DS1307 64 x 8, Serial, I

2C Real-Time Clock

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CONTROL REGISTER

The DS1307 control register is used to control the operation of the SQW/OUT pin.

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

OUT

0

0

SQWE

0

0

RS1

RS0

Bit 7: Output Control (OUT). This bit controls the output level of the SQW/OUT pin when the square-wave output

is disabled. If SQWE = 0, the logic level on the SQW/OUT pin is 1 if OUT = 1 and is 0 if OUT = 0. On initial

application of power to the device, this bit is typically set to a 0.

Bit 4: Square-Wave Enable (SQWE). This bit, when set to logic 1, enables the oscillator output. The frequency of

the square-wave output depends upon the value of the RS0 and RS1 bits. With the square-wave output set to 1Hz,

the clock registers update on the falling edge of the square wave. On initial application of power to the device, this

bit is typically set to a 0.

Bits 1 and 0: Rate Select (RS[1:0]). These bits control the frequency of the square-wave output when the square-

wave output has been enabled. The following table lists the square-wave frequencies that can be selected with the

RS bits. On initial application of power to the device, these bits are typically set to a 1.

RS1

RS0

SQW/OUT OUTPUT

SQWE

OUT

0

0

1Hz

1

X

0

1

4.096kHz

1

X

1

0

8.192kHz

1

X

1

1

32.768kHz

1

X

X

X

0

0

0

X

X

1

0

1