Analog Devices SHARC ADSP-214 Series Hardware Reference Manual page 702

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This sequence applies only to the first time the RTC supply (bat-

tery or I/O) is connected. Once the

value is retained as long as RTC supply (battery or I/O) is valid.

3. After the RTC supply is connected for the first time and the

bit has been cleared, the application is free to power-up and power

-down the core supply any number of times without loss of RTC

functionality (provided the RTC supply—battery or I/O, is valid).

Conversely, if the

remains disabled irrespective of the status of the core supply.

4. The current status of the RTC power-down is updated by hardware

into the initialization status register (

is useful when the rest of the processor wakes up from power-down

and needs to know the status of the RTC.

5. Whenever the ADSP-2147x processor core wakes up from

power-down, the values of the

power-up. At the first seconds' event, an arbitrary value is uploaded

into these registers. To put them in a defined state software must

write the desired value into these registers.In case the

quent power-up, their values are valid throughout, but can be read

by the program only after the first seconds' event after power-up.

The unknown values in the registers at power up can cause event

flags to set before the correct value is written into each of the regis-

ters. By catching the 1 Hz clock edge, the write to

occur a full second before the write to

an extra second of delay between the validity of

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bit has been set, then the RTC oscillator

registers is zero until the first seconds' event after

have been set before core power-down and subse-

, if the value of the

ADSP-214xx SHARC Processor Hardware Reference

bit is set or reset, its

RTC_INITSTAT

. This would cause

out of reset is the same as

) register. This

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