NEC 78K0R/KE3 User Manual page 264

(1) Peripheral enable register 0 (PER0)
PER0 is used to enable or disable use of each peripheral hardware macro. 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 counter is used, be sure to set bit 7 (RTCEN) of this register to 1.
PER0 can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Address: F00F0H After reset: 00H
Symbol <7>
PER0 RTCEN
RTCEN
0
1
Note RTCEN is used to supply or stop the clock used when accessing the real-time counter (RTC)
register from the CPU. RTCEN cannot control supply of the operating clock (f
Cautions 1. When using the real-time counter, first set RTCEN to 1, while oscillation of the
(2) Real-time counter control register 0 (RTCC0)
The RTCC0 register is an 8-bit register that is used to start or stop the real-time counter operation, control the
RTCCL and RTC1HZ pins, and set a 12- or 24-hour system and the constant-period interrupt function.
RTCC0 can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
264
CHAPTER 7 REAL-TIME COUNTER
Figure 7-2. Format of Peripheral Enable Register 0 (PER0)
R/W
6 <5>
0 DACEN
Control of real-time counter (RTC) input clock supply
Stops supply of input clock.
• SFR used by the real-time counter (RTC) cannot be written.
• The real-time counter (RTC) is in the reset status.
Supplies input clock.
• SFR used by the real-time counter (RTC) can be read/written.
subsystem clock (f
SUB
real-time counter is ignored, and, even if the register is read, only the default
value is read.
2. Be sure to clear bits 1, 6 of the PER0 register to 0.
User's Manual U17854EJ9V0UD
<4> <3>
IIC0EN SAU1EN
) is stable. If RTCEN = 0, writing to a control register of the
<2> 1
SAU0EN 0 TAU0EN
Note
) to RTC.
SUB
<0>