Functional Description
18-8
ADSP-214xx SHARC Processor Hardware Reference
interrupt is enabled, the RTC generates an interrupt on the day and time
specified. The alarm interrupt and day alarm interrupt can be enabled or
disabled independently.
Stopwatch
The RTC provides a stopwatch function that acts as a countdown timer.
The application can program a second count into the RTC Stopwatch
Count register (
RTC_SWCNT
). When the stopwatch interrupt is enabled and
the specified number of seconds have elapsed, the RTC generates an
interrupt.
Calibration
To guard against the possibility of long term (> 1 day) errors, the RTC
provides a calibration feature using 4 bits of the
RTC_INIT
register (not
available for the stopwatch function).
This is a simple a time correction at the end of every day (when the clock
register changes from a Day:Hour:Min:Sec value of XXX:23:59:59 to
YYY:00:00:00). It functions by adding or subtracting an integer number
of seconds (maximum of 7) from the start of the next day, to correct accu-
mulated time error over the course of the previous day. The number of
seconds that are added or subtracted is defined in the
RTC_INIT
register,
CALIB
field.
As an example, if there is a –50 ppm error in the 1Hz frequency, this
translates into 86400
×
50 ppm seconds (=+4.32 seconds) error at the end
of the day. That is at 00:00:00, RTC time is 4.32 seconds ahead of actual
time. The RTC can correct this by adding 4 seconds (if 4 is the value writ-
ten into the calibration register) to the time at 00:00:00. Therefore, from
23:59:59, the timer counter jumps directly to 00:00:04, (there is no
00:00:00 to 00:00:03 time occurances). At the instant it jumps to
00:00:04, the error reduces to +0.32 seconds over the course of the day,
which is only 3.7 ppm.
www.BDTIC.com/ADI
Содержание SHARC ADSP-214 Series
Страница 60: ...Contents lx ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...