Cirrus Logic CS48AU2B - Manual (Page 6)

CS48AU2B Data Sheet
Dedicated 32-bit Audio DSP for Audyssey Laboratories Technology
6 Copyright 2009 Cirrus Logic DS876F3
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3. Code Overlays
The suite of software available for the CS48AU2B 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 (2 Ö n channels). Generally speaking, these modules
increase the number of valid channels in the audio I/O buffer.
3. Virtualizer-processor - Any module that encodes PCM data into fewer output channels than
input channels (n Ö 2 channels) with the effect of providing “phantom” speakers to represent the
physical audio channels that were eliminated. Generally speaking, these modules reduce the
number of valid channels in the audio I/O buffer.
4. Post-processors - Any module that processes audio I/O buffer PCM data in-place after the
matrix- or virtualizer-processors. Examples are bass management, audio manager, tone control,
Audyssey Dynamic Volume, Audyssey Dynamic EQ, Audyssey EQ, Audyssey BassXT, delay, &
customer-specific effects, etc.
The certified DSP firmware or application codes provided by Cirrus Logic (under a licensed to you
from Audyssey Laboratories) may enable some or all of the Audyssey Laboratories algorithms.
These licensed processing blocks can be used in combination with a host standard post-processing
signal blocks (tone control, Bass Management, delays, etc.) or lower level primitives such as a filter
or math function.
A product-specific signal flow is generated by the designer using DSP Composer.
Once all of the custom coefficient files supplied by Audyssey Laboratories have been loaded and the
signal flow has been set, the user can perform a “generate deliverables” inside DSP Composer.
This generates a collection of files that can be easily converted to .c or .h files by the designer for
storage inside the host controller OR can be converted into a small image that can either be stored in
an external serial FLASH/EEPROM, or downloaded via a host controller through the
SPI ™ /I
2
C ® serial
port.
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
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).
Table 2 below lists the firmware available based on device selection. Please refer to AN298,
CS485xx Firmware User’s Manual for the latest listing of application codes and Cirrus Framework ™
modules available.