PC97307 datasheet(136/218 Pages) NSC

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136

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

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7.3

Eight register banks, each containing eight registers, con-

trol UART operation. All registers use the same 8-byte ad-

dress space to indicate offsets 00h through 07h, and the

active bank must be selected by the software.

The register bank organization enables access to the banks

as required for activation of all module modes, while main-

taining transparent compatibility with 16450 or 16550 soft-

ware, which activates only the registers and specific bits

used in those devices. For details, See Section 7.4.

The Bank Selection Register (BSR) selects the active bank

and is common to all banks. See Figure 7-1. Therefore,

each bank defines seven new registers.

FIGURE 7-1. Register Bank Architecture

The default bank selection after system reset is 0, which

places the module in the UART 16550 mode. Additionally,

setting the baud rate in bank 1 (as required to initialize the

16550 UART) switches the module to a Non-Extended

UART mode. This ensures that running existing 16550 soft-

ware will switch the system to the 16550 configuration with-

out software modification.

Table 7-1 shows the main functions of the registers in each

bank. Banks 0-3 control both UART and infrared modes of

operation; banks 4-7 control and configure the infrared

modes only.

BANK 0

BANK 1

BANK 2

BANK 3

BANK 4

BANK 5

BANK 6

BANK 7

Offset 07h

Offset 06h

Offset 05h

Offset 04h

LCR/BSR

Offset 02h

Offset 01h

Offset 00h

Common

Throughout

All Banks

16550 Banks

TABLE 7-1. Register Bank Summary

Banks 0 and 1 are the 16550 register banks. The registers

in these banks are equivalent to the registers contained

in the 16550 UARTs and are accessed by 16550 soft-

ware drivers as if the module was a 16550. Bank 1 con-

tains the baud divisor ports. Bank 0 registers control all

other aspects of the UART function, including data

transfers, format setup parameters, interrupt setup and

status monitoring.

Bank 2 contains the non-legacy Baud Generator Divisor

ports, and controls the extended features special to this

UART, that are not included in the 16550 repertoire.

These include DMA usage. See ”Extended UART

Mode” on page 137.

Bank 3 contains the Module Revision ID and shadow regis-

ters. The Module Revision ID (MRID) register contains

a code that identifies the revision of the module when

read by software. The shadow registers contain the

identical content as reset-when-read registers within

bank 0. Reading their contents from the shadow regis-

ters lets the system read the register content without re-

setting them.

Bank 4 contains setup parameters for the Infra-red modes.

Bank 5 registers control infrared parameters related to the

logical system I/O parameters.

Bank 6 registers control physical characteristics involved

in infrared communications (e.g. pulse width selection).

Bank 7 registers are dedicated to Consumer-IR configura-

tion and control.

7.4

UART MODES – DETAILED DESCRIPTION

The UART modes support serial data communications with

a remote peripheral device or modem using a wired inter-

face.

Bank

UART

Mode

Main Functions

Global Control and Status

Legacy Bank

Baud Generator Divisor,

Extended Control and Status

Module Revision ID and

Shadow Registers

IR mode setup

Infrared Control

Infrared Physical Layer

Conﬁguration

Consumer-IR and Optical

Transceiver Conﬁguration

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