SH7750_08 Datasheet, PDF (411/1162 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 11 Realtime Clock (RTC)
Bit 2—30-Second Adjustment (ADJ): Used for 30-second adjustment. When 1 is written to this
bit, a value up to 29 seconds is rounded down to 00 seconds, and a value of 30 seconds or more is
rounded up to 1 minute. The frequency divider circuits (RTC prescaler and R64CNT) are also
reset at this time. This bit always returns 0 if read.
Bit 2: ADJ
0
1
Description
Normal clock operation
30-second adjustment performed
(Initial value)
Bit 1—Reset (RESET): The frequency divider circuits are initialized by writing 1 to this bit.
When 1 is written to the RESET bit, the frequency divider circuits (RTC prescaler and R64CNT)
are reset and the RESET bit is automatically cleared to 0 (i.e. does not need to be written with 0).
Bit 1: RESET
0
1
Description
Normal clock operation
Frequency divider circuits are reset
(Initial value)
Bit 0—Start Bit (START): Stops and restarts counter (clock) operation.
Bit 0: START
Description
0
Second, minute, hour, day, day-of-week, month, and year counters are
stopped*
1
Second, minute, hour, day, day-of-week, month, and year counters operate
normally*
(Initial value)
Note: * The 64 Hz counter continues to operate unless stopped by means of the RTCEN bit.
11.2.17 RTC Control Register 3 (RCR3) and Year-Alarm Register (RYRAR)
(SH7750R Only)
RCR3 and RYRAR are readable/writable registers. RYRAR is the alarm register for the RTC's
BCD-coded year-value counter RYRCNT. When the YENB bit of RCR3 is set to 1, the RYRCNT
value is compared with the RYRAR value. Comparison between the counter and the alarm register
only takes place with the alarm registers in which the ENB and YENB bits are set to 1. The alarm
flag of RCR1 is only set to 1 when the respective values all match.
The setting range of RYRAR is decimal 0000 to 9999, and normal operation is not obtained if a
value beyond this range is set here.
Rev.7.00 Oct. 10, 2008 Page 327 of 1074
REJ09B0366-0700