NuMicro® NUC029LEE/NUC029SEE
32-bit Arm
®
Cortex
®
-M0 Microcontroller
Aug, 2018
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6.12.3 Block Diagram
The block diagram of Real Time Clock is depicted as follows:
RTC Time Counter
Control Unit
Time Loading
Register
(TLR)
Calendar
Loading
Register
( CLR)
Time Alarm
Register
(TAR)
Calendar
Alarm Register
(CAR)
1/128 change
1/64 change
1/32 change
1/16 change
1/8 change
1/4 change
1/2 change
1 change
(sec)
111
110
101
100
011
010
001
000
TTR (TTR[2:0])
TIF (RIIR[1])
TIER (RIER[1])
Compare
Operation
AIER (RIER[0])
Alarm Interrupt
RTC_CLK
Frequency
Compensation
Frequency
Compensation
Register
(FCR)
AER
WEEKDAY
LEAPYEAR
24H/12H
AIF (RIIR[0])
Wakeup CPU from
Power-down mode
Tick Interrupt
80 Bytes Spare Registers
(SPR0 ~ SPR19)
LIRC
0
1
RTC_SEL_10K
(CLKSEL2[18])
LXT
INIR
INIT
AER
LIR
TSSR
DWR
Figure 6.12-1 RTC Block Diagram
6.12.4 Basic Configuration
RTC controller clock enable is in RTC_EN (APBCLK[1]) and low speed 32 kHz oscillator is
enabled by XTL32K_EN (PWRCON[1]).
6.12.5 Functional Description
6.12.5.1 RTC Initiation
When a RTC block is powered on, RTC is at reset state. User has to write a number 0xa5eb1357
to INIR (INIR [31:0] RTC Initiation) register to make RTC leaving reset state. Once the INIR is
written as 0xa5eb1357, the RTC will be in normal active state permanently. User can read Active
bit (INIR[0] RTC Active Status) to check the RTC is at normal active state or reset state.
6.12.5.2 Access to RTC register
Due to clock frequency difference between RTC clock and system clock, when user write new
data to any one of the RTC registers, the data will not be updated until 2 RTC clocks later (about
60us).
In addition, user must be aware that RTC controller does not check whether loaded data is out of
bounds or not in TLR, CLR, TAR and CAR registers. RTC does not check rationality between
DWR and CLR either.