Revision 1.1
87
www.national.com
G
SuperI/O Module
(Continued)
Table 4-18. RTC Registers
Bit
Description
Index 00h
Width: Byte
Seconds Register - SEC (R/W)
Reset Type: V
PP
PUR
7:0
Seconds Data.
Values may be 00 to 59 in BCD format or 00 to 3B in binary format.
Index 01h
Width: Byte
Seconds Alarm Register - SECA (R/W)
Reset Type: V
PP
PUR
7:0
Seconds Alarm Data.
Values may be 00 to 59 in BCD format or 00 to 3B in binary format.
When bits 7 and 6 are both set to one (“11”), unconditional match is selected.
Index 02h
Width: Byte
Minutes Register - MIN (R/W)
Reset Type: V
PP
PUR
7:0
Minutes Data.
Values can be 00 to 59 in BCD format, or 00 to 3B in binary format.
Index 03h
Width: Byte
Minutes Alarm Register - MINA (R/W)
Reset Type: V
PP
PUR
7:0
Minutes Alarm Data.
Values can be 00 to 59 in BCD format, or 00 to 3B in binary format.
When bits 7 and 6 are both set to 1, unconditional match is selected. See Section 4.5.3.2 "Alarms" on page 82 for more
information about “unconditional” matches.
Index 04h
Width: Byte
Hours Register - HOR (R/W)
Reset Type: V
PP
PUR
7:0
Hours Data.
For 12-hour mode, values can be 01 to 12 (AM) and 81 to 92 (PM) in BCD format, or 01 to 0C (AM) and 81 to
8C (PM) in binary format. For 24-hour mode, values can be 0 to 23 in BCD format or 00 to 17 in binary format.
Index 05h
Width: Byte
Hours Alarm Register - HORA (R/W)
Reset Type: V
PP
PUR
7:0
Hours Alarm Data.
For 12-hour mode, values may be 01 to 12 (AM) and 81 to 92 (PM) in BCD format or 01 to 0C (AM) and
81 to 8C (PM) in Binary format. For 24-hour mode, values may be 0 to 23 in BCD format or 00 to 17 in Binary format.
When bits 7 and 6 are both set to one (“11”), unconditional match is selected.
Index 06h
Width: Byte
Day of Week Register - DOW (R/W)
Reset Type: V
PP
PUR
7:0
Day Of Week Data.
Values may be 01 to 07 in BCD format or 01 to 07 in binary format.
Index 07h
Width: Byte
Date of Month Register - DOM (R/W)
Reset Type: V
PP
PUR
7:0
Date Of Month Data.
Values may be 01 to 31 in BCD format or 01 to 1F in binary format.
Index 08h
Width: Byte
Month Register - MON (R/W)
Reset Type: V
PP
PUR
7-0
Month Data.
Values may be 01 to 12 in BCD format or 01 to 0C in binary format.
Index 09h
Width: Byte
Year Register - YER (R/W)
Reset Type: V
PP
PUR
7:0
Year Data.
Values may be 00 to 99 in BCD format or 00 to 63 in binary format.
Index 0Ah
Width: Byte
This register controls test selection, among other functions. This register cannot be written before reading bit 7 of CRD.
RTC Control Register A - CRA (R/W)
Reset Type: Bit Specific
7
Update in Progress. (RO)
This bit is not affected by reset. This bit reads 0 when bit 7 of the CRB register is 1.
0: Timing registers not updated within 244
μ
s.
1: Timing registers updated within 244
μ
s.
Divider Chain Control.
These bits control the configuration of the divider chain for timing generation and register bank
selection. See Table 4-19 on page 89. They are cleared to 000 as long as bit 7 of CRD is 0.
Periodic Interrupt Rate Select.
These bits select one of fifteen output taps from the clock divider chain to control the rate of
the periodic interrupt. See Table 4-20 on page 89 and Figure 4-7 on page 81. They are cleared to 000 as long as bit 7 of
CRD is 0.
6:4
3:0