Emerson PMPPC7448 user manual Don’t care bit

Real-Time Clock: Clock Operation

ST: Stop bit

1=Stops the oscillator

0=Restarts the oscillator within one second

CEB: Century Enable Bit

1=Causes CB to toggle either from 0 to 1 or from 1 to 0 at the turn of the century 0=CB will not toggle

CB: Century Bit

Day: Day of the week

Date: Day of the month

OUT: Output level

1=Default at initial power-up

0=FT/OUT (pin 7) driven low when FT is also zero

FT: Frequency Test bit

1=When oscillator is running at 32,768 Hz, the FT/OUT pin will toggle at 512 Hz 0=The FT/OUT pin is an output driver (default at initial power-up)

S:Sign bit

1=Positive calibration 0=Negative calibration

Calibration: Calibration bits The calibration circuit adds or subtracts counts from the oscillator divider circuit at the divide by 256 stage. The number of times pulses are blanked (subtracted, neg- ative calibration) or split (added, positive calibration) depends on this five-bit byte. Adding counts accelerates the clock, and subtracting counts slows the clock down.

X:Don’t care bit

10006757-02 PmPPC7448 User’s Manual

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