AMD Geode SC1200/SC1201 Processor Data Book
111
SuperI/O Module
32579B
5.5.3
RTC Registers
ing normal operation mode (i.e.,when VSB is within the rec-
ommended operation range). This access is disabled
during battery-backed operation. The write operation to
these registers is also disabled if bit 7 of the CRD Register
is 0.
Note:
Before attempting to perform any start-up proce-
dures, read about bit 7 (VRT) of the CRD Register.
This section describes the RTC Timing and Control Regis-
ters that control basic RTC functionality.
Table 5-19. RTC Register Map
Index
Type
Name
Reset
Type
00h
R/W
SEC. Seconds Register
VPP PUR
01h
R/W
SECA. Seconds Alarm Register
VPP PUR
02h
R/W
MIN. Minutes Register
VPP PUR
03h
R/W
MINA. Minutes Alarm Register
VPP PUR
04h
R/W
HOR. Hours Register
VPP PUR
05h
R/W
HORA. Hours Alarm Register
VPP PUR
06h
R/W
DOW. Day Of Week Register
VPP PUR
07h
R/W
DOM. Date Of Month Register
VPP PUR
08h
R/W
MON. Month Register
VPP PUR
09h
R/W
YER. Year Register
VPP PUR
0Ah
R/W
CRA. RTC Control Register A
Bit specific
0Bh
R/W
CRB. RTC Control Register B
Bit specific
0Ch
RO
CRC. RTC Control Register C
Bit specific
0Dh
RO
CRD. RTC Control Register D
VPP PUR
Programmable1
R/W
DOMA. Date of Month Alarm Register
VPP PUR
Programmable1
R/W
MONA. Month Alarm Register
VPP PUR
Programmable1
R/W
CEN. Century Register
VPP PUR
1.
Table 5-20. RTC Registers
Bit
Description
Index 00h
Seconds Register - SEC (R/W)
Reset Type: VPP PUR
7:0
Seconds Data. Values may be 00 to 59 in BCD format or 00 to 3B in binary format.
Index 01h
Seconds Alarm Register - SECA (R/W)
Reset Type: VPP 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
Minutes Register - MIN (R/W)
Reset Type: VPP PUR
7:0
Minutes Data. Values can be 00 to 59 in BCD format, or 00 to 3B in binary format.