RL78/G1H CHAPTER 9 REAL-TIME CLOCK
R01UH0575EJ0120 Rev. 1.20 Page 245 of 920
Dec 22, 2016
9.3.7 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).
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 (bit 3 of the RTCC0 register) is set to 1 after reset.
Figure 9 - 9 Format of Hour count register (HOUR)
Caution 1. Bit 5 (HOUR20) of the HOUR register indicates AM(0)/PM(1) if AMPM = 0 (if the 12-hour system is
selected).
Caution 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 9.4.3 Reading/writing real-time clock.
Address: FFF94H After reset: 12H R/W
Symbol76543210
HOUR 0 0 HOUR20 HOUR10 HOUR8 HOUR4 HOUR2 HOUR1
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