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In IGEP Boards, MPU and PMIC contains each one a RTC clock:
* '''RTC System clock''': system clock is controlled by OMAP processors using its internal RTC peripheral. Every bootup, the default firmware copies the hardware clock data from /dev/rtc to system clock data to preserve the clock.
* '''RTC Hardware clock''': hardware clock is controlled by PMIC IC using its internal RTC peripheral. RTC PMIC can afford two behaviours:
** RTC battery is not used: PMIC RTC peripheral keeps hardware clock alive when OS isn't running and power source is active.
** RTC battery is used: PMIC RTC peripheral keeps hardware clock alive when OS isn't running and backup battery powers the backup state as far as the input voltage is high enough.
= Requirements =
