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RL78/G1A CHAPTER 7 REAL-TIME CLOCK
7.3.2 Subsystem clock supply mode control register (OSMC)
The WUTMMCK0 bit can be used to select the count clock (fRTC) of the real-time clock.
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 5 CLOCK GENERATOR.
The OSMC register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 7-3. Format of Subsystem Clock Supply Mode Control Register (OSMC)
Address: F00F3H After reset: 00H R/W
Symbol 7 6 5 4 3 2 1 0
OSMC RTCLPC 0 0
WUTMMCK0
0 0 0 0
WUTMMCK0
Selection of operation clock (fRTC) for real-time clock and 12-bit interval timer.
0 Subsystem clock (fSUB)
1 Low-speed on-chip oscillator clock (fIL)
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 (TYP.)) is selected, only the constant-period
interrupt function is available. The 25- to 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) × fSUB/fIL.
R01UH0305EJ0200 Rev.2.00 297
Jul 04, 2013