4,199
edits
Changes
From IGEP - ISEE Wiki
m
In IGEP Boardshave two RTC clocks, each one located at MPU and PMIC contains each one a RTC clock:
→Overview
Real time clock (RTC) is a computer clock (most often in the form of an integrated circuit) that keeps track of the current time. RTCs are present in almost any electronic device which needs to keep accurate time. More general information [http://en.wikipedia.org/wiki/Real-time_clock here].<br>
* '''RTC System clock''': system clock is controlled by OMAP processors MPU using its internal RTC peripheral. Every bootupboot-up, the default firmware (/etc/init.d/hwclock.sh) copies the hardware clock data from /dev/rtc to system clock data to keeps clock up to date.
* '''RTC Hardware clock''': hardware clock is controlled by PMIC IC using its internal RTC peripheral. RTC PMIC can afford 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 PMIC RTC Hardware clock peripheral will lose its clock.** '''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.
== Simplified RTC diagram ==
