Datasheet

DS1307 64 x 8, Serial, I

C 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.

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.

Bits 1, 0: Rate Select (RS1, RS0). 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.

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