Datasheet

RL78/L12 CHAPTER 7 REAL-TIME CLOCK
R01UH0330EJ0200 Rev.2.00 287
Dec 13, 2013
7.3.1 Peripheral enable register 0 (PER0)
This register is used to enable or disable supplying the clock to the peripheral hardware. Clock supply to a hardware
macro that is not used is stopped in order to reduce the power consumption and noise.
When the real-time clock is used, be sure to set bit 7 (RTCEN) of this register to 1.
The PER0 register can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 7-2. Format of Peripheral Enable Register 0 (PER0)
Address: F00F0H After reset: 00H R/W
Symbol <7> 6 <5> <4> 3 <2> 1 <0>
PER0 RTCEN 0 ADCEN IICA0EN 0 SAU0EN 0 TAU0EN
RTCEN
Real-time clock (RTC) and
12-bit interval timer
LCD driver/controller and clock output/buzzer output controller
When subsystem clock (fSUB)
is selected
When subsystem clock (fSUB)
is not selected
0
Stops input clock supply.
• SFR used by the real-time
clock (RTC) and 12-bit
interval timer cannot be
written.
• The real-time clock (RTC)
and 12-bit interval timer
are in the reset status.
Stops input clock and
subsystem clock supply.
• SFR used by the LCD
driver/controller and clock
output/buzzer output can
be read and written.
Enables input clock and
main system clock supply.
• SFR used by the LCD
driver/controller and clock
output/buzzer output can
be read and written.
1
Enables input clock supply.
• SFR used by the real-time
clock (RTC) and 12-bit
interval timer can be read
and written.
Enables input clock and
subsystem clock supply.
• SFR used by the LCD
driver/controller and clock
output/buzzer output can
be read and written.
Cautions 1. When using the real-time clock, first set the RTCEN bit to 1 and then set the
following registers, while oscillation of the count clock (f
RTC) is stable. If RTCEN
= 0, writing to the control registers of the real-time clock is ignored, and, even if
the registers are read, only the default values are read (except for the subsystem
clock supply mode control register (OSMC), port mode register 3 (PM3), port
register 3 (P3)).
• 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)
2. The subsystem clock supply to peripheral functions other than the real-time
clock, 12-bit interval timer, and LCD driver/controller can be stopped in HALT
<R>
<R>