audio-mojo savfire tm audio reference design
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1www.quickfiltertech.com
Audio-MojoApplication-Specific Development Board for
Audio Applications using the QF1D512
April 2007www.quickfiltertech.com
2www.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
3www.quickfiltertech.com
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
4www.quickfiltertech.com
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
5www.quickfiltertech.com
Audio Mojo
AudioInputs
AudioOutputs
ProgrammingHeader
Ext Power
CodecConfig
Signal RoutingQF1D512s
uC Codec
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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
7www.quickfiltertech.com
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
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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
9www.quickfiltertech.com
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
10www.quickfiltertech.com
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
11www.quickfiltertech.com
Logarithmic Filter Response Option
Graphic Filter Editor
QF Pro Software Upgrades
Simultaneous capture & display of two channels
12www.quickfiltertech.com
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
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QF1D512Applications Ideas
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QF1D512
HostuC
ADC
QF1D512HostuCADC
External ADC or codec
Internal ADC / Coprocessor
Audio ApplicationsFlexible Interface Options
15www.quickfiltertech.com
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
16www.quickfiltertech.com
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
17www.quickfiltertech.com
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
18www.quickfiltertech.com
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
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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
20www.quickfiltertech.com
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
21www.quickfiltertech.com
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
22www.quickfiltertech.com
Audio ApplicationBass Management
Data InQF1D512
f
Bass / Sub Data Out
100Hz LPF
MCU*(eg ATtiny)
* inexpensive (40 cent) MCU can be used for loading the configuration parameters upon start up if a host MCU not present
23www.quickfiltertech.com
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*
* inexpensive (40 cent) MCU can be used for loading the configuration parameters upon start up if a host MCU not present
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