ADSP-BF537 Blackfin Processor Hardware Reference
18-9
Real-Time Clock
technique is to only post writes to
RTC_STAT
,
RTC_ALARM
,
RTC_SWCNT
,
RTC_ICTL
, or
RTC_PREN
immediately after a seconds interrupt or event. All
five registers may be written in the same second.
W1C bits in the
RTC_ISTAT
register take effect immediately.
Register Reads
There is no latency when reading RTC MMRs, as the values come from
the read shadow registers. The shadows are updated and ready for reading
by the time any RTC interrupts or event flags for that second are asserted.
Once the internal V
dd
logic completes its initialization sequence after
SCLK
starts, there is no point in time when it is unsafe to read the RTC MMRs
for synchronization reasons. They always return coherent values, although
the values may be unknown.
Deep Sleep
When the Dynamic Power Management Controller (DPMC) state is deep
sleep, all clocks in the system (except
RTXI
and the RTC 1 Hz tick) are
stopped. In this state, the RTC V
dd
counters continue to increment. The
internal V
dd
shadow registers are not updated, but neither can they be
read.
During deep sleep state, all bits in
RTC_ISTAT
are cleared. Events that
occur during deep sleep are not recorded in
RTC_ISTAT
. The internal V
dd
RTC control logic generates a virtual 1 Hz tick within one
RTXI
period
(30.52
μ
s) after
SCLK
restarts. This loads all shadow registers with
up-to-date values and sets the seconds event flag. Other event flags may
also be set. When the system wakes up from deep sleep, whether by an
RTC event or a hardware reset, all of the RTC events that occurred during
that second (and only that second) are reported in
RTC_ISTAT
.
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 ...