NEC 78K0R/KE3 User Manual page 269

(5) Sub-count register (RSUBC)
The RSUBC register is a 16-bit register that counts the reference time of 1 second of the real-time counter. It
takes a value of 0000H to 7FFFH and counts 1 second with a clock of 32.768 kHz.
RSUBC can be set by a 16-bit memory manipulation instruction.
Reset signal generation clears this register to 0000H.
Cautions 1. When a correction is made by using the SUBCUD register, the value may become 8000H
or more.
2. This register is also cleared by reset effected by writing the second count register.
3. The value read from this register is not guaranteed if it is read during operation, because
a value that is changing is read.
Address: FFF90H After reset: 0000H
Symbol 7
RSUBC SUBC7
Address: FFF91H After reset: 0000H
Symbol 7
RSUBC SUBC15
(6) Second count register (SEC)
The SEC register is an 8-bit register that takes a value of 0 to 59 (decimal) and indicates the count value of
seconds.
It counts up when the sub-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.
SEC can be set by an 8-bit memory manipulation instruction.
Reset signal generation clears this register to 00H.
Address: FFF92H After reset: 00H
Symbol 7
SEC 0
CHAPTER 7 REAL-TIME COUNTER
Figure 7-6. Format of Sub-Count Register (RSUBC)
R
6 5
SUBC6 SUBC5
R
6 5
SUBC14 SUBC13 SUBC12
Figure 7-7. Format of Second Count Register (SEC)
R/W
6 5
SEC40 SEC20
User's Manual U17854EJ9V0UD
4 3
SUBC4 SUBC3 SUBC2
4 3
SUBC11 SUBC10
4 3
SEC10 SEC8
2 1
SUBC1 SUBC0
2 1
SUBC9 SUBC8
2 1
SEC4 SEC2 SEC1
0
0
0
269