DS1339 Maxim, DS1339 Datasheet - Page 13

• Manufacturer Part Number: DS1339
• Description: The DS1339 serial real-time clock (RTC) is a low-power clock/date device with two programmable time-of-day alarms and a programmable square-wave output
• Manufacturer: Maxim

Table 4. Alarm Mask Bits
SPECIAL-PURPOSE REGISTERS
The DS1339 has two additional registers (control and status) that control the RTC, alarms, and square-wave
output.
CONTROL REGISTER (0Eh)
Bit 7: Enable Oscillator (EOSC). This bit when set to logic 0 starts the oscillator. When this bit is set to a logic 1,
the oscillator is stopped. This bit is enabled (logic 0) when power is first applied.
Bit 5: Battery-Backed Square-Wave and Interrupt Enable (BBSQI). This bit when set to a logic 1 enables the
square wave or interrupt output when V
BBSQI is a logic 0, the SQW/INT pin goes high impedance when V
disabled (logic 0) when power is first applied.
Bits 4 and 3: Rate Select (RS2 and RS1). These bits control the frequency of the square-wave output when the
square wave has been enabled.
These bits are both set to logic 1 (32kHz) when power is first applied.
Table 5. SQW/INT Output
INTCN
DY/DT
DY/DT
EOSC
0
0
0
0
1
1
1
BIT 7
X
X
X
X
X
X
X
0
1
0
1
RS2
X
X
X
0
0
1
1
A1M4
A2M4
1
1
1
1
0
0
ALARM 1 REGISTER MASK BITS
ALARM 2 REGISTER MASK BITS
1
1
1
0
0
BIT 6
0
RS1
X
X
X
0
1
0
1
A1M3
1
1
1
0
0
0
(Bit 7)
(Bit 7)
A2M3
BBSQI
Table 5
BIT 5
32.768kHz
A2F + A1F
SQW/INT
4.096kHz
8.192kHz
1
1
0
0
0
OUTPUT
1Hz
A1F
A2F
A1M2
1
1
0
0
0
0
CC
shows the square-wave frequencies that can be selected with the RS bits.
is absent and the DS1339 is being powered by the V
BIT 4
A2M2
RS2
A1M1
1
0
0
0
0
A2IE
1
0
0
0
0
0
X
X
X
X
0
1
1
13 of 20
A1IE
Alarm once per second
Alarm when seconds match
Alarm when minutes and seconds match
Alarm when hours, minutes, and seconds match
Alarm when date, hours, minutes, and seconds
match
Alarm when day, hours, minutes, and seconds match
Alarm once per minute (00 sec. of every min.)
Alarm when minutes match
Alarm when hours and minutes match
Alarm when date, hours, and minutes match
Alarm when day, hours, and minutes match
BIT 3
X
X
X
X
1
0
1
RS1
CC
falls below the power-fail trip point. This bit is
INTCN
BIT 2
DS1339 I
ALARM RATE
ALARM RATE
2
C Serial Real-Time Clock
BIT 1
A2IE
BACKUP
pin. When
BIT 0
A1IE