Cirrus Logic AN298 - Manual (Page 3)

AN298RC14 3
2 Overview
2 Overview
The firmware that runs on this device expects a stereo or multi-channel PCM input source. This section describes the
different overlays as well as the functionality of the various processor module overlays.
Figure 2-1. CS485xx Firmware Block Diagram
2.1 Firmware Overlays
The data flows through a series of four firmware overlays that contain one or more firmware modules. A firmware module
provides the specific application affectionately and is controlled by the host via a Firmware Manager that defines the
control interface. The overlays segment the firmware module functionality into four independent groups depending on
function:
OS Overlay
• Manages the overall operation of the DSP. Also handles host communication, data inputs and outputs and various
other critical internal tasks.
Matrix Processing Module Overlay
• Performs additional channel generation, upmixing, downmixing. This segment is where algorithms such as Pro
Logic
® IIx, Neo6 ™ , and COMS2 reside.
Virtual Processing Module Overlay
• Performs stereo virtualizing to simulate multi-channel systems, such as Dolby ® Audistry ® , Dolby Headphone ® , and
Dolby Virtual Surround ® .
Post Processing Module Overlay
• This segment specifically caters to firmware that performs post-processing tasks. It allows the system designer
flexibility in “tweaking” the system for optimal audio performance and effects. This is also the segment in which
firmware modules such as the Audio Manager, Bass Manager, Tone Control, Delay, THX
® , and Parametric-EQ
Module will reside.
Mid-Processor Overlay
PCM Outputs
Post-Processor Overlay (with APP loaded)
ID = 0x83 ID = 0xD9 ID = 0xD5 ID = 0xD4
Tone
Control
Module
Re-Eq
Module
Bass
Management
Module
Parametric
EQ
Module
Delay
Module
Audio Manager
Module
Includes:
Gain (master)
Mute (master)
Channel Trim
Channel Remap
Up-sampler
Mid-Processor Module
e.g. PLII, PLIIx, Neo6, Crossbar,
Viva+, COMS2, Neural Surround,
Circle Surround 2
Virtualizer-Processor
Module
e.g. DVS2, DH2, SRS TSXT,
Audistry
Virtualizer -Processor Overlay Mid-Processor Overlay
PCM inputs
Down-
sampler