Datasheet

RL78/L12 CHAPTER 5 CLOCK GENERATOR
R01UH0330EJ0200 Rev.2.00 145
Dec 13, 2013
5.3.7 Subsystem clock supply mode control register (OSMC)
This register is used to reduce power consumption by stopping as many unnecessary clock functions.
If the RTCLPC bit is set to 1, power consumption can be reduced, because clock supply to the peripheral functions,
except the real-time clock, 12-bit interval timer, and LCD driver/controller, is stopped in HALT mode while subsystem clock
is selected as CPU clock. Set bit 7 (RTCEN) of peripheral enable registers 0 (PER0) to 1 before this setting.
In addition, the OSMC register can be used to select the operation clock of the real-time clock, 12-bit interval timer, and
LCD driver/controller.
The OSMC register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 5-8. 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
RTCLPC Setting in HALT mode while subsystem clock is selected as CPU clock
0 Enables supply of subsystem clock to peripheral functions
(See Table 19-1 for peripheral functions whose operations are enabled.)
1
Stops supply of subsystem clock to peripheral functions other than real-time clock, 12-bit
interval timer, and LCD driver/controller.
WUTMMCK0
Note
Selection of operation clock for real-time
clock, 12-bit interval timer, and LCD
driver/controller
Selection of clock output from PCLBUZn pin
of clock output/buzzer output
0 Subsystem clock (fSUB)
Selecting the subsystem clock (f
SUB) is
enabled.
1 Low-speed on-chip oscillator clock (fIL)
Selecting the subsystem clock (f
SUB) is
disabled.
Note Be sure to select the subsystem clock (WUTMMCK0 bit = 0) if the subsystem clock is oscillating.
Cautions 1. The subsystem clock and low-speed on-chip oscillator clock can only be switched
by using the WUTMMCK0 bit if the real-time clock, 12-bit interval timer, and LCD
driver/controller are all stopped.
These are stopped as follows:
Real-time clock: Set the RTCE bit to 0.
12-bit interval timer: Set the RINTE bit to 0.
LCD driver/controller: Set the SCOC and VLCON bits to 0.
2. Do not select f
SUB as the clock output or buzzer output clock when the WUTMMCK0
bit is set to 1.
Remark RTCE: Bit 7 of real-time clock control register 0 (RTCC0)
RINTE: Bit 15 of the interval timer control register (ITMC)
SCOC: Bit 6 of LCD mode register 1 (LCDM1)
VLCON: Bit 5 of LCD mode register 1 (LCDM1)
<R>
<R>