PIC and RTC DS1307 problem - hardware vs software ?

[jorge]

Hi everyone ( specially Melabs PBP PRO´s )

i ve almost a two years old project that suffers from specific a RTC problem that i ve been unable to workaround .. All the RTC program routines and PIC code are working ok and this only happens once in a while. Capacitors on power leads ( 10uf) and system gets power from a standard SMD LM7805 with 100uf !! capacitors.
Standard DS1307 to PIC ( from manufacturer app note) schematics used.

The problem is that from time to time (without any specific reason – noise I guess… ) the dallas RTC DS1307 get´s all it ´s internal data corrupted and i ve to program it again with valid clock and date settings.
Fist I manage to insert an auto-routine that when detect that no valid data was inside the RTC anymore it would program it with the manufacture date and alert the user to set date/time again asap.
This would be fine, but creates another problem….until the user sets the current clock&date again, all the data after the this “auto-date” solution must be cross reference to the last valid RTC reading to extrapolate the actual date of the recordings of all the probes values… ( otherwise all the new values are referenced / starting based in the manufactured auto start date)

Last note: the DS1307 battery is assembled and in good condition all the times.


So, my question(s) are:

-i know that the DS1307 can suffer from similar problems in noisy conditions or when a bad write command is given and gets interrupted ( which doesn’t seem to be the case), but can I ve any hardware solution or a cleaver software workaround to this ?

- Any of you PRO´s had any similar problem with the DS1307 RTC and/or have any “advice” in terms of schematics?

Thanks in advance for any help !:-)

Any advice or information would be really good.

Regards,
Jorge