DS1248 datasheet(6/21 Pages) DALLAS

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DS1248/DS1248P

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PHANTOM CLOCK REGISTER DEFINITION Figure 2

AM/PM/12/24 MODE

Bit 7 of the hours register is defined as the 12-hour or 24-hour mode-select bit. When high, the 12-hour

mode is selected. In the 12-hour mode, bit 5 is the AM/PM bit with logic high being PM. In the 24-hour

mode, bit 5 is the second 10-hour bit (20–23 hours).

OSCILLATOR AND RESET BITS

Bits 4 and 5 of the day register are used to control the RESET and oscillator functions. Bit 4 controls the

RESET

(pin 1). When the RESET bit is set to logic 1, the RESET input pin is ignored. When the RESET

bit is set to logic 0, a low input on the RESET pin will cause the phantom clock to abort data transfer

without changing data in the watch registers. Bit 5 controls the oscillator. When set to logic 1, the

oscillator is off. When set to logic 0, the oscillator turns on and the watch becomes operational. These bits

are shipped from the factory set to a logic 1.

ZERO BITS

Registers 1, 2, 3, 4, 5, and 6 contain one or more bits which will always read logic 0. When writing these

locations, either a logic 1 or 0 is acceptable.

DS1248 Datasheet(PDF) 6 Page - Dallas Semiconductor