PC97338 datasheet(146/221 Pages) NSC

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5.0 Serial Communications

Controllers (SCC1 and SCC2)

Two serial communications control modules are pro-

vided: SCC1 and SCC2. Either module supports a

UART mode of operation and is backward compatible

with the 16550 and 16450. In addition to UART mode,

SCC2 also provides infrared capabilities by support-

ing 5 additional operating modes.

The description of the UART mode in the following

sections applies to both SCC1 and SCC2; the de-

scription of the infrared modes applies to SCC2 only.

The infrared modes supported by SCC2 are: Sharp-

IR, IrDA 1.0 SIR, IrDA 1.1 MIR and FIR, and Consum-

er Electronics IR (also referred to as TV Remote or

Consumer Remote Control).

In order to support existing legacy software based

upon the 16550 UART, both modules provide a spe-

cial fallback mechanism that automatically sets the

operational mode to 16550 compatibility mode when

the baud generator divisor is accessed through the

legacy ports in bank 1.

The modules' architecture has been optimized to

meet the requirements of a variety of UART and infra-

red based applications. DMA support for all operation-

al modes has been incorporated into the architecture.

The modules can use either 1 or 2 DMA channels.

One channel is required for infrared based applica-

tions since infrared communications work in half du-

plex fashion. Two channels would normally be

needed to handle high-speed full duplex UART based

applications.

To further ease driver design and simplify the imple-

mentation of infrared protocols, a 12-bit timer with 125

us resolution has also been included.

Note: Upon reset, SCC2 can wake up in either UART

mode or SIR mode depending on the state of the

CFG0 strap pin.

— If CFG0 is sampled low, SCC2 wakes up in SIR

mode.

— If CFG0 is sampled high, SCC2 wakes up in

UART mode.

5.1

FEATURES

• Fully compatible with 16550 and 16450

• Extended UART mode

• Sharp-IR with selectable internal or external

modulation/demodulation

• IrDA 1.0 SIR with up to 115.2 kbaud data rate

• IrDA 1.1 MIR and FIR with 0.576, 1.152 and 4.0

Mbps data rates

• Consumer Electronic IR mode

• UART mode data rates up to 1.5 Mbps

• Back-to-Back infrared frame transmission and re-

ception

• Full duplex infrared frame transmission and re-

ception

• Transmit deferral

• Automatic fallback to 16550 compatibility mode

• IrDA modes pipelining

• Selectable 16 or 32 level FIFOs

• Support for Plug-n-Play Infrared Adapters

• Automatic or manual transceiver configuration

• 12-bit timer for infrared protocol support

5.2

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 fea-

tures are common to some or to all modes.

5.3

UART MODE

This mode is designed to support serial data commu-

nications with a remote peripheral module or modem

using a wired interface. The module provides transmit

and receive channels that can operate concurrently to

handle full-duplex operation. They perform parallel-

to-serial conversion on data characters received from

the CPU or a DMA controller, and serial-to-parallel

conversion on data characters received from the seri-

al interface. The format of the serial data stream is

shown in Figure 88. A data character contains 5 to 8

data bits. It is preceded by a start bit and is followed

by an optional parity bit and a stop bit. Data is trans-

ferred in Little Endian order (LEAST significant bit

first).

FIGURE 88. Composite Serial Data

START -LSB- DATA 5-8 -MSB- PARITY

STOP

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