CS485NI-XYZR View Datasheet(PDF) - Cirrus Logic

Part Name

Description

Manufacturer

CS485NI-XYZR

32-bit Audio Decoder DSP Family

Cirrus Logic 

CS485xx Family Data Sheet

32-bit Audio Decoder DSP Family

3. Code Overlays

The suite of software available for the CS485xx family consists of an operating system (OS) and a

library of overlays. The overlays have been divided into three main groups called Matrix-processors,

Virtualizer-processors, and Post-processors. All software components are defined below:

1. OS/Kernel - Encompasses all non-audio processing tasks, including loading data from external

memory, processing host messages, calling audio-processing subroutines, error concealment,

etc.

2. Matrix-processor- Any Module that performs a matrix decode on PCM data to produce more

output channels than input channels (2Ön channels). Examples are Dolby ProLogic IIx and DTS

Neo:6. Generally speaking, these modules increase the number of valid channels in the audio

I/O buffer.

T 3. 3. Virtualizer-processor - Any module that encodes PCM data into fewer output channels than

F input channels (nÖ2 channels) with the effect of providing “phantom” speakers to represent the

physical audio channels that were eliminated. Examples are Dolby Headphone® and Dolby

A Virtual Speaker®. Generally speaking, these modules reduce the number of valid channels in the

audio I/O buffer.

R 4. 4. Post-processors - Any module that processes audio I/O buffer PCM data in-place after the

D matrix- or virtualizer-processors. Examples are bass management, audio manager, tone control,

EQ, delay, customer-specific effects, etc.

The bulk of each overlay is stored in ROM within the CS485xx, but a small image is required to

L I configure the overlays and boot the DSP. This small image can either be stored in an external serial

FLASH/EEPROM, or downloaded via a host controller through the SPI™/I2C® serial port.

IA H The overlay structure reduces the time required to reconfigure the DSP when a processing change is

requested. Each overlay can be reloaded independently without disturbing the other overlays. For

T P example, when a new matrix-processor is selected, the OS, virtualizer-, and post-processors do not

need to be reloaded — only the new matrix-processor (the same is true for the other overlays).

N L Table 2 below lists the firmware available based on device selection. Please refer AN298, CS485xx

E E Firmware User’s Manual for the latest listing of application codes and Cirrus Framework™ modules

CONFID D available.

6

©Copyright 2008 Cirrus Logic, Inc.

DS734F2

CONFIDENTIAL

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