Datasheet

CHAPTER 9 REAL-TIME COUNTER
User’s Manual U18698EJ1V0UD
264
9.3 Registers Controlling Real-Time Counter
Timer real-time counter is controlled by the following 16 registers.
(1) Real-time counter clock selection register (RTCCL)
This register controls the mode of real-time counter.
RTCCL can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 9-2. Format of Real-time Counter Clock Selection Register (RTCCL)
Address: FF54H After reset: 00H R/W
Symbol 7 6 5 4 3 2 <1> <0>
RTCCL 0 0 0 0 0 0 RTCCL1 RTCCL0
RTCCL1 RTCCL0 Control of real-time counter (RTC) input clock (fRTC)
0 0
f
SUB
0 1
f
PRS/2
7
1 0
f
PRS/2
8
1 1
Setting prohibited
Remark • When f
PRS = 4.19 MHz, fRTC = fPRS/2
7
= 32.768 kHz
• When fPRS = 8.38 MHz, fRTC = fPRS/2
8
= 32.768 kHz
(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.