Section 20 Realtime Clock (RTC)
Rev.1.00 Dec. 13, 2005 Page 712 of 1286
REJ09B0158-0100
20.3.1
64 Hz Counter (R64CNT)
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 Hz 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.
0
1
2
3
4
5
6
7
—
—
—
—
—
—
—
0
64 Hz
32 Hz
16 Hz
8 Hz
4 Hz
2 Hz
1 Hz
—
R
R
R
R
R
R
R
R
BIt:
Initial value:
R/W:
20.3.2 Second
Counter
(RSECCNT)
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.
0
1
2
3
4
5
6
7
—
—
—
—
—
—
—
0
1-second units
10-second units
—
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R
BIt:
Initial value:
R/W:
Summary of Contents for SH7780 Series
Page 2: ...Rev 1 00 Dec 13 2005 Page ii of l ...
Page 28: ...Rev 1 00 Dec 13 2005 Page xxviii of l ...
Page 50: ...Rev 1 00 Dec 13 2005 Page l of l ...
Page 82: ...Section 1 Overview Rev 1 00 Dec 13 2005 Page 32 of 1286 REJ09B0158 0100 ...
Page 122: ...Section 3 Instruction Set Rev 1 00 Dec 13 2005 Page 72 of 1286 REJ09B0158 0100 ...
Page 146: ...Section 4 Pipelining Rev 1 00 Dec 13 2005 Page 96 of 1286 REJ09B0158 0100 ...
Page 196: ...Section 6 Floating Point Unit FPU Rev 1 00 Dec 13 2005 Page 146 of 1286 REJ09B0158 0100 ...
Page 292: ...Section 9 L Memory Rev 1 00 Dec 13 2005 Page 242 of 1286 REJ09B0158 0100 ...
Page 492: ...Section 12 DDR SDRAM Interface DDRIF Rev 1 00 Dec 13 2005 Page 442 of 1286 REJ09B0158 0100 ...
Page 674: ...Section 15 Clock Pulse Generator CPG Rev 1 00 Dec 13 2005 Page 624 of 1286 REJ09B0158 0100 ...
Page 692: ...Section 16 Watchdog Timer and Reset Rev 1 00 Dec 13 2005 Page 642 of 1286 REJ09B0158 0100 ...
Page 726: ...Section 18 Timer Unit TMU Rev 1 00 Dec 13 2005 Page 676 of 1286 REJ09B0158 0100 ...
Page 1032: ...Section 25 Audio Codec Interface HAC Rev 1 00 Dec 13 2005 Page 982 of 1286 REJ09B0158 0100 ...
Page 1150: ...Section 28 General Purpose I O GPIO Rev 1 00 Dec 13 2005 Page 1100 of 1286 REJ09B0158 0100 ...
Page 1184: ...Section 29 User Break Controller UBC Rev 1 00 Dec 13 2005 Page 1134 of 1286 REJ09B0158 0100 ...
Page 1266: ...Section 31 Electrical Characteristics Rev 1 00 Dec 13 2005 Page 1216 of 1286 REJ09B0158 0100 ...
Page 1328: ...Appendix Rev 1 00 Dec 13 2005 Page 1278 of 1286 REJ09B0158 0100 ...
Page 1336: ...Rev 1 00 Dec 13 2005 Page 1286 of 1286 REJ09B0158 0100 ...
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