Preliminary Information
X1288
Table 1. Clock/Control Memory Map (Continued)
Bit
Reg
3
Addr.
000F
000E
000D
000C
000B
000A
0009
0008
0007
Type
Name
Y2K1
DWA1
YRA1
MOA1
DTA1
HRA1
MNA1
SCA1
Y2K0
7
6
5
4
±
2
1
(optional) Range
Alarm1
(EEPROM)
Read-only - Default = 20h
20
20h
00h
EDW1
0
0
0
0
DY2
DY1
DY0
0-6
Unused - Default = RTC Year value (No EEPROM) - Future expansion
EMO1
EDT1
EHR1
EMN1
ESC1
0
0
0
A1G20
A1D20
A1H20
A1M20
A1S20
A1G13
A1D13
A1H13
A1M13
A1S13
A1G12
A1D12
A1H12
A1M12
A1S12
A1G11
A1D11
A1H11
A1M11
A1S11
A1G10
A1D10
A1H10
A1M10
A1S10
1-12
1-31
0-23
0-59
0-59
20
00h
00h
00h
00h
00h
20h
A1D21
A1H21
A1M21
A1S21
0
A1M22
A1S22
Alarm0
(EEPROM)
Read-only - Default = 20h
0006
0005
0004
0003
0002
0001
0000
DWA0
YRA0
MOA0
DTA0
HRA0
MNA0
SCA0
EDW0
0
0
0
0
DY2
DY1
DY0
0-6
00h
Unused - Default = RTC Year value (No EEPROM) – Future expansion
EMO0
EDT0
EHR0
EMN0
ESC0
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
A0D21
A0H21
A0M21
A0S21
0
A0M22
A0S22
ALARM REGISTERS
REAL TIME CLOCK REGISTERS
There are two alarm registers whose contents mimic the
contents of the RTC register, but add enable bits and
exclude the 24 hour time selection bit. The enable bits
specify which registers to use in the comparison between
the Alarm and Real Time Registers. For example:
Clock/Calendar Registers (SSEC, SC, MN, HR, DT,
MO, YR)
These registers depict BCD representations of the
time. As such, SSEC (1/100 Second) range from 00 to
99, 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. The SSEC
register is read-only.
– Setting the Enable Month bit (EMOn*) bit in combina-
tion with other enable bits and a specific alarm time,
the user can establish an alarm that triggers at the
same time once a year.
*n = 0 for Alarm 0: N = 1 for Alarm 1
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’.
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.
24 Hour Time
– The user can set the X1288 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.
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.
– 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
13 of 31
REV 1.1.30 3/24/04
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