ADSP-BF537 Blackfin Processor Hardware Reference
1-21
Introduction
The 32.768 kHz input clock frequency is divided down to a 1 Hz signal
by a prescaler. The counter function of the timer consists of four counters:
a 60 second counter, a 60 minute counter, a 24 hours counter, and a
32768 day counter.
When enabled, the alarm function generates an interrupt when the output
of the timer matches the programmed value in the alarm control register.
There are two alarms. The first alarm is for a time of day. The second
alarm is for a day and time of that day.
The stopwatch function counts down from a programmed value, with one
minute resolution. When the stopwatch is enabled and the counter under-
flows, an interrupt is generated.
Like the other peripherals, the RTC can wake up the processor from sleep
mode or deep sleep mode upon generation of any RTC wakeup event. An
RTC wakeup event can also wake up the on-chip internal voltage regula-
tor from a powered down state.
Watchdog Timer
The processor includes a 32-bit timer that can be used to implement a
software watchdog function. A software watchdog can improve system
availability by forcing the processor to a known state through generation
of a hardware reset, nonmaskable interrupt (NMI), or general-purpose
interrupt, if the timer expires before being reset by software. The pro-
grammer initializes the count value of the timer, enables the appropriate
interrupt, then enables the timer. Thereafter, the software must reload the
counter before it counts to zero from the programmed value. This protects
the system from remaining in an unknown state where software that
would normally reset the timer has stopped running due to an external
noise condition or software error.
Summary of Contents for Blackfin ADSP-BF537
Page 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Page 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Page 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...