ADSP-214xx SHARC Processor Hardware Reference 18-3
Real-Time Clock—ADSP-2147x
Pin Descriptions
The pins used for the real-time clock are described in the ADSP-2147x
data sheet.
Clocking
The RTC timer is clocked by a 32.768 kHz crystal external to the proces-
sor. The RTC system registers are clocked by this crystal.
There is no way to disable the RTC counters from software. If a given sys-
tem does not require the RTC functionality, then it may be disabled with
hardware tie-offs. Tie the RTXI pin to EGND, tie the RTCVDD pin to EVDD, and
leave the RTXO pin unconnected.
Register Overview
This section provides basic information on the RTC control and status
registers only. Complete bit information can be found at “Real-Time
Clock Registers” on page A-209.
Control Register (RTC_CTL). Used to control interrupts.
Clock Register (RTC_CLOCK). Used to read or write the current time
and is updated every second.
Initialization Register (RTC_INIT). Used to enable the RTC. This regis-
ter should only be written during initialization and not during normal
operation.
Alarm Register (RTC_INIT). Used to enable the alarm functions.
Status Register (RTC_STAT). Used to report various RTC events.
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