Functional Description
18-6 ADSP-214xx SHARC Processor Hardware Reference
the external battery or I/O supply) and is active irrespective of the status
of the processor core supply (V
DDINT
). When the processor core and I/O
supply are valid:
• the current time is updated every second into the RTC clock regis-
ter (RTC_CLOCK)
• interrupts can be issued periodically every second, every minute,
every hour or every day
Each of the interrupts can be independently controlled, described in
“Interrupts” on page 18-10.
It is the responsibility of the program to set the correct time by a software
write into the RTC_CLOCK register. Once set, the counters maintain time as
long as the RTC supply is valid.
Partitioning
The RTC is partitioned into two blocks. The counting and clock function
is provided in the I/O voltage domain (V
DDEXT
), while the control and
access function and the user interface are provided in the core voltage
domain. The RTC I/O operates on a dedicated power supply provided by
the external 3.3 V (nominal) lithium coin cell. The RTC also has the abil-
ity to switch to the I/O supply (V
DDEXT
). The RTC core operates on the
nominal core voltage supply (V
DDINT
). The interface between both
blocks is provided by a set of level shifters. The partitioning at chip level is
shown in Figure 18-2.
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