NUC140LC1CN Datasheet, PDF (40/77 Pages) List of Unclassifed Manufacturers – 32-BIT MICROCONTROLLER

NuMicro™ NUC140 Data Sheet
5.8 Real Time Clock (RTC)
5.8.1 Overview
Real Time Clock (RTC) controller provides user the real time and calendar message. The clock
source of RTC is from an external 32.768 kHz low speed crystal connected at pins X32I and
X32O (reference to pin descriptions) or from an external 32.768 kHz low speed oscillator output
fed at pin X32I. The RTC controller provides the time message (second, minute, hour) in Time
Loading Register (TLR) as well as calendar message (day, month, year) in Calendar Loading
Register (CLR). The data message is expressed in BCD format. It also offers alarm function that
user can preset the alarm time in Time Alarm Register (TAR) and alarm calendar in Calendar
Alarm Register (CAR).
The RTC controller supports periodic Time Tick and Alarm Match interrupts. The periodic interrupt
has 8 period options 1/128, 1/64, 1/32, 1/16, 1/8, 1/4, 1/2 and 1 second which are selected by
TTR (TTR[2:0]). When RTC counter in TLR and CLR is equal to alarm setting time registers TAR
and CAR, the alarm interrupt flag (RIIR.AIF) is set and the alarm interrupt is requested if the alarm
interrupt is enabled (RIER.AIER=1). Both RTC Time Tick and Alarm Match can cause chip wake-
up from power down mode if wake-up function is enabled (TWKE (TTR[3])=1).
5.8.2
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Features
There is a time counter (second, minute, hour) and calendar counter (day, month, year) for
user to check the time
Alarm register (second, minute, hour, day, month, year)
12-hour or 24-hour mode is selectable
Leap year compensation automatically
Day of week counter
Frequency compensate register (FCR)
All time and calendar message is expressed in BCD code
Support periodic time tick interrupt with 8 period options 1/128, 1/64, 1/32, 1/16, 1/8, 1/4, 1/2
and 1 second
Support RTC Time Tick and Alarm Match interrupt
Support wake-up chip from power down mode
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Publication Release Date: Jan. 2, 2012
Revision V3.02