RL78/G13 CHAPTER 7 REAL-TIME CLOCK
R01UH0146EJ0100 Rev.1.00 442
Sep 22, 2011
(8) Day count register (DAY)
The DAY register is an 8-bit register that takes a value of 1 to 31 (decimal) and indicates the count value of days.
It counts up when the hour counter overflows.
This counter counts as follows.
• 01 to 31 (January, March, May, July, August, October, December)
• 01 to 30 (April, June, September, November)
• 01 to 29 (February, leap year)
• 01 to 28 (February, normal 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 hour 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 31 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 DAY register can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 01H.
Figure 7-9. Format of Day Count Register (DAY)
Address: FFF96H After reset: 01H R/W
Symbol 7 6 5 4 3 2 1 0
DAY 0 0 DAY20 DAY10 DAY8 DAY4 DAY2 DAY1
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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