Programming Model
19-8
ADSP-214xx SHARC Processor Hardware Reference
period value into the 32-bit
WDTCNT
register before the watchdog is
enabled. Once the watchdog is started, the period value cannot be altered.
To start the watchdog timer:
1. Unlock the WDT configuration registers by writing the unlock
“command” value to the
WDTUNLOCK
register. Select the
WDTCLK
by
programming the
WDTCLKSEL
bit.
By Default, the resonator output is
WDTCLK
.
2. Set the trip counter value for the watchdog timer by writing to the
WDTTRIP
register.
3. Set the count value for the watchdog timer by writing the count
value into the watchdog period register (
WDTCNT
). Since the watch-
dog timer is not yet enabled, the write to the
WDTCNT
registers
automatically pre-loads the
WDTCURCNT
register as well. Note that
sufficient time must be provided for the write to the
WDTCURCNT
reg-
ister to occur (2.5
WDTCLK
cycles max.), before enabling WDT.
4. Enable the watchdog timer in
WDTCTL
.
5. Lock the WDT configuration registers by writing to the
WDTUNLOCK
register. The watchdog timer begins counting down, decrementing
the value in the
WDTCURCNT
register every
WDT_CLKIN
cycle. If soft-
ware does not serve the watchdog in time,
WDTCURCNT
continues
decrementing until it reaches 0 and the system is reset.
The counter now reloads the
WDTCURCNT
value from
WDTCNT
and
keeps decrementing. Additionally, the WDRO latch bit in the
WDT-
STATUS
register is set and can be interrogated by software. This
occurs up to the number of times programmed in the
WDTTRIP
reg-
ister. When
WDTTRIP
expires, WDT holds the
WDTRSTO
asserted.
6. To prevent the watchdog from expiring, software serves the watch-
dog by unlocking the WDT configuration space and performing
dummy writes to the
WDTCURCNT
register address in time. The values
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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...