Audio-Mojo SavFIRe TM Audio Reference Design

1www.quickfiltertech.com

Audio-MojoApplication-Specific Development Board for

Audio Applications using the QF1D512

April 2007www.quickfiltertech.com


Audio-MojoSavFIReTM Audio Reference

Design• Demonstrates equalization and

crossover functionality

• 2 QF1D512s, stereo codec, uC/EE

• Use standalone, or,

• Plugs into QF1D512-DK Dev Kit

• Preconfigured for use as 2-channel EQ or 1 channel crossover

• Design/modify filters using Quickfilter Pro Software

• Verify filter response on DK

• Download to Audio-Mojo

• Use standalone with new settings

Audio-Mojo Board

Audio-Mojo mounted on QF1D512-DK


Audio Mojo Overview

Demonstrate QF capability for audio As an equalizer As a crossover

Proof of concept / reference design Schematics and software available

Development Tool User can experiment with his own filter designs Can save his config to the board and then...

Standalone operation User can implement in his system without dev kit


Audio-Mojo Block Diagram

AnalogIn ADC

I2S

STEREO CODECCS4270

DACI2SAnalog

Out

QF1D512

f

QF1D512

f

L

L

R

R

uC*ATtiny85

Config Programmingheader

GND

Header

To QF1D512-DK

(optional)

To Atmel programmeror QF1D512-DK

(optional)

Header

Ext. Pwr

* uC used for configuration only using stored settings / filters in on-chip EEPROMNot used in the signal data path


Audio Mojo

AudioInputs

AudioOutputs

ProgrammingHeader

Ext Power

CodecConfig

Signal RoutingQF1D512s

uC Codec


Configuration Example 1

Equalizer

Each filter processes data from only one channel Use LRCK signal from codec to frame channels

Independent filtering per channel.

Analog In

Codec

L-Ch

R-Ch

QF1D512

f

QF1D512

f

Left RightAnalog OutL-Ch

R-Ch

DK Monitor

L-Ch R-Ch L-Ch’ R-Ch L-Ch’ R-Ch’

Output from codec Output from 1st QF1D512 Output from 2nd QF1D512

LRCK


Configuration Example 2

Crossover

Both channels fed with same signal HPF on Left channel, LPF on right channel Analog outputs become high frequency content (L) and

low frequency content (R) Can also be combined with equalization

Analog In

Codec

L-Ch

R-Ch

Left / High Right / LowAnalog OutHigh

Low

DK MonitorQF1D512

f

QF1D512

f


Standalone Mode User provides power source uC loads QF1D512 SavFIRes on power up User can input analog data and monitor

analog outputs

Development Connect to Atmel programmer via topside

header (J3) Use QF Pro to design and save Config data Import Configs to Dev Tool & download

configs to uC

Standalone Use


Monitor Mode Uses QF1D512 SavFIRes on Audio-Mojo board uC loads SavFIRes at power up with default settings User applies analog inputs and monitor analog outputs Display FFT of frequency response (Monitor mode) No filter thumbnails / Edit disabled

Dev Kit Mode Uses QF1D512 SavFIRes on dev board QF Pro software can be used to modify filter responses Support “near real time” adjustment of filter parameters

e.g. Graphic EQ User can apply analog inputs and monitor analog outputs Download configs to Audio-Mojo board for standalone use

Use with Development Kit


Runs out of the box, no cables or other hardware to make

Modify and see results of filter changes in “near real time” with no need for a new build each time

View FFTs of actual end hardware performance, not just theoretical results

Advantages of use with Dev Kit


Logarithmic Filter Response Option

Graphic Filter Editor

QF Pro Software Upgrades

Simultaneous capture & display of two channels


Atmel programmer Export hex files from QF Pro for

download to ATtiny

QF Dev Kit Connect programming header to J4 Download configs directly to the ATtiny from the QF Pro

software

Note: Tiny memory is partitioned to simplify the task: Program memory (user need not alter!) SavFIRe configs (4) = 2 complete 2-channel configs

Programming Options


QF1D512Applications Ideas


QF1D512

HostuC

ADC

QF1D512HostuCADC

External ADC or codec

Internal ADC / Coprocessor

Audio ApplicationsFlexible Interface Options


Audio ApplicationsFlexible Interface Options - 2

Accepts serial digital data SPI or I2S directly S/P-DIF after conversion

Precision filtering without dedicated computing resource System uC can load config / filter data

QF1D512

Convertere.g.CS8420

AnalogIn ADC

I2S, SPI

I2S, SPI

S/P-DIF

DigitalIn

DigitalFiltered

Data Out

SPI


Audio Application:Stereo / Multi-channel Filtering

Each filter processes data from only one ADC input. Independent filtering per channel. Add as many chips as needed for channel count.

QF1D512Ch1 Filter

Analog In

ADC QF1D512Ch2 Filter

Ch1Ch2

Digital Out

e.g. CS53xx


Audio ApplicationEqualizer

Use single device with optimized ”shape” for the whole band Use Number of Taps to implement variable delay

Cascade multiple chips in series Dedicate each device to a particular frequency band Not suitable for applications where latency is an issue!

QF1D512QF1D512 QF1D512

f0 f2f1

QF1D512

f

Data InFiltered

Data Out

Data InFiltered

Data Out

f f f


Audio ApplicationDigital Wireless Headphones - 1

QF1D512 filters out any unwanted noise, shapes frequency response to suit headphone driver & enclosure

DAC only if digital data transmitted, codec otherwise Analog Power Drive

WirelessReceiver / Codec

DAC /Codec

AMP

QF1D512

f

e.g. MAX4411

e.g. CS433x

QF1D512

f

Left Right


Audio ApplicationDigital Wireless Headphones - 2

QF1D512 filters out any unwanted noise, shapes frequency response to suit headphone driver & enclosure Greater control than the built in tone response of the CS44L11

Digital end-to-end solution

WirelessReceiver

DIGITAL AMP

QF1D512

f

e.g. CS44L11

QF1D512

f

Left Right


Audio ApplicationDigital Wireless Speaker

QF1D512 filters out any unwanted noise, shapes & limits frequency response to suit driver unit & enclosure

Assumes digital transmitted data (I2S) Power Amp may be digital or DAC + analog, as required

WirelessReceiver

POWER AMP

QF1D512

f

Equalizer

QF1D512

f

Additional QF1D512 crossovers + power amps as needed for

multi-driver configurations


Audio ApplicationPre-Crossover Filtering

Data InQF1D512

f

to digital crossover circuit

• Bandpass for protection of speakers• RF interference rejection• Notch for rec vs. playback audio compensation

MCU*(eg ATtiny)

* inexpensive (40 cent) MCU can be used for loading the configuration parameters upon start up if a host MCU not present


Audio ApplicationBass Management

Data InQF1D512

f

Bass / Sub Data Out

100Hz LPF

MCU*(eg ATtiny)



Audio ApplicationDigital crossover

Connect as many chips as needed to sub-divide band

QF1D512

f

Data InHF / Tweeter Data Out

QF1D512

f

QF1D512

f

QF1D512

f

Equalizer

Bass / Sub Data Out

Mid-range Data OutMCU*


Audio-Mojo SavFIRe TM Audio Reference Design

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