5.7.2 Watchdog Timer (WDT)

The PIC16F, PIC18F and PIC32CM MCUs feature a Watchdog Timer (WDT) to monitor program execution and recover from software faults, such as runaway or deadlocked code. The WDT operates asynchronously from a dedicated, CPU-independent clock source, ensuring it functions even if the main clock fails. The PIC16F, PIC18F, and PIC32CM WDTs support normal and window (WWDT) modes, where the WDT must be cleared within a specific time window to avoid a system reset.

The following table provides a comparison of features of the PIC16F, PIC18F, and PIC32CM.

Table 5-27. PIC16F, PIC18F, and PIC32CM WDT Features
FeaturePIC16F WDT/WWDTPIC18F WDT/WWDTPIC32CM WDT/WWDT
OperationAsynchronousAsynchronousAsynchronous
Clock Source

Selectable: LFINTOSC (31 kHz),

MFINTOSC (31.25/500 kHz),

or SOSC

Selectable: LFINTOSC (31 kHz),

MFINTOSC (31.25/500 kHz),

or SOSC

Dedicated internal oscillator
Window Mode SupportedSupportedSupported
Time-out PeriodsFrom 1 ms up to 256 secondsFrom 1 ms to 256 secondsNormal: 8 to 16,384 cycles Windowed: 16 to 32,768 cycles
Early Warning InterruptN/AN/ASupported
Always-On CapabilitySupportedSupportedSupported
Configuration (Change) ProtectionSupportedSupportedSupported
Operation in Sleep ModesSupported Supported Supported
Reset Action Triggers a System Reset on timeout or window violationAsserts a hardware device ResetSystem reset on time-out or window violation
Interrupt on TimeoutSupported Supported Supported (early warning)
Runtime Enable/DisableSupported Supported Supported