RTC Programming Model
18-14
ADSP-BF537 Blackfin Processor Hardware Reference
Interrupts
The RTC can provide interrupts at several programmable intervals:
• Per second, minute, hour, and day—based on increments to the
respective counters in
RTC_STAT
• On countdown from a programmable value—value in
RTC_SWCNT
transitions to 0 or is written with 0 by software (whether it was pre-
viously running or already stopped with a count of 0)
• Daily at a specific time—all fields of
RTC_ALARM
must match
RTC_STAT
except the day field
• On a specific day and time—all fields of
RTC_ALARM
register must
match
RTC_STAT
The RTC can be programmed to provide an interrupt at the completion
of all pending writes to any of the 1 Hz registers (
RTC_STAT
,
RTC_ALARM
,
RTC_SWCNT
,
RTC_ICTL
, and
RTC_PREN
). The eight RTC interrupt events can
be individually masked or enabled by the RTC interrupt control register
(
RTC_ICTL
). The seconds interrupt is generated on each 1 Hz clock tick, if
enabled. The minutes interrupt is generated at the 1 Hz clock tick that
advances the seconds counter from 59 to 0. The hour interrupt is gener-
ated at the 1 Hz clock tick that advances the minute counter from 59 to 0.
The 24-hour interrupt occurs once per 24-hour period at the 1 Hz clock
tick that advances the time to midnight (00:00:00). Any of these inter-
rupts can generate a wakeup request to the processor, if enabled. All
implemented bits are read/write.
This register is only partially cleared at reset, so some events may appear to
be enabled initially. However, the RTC interrupt and the RTC wakeup to
the PLL are handled specially and are masked (forced low) until after the
first write to the
RTC_ICTL
register is complete. Therefore, all interrupts
act as if they were disabled at system reset (as if all bits of
RTC_ICTL
were
zero), even though some bits of
RTC_ICTL
may read as nonzero. If no RTC
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 ...