8 Real-TiMe ClOCK (RTC)
S1C17624/604/622/602/621 TeChniCal Manual
Seiko epson Corporation
8-11
D1
RTCiMD: RTC interrupt Mode Select Bit
This bit specifies whether RTC interrupts are to be generated by an edge or level of the interrupt request
signal.
1 (R/W): Level sensed (software reset value)
0 (R/W): Edge triggered
When an edge-triggered interrupt is selected and used to turn off SLEEP mode via the CLG, note that
no interrupts will be generated because the ITC is inactive. When an RTC interrupt handler routine must
be executed after exiting SLEEP mode, select a level-sensed interrupt.
D0
RTCien: RTC interrupt enable Bit
This bit enables or disables RTC interrupt request output to the ITC.
1 (R/W): Enable interrupts
0 (R/W): Disable interrupts (software reset value)
To generate an RTC interrupt or use an RTC interrupt request signal to turn off SLEEP mode, set this
bit to 1. When this bit is 0, no interrupts are generated and SLEEP mode cannot be turned off.
note: The value of RTCIEN is indeterminate after power-on, and not initialized to 0 by initial reset. To
prevent the occurrence of unwanted RTC interrupts, be sure to clear this bit in software after
power-on and initial reset.
RTC Control 0 Register (RTC_CnTl0)
Register name address
Bit
name
Function
Setting
init. R/W
Remarks
RTC Control 0
Register
(RTC_CnTl0)
0x5142
(8 bits)
D7–5 –
reserved
–
–
–
0 when being read.
D4
RTC24h
24H/12H mode select
1 24H
0 12H
X (0) R/W
D3
–
reserved
–
–
–
0 when being read.
D2
RTCaDJ
30-second adjustment
1 Adjust
0 –
X (0) R/W
D1
RTCSTP
Divider run/stop control
1 Stop
0 Run
X (0) R/W
D0
RTCRST
Software reset
1 Reset
0 –
X (0) R/W
Init.: ( ) indicates the value set after a software reset (RTCRST
→
1
→
0) is performed.
D[7:5]
Reserved
D4
RTC24h: 24h/12h Mode Select Bit
This bit selects whether to use the hour counter in 24-hour or 12-hour mode.
1 (R/W): 24-hour mode
0 (R/W): 12-hour mode (software reset value)
The count range of hour counters changes with this selection. Basically, this setting should be changed
while the counters are idle. Since this register is assigned a control bit (D1) to start the counters, 12-
hour or 24-hour mode may be selected when starting the counters.
note: Rewriting RTC24H may corrupt the count data for hours, days, months, years, or days of the
week. Therefore, after changing the RTC24H setting, be sure to set data back in these coun-
ters again.
D3
Reserved
D2
RTCaDJ: 30-second adjustment Bit
This bit executes 30-second correction.
1 (W):
Execute 30-second correction
0 (W):
Has no effect
1 (R):
30-second correction being executed
0 (R):
30-second correction completed (not being executed) (software reset value)
The description “30-second correction” means adding 1 to the minutes when seconds of the time clock
are in the 30-to-59 second range, and doing nothing in the 0-to-29 second range. This function may be
used to round up seconds to minutes when resetting seconds in an application.