Imre Bartfai wrote:

> if the amount of data is not huge AND you use appropriate
> PIC (16F87x, 16CE6xx or 16F84), you can use the internal EEPROM.
> Advantage: no external part required, simple programming (except
> 16CE6xx).
> I hope this helps.

Hi Imre,

Your suggestion is very effective, practical and easy to implement without
any additional hardware. Secondly, since there is no battery, there is no
hassle of having to remember to replace the battery once in a year or so.
One requirement of course is that the PIC used should have internal EEPROM.

I use only flash devices (16F628, F870 & F877) and I have used precisely the
same technique in my remote control project that uses 8 relays for
controlling lights and fans. The status of the relays is stored in a byte
and this byte gets saved in the EEPROM every time a relay is turned on or
off. On power-up, this byte value from the EEPROM is read into a variable
that controls the relays.

Assuming the life of each location in the EEPROM is one million erase-write
cycles, if the status of the relay changes 100 times per day, then the
device will last for more than 27 years! Even assuming I continue to use the
gadget, I can switch to another location in the EEPROM for another 27
years!!

I would like to know what others have to say on the subject.

Regards,

Bala

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