
iiiPeriPheraLModuLes1(systeM):reaL-tiMeCLoCk(rtC)
iii-3-16
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s1C33L17teChniCaLManuaL
0x301908:rtCControlregister(prtC_CntL0)
name
address
registername
Bit
Function
setting
init. r/W
remarks
–
rtC24h
–
rtCadJ
rtCstP
rtCrst
D31–5
D4
D3
D2
D1
D0
reserved
24H/12Hmodeselect
reserved
30-secondadjustment
Counterrun/stopcontrol
Softwarereset
–
X
–
X
–
R/W
–
R/W
0whenbeingread.
00301908
(W)
rtCcontrol
register
(pRTC_CNTL0)
–
1 24H
0 12H
1 Stop
0 Run
1 Adjust
0 –
1 Reset
0 –
d[31:5] reserved
d4
rtC24h:24h/12hModeselectBit
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
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
countersagain.
d3
reserved
d2
rtCadJ:30-secondadjustmentBit
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)
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.
Writing 1 to this bit causes the RTC to operate as follows:
When the 10-second counter is 3 or more, the RTC generates a carry over of 1 to start counting by
the 1-minute counter.
When the 10-second counter is 2 or less, the RTC does not generate a carry over of 1.
After being set to 1, this bit remains set for the 4-ms period needed for the processing above, then is
automatically reset to 0.
note: AccessingthecounterswhileRTCADJ=1isprohibited.Writing0tothisbitduringsuchtime
isalsoprohibited,becauseitwouldcausetheRTCtooperateerratically.