cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 421

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

Revision 0.8
5.15 REAL-TIME CLOCK REGISTER DESCRIPTIONS
The registers for the Real-Time Clock (RTC) are divided
into three sets:
• Standard GeodeLink Device MSRs (Shared with DIVIL,
• RTC Specific MSRs
• RTC Native Registers
The MSRs are accessed via the RDMSR and WRMSR pro-
cessor instructions. The MSR address is derived from the
perspective of the CPU Core. See Section 3.2 "CS5535
MSR Addressing" on page 53 for more details on MSR
addressing.
Note 1. Register location is programmable (through the MSR registers) and overlay onto the lower RAM space.
MSR Address
Programmable
Programmable
Programmable
see Section 5.6.1 on page 299.)
I/O Address
51400054h
51400055h
51400056h
51400057h
(Note 1)
(Note 1)
(Note 1)
0Ch
0Dh
0Ah
0Bh
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
Type
Type
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
RO
RO
Register Name
RTC RAM Lock (RTC_RAM_LOCK)
(RTC_DOMA_OFFSET)
RTC Month Alarm Offset (RTC_MONA_OFFSET)
RTC Century Offset (RTC_CEN_OFFSET)
RTC Date of Month Alarm Offset
Width
(Bits)
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
8
Table 5-56. RTC Native Registers Summary
Table 5-55. RTC Specific MSRs Summary
Register Name
Seconds (RTC_SEC)
Seconds Alarm (RTC_SECA)
Minutes (RTC_MIN)
Minutes Alarm (RTC_MINA)
Hours (RTC_HR)
Hours Alarm
Day of Week (RTC_DOW)
Day of Month (RTC_DOM)
Month (RTC_MONTH)
Year (RTC_YEAR)
RTC Control Register A (RTC_CRA)
RTC Control Register B (RTC_CRB)
RTC Control Register C (RTC_CRC)
RTC Control Register D (RTC_CRD)
Date of Month Alarm (RTC_DOMA)
Month Alarm (RTC_MONA)
Century (RTC_CEN)
421
All MSRs are 64 bits, however, the RTC Specific MSRs
(summarized in Table 5-55) are called out as 8 bits. The
RTC module treats writes to the upper 56 bits (i.e., bits
[63:8]) of the 64-bit MSRs as don’t cares and always
returns 0 on these bits.
The Native registers associated with the RTC module are
summarized in Table 5-56 and are accessed as I/O
Addresses.
The reference column in the summary tables point to the
page where the register maps and bit descriptions are
listed.
Reset Value
Reset Value
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
00h
20h
00h
00h
00h
00h
00h
00h
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