A Watchdog Timer (WDT) is a system timer that generates a Reset if the firmware does not
issue a CLRWDT instruction within the time-out period. A Watchdog Timer
is typically used to recover the system from unexpected events. The Windowed Watchdog
Timer (WWDT) differs from nonwindowed operation in that CLRWDT
instructions are only accepted when they are performed within a specific window during
the time-out period.
The WWDT has the following features:
- Selectable clock source
- Multiple operating modes
- WWDT is always on
- WWDT is off when in Sleep
- WWDT is controlled by software
- WWDT is always off
- Configurable time-out period from 1 ms to 256s (nominal)
- Configurable window size from 12.5% to 100% of the time-out period
- Multiple Reset conditions
Figure 1. Windowed Watchdog Timer Block
Diagram
