DS1337 Maxim, DS1337 Datasheet - Page 10

• Manufacturer Part Number: DS1337
• Description: The DS1337 serial real-time clock is a low-power clock/calendar with two programmable time-of-day alarms and a programmable square-wave output
• Manufacturer: Maxim

Table 3. Alarm Mask Bits
SPECIAL-PURPOSE REGISTERS
The DS1337 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 active-low bit when set to logic 0 starts the oscillator. When this bit is set to
logic 1, the oscillator is stopped. This bit is enabled (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. The table below shows the square-wave frequencies that can be selected with the
RS bits. These bits are both set to logic 1 (32kHz) when power is first applied.
SQW/INTB Output
Bit 2: Interrupt Control (INTCN). This bit controls the relationship between the two alarms and the interrupt output
pins. When the INTCN bit is set to logic 1, a match between the timekeeping registers and the alarm 1 registers l
activates the INTA pin (provided that the alarm is enabled) and a match between the timekeeping registers and the
alarm 2 registers activates the SQW/INTB pin (provided that the alarm is enabled). When the INTCN bit is set to
logic 0, a square wave is output on the SQW/INTB pin. This bit is set to logic 0 when power is first applied.
INTCN
DY/DT
DY/DT
EOSC
0
0
0
0
1
Bit 7
X
X
X
X
X
X
X
0
1
0
1
RS2
A1M4
X
0
0
1
1
A2M4
1
1
1
1
0
0
ALARM 1 REGISTER MASK BITS
ALARM 2 REGISTER MASK BITS
0
0
1
1
1
Bit 6
0
RS1
0
1
0
1
X
A1M3
1
1
1
0
0
0
(BIT 7)
(BIT 7)
A2M3
Bit 5
SQW/INTB
32.768kHz
1
1
0
0
0
4.096kHz
8.192kHz
OUTPUT
0
1Hz
A2F
A1M2
1
1
0
0
0
0
Bit 4
A2M2
RS2
A1M1
1
0
0
0
0
A2IE
1
0
0
0
0
0
10 of 16
X
X
X
X
1
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 seconds of every minute)
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
RS1
INTCN
Bit 2
DS1337 I
ALARM RATE
ALARM RATE
2
C Serial Real-Time Clock
Bit 1
A2IE
Bit 0
A1IE