X1228
Table 1. Clock/Control Memory Map (Continued)
Bit
Reg
Addr.
Type
Range
Name
7
6
5
4
3
2
1
0 (optional)
0013
0012
0011
0010
000F
000E
000D
000C
000B
000A
0009
0008
0007
0006
0005
0004
0003
0002
0001
0000
Control
(EEPROM)
DTR
ATR
INT
0
0
0
0
0
0
0
DTR2
ATR2
x
DTR1
ATR1
x
DTR0
00h
00h
00h
18h
20h
00h
ATR5
AL0E
BP0
ATR4
FO1
ATR3
FO0
ATR0
IM
BP2
0
AL1E
BP1
0
x
BL
WD1
WD0
0
0
0
Alarm1
(EEPROM)
Y2K1
A1Y2K21 A1Y2K20 A1Y2K13
0
0
A1Y2K10 19/20
DWA1 EDW1
YRA1
0
0
0
0
DY2
DY1
DY0
0-6
Unused - Default = RTC Year value (No EEPROM) - Future expansion
MOA1 EMO1
0
0
A1G20
A1D20
A1H20
A1M20
A1S20
A1G13
A1D13
A1H13
A1M13
A1S13
A1G12
A1D12
A1H12
A1M12
A1S12
0
A1G11
A1D11
A1H11
A1M11
A1S11
0
A1G10
A1D10
A1H10
A1M10
A1S10
1-12
1-31
0-23
0-59
0-59
00h
00h
00h
00h
00h
20h
00h
DTA1
HRA1
EDT1
EHR1
0
A1D21
A1H21
A1M21
A1S21
0
A1M22
A1S22
0
MNA1 EMN1
SCA1
Y2K0
ESC1
0
Alarm0
(EEPROM)
A0Y2K21 A0Y2K20 A0Y2K13
A0Y2K10 19/20
DWA0 EDW0
YRA0
0
0
0
0
DY2
DY1
DY0
0-6
Unused - Default = RTC Year value (No EEPROM) - Future expansion
MOA0 EMO0
0
0
0
A0G20
A0D20
A0H20
A0M20
A0S20
A0G13
A0D13
A0H13
A0M13
A0S13
A0G12
A0D12
A0H12
A0M12
A0S12
A0G11
A0D11
A0H11
A0M11
A0S11
A0G10
A0D10
A0H10
A0M10
A0S10
1-12
1-31
0-23
0-59
0-59
00h
00h
00h
00h
00h
DTA0
HRA0
EDT0
EHR0
A0D21
A0H21
A0M21
A0S21
0
MNA0 EMN0
SCA0 ESC0
A0M22
A0S22
When there is a match, an alarm flag is set. The occur-
rence of an alarm can be determined by polling the
AL0 and AL1 bits or by enabling the IRQ output, using
it as hardware flag.
Date of the Week Register (DW)
This register provides a Day of the Week status and
uses three bits DY2 to DY0 to represent the seven days
of the week. The counter advances in the cycle 0-1-2-
3-4-5-6-0-1-2-… The assignment of a numerical value
to a specific day of the week is arbitrary and may be
decided by the system software designer. The default
value is defined as ‘0’.
The alarm enable bits are located in the MSB of the
particular register. When all enable bits are set to ‘0’,
there are no alarms.
– The user can set the X1228 to alarm every Wednes-
day at 8:00 AM by setting the EDWn*, the EHRn*
and EMNn* enable bits to ‘1’ and setting the DWAn*,
HRAn* and MNAn* Alarm registers to 8:00 AM
Wednesday.
– A daily alarm for 9:30PM results when the EHRn*
and EMNn* enable bits are set to ‘1’ and the HRAn*
and MNAn* registers are set to 9:30 PM.
24 Hour Time
If the MIL bit of the HR register is 1, the RTC uses a
24-hour format. If the MIL bit is 0, the RTC uses a 12-
hour format and H21 bit functions as an AM/PM indica-
tor with a ‘1’ representing PM. The clock defaults to
standard time with H21=0.
Leap Years
*n = 0 for Alarm 0: N = 1 for Alarm 1
Leap years add the day February 29 and are defined
as those years that are divisible by 4.Years divisible by
100 are not leap years, unless they are also divisible
by 400. This means that the year 2000 is a leap year,
the year 2100 is not. The X1228 does not correct for
the leap year in the year 2100.
REAL TIME CLOCK REGISTERS
Clock/Calendar Registers (SC, MN, HR, DT, MO, YR)
These registers depict BCD representations of the
time. As such, SC (Seconds) and MN (Minutes) range
from 00 to 59, HR (Hour) is 1 to 12 with an AM or PM
indicator (H21 bit) or 0 to 23 (with MIL=1), DT (Date) is
1 to 31, MO (Month) is 1 to 12, YR (Year) is 0 to 99.
Characteristics subject to change without notice. 12 of 31
REV 1.3 3/24/04
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