RL78/G1H CHAPTER 9 REAL-TIME CLOCK
R01UH0575EJ0120 Rev. 1.20 Page 236 of 920
Dec 22, 2016
CHAPTER 9 REAL-TIME CLOCK
9.1 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)
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 oscillation clock (fIL = 15kHz) is selected, only the constant-period interrupt
function is available.
However, the constant-period interrupt interval when f
IL is selected will be calculated with the
constant-period (the value selected with RTCC0 register) × fSUB/fIL.
9.2 Configuration of Real-time Clock
The real-time clock includes the following hardware.
Table 9 - 1 Configuration of Real-time Clock
Item Configuration
Counter Internal 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)
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