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NUC126
Aug. 08, 2018
Page
520
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Rev 1.03
NUC12
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RTC_INIT
available
R/W
R/W
RTC_RWEN
available
R/W
R/W
RTC_FREQADJ
available
R/W
R
RTC_TIME
Not available
R/W
R
RTC_CAL
Not available
R/W
R
RTC_CLKFMT
Not available
R/W
R
RTC_WEEKDAY
Not available
R/W
R
RTC_TALM
Not available
R/W
R
RTC_CALM
Not available
R/W
R
RTC_LEAPYEAR
Not available
R
R
RTC_INTEN
available
R/W
R/W
RTC_INTSTS
available
R/W
R/W
RTC_TICK
Not available
R/W
R
RTC_TAMSK
Not available
R/W
R
RTC_CAMSK
Not available
R/W
R
RTC_LXTCTL
available
R/W
R/W
RTC_LXTOCTL
available
R/W
R/W
RTC_LXTOICTL
available
R/W
R/W
RTC_DSTCTL
Not available
R/W
R
Table 6.14-1 RTC Read/Write Access Attribute
6.14.5.3 Frequency Compensation
The FREQADJ (RTC_FREQADJ[21:0]) allows user to make digital compensation to a clock input for
RTC application more accurate. The FREQADJ default value is 0x00200000 if RTC clock source is
LXT and 0x00080000 if RTC clock source is LIRC, means no frequency compensate for actual RTC
clock frequency. Follow the example and formula below to write compensation value of actual RTC
clock frequency to FREQADJ. Example 1 and example 2 below are the compensation examples for
higher or lower than standard 32 kHz, if RTC clock source is selected from LXT.
Example 1:
Actual frequency measurement: 32773.65 Hz (> 32768 Hz)
FREQADJ = (32768 * 0x200000) / 32773.65 = 0x1FFE96
Example 2:
Actual frequency measurement: 32763.25 Hz (< 32768 Hz)
FREQADJ = (32768 * 0x200000) / 32763.25 = 0x200130
User can enable CLK1HZEN (CLK_CLKOCTL[6]) function and relative clock output pin to measure 1