ADSP-BF59x Blackfin Processor Hardware Reference
10-5
Watchdog Timer
When the watchdog is programmed to generate a reset, it resets the pro-
cessor core and peripherals. If the
NOBOOT
bit in the
SYSCR
register was set
by the time the watchdog resets the part, the chip is not rebooted. This is
recommended behavior in slave boot configurations. The reset handler
may evaluate the
RESET_WDOG
bit in the software reset register
SWRST
to
detect a reset caused by the watchdog. For details, see the
System Reset and
Booting
chapter.
To prevent the watchdog from expiring, software services the watchdog by
performing dummy writes to the
WDOG_STAT
register. The values written
are ignored, but the write commands cause the
WDOG_STAT
register to be
reloaded from the
WDOG_CNT
register.
If the watchdog is enabled with a zero value loaded to the counter and the
WDRO
bit was cleared, the
WDRO
bit of the watchdog control register is set
immediately and the counter remains at zero without further decrements.
If, however, the
WDRO
bit was set by the time the watchdog is enabled, the
counter decrements to 0xFFFF FFFF and continues operation.
Software can disable the watchdog timer only by writing a 0xAD value to
the
WDEN
field in the
WDOG_CTL
register.
Register Definitions
The watchdog timer is controlled by three registers.
Watchdog Count (WDOG_CNT) Register
The
WDOG_CNT
register, shown in
Figure 10-2
, holds the 32-bit unsigned
count value. The
WDOG_CNT
register must always be accessed with 32-bit
read/writes.
A valid write to the
WDOG_CNT
register also preloads the watchdog counter.
For added safety, the
WDOG_CNT
register can be updated only when the
Summary of Contents for ADSP-BF59x Blackfin
Page 64: ...Development Tools 1 22 ADSP BF59x Blackfin Processor Hardware Reference...
Page 74: ...Processor Specific MMRs 2 10 ADSP BF59x Blackfin Processor Hardware Reference...
Page 244: ...Programming Examples 6 40 ADSP BF59x Blackfin Processor Hardware Reference...
Page 700: ...Programming Examples 16 78 ADSP BF59x Blackfin Processor Hardware Reference...
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