DS1337 Datasheet, PDF (9/13 Pages) Dallas Semiconductor – Serial Real-Time Clock

DS1337
Table 2. Alarm Mask Bits
DY/DT
X
X
X
X
ALARM 1 REGISTER MASK BITS
(BIT 7)
A1M4
A1M3
A1M2
A1M1
1
1
1
1
1
1
1
0
1
1
0
0
1
0
0
0
0
0
0
0
0
1
0
0
0
0
ALARM RATE
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
DY/DT
X
X
X
0
1
ALARM 2 REGISTER MASK BITS
(BIT 7)
A2M4
A2M3
A2M2
1
1
1
1
1
0
1
0
0
0
0
0
0
0
0
ALARM RATE
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
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
Bit 6
Bit 5
EOSC
0
0
Bit 4
RS2
Bit 3
RS1
Bit 2
INTCN
Bit 1
A2IE
Bit 0
A1IE
EOSC, Enable Oscillator. This 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.
RS2 and RS1, Rate Select. These bits control the frequency of the square-wave output when the square wave has
been enabled. Table 3 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.
Table 3. Square-Wave Output Frequency
RS2
RS1
0
0
0
1
1
0
1
1
SQUARE-WAVE OUTPUT
FREQUENCY
1Hz
4.096kHz
8.192kHz
32.768kHz
INTCN, Interrupt Control. 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
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