DS3231 rtc interfacing experience...

Dear all,

i want to interface ds3231 with pic controller looking on data sheet i found some extra registers like Aging Offset which are not in ds1307
can any body explain me what are the purpose of that register and why it is used ???

See http://www.soiseek.com/MAXIM/DS3231/14.htm

The aging offset register takes a user-provided value toadd to or subtract from the codes in the capacitancearray registers. The code is encoded in two’s comple-ment, with bit 7 representing the sign bit. One LSB rep-resents one small capacitor to be switched in or out ofthe capacitance array at the crystal pins. The aging off-set register capacitance value is added or subtractedfrom the capacitance value that the device calculatesfor each temperature compensation. The offset registeris added to the capacitance array during a normal tem-perature conversion, if the temperature changes fromthe previous conversion, or during a manual user con-version (setting the CONV bit). To see the effects of theaging register on the 32kHz output frequency immedi-ately, a manual conversion should be started after eachaging register change.Positive aging values add capacitance to the array,slowing the oscillator frequency. Negative valuesremove capacitance from the array, increasing theoscillator frequency.The change in ppm per LSB is different at differenttemperatures. The frequency vs. temperature curve isshifted by the values used in this register. At +25°C,one LSB typically provides about 0.1ppm change infrequency.Use of the aging register is not needed to achieve theaccuracy as defined in the EC tables, but could beused to help compensate for aging at a given tempera-ture. See theTypical Operating Characteristicssectionfor a graph showing the effect of the register on accu-racy over temperature.

how do i change these value if my system will off for one month ......???
that means i have to always turn on my microcontroller so that i can set these value.