this would be to save two
> > copies with a scheme such as CRC applied to each copy to check if it is
> > valid.  If upon turning the power back on, a copy fails the CRC the other
> > one would be used.  The bad copy would be fixed by rewriting it from the
> > good one.  (If both copies fail CRC, obviously this is a problem.  This
> > shouldn't happen if it is just power on/off causing garbled data to be
> > written)
>

> A method I have used keeps two copies of the data and a pointer byte.
> I write alternately to the one or the other.  I first write the data and
> then write the single pointer byte to indicate which of the entries
> contain the most recent info.  This method makes sure that the data you
> read is always valid (although it might not be the newest data).
>
> Niki

I resolved my problem with 1000uf Capacitor on Power of PIC16f84! And a circuit
 that verify if
the power off. When this happen, i have disponible time to record my information
 with garanty, i
think!
I put jumper, for the user configurate for a new sequence of Disponible address,
 for example:

JUMPER       POSITIONS
0 0 0        0,1,2
0 0 1        2,3,4
0 1 0        5,6,7
.               .
.               .
.               .

Mig.