DS1685/DS1687 3V/5V Real-Time Clocks
“don’t care” codes in all three time alarm bytes create an interrupt every second. The three time-alarm bytes can be
used with the date alarm as described in the
Wake-Up/Kickstart
section. The century counter is discussed later in
this text.
All registers can be directly written or read except for the following:
1)
Registers C and D are read-only.
2)
Bit 7 of Register A is read-only.
3)
Bit 7 of the seconds byte is read-only.
Table 2A. Time, Calendar, and Alarm Data Modes—BCD Mode (DM = 0)
ADDRESS
00H
01H
02H
03H
04H
05H
06H
07H
08H
09H
0AH
0BH
0CH
0DH
48H
49H
10 Date
BIT 7
0
0
0
0
AM/PM
0
AM/PM
0
0
0
0
UIP
SET
IRQF
VRT
0
0
0
0
0
10 Year
DV2
PIE
PF
0
DV1
AIE
AF
0
DV0
UIE
UF
0
Century
Date
RS3
SQWE
0
0
RS2
DM
0
0
BIT 6
BIT 5
10 Seconds
10 Seconds
10 Minutes
10 Minutes
0
0
0
0
10 Hour
10 Hour
10 Hour
10 Hr
0
10 Date
10 Month
0
Date
Month
Year
RS1
24/12
0
0
RS0
DSE
0
0
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
FUNCTION
Seconds
Seconds
Alarm
Minutes
Minutes
Alarm
Hours
Hours
Alarm
Day
Day
Date
Month
Year
Control
Control
Control
Control
Bank 1
Century
Bank 1
Date Alarm
00-99
01-31
RANGE
00-59
00-59
00-59
00-59
1-12
+AM/PM
00-23
1-12
+AM/PM
00-23
01-07
01-31
01-12
00-99
Seconds
Seconds
Minutes
Minutes
Hours
Hours
X = Read/Write Bit.
Note 1:
Unless otherwise specified, the state of the registers is not defined when power is first applied.
Note 2:
Except for the seconds register, 0 bits in the time and date registers can be written to a 1, but may be modified when the clock updates.
0 bits should always be written to 0 except for alarm mask bits.
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