Rainbow Electronics DS1677 - Manual (Page 6)

DS1677
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TIME OF DAY ALARM BITS Table 1
ALARM REGISTER MASK BITS (BIT 7)
SECONDS MINUTES HOURS DAYS
1 1 1 1 Alarm once per second.
0 1 1 1 Alarm when seconds match.
0 0 1 1 Alarm when minutes and seconds match.
0 0 0 1 Alarm when hours, minutes and seconds match.
0 0 0 0 Alarm when day, hours, minutes and seconds match.
SPECIAL PURPOSE REGISTERS
The DS1677 has two additional registers (control register and status register) that control the Real Time
Clock and interrupts.
CONTROL REGISTER
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
EOSC WP AIS1 AIS0 0 0 0 AIE
EOSC (Enable Oscillator) – This bit, when set to logic 0 will start the oscillator. When this bit is set
to a logic 1, the oscillator is stopped and the DS1677 is placed into a low–power standby mode with a
current drain of less than 200 nanoamps when in battery back–up mode. When the DS1677 is powered
by V
CC
, the oscillator is always on regardless of the status of the EOSC bit; however, the real time clock is
incremented only when EOSC is a logic 0.
WP (Write Protect) – Before any write operation to the real time clock or any other registers, this bit
must be logic 0. When high, the write protect bit prevents a write operation to any register.
AIS0–AIS1 (Analog Input Select) – These 2 bits are used to determine the analog input for the
analog–to–digital conversion. Table 2 lists the specific analog input that is selected by these 2 bits.
AIE (Alarm Interrupt Enable) – When set to a logic 1, this bit permits the Interrupt Request Flag
(IRQF) bit in the status register to assert INT. When the AIE bit is set to logic 0, the IRQF bit does not
initiate the INT signal.
ANALOG INPUT SELECTION Table 2
AIS1 AIS0 ANALOG INPUT
0 0 NONE
0 1 AIN0
1 0 AIN1
1 1 AIN2
STATUS REGISTER
BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0
CU LOBAT 0 0 0 0 0 IRQF