LM3S8971 Datasheet, PDF (32/577 Pages) List of Unclassifed Manufacturers – Microcontroller

Architectural Overview
1.4.2.2
1.4.3
1.4.3.1
1.4.3.2
wave is modulated to encode an analog signal. Typical applications include switching power supplies
and motor control.
On the LM3S8971, PWM motion control functionality can be achieved through dedicated, flexible
motion control hardware (the PWM pins) or through the motion control features of the general-purpose
timers (using the CCP pins).
PWM Pins (see page 467)
The LM3S8971 PWM module consists of three PWM generator blocks and a control block. Each
PWM generator block contains one timer (16-bit down or up/down counter), two comparators, a
PWM signal generator, a dead-band generator, and an interrupt/ADC-trigger selector. The control
block determines the polarity of the PWM signals, and which signals are passed through to the pins.
Each PWM generator block produces two PWM signals that can either be independent signals or
a single pair of complementary signals with dead-band delays inserted. The output of the PWM
generation blocks are managed by the output control block before being passed to the device pins.
CCP Pins (see page 207)
The General-Purpose Timer Module's CCP (Capture Compare PWM) pins are software programmable
to support a simple PWM mode with a software-programmable output inversion of the PWM signal.
QEI (see page 503)
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,
you can track the position, direction of rotation, and speed. 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.
Analog Peripherals
To handle analog signals, the LM3S8971 microcontroller offers an Analog-to-Digital Converter
(ADC).
For support of analog signals, the LM3S8971 microcontroller offers one analog comparator.
ADC (see page 260)
An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a
discrete digital number.
The LM3S8971 ADC module features 10-bit conversion resolution and supports eight input channels,
plus an internal temperature sensor. Four buffered sample sequences allow rapid sampling of up
to eight analog input sources without controller intervention. Each sample sequence provides flexible
programming with fully configurable input source, trigger events, interrupt generation, and sequence
priority.
Analog Comparators (see page 456)
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
A comparator can compare a test voltage against any one of these voltages:
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October 01, 2007
Preliminary