PC97307 datasheet(135/218 Pages) NSC

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UART1 and UART2 (with IR) (Logical Devices 5 and 6)

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7.0

UART1 and UART2 (with IR)

(Logical Devices 5 and 6)

This section describes the functionality of the Legacy UART

(16450/16550), Enhanced UART and the IR modes.

UART1 supports standard 16450/16550 mode.

UART2 supports standard 16450/16550, Enhanced UART

and IR modes.

UART1 implements a subset of UART2 functionality. It sup-

ports UART mode hard-wired communications, but does

not support IR communication. Therefore, all explanations

of IR communication in this section do not apply to UART1.

The UART module provides advanced, versatile serial com-

munications features with infrared capabilities. It supports

four modes of operation: UART, Sharp-IR, IrDA 1.0 SIR

(hereafter called SIR) and Consumer-IR (also called TV-

Remote or Consumer remote-control). In UART mode, the

module can function as a standard 16450 or 16550, or as

an Extended UART.

Existing 16550-based legacy software is completely and

transparently supported. Module organization and specific

fallback mechanisms switch the module to 16550 compati-

bility mode upon reset or when initialized by 16550 soft-

ware.

The module includes two DMA channels that can support all

operational modes. The device can use either 1 or 2 DMA

channels. One channel is required for infrared based appli-

cations since infrared communications work in half duplex

fashion. Two channels would normally be needed to handle

high-speed full duplex UART based applications.

7.1

FEATURES

• Fully compatible with 16550 and 16450 devices

• Automatic fallback to 16550 compatibility mode

• Extended UART mode

• UART baud rates up to 1.5 Mbps

• Sharp-IR with selectable internal or external modula-

tion/demodulation

• IrDA 1.0 SIR with data rates up to 115.2 Kbps

• Consumer-IR (TV-Remote) mode

• Full duplex infrared capability for diagnostics

• Transmission deferral (in Consumer-IR mode)

• Selectable 16 or 32-level transmission and reception

FIFOs (RX_FIFO & TX_FIFO respectively)

• Multiple optical transceiver support

• Automatic or manual transceiver conﬁguration

• Support for Plug-n-Play infrared adapters

7.2

FUNCTIONAL MODES OVERVIEW

This multi-mode module can be configured to act as any

one of several different functions. Although each mode is

unique, certain system resources and features are common

to some or to all modes.

7.2.1

UART Modes: 16450 or 16550, and Extended

UART modes support serial data communications with a re-

mote peripheral device or modem using a wired interface.

The device transmits and receives data concurrently in full-

duplex operation, performing parallel-to-serial and serial-to-

parallel conversion and other functions required to ex-

change parallel data with the system. It also interfaces with

external devices using a programmable serial communica-

tions format.

The following UART modes are supported:

• 16450 or 16550 mode (Non-Extended modes)

• Extended mode

The 16450 or 16550 mode is functionally and software-

compatible with the standard 16450 or 16550 UARTs. This

is the default mode of operation after power up, after reset

or when initialized by software written for the 16450 or

16550 UART (Special mechanisms switch the module auto-

matically to 16550 UART mode when standard 16550 soft-

ware is run).

The 16550 UART mode has all the features of the 16450

mode, with the addition of 16-byte data FIFOs for more effi-

cient data I/O.

In Extended mode, additional features become available

that enhance the UART performance, such as additional in-

terrupts and DMA ability (see “Extended UART Mode” on

page 137).

The UART supports baud rates of up to 115.2 Kbps in

16450 or 16550 mode, and up to 1.5 Mbps in Extended

mode.

7.2.2

Sharp-IR, IrDA SIR Infrared Modes

The Sharp-IR mode provides bidirectional communication

by transmitting and receiving infrared radiation. In this

mode, infrared I/O circuits was added to the UART, which

operates at 38.4 Kbps in half-duplex, using normal UART

serial data formats with Digital Amplitude Shift Keying

(DASK) modulation. The modulation/demodulation can be

operated internally or externally.

In SIR mode, the system functions similarly to the Sharp-IR

mode, but at 115.2 Kbps.

7.2.3

Consumer IR Mode

Consumer-IR mode supports all the protocols presently

used in remote-controlled home entertainment equipment:

RC-5, RC-6, RECS 80, NEC and RCA. The serial format is

not compatible with UART operation, and specific circuitry

performs all the hardware tasks required for signal condi-

tioning and formatting. The software is responsible for the

generation of the infrared code to be transmitted, and for the

interpretation of the received code.

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