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RL78/G1A CHAPTER 7 REAL-TIME CLOCK
7.3.7 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 two cycles of 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).
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If the AMPM bit value is changed, the values of the HOUR register change according to the specified time system.
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 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 7.4.3 Reading/writing real-time clock.
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Jul 04, 2013