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CHAPTER 9 REAL-TIME COUNTER
User’s Manual U19780EJ2V0UD
294
(6) Minute count register (MIN)
The MIN register is an 8-bit register that takes a value of 0 to 59 (decimal) and indicates the count value of
minutes.
It counts up when the second counter overflows.
When data is written to this register, it is written to a buffer and then to the counter up to 2 clocks (32.768 kHz)
later. Set a decimal value of 00 to 59 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.
MIN can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Figure 9-7. Format of Minute Count Register (MIN)
Address: FF73H After reset: 00H R/W
Symbol
7 6 5 4 3 2 1 0
MIN
0 MIN40
MIN20
MIN10 MIN8 MIN4 MIN2 MIN1
(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, 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 (32.768 kHz)
later. Set a decimal value of 00 to 23, 01 to 12, or 21 to 32 by using BCD code. If a value outside the range is
set, the register value returns to the normal value after 1 period.
HOUR 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 9-8. Format of Hour Count Register (HOUR)
Address: FF74H After reset: 12H R/W
Symbol
7 6 5 4 3 2 1 0
HOUR 0
0
HOUR20
HOUR10
HOUR8 HOUR4 HOUR2 HOUR1
Caution Bit 5 (HOUR20) of HOUR indicates AM(0)/PM(1) if AMPM = 0 (if the 12-hour system is selected).