– Output PWM signal is constructed based on actions taken as a result of the counter and
PWM comparator output signals
– Produces two independent PWM signals
■ Dead-band generator
– Produces two PWM signals with programmable dead-band delays suitable for driving a half-H
bridge
– Can be bypassed, leaving input PWM signals unmodified
■ Can initiate an ADC sample sequence
The control block determines the polarity of the PWM signals and which signals are passed through
to the pins. The output of the PWM generation blocks are managed by the output control block
before being passed to the device pins. The PWM control block has the following options:
■ PWM output enable of each PWM signal
■ Optional output inversion of each PWM signal (polarity control)
■ Optional fault handling for each PWM signal
■ Synchronization of timers in the PWM generator blocks
■ Synchronization of timer/comparator updates across the PWM generator blocks
■ Extended PWM synchronization of timer/comparator updates across the PWM generator blocks
■ Interrupt status summary of the PWM generator blocks
■ Extended PWM fault handling, with multiple fault signals, programmable polarities, and filtering
■ PWM generators can be operated independently or synchronized with other generators
1.3.5.2 QEI (see page 900)
A quadrature encoder, also known as a 2-channel incremental encoder, converts linear displacement
into a pulse signal. By monitoring both the number of pulses and the relative phase of the two signals,
the position, direction of rotation, and speed can be tracked. In addition, a third channel, or index
signal, can be used to reset the position counter. The Stellaris quadrature encoder with index (QEI)
module interprets the code produced by a quadrature encoder wheel to integrate position over time
and determine direction of rotation. In addition, it can capture a running estimate of the velocity of
the encoder wheel. The input frequency of the QEI inputs may be as high as 1/4 of the processor
frequency (for example, 20 MHz for a 80-MHz system).
The LM3S6G65 microcontroller includes two QEI modules providing control of two motors at the
same time with the following features:
■ Position integrator that tracks the encoder position
■ Programmable noise filter on the inputs
■ Velocity capture using built-in timer
July 24, 201250
Texas Instruments-Production Data
Architectural Overview
OBSOLETE: TI has discontinued production of this device.
