isl12022m Intersil Corporation, isl12022m Datasheet - Page 20

• Manufacturer Part Number: isl12022m
• Description: Real Time Clock With Embedded Crystal, ??5ppm Accuracy
• Manufacturer: Intersil Corporation

DST Control Registers (DSTCR)
8 bytes of control registers have been assigned for the
Daylight Savings Time (DST) functions. DST beginning (set
Forward) time is controlled by the registers DstMoFd,
DstDwFd, DstDtFd, and DstHrFd. DST ending time (set
Backward or Reverse) is controlled by DstMoRv, DstDwRv,
DstDtRv and DstHrRv.
Tables 20 and 21 describe the structure and functions of the
DSTCR.
DST FORWARD REGISTERS (20H TO 23H)
DST forward is controlled by the following DST Registers:
DST Enable
DSTE is the DST Enabling Bit located in bit 7 of register 20h
(DstMoFdxx). Set DSTE = 1 will enable the DSTE function.
Upon powering up for the first time (including battery), the
DSTE bit defaults to “0”. When DSTE is set to “1” the RTC
time must be at least one hour before the scheduled DST
time change for the correction to take place. When DSTE is
set to “0”, the DSTADJ bit in the Status Register
automatically resets to “0”.
DST Month Forward
DstMoFd sets the Month that DST starts. The format is the
same as for the RTC register month, from 1 to 12. The
default value for the DST begin month is 00h.
DST Day/Week Forward
DstDwFd contains both the Day of the Week and the Week
of the Month data for DST Forward control. DST can be
controlled either by actual date or by setting both the Week
of the month and the Day of the Week. DstDwFdE sets the
priority of the Day/Week over the Date. For DstDwFdE = 1,
Day/Week is the priority. You must have the correct Day of
Week entered in the RTC registers for the Day/Week
correction to work properly.
ADDRESS
ADDRESS
24h
25h
26h
27h
20h
21h
22h
23h
Month Reverse
Month Forward
Hour Reverse
Date Reverse
Day Reverse
Hour Forward
Date Forward
Day Forward
FUNCTION
NAME
20
DSTE
7
0
0
0
0
7
0
0
0
DwFdE
DwRvE
TABLE 20. DST FORWARD REGISTERS
TABLE 21. DST REVERSE REGISTERS
6
0
0
0
6
0
0
0
WkFd12
ISL12022M
HrFd21
DtFd21
WkRv12
DtRv21
HrRv21
5
0
5
0
• Bits 0, 1, 2 contain the Day of the week information which
• Bits 3, 4, 5 contain the Week of the Month information that
DST Date Forward
DstDtfd controls which Date DST begins. The format for the
Date is the same as for the RTC register, from 1 to 31. The
default value for DST forward date is 00h. DstDtFd is only
effective if DstDwFdE = 0.
DST Hour Forward
DstHrFd controls the hour that DST begins. The RTC hour and
DstHrFd registers have the same formats except there is no
Military bit for DST hour. The user sets the DST hour with the
same format as used for the RTC hour (AM/PM or MIL) but
without the MIL bit, and the DST will still advance as if the MIL
bit were there. The default value for DST hour Forward is 00h.
DST REVERSE REGISTERS (24H TO 27H)
DST end (reverse) is controlled by the following DST Registers:
DST Month Reverse
DstMoRv sets the Month that DST ends. The format is the
same as for the RTC register month, from 1 to 12. The
default value for the DST end month is October (10h).
DST Day/Week Reverse
DstDwRv contains both the Day of the Week and the Week of
the Month data for DST Reverse control. DST can be controlled
either by actual date or by setting both the Week of the month
and the Day of the Week. DstDwRvE sets the priority of the
Day/Week over the Date. For DstDwRvE = 1, Day/Week is the
priority. You must have the correct Day of Week entered in the
RTC registers for the Day/Week correction to work properly.
MoFd20
WkFd11
MoRv20
DtFd20
HrFd20
WkRv11
DtRv20
HrRv20
sets the Day of the Week that DST starts. Note that Day of
the week counts from 0 to 6, like the RTC registers. The
default for the DST Forward Day of the Week is 00h
(normally Sunday).
sets the week that DST starts. The range is from 1 to 5, and
Week 7 is used to indicate the last week of the month. The
default for the DST Forward Week of the Month is 00h.
4
4
MoFd13
WkFd10
WkRv10
MoRv13
DtFd13
HrFd13
DtRv13
HrRv13
3
3
DwRv12
MoRv12
MoFd12
DwFd12
DtRv12
HrRv12
HrFd12
DtFd12
2
2
MoRv11
DwRv11
HrRv11
MoFd11
DwFd11
DtRv11
HrFd11
DtFd11
1
1
December 18, 2008
DwRv10
MoFd10
DwFd10
MoRv10
DtRv10
HrRv10
DtFd10
HrFd10
FN6668.4
0
0