8 Real-TiMe ClOCK (RTC)
8-16
Seiko epson Corporation
S1C17624/604/622/602/621 TeChniCal Manual
D[7:4]
RTCYh[3:0]: RTC 10-year Counter Bits
These bits comprise a 4-bit BCD counter used to count tens of years. The counter counts from 0 to 9
with a carry over of 1 from the 1-year counter.
D[3:0]
RTCYl[3:0]: RTC 1-year Counter Bits
These bits comprise a 4-bit BCD counter used to count units of years.
The counter counts from 0 to 9 with a carry over of 1 from the month counter. This counter is reset to 0
after 9 and outputs a carry over of 1 to the 10-year counter.
RTC Days of Week Register (RTC_WeeK)
Register name address
Bit
name
Function
Setting
init. R/W
Remarks
RTC Days of
Week Register
(RTC_WeeK)
0x514a
(8 bits)
D7–3 –
reserved
–
–
–
0 when being read.
D2–0 RTCWK[2:0] RTC days of week counter
RTCWK[2:0]
Days of week X (
*
) R/W
0x7
0x6
0x5
0x4
0x3
0x2
0x1
0x0
–
Saturday
Friday
Thursday
Wednesday
Tuesday
Monday
Sunday
*
Software reset (RTCRST
→
1
→
0) does not affect the counter values. This register retains the value set before a software reset is
performed.
notes: • Data should not be read from or written to the counters while 1 is being carried over. (See
Section 8.3.5, “Counter Hold and Busy Flag,” and Section 8.3.7, “Counter Read.”)
• Rewriting RTC24H/RTC_CNTL0 register may corrupt the count data in this register. Therefore,
after changing the RTC24H setting, be sure to set up this register again.
D[7:3]
Reserved
D[2:0]
RTCWK[2:0]: RTC Days of Week Counter Bits
This is a septenary counter (that counts from 0 to 6) representing days of the week. This counter counts
at the same timing as the 1-day counter.
The correspondence between the counter values and days of the week can be set in a program as de-
sired. Table 8.5.3 lists the basic correspondence.
5.3 Correspondence between Counter Values and Days of the Week
Table 8.
RTCWK[2:0]
Days of the week
0x6
Saturday
0x5
Friday
0x4
Thursday
0x3
Wednesday
0x2
Tuesday
0x1
Monday
0x0
Sunday
(Default: indeterminate, software reset: previous value retained)