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* '''RTC System Hardware clock''': system hardware clock is controlled by OMAP processors PMIC using its internal RTC peripheral. Every bootupRTC PMIC affords two behaviours:** '''RTC battery is not used''': PMIC RTC peripheral keeps hardware clock alive when OS isn't running and power source is active. If the power source fails, the default firmware copies the hardware PMIC RTC peripheral will lose its clock data from /dev/rtc to system clock data to .** '''RTC battery is used''': PMIC RTC peripheral keeps hardware clock up to datealive when OS isn't running and backup battery powers the backup state as far as the input voltage is high enough (at least 2 weeks into IGEPv2).
=Rectify clock drift=IGEP Boards use as a source clock a an external 32.768kHz ,768 kHz crystal. This passive component can add clock drifts due:
*General drift error*Ambient temperature drift error*Aging drift error
* ...
= Requirements ===Correct system clock====Hardware clock will be compensated automatically, to transfer hardware clock to system clock is necessary use hwclock command: