RL78/G13 CHAPTER 7 REAL-TIME CLOCK
R01UH0146EJ0100 Rev.1.00 444
Sep 22, 2011
(10) Month count register (MONTH)
The MONTH register is an 8-bit register that takes a value of 1 to 12 (decimal) and indicates the count value of
months.
It counts up when the day 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 day count register overflows while this register is being written, this register ignores the overflow and is set to
the value written. Set a decimal value of 01 to 12 to this register in BCD code. If a value outside the range is set,
the register value returns to the normal value after 1 period.
The MONTH register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 01H.
Figure 7-11. Format of Month Count Register (MONTH)
Address: FFF97H After reset: 01H R/W
Symbol 7 6 5 4 3 2 1 0
MONTH 0 0 0 MONTH10 MONTH8 MONTH4 MONTH2 MONTH1
Caution 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.
(11) Year count register (YEAR)
The YEAR register is an 8-bit register that takes a value of 0 to 99 (decimal) and indicates the count value of years.
It counts up when the month count register (MONTH) overflows.
Values 00, 04, 08, …, 92, and 96 indicate a leap year.
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 MONTH register overflows while this register is being written, this register ignores the overflow and is set to
the value written. Set a decimal value of 00 to 99 to this register in BCD code. If a value outside the range is set,
the register value returns to the normal value after 1 period.
The YEAR register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 7-12. Format of Year Count Register (YEAR)
Address: FFF98H After reset: 00H R/W
Symbol 7 6 5 4 3 2 1 0
YEAR YEAR80 YEAR40 YEAR20 YEAR10 YEAR8 YEAR4 YEAR2 YEAR1
Caution 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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