S35392A Datasheet, PDF (13/48 Pages) Seiko Instruments Inc – 2-WIRE REAL-TIME CLOCK

Rev.3.2_02
2-WIRE REAL-TIME CLOCK
S-35392A
2. Status register 1
Status register 1 is a 1-byte register that is used to display and set various modes. The bit configuration is shown below.
B7
B6
B5
B4
B3
B2
B1
B0
RESET 12 / 24
SC0
SC1
INT1
INT2
BLD
POC
W
R/W
R/W
R/W
R
R
R
R
R:
W:
R / W:
Read
Write
Read / write
Figure 10 Status Register 1
B0: POC
This flag is used to confirm whether the power is on. The power-on detection circuit operates at power-on and B0 is
set to "1". This flag is read-only. Once it is read, it is automatically set to "0". When this flag is "1", be sure to initialize.
Regarding the operation after power-on, refer to " Power-on Detection Circuit and Register Status".
B1: BLD
This flag is set to "1" when the power supply voltage decreases to the level of detection voltage (V_DET) or less. Users
can detect a drop in the power supply voltage. This flag is set to "1" once, it is not set to "0" again even if the power
supply increases to the level of detection voltage (V_DET) or more. This flag is read-only. When this flag is "1", be sure
to initialize. Regarding the operation of the power supply voltage detection circuit, refer to " Low Power Supply
Voltage Detection Circuit".
B2: INT2, B3: INT1
This flag indicates the time set by alarm and when the time has reached it. This flag is set to "1" when the time that
users set by using the alarm function has come. The INT1 flag in the alarm 1 function and the INT2 flag at alarm 2
interrupt mode are set to "0". Set "0" in INT1AE (B5 in the status register 2) or in INT2AE (B1 in the status register 2)
after reading "1" in the INT1 flag or in the INT2 flag. This flag is read-only. This flag is read once, it is set to "0"
automatically.
B4: SC1, B5: SC0
These flags are SRAM type registers, they are 2 bits as a whole, can be freely set by users.
B6: 12 / 24
This flag is used to set 12-hour or 24-hour mode. Set the flag ahead of write operation of the real-time data register in
case of 24-hour mode.
0: 12-hour mode
1: 24-hour mode
B7: RESET
The internal IC is initialized by setting this bit to "1". This bit is write-only. It is always "0" when reading. When
applying the power supply voltage to the IC, be sure to write "1" to this bit to initialize the circuit. Regarding each
status of registers after initialization, refer to " Register Status After Initialization".
13