LM3S8971 Luminary Micro, Inc, LM3S8971 Datasheet - Page 36

• Manufacturer Part Number: LM3S8971
• Description: Lm3s8971 Arm Microcontroller
• Manufacturer: Luminary Micro, Inc

Architectural Overview
1.4.4
1.4.4.1
1.4.4.2
36
The LM3S8971 microcontroller provides one 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:
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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 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.
Serial Communications Peripherals
The LM3S8971 controller supports both asynchronous and synchronous serial communications
with:
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UART (see page 302)
A Universal Asynchronous Receiver/Transmitter (UART) is an integrated circuit used for RS-232C
serial communications, containing a transmitter (parallel-to-serial converter) and a receiver
(serial-to-parallel converter), each clocked separately.
The LM3S8971 controller includes one fully programmable 16C550-type UARTthat supports data
transfer speeds up to 3.125 Mbps. (Although similar in functionality to a 16C550 UART, it is not
register-compatible.) In addition, each UART is capable of supporting IrDA.
Separate 16x8 transmit (TX) and 16x12 receive (RX) FIFOs reduce CPU interrupt service loading.
The UART can generate individually masked interrupts from the RX, TX, modem status, and error
conditions. The module provides a single combined interrupt when any of the interrupts are asserted
and are unmasked.
SSI (see page 343)
Synchronous Serial Interface (SSI) is a four-wire bi-directional communications interface.
The LM3S8971 controller includes one SSI module that provides the functionality for synchronous
serial communications with peripheral devices, and can be configured to use the Freescale SPI,
MICROWIRE, or TI synchronous serial interface frame formats. The size of the data frame is also
configurable, and can be set between 4 and 16 bits, inclusive.
The SSI module performs serial-to-parallel conversion on data received from a peripheral device,
and parallel-to-serial conversion on data transmitted to a peripheral device. The TX and RX paths
are buffered with internal FIFOs, allowing up to eight 16-bit values to be stored independently.
An individual external reference voltage
A shared single external reference voltage
A shared internal reference voltage
One fully programmable 16C550-type UART
One SSI module
One CAN unit
Ethernet controller
Preliminary
July 26, 2008