LM3S1512_16 Datasheet, PDF (42/660 Pages) Texas Instruments – Stellaris LM3S1512 Microcontroller

Architectural Overview
1.4.1.5
1.4.1.6
1.4.2
1.4.2.1
1.4.2.2
1.4.3
1.4.3.1
System Control Block (SCB) (see page 92)
The SCB provides system implementation information and system control, including configuration,
control, and reporting of system exceptions.
Memory Protection Unit (MPU) (see page 92)
The MPU supports the standard ARMv7 Protected Memory System Architecture (PMSA) model.
The MPU provides full support for protection regions, overlapping protection regions, access
permissions, and exporting memory attributes to the system.
Motor Control Peripherals
To enhance motor control, the LM3S1512 controller features Pulse Width Modulation (PWM) outputs
and the Quadrature Encoder Interface (QEI).
PWM
Pulse width modulation (PWM) is a powerful technique for digitally encoding analog signal levels.
High-resolution counters are used to generate a square wave, and the duty cycle of the square
wave is modulated to encode an analog signal. Typical applications include switching power supplies
and motor control.
On the LM3S1512, PWM motion control functionality can be achieved through:
■ The motion control features of the general-purpose timers using the CCP pins
CCP Pins (see page 337)
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 558)
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 LM3S1512 microcontroller offers an Analog-to-Digital Converter
(ADC).
For support of analog signals, the LM3S1512 microcontroller offers three analog comparators.
ADC (see page 391)
An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a
discrete digital number.
The LM3S1512 ADC module features 10-bit conversion resolution and supports two 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
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July 15, 2014
Texas Instruments-Production Data