Analog Devices ADSP-BF59x Blackfin, Hardware Reference Manual, Page: 348 / 772

Overview and Features
10-2 ADSP-BF59x Blackfin Processor Hardware Reference
Watchdog timer key features include:
• 32-bit watchdog timer
• 8-bit disable bit pattern
• System reset on expire option
• NMI on expire option
• General-purpose interrupt option
Typically, the watchdog timer is used to supervise stability of the system
software. When used in this way, software reloads the watchdog timer in a
regular manner so that the downward counting timer never expires (never
becomes 0). An expiring timer then indicates that system software might
be out of control. At this point a special error handler may recover the sys-
tem. For safety, however, it is often better to reset and reboot the system
directly by hardware control.
Especially in slave boot configurations, a processor reset cannot automati-
cally force the Blackfin device to be rebooted. In this case, the processor
may reset without booting again and may negotiate with the host device
by the time program execution starts. Alternatively, a watchdog event can
cause an NMI event. The NMI service routine may request the host device
reset and/or reboot the Blackfin processor.
The watchdog timer is often programmed to let the processor wake up
from sleep mode after a programmable period of time.
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For easier debugging, the watchdog timer does not decrement
(even if enabled) when the processor is in emulation mode.