RL78/G1H CHAPTER 9 REAL-TIME CLOCK
R01UH0575EJ0120 Rev. 1.20 Page 240 of 920
Dec 22, 2016
9.3.2 Subsystem clock supply mode control register (OSMC)
The WUTMMCK0 bit can be used to select the real-time clock count clock (fRTC).
In addition, by stopping clock functions that are unnecessary, the RTCLPC bit can be used to reduce power
consumption. For details about setting the RTCLPC bit, see CHAPTER 6 CLOCK GENERATOR.
The OSMC register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 9 - 3 Format of Subsystem clock supply mode control register (OSMC)
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 (f
IL = 15 kHz) is selected, only the constant-period interrupt function
is available.
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.
Address: F00F3H After reset: 00H R/W
Symbol76543210
OSMCRTCLPC00WUTMMCK00000
WUTMMCK0 Selection of count clock (f
RTC) for real-time clock, 12-bit interval timer, and timer RJ operation clock
0 Subsystem clock (f
SUB)
• The subsystem clock is selected as the count clock for the real-time clock and the 12-bit interval timer.
• The low-speed on-chip oscillator cannot be selected as the count source for timer RJ.
1 Low-speed on-chip oscillator clock (f
IL)
• The low-speed on-chip oscillator clock is selected as the count clock for the real-time clock and the 12-
bit interval timer.
• Either the low-speed on-chip oscillator or the subsystem clock can be selected as the count source for
timer RJ.
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