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.
The LM3S6G65 microcontroller has two Watchdog Timer modules: Watchdog Timer 0 uses the
system clock for its timer clock; Watchdog Timer 1 uses the PIOSC as its timer clock. The Stellaris
Watchdog Timer module has 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
1.3.4.7 Programmable GPIOs (see page 408)
General-purpose input/output (GPIO) pins offer flexibility for a variety of connections. The Stellaris
GPIO module is comprised of seven physical GPIO blocks, each corresponding to an individual
GPIO port. The GPIO module is FiRM-compliant (compliant to the ARM Foundation IP for Real-Time
Microcontrollers specification) and supports 0-46 programmable input/output pins. The number of
GPIOs available depends on the peripherals being used (see “Signal Tables” on page 925 for the
signals available to each GPIO pin).
■ Up to 46 GPIOs, depending on configuration
■ Highly flexible pin muxing allows use as GPIO or one of several peripheral functions
■ 5-V-tolerant in input configuration
■ Two means of port access: either Advanced High-Performance Bus (AHB) with better back-to-back
access performance, or the legacy Advanced Peripheral Bus (APB) for backwards-compatibility
with existing code
■ Fast toggle capable of a change every clock cycle for ports on AHB, every two clock cycles for
ports on APB
■ Programmable control for GPIO interrupts
– Interrupt generation masking
– Edge-triggered on rising, falling, or both
– Level-sensitive on High or Low values
■ Bit masking in both read and write operations through address lines
■ Can be used to initiate an ADC sample sequence
■ Pins configured as digital inputs are Schmitt-triggered
■ Programmable control for GPIO pad configuration
July 24, 201248
Texas Instruments-Production Data
Architectural Overview
OBSOLETE: TI has discontinued production of this device.
