Datasheet

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
1.3.10.2 QEI (see page 1872)
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 TM4C129ENCPDT 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, 30 MHz for a 120-MHz system).
The TM4C129ENCPDT microcontroller includes one QEI module providing control of one motor
with the following features:
■ Position integrator that tracks the encoder position
■ Programmable noise filter on the inputs
■ Velocity capture using built-in timer
■ The input frequency of the QEI inputs may be as high as 1/4 of the processor frequency (for
example, 12.5 MHz for a 50-MHz system)
■ Interrupt generation on:
– Index pulse
– Velocity-timer expiration
– Direction change
– Quadrature error detection
81June 18, 2014
Texas Instruments-Production Data
Tiva
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TM4C129ENCPDT Microcontroller