Saving date and time between reboots

[RazZziel]

My OLinuxino with ArchLinux resets the date and time when I disconnect it from the power supply and re-connect it again.

For my application, I need it to keep date and time for weeks without external power. I don't need the board to boot on battery, just to keep date and time for long periods of time powered off.

What can I do? Can I plug a small button battery like in the Beagleboard XM?

[olimex]

you can use MOD-RTC

[RazZziel]

I plan to use the UEXT port for other peripherals (i.e. MOD-GPS)

Besides, the OLinuXino-MAXI already has an RTC according to the manual. Can't I attach a RTC backup battery somewhere?

[IWriteCode]

The manual ( http://www.freescale.com/files/dsp/doc/ref_manual/IMX23RM.pdf ) states:

A 32-bit second counter has enough resolution to count up to 136 years with one-second increments. The
RTC can continue to count time as long as a voltage is applied to the BATT pin, irrespective of whether
the rest of the chip is powered up. The normal digital reset has no effect on the master RTC registers
located in the crystal power and clock domain. A special first-power-on reset establishes the default value
of the master RTC registers when a voltage is first applied to the BATT pin (battery insertion).

So attaching a battery to the LIPO_BAT should fire things up...