r5s77631ay266bgv Renesas Electronics Corporation., r5s77631ay266bgv Datasheet - Page 830

• Manufacturer Part Number: r5s77631ay266bgv
• Description: Renesas 32-bit Risc Microcomputer Superhtm Risc Engine Family Sh-4a Series
• Manufacturer: Renesas Electronics Corporation.

Section 22 Realtime Clock (RTC)
22.4
22.4.1
R64CNT is an 8-bit read-only register that indicates a state of 64 Hz to 1 Hz within the RTC
frequency divider.
If this register is read when a carry is generated from the 128 kHz frequency division stage, bit 7
(CF) in RTC control register 1 (RCR1) is set to 1, indicating the simultaneous occurrence of the
carry and the 64 Hz counter read. In this case, the read value is not valid, and so R64CNT must be
read again after first writing 0 to the CF bit in RCR1 to clear it.
When the RESET bit or ADJ bit in RTC control register 2 (RCR2) is set to 1, the RTC frequency
divider is initialized and R64CNT is initialized to H'00.
R64CNT is not initialized by a power-on or manual reset.
Bit 7 is always read as 0 and cannot be modified.
22.4.2
RSECCNT is an 8-bit readable/writable register used as a counter for setting and counting the
BCD-coded second value in the RTC. It counts on the carry (transition of the R64CNT.1Hz bit
from 1 to 0) generated once per second by the 64 Hz counter.
The setting range is decimal 00 to 59. The RTC will not operate normally if any other value is set.
Write processing should be performed after stopping the count with the START bit in RCR2, or
by using the carry flag.
RSECCNT is not initialized by a power-on or manual reset.
Bit 7 is always read as 0. A write to this bit is invalid, but the write value should always be 0.
Rev. 1.00 Oct. 01, 2007 Page 764 of 1956
REJ09B0256-0100
Register Descriptions
64 Hz Counter (R64CNT)
Second Counter (RSECCNT)
Initial value:
Initial value:
R/W:
R/W:
Bit:
Bit:
—
—
R
R
7
0
7
0
1 Hz
R/W
—
—
10-second units
R
6
6
2 Hz
R/W
—
—
R
5
5
4 Hz
R/W
—
—
R
4
4
8 Hz
R/W
—
—
R
3
3
1-second units
16 Hz
R/W
—
—
R
2
2
32 Hz
R/W
—
—
R
1
1
64 Hz
R/W
—
—
R
0
0