Texas Instruments 2.4 GHz Bi-directional Audio Streaming with Karaoke for DVDs and Set Top Boxes Application Note

Texas Instruments
Brand
Texas Instruments
Model
2.4 GHz Bi-directional Audio Streaming with Karaoke for DVDs and Set Top Boxes
Category
Audio cards
Type
Application Note
Application Report
SWRA440–November 2013
2.4-GHz Bi-directional Audio Streaming with Karaoke for
DVDs and Set Top Boxes (STB) using CC853x
Vikas Thawani and Sanjay Dixit................................................................................ Low-Power Wireless
ABSTRACT
This application note describes the power of the CC853x, which is a 2.4-GHz RF SoC for wireless audio
streaming. A standard CC853x wireless headset development kit is used to make a wireless demo for
audio transmission and reception in a standard IR (infrared) Remote-DVD/STB-TV system. Two audio
channels are transmitted from Remote to DVD, and stereo audio channels are transmitted from DVD to
Remote. The built-in Audio protocol of CC853x makes multiple audio channels to co-exist simultaneously.
The target applications for the demo are DVD and STBs without doing any software modification to the
existing IR-based system.
Contents
1 CC85xx ....................................................................................................................... 1
2 Existing Remote-STB/DVD-TV system: .................................................................................. 2
3 Modified System to Establish Bi-Directional Audio Link ............................................................... 2
4 Conclusion ................................................................................................................... 6
5 References ................................................................................................................... 6
6 Schematics ................................................................................................................... 7
List of Figures
1 Typical CC85xx and TLV320AIC3204 Application Schematic........................................................ 2
2 Audio Conversion Signal Chain........................................................................................... 3
3 CC85xx Headset EVM (Master or Slave)................................................................................ 3
4 Demo Architecture.......................................................................................................... 4
5 IR Commands from Remote............................................................................................... 4
6 Karaoke MIC Audio into Right Channel.................................................................................. 5
7 Processing of Received RC5 Remote Commands..................................................................... 5
8 Add the Received Karaoke Sound to TV Audio Input.................................................................. 6
9 STB/DVD Stereo Audio Added to MIC Input for Transmission to Remote.......................................... 6
10 Remote-Side Schematics ................................................................................................. 7
11 STB-Side Schematics ..................................................................................................... 8
List of Tables
1 CC85xx
The CC85xx are TI’s wireless audio devices that use 2.4-Ghz unlicensed industrial, scientific, and medical
(ISM) band. This CC85xx family offers state-of-the-art co-existence and robustness, excellent link budget
and low-power operation while streaming high-quality audio wirelessly. This family has built-in audio
protocol providing excellent robustness and co-existence through multiple techniques such as adaptive-
frequency hopping and forward-error correction. CC85xx devices operate autonomously and can be used
with or without external MCU. The control interface for CC85xx is SPI and the Audio interface is I2S and
USB (CC85x1 only). Different members of the CC85xx family differ in the number of audio channels that
can be streamed simultaneously and in USB audio support.
1
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Existing Remote-STB/DVD-TV system:
www.ti.com
2 Existing Remote-STB/DVD-TV system:
The bidirectional wireless Audio demo described in the application note uses the existing IR system. The
system consists of IR remote, DVD or STB and an LCD TV. DVD or STB has an IR receiver that decodes
IR commands transmitted by remote and controls the DVD operation. This IR system has the following
limitations:
• Range of control
• Line of sight is required for control
3 Modified System to Establish Bi-Directional Audio Link
A typical application schematic of the CC85xx Headset reference design kit is shown in Figure 1.
Figure 1. Typical CC85xx and TLV320AIC3204 Application Schematic
The TLV320AIC3204 is a low-power stereo codec that forms the data converter of the system. MIC input
goes to ADC and is converted to I2S digital audio, whereas the I2S digital audio received is converted to
analog audio by DAC and routed to the headphone output. I2S audio is interfaced with CC8531 that forms
the link between I2S and RF. CC2590 has additional PA and LNA that are used to extend the RF range.
Figure 2 illustrates this architecture.
2
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AudioCodec ADC
AudioCodecDAC
CC8531
CC8531
Analog Audio
RFM
RFP
RFM
RFP
AnalogIN
I2S Audio
I2S Audio
www.ti.com
Modified System to Establish Bi-Directional Audio Link
Figure 2. Audio Conversion Signal Chain
The CC85xx headset development kit consists of two similar EVMs, configured as master and slave.
Figure 3 illustrates the CC85xx headset EVM (master or slave).
Figure 3. CC85xx Headset EVM (Master or Slave)
The demo architecture is illustrated in Figure 4.
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IRcommands
fromRemote
Pinof AudiocodeconCC853xEVM
+
C1
1µF
1
GND
2
VS
3
OUT
U2
TSOP312XX
R1
10k
R2
5.6k
Q1
BC557
R3
1k
VBAT
VBAT
MICL
Modified System to Establish Bi-Directional Audio Link
www.ti.com
Figure 4. Demo Architecture
The default configuration is half duplex and is factory programmed. The following steps were performed to
configure the demo:
1. The EVM was reprogrammed to full duplex mode with both master and slave transmitting and
receiving at the same time.
2. IR commands from Remote are captured by IR receiver TSOP312xx (Figure 5), stepped down in
voltage level and fed to the MICL pin of audio codec on Headset EVM located at the remote side.
Figure 5. IR Commands from Remote
3. Karaoke MIC voice data is captured by the Electret Microphone, stepped up in voltage level by 2 stage
amplifier, and fed to MICR input of Headset EVM located at the remote side.
4
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HPL pin
ofaudiocodeconCC853xevm
R15
4.7k
R16
5.6k
C10
10µF
R21
10k
R22
220k
R23
27k
R24
4.7k
C11
10nF
1
2
U1-A
74HCT14
3
4
U1-B
74HCT14
5
6
U1-C
74HCT14
9
8
U1-D
74HCT14
11
10
U1-E
74HCT14
13
12
U1-F
74HCT14
A
K
D1
MLED71
1
J3
R1
5.6k
C1
560pF
R2
4.7k
1 2
JMP1
1 2
JMP2
D2
BAT85
R3
220
R4
220
5
IN+
6
IN-
7
OUT
U2-B
LM393D
5V
HPL
5V
IR_OUT
ElectretMic
Q2
Q3
R5
4.7k
R6
4.7k
+
C3
1µF
+
C4
R7
1k
R8
470k
R9
1k
R10
220
+
C5
C6
R11
220k
R12
470k
R13
1k
C7
VBAT
VBAT
VBAT
1µF
1µF
R14
2.2k
MICBIAS
IN1RofCodec
MICJack
KaraokeMicaudio
intorightchannel
CC8531HeadsetEVM
+
1µF
10µF
+
www.ti.com
Modified System to Establish Bi-Directional Audio Link
Figure 6. Karaoke MIC Audio into Right Channel
4. A wireless audio link is established between the remote-side EVM and the STB/DVD-side EVM. This
enables the STB/DVD EVM to receive IR commands in RF format, and CC8531 converts the received
signal in digital I2S format. Audio codec on the EVM converts the digital audio to analog. This signal is
converted to 5-V logic level RC5 signal. A 36-kHz square wave is used to modulate RC5 and drive an
IR LED. This IR LED, when kept in front of STB/DVD, will respond to IR commands without opening
the STB/DVD.
Figure 7. Processing of Received RC5 Remote Commands
5. The right RF channel received on the STB/DVD side is Karaoke voice that is converted back to digital
I2S. The digital I2S audio is converted back to analog output received at right Headphone channel, and
is fed into TV audio along with STB/DVD audio. Hence, a karaoke effect is in place.
5
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Transmittedforremoteside.
C5
1µF
C6
1µF
1
3
2
J4
STB_LOUT
STB_ROUT
MICL
MICR
C9
1µF
R17
4.7k
R18
4.7k
R19
4.7k
R20
4.7k
1
3
2
J5
HPR
STB_LOUT
STB_ROUT
TV_LIN
TV_RIN
Conclusion
www.ti.com
Figure 8. Add the Received Karaoke Sound to TV Audio Input
6. The STB/DVD stereo audio output is also fed to Microphone MICL and MICR inputs of DVD/STB-side
EVM. Remote side EVM receives the audio wirelessly. CC853x converts RF audio to digital I2S audio.
Audio codec on board changes digital audio to analog output that is routed to headphones connected
at the Headphone jack of the remote-side EVM. Thus, the person viewing a movie can listen to audio
on headphones and mute the TV output, a case helpful for viewing late night television.
Figure 9. STB/DVD Stereo Audio Added to MIC Input for Transmission to Remote
The previous steps help to setup a four channel wireless audio link between Remote and STB. Two
channels, MIC and IR commands, are streamed from remote to STB/DVD, and two stereo audio channels
are streamed from STB/DVD side to Remote headphones. Throughout the demo, no software changes
were made either on the remote side or on the DVD/STB side.
4 Conclusion
The remote EVM can be hooked to any standard IR Remote. The STB EVM can be placed in front of any
STB/DVD and has the capability to communicate with the IR receiver inside. This demo can further be
extended if a voice decoding engine is made on the STB side, and STB can be controlled by voice
commands from Remote. CC8531 can support wireless streaming of up to 4 audio channels
simultaneously. There are no audio dropouts, as shown in the above demo, and multiple channels can co-
exist. This fact makes CC85xx an excellent choice for applications like wireless headphones, wireless
loudspeakers and wireless 2.1 audio systems.
5 References
Use the following references for additional information:
1. CC85xx datasheet (SWRS091)
2. CC85xx Headset Quick Start Guide (SWRU282)
3. CC85xxDK Headset User's Guide (SWRU281)
4. CC85xx Design Documents (SWRR079)
6
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IRcommands
fromRemote
ElectretMic
Pinof AudiocodeconCC853xEVM
R1onCC853xEVMpoppedout
Todisablekaraoke-InstallJMP2
ToenableKaraoke,installJMP1
MICRinputofCC853xEVM
Notes:
1.RemotecanbepoweredfromaLiionbattery.
+
C1
1µF
Q2
Q3
J1
R5
4.7k
R6
4.7k
+
C3
1µF
+
C4
1µF
R7
1k
R8
470k
R9
1k
R10
220
+
C5
1µF
+
C6
1µF
R11
220k
R12
470k
R13
1k
1
GND
2
VS
3
OUT
U2
TSOP312XX
1
1
2
2
J3
CONN_1706358
+
C2
1µF
1 2
JMP1
1
2
JMP2
R1
10k
R2
5.6k
Q1
BC557
R3
1k
VBAT
VBAT
VBAT
VBAT
VBAT
MICR
VBAT
MICL
USBisusedfortesting.
www.ti.com
Schematics
6 Schematics
Figure 10 and Figure 11 illustrate the Remote-side and STB-side schematics for audio streaming using CC853x.
Figure 10. Remote-Side Schematics
7
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CC8531HeadsetEVM
Transmittedforremoteside
HPL pin
ofaudiocodeconCC853xevm
CC8531HeadsetEVM
Notes:
1.Wholesystemcanbepoweredfrom5VatSTBside.7805optionisonPCB.
2.J4isdualRCA connectorwhereSTBstereoaudioisrouted.
3.J5isdualRCA connectorwhereKaraokeisaddedandstereoaudioisfedto TV.
4.IRLEDshouldbeplacedcloseenoughsothatitisabletocommunicatewithIRReceiverinsideSTB/DVD.
5.EitherofJMP1orJMP2isusedaccordingtopolarityofIRreceiverinsideSTB/DVD.
C9
1µF
R15
4.7k
R16
5.6k
R17
4.7k
R18
4.7k
R19
4.7k
R20
4.7k
C10
10nF
R21
10k
R22
220k
R23
27k
R24
4.7k
C11
10nF
1
2
U1-A
74HCT14
3
4
U1-B
74HCT14
5
6
U1-C
74HCT14
9
8
U1-D
74HCT14
11
10
U1-E
74HCT14
13
12
U1-F
74HCT14
A
K
D1
MLED71
1
J3
R1
5.6k
C1
560pF
R2
4.7k
1 2
JMP1
1 2
JMP2
D2
BAT85
R3
220
R4
220
3
IN+
2
IN-
1
OUT
8
VCC
4
GND
U2-A
LM393D
5
IN+
6
IN–
7
OUT
U2-B
LM393D
C2
0.1µF
R5
4.7k
1
IN
2
GND
3
OUT
U3
MC7805CT
C3
10µF
C4
10µF
C5
1µF
C6
1µF
1
3
2
J4
1
3
2
J5
5V
HPL
HPR
5V
STB_LOUT
STB_ROUT
STB_LOUT
STB_ROUT
TV_LIN
TV_RIN
IR_OUT
5V
5V
MICL
MICR
Schematics
www.ti.com
Figure 11. STB-Side Schematics
8
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Texas Instruments 2.4 GHz Bi-directional Audio Streaming with Karaoke for DVDs and Set Top Boxes Application Note

Texas Instruments
Brand
Texas Instruments
Model
2.4 GHz Bi-directional Audio Streaming with Karaoke for DVDs and Set Top Boxes
Category
Audio cards
Type
Application Note
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