Datasheet

DS1557 4Meg, Nonvolatile, Y2K-Compliant Timekeeping RAM
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CLOCK OPERATIONS
Table 2 and the following paragraphs describe the operation of RTC, alarm, and watchdog functions.
Table 2. Register Map
DATA
ADDRESS
B
7
B
6
B
5
B
4
B
3
B
2
B
1
B
0
FUNCTION/RANGE
7FFFFh 10 Year Year Year 00-99
7FFFEh X X X
10
Month
Month Month 01-12
7FFFDh X X 10 Date Date Date 01-31
7FFFCh X FT X X X Day Day 01-07
7FFFBh X X 10 Hour Hour Hour 00-23
7FFFAh X 10 Minutes Minutes Minutes 00-59
7FFF9h
OSC
10 Seconds Seconds Seconds 00-59
7FFF8h W R 10 Century Century Control 00-39
7FFF7h WDS BMB4 BMB3 BMB2 BMB1 BMB0 RB1 RB0 Watchdog
7FFF6h AE Y Abe Y Y Y Y Y Interrupts
7FFF5h AM4 Y 10 Date Date Alarm Date 01-31
7FFF4h AM3 Y 10 Hours Hours Alarm Hours 00-23
7FFF3h AM2 10 Minutes Minutes Alarm Minutes 00-59
7FFF2h AM1 10 Seconds Seconds Alarm Seconds 00-59
7FFF1h Y Y Y Y Y Y Y Y Unused
7FFF0h WF AF 0 BLF 0 0 0 0 Flags
X = Unused, Read/Writeable Under Write and Read Bit Control AE = Alarm Flag Enable
Y = Unused, Read/Writeable Without Write and Read Bit Control FT = Frequency Test Bit
OSC = Oscillator Start/Stop Bit
ABE = Alarm in Battery-BackUp Mode Enable
W = Write Bit AM1 to AM4 = Alarm Mask Bits
R = Read Bit WF = Watchdog Flag
WDS = Watchdog Steering Bit AF = Alarm Flag
BMB0 to BMB4 = Watchdog Multiplier Bits 0 = 0 (Read Only)
RB0 to RB1 = Watchdog Resolution Bits BLF = Battery Low Flag