X1228 Datasheet, PDF (12/31 Pages) Xicor Inc. – Real Time Clock/Calendar/CPU Supervisor with EEPROM

X1228
Table 1. Clock/Control Memory Map (Continued)
Addr.
Type
Reg
Name
7
6
5
Bit
4
3
2
Range
1
0 (optional)
0013 Control DTR
0
0
0
0
0
DTR2
DTR1
DTR0
00h
0012 (EEPROM) ATR
0
0
ATR5
ATR4
ATR3
ATR2
ATR1
ATR0
00h
0011
INT
IM
AL1E AL0E
FO1
FO0
x
x
x
00h
0010
BL
BP2
BP1
BP0
WD1
WD0
0
0
0
18h
000F Alarm1 Y2K1 0
0 A1Y2K21 A1Y2K20 A1Y2K13
0
0
A1Y2K10 19/20 20h
000E (EEPROM) DWA1 EDW1
0
0
0
0
DY2
DY1
DY0
0-6 00h
000D
YRA1
Unused - Default = RTC Year value (No EEPROM) - Future expansion
000C
MOA1 EMO1
0
0
A1G20 A1G13 A1G12 A1G11 A1G10 1-12 00h
000B
DTA1 EDT1
0
A1D21 A1D20 A1D13 A1D12 A1D11 A1D10 1-31 00h
000A
HRA1 EHR1
0
A1H21 A1H20 A1H13 A1H12 A1H11 A1H10 0-23 00h
0009
MNA1 EMN1 A1M22 A1M21 A1M20 A1M13 A1M12 A1M11 A1M10 0-59 00h
0008
SCA1 ESC1 A1S22 A1S21 A1S20 A1S13 A1S12 A1S11 A1S10 0-59 00h
0007 Alarm0 Y2K0 0
0 A0Y2K21 A0Y2K20 A0Y2K13
0
0
A0Y2K10 19/20 20h
0006 (EEPROM) DWA0 EDW0
0
0
0
0
DY2
DY1
DY0
0-6 00h
0005
YRA0
Unused - Default = RTC Year value (No EEPROM) - Future expansion
0004
MOA0 EMO0
0
0
A0G20 A0G13 A0G12 A0G11 A0G10 1-12 00h
0003
DTA0 EDT0
0
A0D21 A0D20 A0D13 A0D12 A0D11 A0D10 1-31 00h
0002
HRA0 EHR0
0
A0H21 A0H20 A0H13 A0H12 A0H11 A0H10 0-23 00h
0001
MNA0 EMN0 A0M22 A0M21 A0M20 A0M13 A0M12 A0M11 A0M10 0-59 00h
0000
SCA0 ESC0 A0S22 A0S21 A0S20 A0S13 A0S12 A0S11 A0S10 0-59 00h
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.
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.
*n = 0 for Alarm 0: N = 1 for Alarm 1
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.
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’.
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
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.
REV 1.3 3/24/04
www.xicor.com
Characteristics subject to change without notice. 12 of 31