LM3S818 Luminary Micro, Inc, LM3S818 Datasheet - Page 27

• Manufacturer Part Number: LM3S818
• Description: Lm3s818 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

1.4.2.2
1.4.3
1.4.3.1
1.4.3.2
February 6, 2007
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 (“16-Bit PWM Mode” on page 153)
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 (Section 16 on page 344)
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 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 LM3S818 controller offers an Analog-to-Digital Converter (ADC) and
an analog comparator.
ADC (Section 11 on page 199)
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 10-bit conversion resolution and supports six input channels,
plus an internal temperature sensor. Four buffered sample sequences allow rapid sampling of up
to six 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 Comparator (Section 14 on page 300)
An analog comparator is a peripheral that compares two analog voltages, and provides a logical
output that signals the comparison result.
The LM3S818 controller provides one independent integrated analog comparator that can be
configured to drive an output or generate an interrupt or ADC event.
A comparator can compare a test voltage against any one of these voltages:
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 or triggers to the
ADC to cause it to start capturing a sample sequence. The interrupt generation and ADC triggering
logic is separate. This means, for example, that an interrupt can be generated on a rising edge and
the ADC triggered on a falling edge.
An individual external reference voltage
A single external reference voltage
A shared internal reference voltage
Preliminary
LM3S818 Data Sheet
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