LM3S5D56 Datasheet, PDF (60/1146 Pages) Texas Instruments – Stellaris® LM3S5D56 Microcontroller

Architectural Overview
1.3.6
1.3.6.1
■ 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
Analog
The LM3S5D56 microcontroller provides analog functions integrated into the device, including:
■ Two 12-bit Analog-to-Digital Converters (ADC) with eight analog input channels and a sample
rate of one million samples/second
■ Two analog comparators
■ 16 digital comparators
■ On-chip voltage regulator
The following provides more detail on these analog functions.
ADC (see page 538)
An analog-to-digital converter (ADC) is a peripheral that converts a continuous analog voltage to a
discrete digital number. The Stellaris ADC module features 12-bit conversion resolution and supports
eight input channels plus an internal temperature sensor. Four buffered sample sequencers allow
rapid sampling of up to eight analog input sources without controller intervention. Each sample
sequencer provides flexible programming with fully configurable input source, trigger events, interrupt
generation, and sequencer priority. Each ADC module has a digital comparator function that allows
the conversion value to be diverted to a comparison unit that provides eight digital comparators.
The LM3S5D56 microcontroller provides two ADC modules with the following features:
■ Eight shared analog input channels
■ 12-bit precision ADC with an accurate 10-bit data compatibility mode
■ Single-ended and differential-input configurations
■ On-chip internal temperature sensor
■ Maximum sample rate of one million samples/second
■ Optional phase shift in sample time programmable from 22.5º to 337.5º
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January 23, 2012
Texas Instruments-Production Data