LM3S6950 Luminary Micro, Inc, LM3S6950 Datasheet - Page 34

• Manufacturer Part Number: LM3S6950
• Description: Lm3s6950 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

Architectural Overview
1.4.2.2
1.4.3
1.4.3.1
34
wave is modulated to encode an analog signal. Typical applications include switching power supplies
and motor control.
On the LM3S6950, PWM motion control functionality can be achieved through:
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PWM Pins (see page 440)
The LM3S6950 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. 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 216)
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 476)
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
For support of analog signals, the LM3S6950 microcontroller offers three analog comparators.
Analog Comparators (see page 427)
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S6950 microcontroller provides three independent integrated analog comparators that can
be configured to drive an output or generate an interrupt .
A comparator can compare a test voltage against any one of these voltages:
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The comparator can provide its output to a device pin, acting as a replacement for an analog
comparator on the board, or it can be used to signal the application via interrupts to cause it to start
capturing a sample sequence.
Dedicated, flexible motion control hardware using the PWM pins
The motion control features of the general-purpose timers using the CCP pins
An individual external reference voltage
A shared single external reference voltage
A shared internal reference voltage
Preliminary
July 25, 2008