AMD SC2200 5.5.3 RTC Registers, Table 5-19. RTC Register Map, Table 5-20. RTC Registers

AMD Geode™ SC2200 Processor Data Book 117

SuperI/O Module 32580B

5.5.3 RTC Registers

The RTC registers can be accessed (see Section 5.4.2.1

"LDN 00h - Real-Time Clock" on page 104) 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

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

Programmable1R/W DOMA. Date of Month Alarm Register VPP PUR

Programmable1R/W MONA. Month Alarm Register VPP PUR

Programmable1R/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 104.

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.

Index 03h Minutes Alarm Reg ister - MINA (R/W) Reset Type: VPP 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 5.5.2.5 "Alarms" on page 113 for more

information about “unconditional” matches.