W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 105

• Manufacturer Part Number: W83977AF
• Description: W83877TF Plus Kbc, Cir, RTC
• Manufacturer: Information Storage Devices, Inc

6. REAL-TIME CLOCK (RTC) AND "ON-NOW" CONTROL
The RTC with 242 bytes of RAM is a low-power device that provides a time-of-day clock in various
formats, and a calendar with century register. It has two alarms and three programmable interrupts.
It is also equipped with external battery backup capability for keeping time and saving RAM data
under power-failure situation.
The RTC software is compatible with the MC146818 Clock chip.
The "On-Now" Control enables PC to be powered on by several trigger events, a telephone ring for
example. Also, it allows a safely controlled power-off procedure executed in an orderly fashion.
6.1 REGISTER ADDRESS MAP
Table 6.1.1, table 6.1.2, and table 6.1.3 show the register map of RTC and "On-Now". These
registers are separated into three banks: Bank 0, Bank 1, and Bank 2. Bank 0 contains 10 bytes of
time, calendar, and alarm A data, four bytes of control/status registers, and 114 bytes of general
purpose user RAM.
TABLE 6.1.1 - REAL TIME CLOCK ADDRESS MAP BANK 0
ADDRESS
0Eh-7Fh
0Ah
0Bh
0Ch
0Dh
00h
01h
02h
03h
04h
05h
06h
07h
08h
09h
REGISTER 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
R
- 93 -
Register 00h : Seconds
Register 01h : Seconds Alarm A
Register 02h : Minutes
Register 03h : Minutes Alarm A
Register 04h : Hours
Register 05h : Hours Alarm A
Register 06h : Day of Week
Register 07h : Date of Month
Register 08h: Month
Register 09h : Year
Register 0Ah : Control Register
Register 0Bh : Control Register (Bit 0 is Read only)
Register 0Ch : Status Register
Register 0Dh : Status Register
Register 0Eh-7Fh : User RAM
W83977F/ W83977AF
REGISTER FUNCTION
Publication Release Date:March 1998
PRELIMINARY
Revision 0.58