SuperI/O Module

32579B

5.5.3RTC Registers

The RTC registers can be accessed (see Section 5.4.2.1 "LDN 00h - Real-Time Clock" on page 98) at any time dur- 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

 

 

 

Reset

Index

Type

Name

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.Overlaid on RAM bytes in range 0Eh-7Fh. See Section 5.4.2.1 "LDN 00h - Real-Time Clock" on page 98.

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.

 

 

 

 

AMD Geode™ SC1200/SC1201 Processor Data Book

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AMD SC1201, SC1200 manual RTC Registers, RTC Register Map, Index Type Name, Vpp Pur