CS492505-CL View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS492505-CL

Multi-Channel Digital Audio Decoders

Cirrus Logic 

CS4923/4/5/6/7/8/9

6. CONTROL

Control of the CS4923/4/5/6/7/8/9 can be

accomplished through one of four methods. The

CS492X supports I2C and SPI serial

communication. In addition the CS492X supports

both a Motorola and Intel byte wide parallel host

control mode. Only one of the four communication

modes can be selected for control. The states of the

RD, WR, and PSEL pins at the rising edge of

RESET determine the interface type as shown in

table 2.

RD

(Pin 5)

1

1

0

1

WR

(Pin 4)

1

1

1

0

PSEL

(Pin 19)

1

0

X

X

Host Interface Mode

8-bit Motorola

8-bit Intel

Serial I2C

Serial SPI

Table 2. Host Modes

Whichever host communication mode is used, host

control of the CS4923/4/5/6/7/8/9 is handled

through the application software running on the

DSP. Configuration and control of the CS492X

decoder and its peripherals are indirectly executed

through a messaging protocol supported by the

downloaded application code. In other words

successful communication can only be

accomplished by following the low level hardware

communication format and high level messaging

protocol. The specifications of the messaging

protocol can be found in any of the application

code user’s guides.

It should be noted that when using the CS4926 or

CS4928 for DTS decoding, an external memory

interface must be used for DTS tables that are

required for decoding. (see section 6.5 for

information on external memory). The external

memory interface and the parallel interface modes

can not be used together. For this reason the system

designer must use one of the serial communication

modes with external memory if designing with the

CS4926 or CS4928 for DTS decode. An image of

the DTS tables is available from the factory.

Below is a brief discussion of each of the

communication modes available for the

CS4923/4/5/6/7/8/9. For a complete description of

these communication modes along with flow

charts, pseudocode and restrictions, please consult

the CS4923/4/5/6/7/8/9 Hardware User’s Guide. A

complete understanding of the decoder and its

operation can not be accomplished without

consulting the CS4923/4/5/6/7/8/9 Hardware

User’s Guide and the application code user’s

guides.

6.1 Boot and Control Mode Overview

Regardless of which communication mode is used,

the CS4923/4/5/6/7/8/9 must be booted and loaded

with code at run time. The general sequence from a

hardware perspective is as follows:

5) RESET Low

6) Set Communication Configuration Pins

7) RESET High

8) Download Code

9) Configure Hardware

10) Configure Application Code

11) Kickstart the Decoder

The host has three options for code download:

• Parallel Download through the parallel host in-

terface

• Serial download through either the SPI or I2C

interface

• Autoboot with external memory when using a

serial communication mode.

Once again the CS4923/4/5/6/7/8/9 Hardware

User’s Guide should be consulted for a complete

description of the boot and download procedure

including the necessary communication

handshaking. Hardware configuration is also

DS262F2

33

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