RL78/G13 CHAPTER 7 REAL-TIME CLOCK
R01UH0146EJ0100 Rev.1.00 440
Sep 22, 2011
(7) Hour count register (HOUR)
The HOUR register is an 8-bit register that takes a value of 00 to 23 or 01 to 12 and 21 to 32 (decimal) and
indicates the count value of hours.
It counts up when the minute counter overflows.
When data is written to this register, it is written to a buffer and then to the counter up to 2 clocks (f
RTC) later. Even
if the minute count register overflows while this register is being written, this register ignores the overflow and is set
to the value written. Specify a decimal value of 00 to 23, 01 to 12, or 21 to 32 by using BCD code according to the
time system specified using bit 3 (AMPM) of real-time clock control register 0 (RTCC0).
If the AMPM bit value is changed, the values of the HOUR register change according to the specified time system.
If a value outside the range is set, the register value returns to the normal value after 1 period.
The HOUR register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 12H.
However, the value of this register is 00H if the AMPM bit (bit 3 of the RTCC0 register) is set to 1 after reset.
Figure 7-8. Format of Hour Count Register (HOUR)
Address: FFF94H After reset: 12H R/W
Symbol 7 6 5 4 3 2 1 0
HOUR 0 0 HOUR20 HOUR10 HOUR8 HOUR4 HOUR2 HOUR1
Cautions 1. Bit 5 (HOUR20) of the HOUR register indicates AM(0)/PM(1) if AMPM = 0 (if the 12-hour system
is selected).
2. When it reads or writes from/to the register while the counter is in operation (RTCE = 1),
follow the procedures described in the section 7.4.3 Reading/writing real-time clock.
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