11 Watchdog Timers
A watchdog timer can generate an interrupt or a reset when a time-out value is reached. The
watchdog timer is used to regain control when a system has failed due to a software error or due
to the failure of an external device to respond in the expected way. The LM3S6G65 microcontroller
has two Watchdog Timer Modules, one module is clocked by the system clock (Watchdog Timer
0) and the other is clocked by the PIOSC (Watchdog Timer 1). The two modules are identical except
that WDT1 is in a different clock domain, and therefore requires synchronizers. As a result, WDT1
has a bit defined in the Watchdog Timer Control (WDTCTL) register to indicate when a write to a
WDT1 register is complete. Software can use this bit to ensure that the previous access has
completed before starting the next access.
The Stellaris
®
LM3S6G65 controller has two Watchdog Timer modules with the following features:
■ 32-bit down counter with a programmable load register
■ Separate watchdog clock with an enable
■ Programmable interrupt generation logic with interrupt masking
■ Lock register protection from runaway software
■ Reset generation logic with an enable/disable
■ User-enabled stalling when the microcontroller asserts the CPU Halt flag during debug
The Watchdog Timer can be configured to generate an interrupt to the controller on its first time-out,
and to generate a reset signal on its second time-out. Once the Watchdog Timer has been configured,
the lock register can be written to prevent the timer configuration from being inadvertently altered.
July 24, 2012508
Texas Instruments-Production Data
Watchdog Timers
OBSOLETE: TI has discontinued production of this device.
