Kontron KBox C-102 Series, Руководство пользователя

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KBox C-102 - User Guide, Rev. 1.0
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4.1. RTC (GoldCap)
The baseboard of the KBox C-102 provides an “external RTC” module connected via the I 2 C Bus. An RTC module of type
RV-8803-C7 or compatible is used. To provide a valid date and time when no power is connected to the system, the
RTC module is equipped with a goldcap buffer.
4.1.1. RTC Buffer Time
The RTC buffer time is depending of the ambient temperature. For a better understanding the different behavior of
the goldcap buffer integrated in your system, refer to the diagram below:
Figure 3: RTC buffer time depending on temperature
If the time is not valid this is indicated by a status bit in the RTC registers. For details see the RV-8803-C7 application
manual.
To get the maximum buffer time, it is necessary to have the system a certain time powered
on. This ensures that the buffer capacitors are fully loaded.
The buffer time depends on the ambient temperature and on how long the system is
connected to the power supply.
4.1.2. Setting the RTC
During startup, the uEFI performs a comparison of chipset clock and “external RTC” module and sets the chipset clock
accordingly, if the RTC time is valid. Further it is possible to set the time manually by accessing the RTC over the I
2
C
Bus.
0
0,5
1
1,5
2
2,5
3
3,5
4
4,5
5
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
0 °C
25 °C
50 °C
RTC Threshold
time / days
vo
lt
age
/
V