8 Real-TiMe ClOCK (RTC)
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
8-9
Also be sure to write 1 to RTCIRQ to reset it.
When a software reset is performed (RTCRST
→
1
→
0), RTCIRQ and RTCIEN are reset to 0 to disable the
interrupt request output. Also RTCT[2:0] is reset to 0x1.
Details of Control Registers
8.5
5.1 RTC Register List
Table 8.
address
Register name
Function
0x506e
RTC_CC
RTC Clock Control Register
Controls the RTC clock source.
0x5140
RTC_INTSTAT
RTC Interrupt Status Register
Indicates RTC interrupt status.
0x5141
RTC_INTMODE
RTC Interrupt Mode Register
Sets up RTC interrupt modes.
0x5142
RTC_CNTL0
RTC Control 0 Register
Controls the RTC.
0x5143
RTC_CNTL1
RTC Control 1 Register
0x5144
RTC_SEC
RTC Second Register
Second counter data
0x5145
RTC_MIN
RTC Minute Register
Minute counter data
0x5146
RTC_HOUR
RTC Hour Register
Hour counter data
0x5147
RTC_DAY
RTC Day Register
Day counter data
0x5148
RTC_MONTH
RTC Month Register
Month counter data
0x5149
RTC_YEAR
RTC Year Register
Year counter data
0x514a
RTC_WEEK
RTC Days of Week Register
Days of week counter data
The following describes each RTC register. These are all 8-bit registers.
notes: • When data is written to the register, the “Reserved” bits must always be written as 0 and not 1.
• The contents of all RTC control registers are indeterminate when power is turned on, and are
not initialized to specific values by initial reset. These registers should be initialized in software.
• If 1 is being carried over when the counters are accessed for read, the correct counter value
may not be read out. Moreover, attempting to write to a counter or other control register may
corrupt the counter value. Therefore, do not write to counters while 1 is being carried over. For
the correct method of operation, see Section 8.3.5, “Counter Hold and Busy Flag,” and Section
8.3.7, “Counter Read.”
RTC Clock Control Register (RTC_CC)
Register name address
Bit
name
Function
Setting
init. R/W
Remarks
RTC Clock
Control Register
(RTC_CC)
0x506e
(8 bits)
D7–1 –
reserved
–
–
–
0 when being read.
D0
RTCCe
RTC clock enable
1 Enable
0 Disable
0
R/W
D[7:1]
Reserved
D0
RTCCe: RTC Clock enable Bit
Enables or disables the OSC1 clock supply to the RTC.
1 (R/W): Enabled (on)
0 (R/W): Disabled (off) (default)
The RTCCE default setting is 0, which disables the clock supply. Setting RTCCE to 1 sends the OSC1
clock to the RTC. When the OSC1 oscillator circuit is stopped, writing 1 to RTCCE turns it on (note,
however, that the OSC1 clock is not supplied to other peripheral circuits than the RTC). When RTCCE
is set to 1, the OSC1 oscillator circuit does not stop even if the IC enters SLEEP mode (the OSC1 clock
will be supplied to the RTC only).
When RTCCE is set to 0, RTC interrupt requests generated by RTCIEN/RTC_INTMODE register and
RTCIRQ/RTC_INTSTAT register are masked to prevent occurrence of undesired interrupts.