DS1629 View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated

Part Name

Description

Manufacturer

DS1629

2-Wire Digital Thermometer and Real Time Clock

Dallas Semiconductor -> Maxim Integrated 

DS1629

OPERATION-Real Time Clock/Calendar

DS1629 real-time clock/calendar data is accessed with the 2-wire command protocol C0h. If the R/ W bit

in the 2-wire control byte is set to 0, the bus master will set the clock (write to the clock register). The bus

master sets the R/ W bit to 1 to read the current time (read from the clock register). Refer to the “2-Wire

Serial Bus” section for details on this protocol.

The format of the clock register is shown below in Figure 2. Data format for the clock register is binary-

coded decimal (BCD). Most of the clock register is self-explanatory, but a few of the bits require

elaboration.

CH = Clock halt bit. This bit is set to 0 to enable the oscillator and set to 1 to disable it. If the bit is

changed during a write to the clock register, the oscillator will not be started (or stopped) until the bus

master issues a STOP pulse. The DS1629 power-up default has the oscillator enabled (CH=0) so that

OSC can be used for clocking a microcontroller at power-up.

12/24 = Clock mode bit. This bit is set high when the clock is in the 12-hour mode and set to 0 in the 24-

hour mode. Bit 5 of byte 02h of the clock register contains the MSb of the hours (1 for hours 20-23) if the

clock is in the 24-hour mode. If the clock mode is set to the 12-hour mode, this is the AM/PM bit. In the

12-hour mode, a 0 in this location denotes AM and a 1 denotes PM. When setting the clock, this bit must

be written to according to the clock mode used.

Bits in the clock register filled with 0 are a "don't care" on a write, but will always read out as 0.

DS1629 CLOCK REGISTER FORMAT Figure 2

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