Datasheet

RL78/L12 CHAPTER 7 REAL-TIME CLOCK
R01UH0330EJ0200 Rev.2.00 284
Dec 13, 2013
CHAPTER 7 REAL-TIME CLOCK
7.1 Functions of Real-time Clock
The real-time clock has the following features.
• Having counters of year, month, week, day, hour, minute, and second, and can count up to 99 years.
• Constant-period interrupt function (period: 0.5 seconds, 1 second, 1 minute, 1 hour, 1 day, 1 month)
• Alarm interrupt function (alarm: week, hour, minute)
• Pin output function of 1 Hz (44, 48, 52, and 64-pin products only)
The real-time clock interrupt signal (INTRTC) can be utilized for wakeup from STOP mode and triggering an A/D
converter's SNOOZE mode.
Caution The count of year, month, week, day, hour, minutes and second can only be performed when a
subsystem clock (f
SUB = 32.768 kHz) is selected as the operation clock of the real-time clock.
When the low-speed on-chip oscillator clock (fIL = 15 kHz) is selected, only the constant-period
interrupt function is available. The 32-pin products have the constant-period interrupt function
only, because these products have no subsystem clock.
However, the constant-period interrupt interval when f
IL is selected will be calculated with the
constant-period (the value selected with RTCC0 register) × f
SUB/fIL.
7.2 Configuration of Real-time Clock
The real-time clock includes the following hardware.
Table 7-1. Configuration of Real-time Clock
Item Configuration
Counter Counter (16-bit)
Control registers Peripheral enable register 0 (PER0)
Subsystem clock supply mode control register (OSMC)
Real-time clock control register 0 (RTCC0)
Real-time clock control register 1 (RTCC1)
Second count register (SEC)
Minute count register (MIN)
Hour count register (HOUR)
Day count register (DAY)
Week count register (WEEK)
Month count register (MONTH)
Year count register (YEAR)
Watch error correction register (SUBCUD)
Alarm minute register (ALARMWM)
Alarm hour register (ALARMWH)
Alarm week register (ALARMWW)
<R>
<R>