2.4 ghz bi-directional audio streaming with karaoke for

Application ReportSWRA440–November 2013

2.4-GHz Bi-directional Audio Streaming with Karaoke forDVDs and Set Top Boxes (STB) using CC853x

Vikas Thawani and Sanjay Dixit................................................................................ Low-Power Wireless

ABSTRACTThis application note describes the power of the CC853x, which is a 2.4-GHz RF SoC for wireless audiostreaming. A standard CC853x wireless headset development kit is used to make a wireless demo foraudio transmission and reception in a standard IR (infrared) Remote-DVD/STB-TV system. Two audiochannels are transmitted from Remote to DVD, and stereo audio channels are transmitted from DVD toRemote. 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 theexisting IR-based system.

Contents1 CC85xx ....................................................................................................................... 12 Existing Remote-STB/DVD-TV system: .................................................................................. 23 Modified System to Establish Bi-Directional Audio Link ............................................................... 24 Conclusion ................................................................................................................... 65 References ................................................................................................................... 66 Schematics ................................................................................................................... 7

List of Figures

1 Typical CC85xx and TLV320AIC3204 Application Schematic ........................................................ 22 Audio Conversion Signal Chain ........................................................................................... 33 CC85xx Headset EVM (Master or Slave)................................................................................ 34 Demo Architecture .......................................................................................................... 45 IR Commands from Remote............................................................................................... 46 Karaoke MIC Audio into Right Channel .................................................................................. 57 Processing of Received RC5 Remote Commands ..................................................................... 58 Add the Received Karaoke Sound to TV Audio Input.................................................................. 69 STB/DVD Stereo Audio Added to MIC Input for Transmission to Remote .......................................... 610 Remote-Side Schematics ................................................................................................. 711 STB-Side Schematics ..................................................................................................... 8

List of Tables

1 CC85xxThe 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 budgetand low-power operation while streaming high-quality audio wirelessly. This family has built-in audioprotocol 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 usedwith or without external MCU. The control interface for CC85xx is SPI and the Audio interface is I2S andUSB (CC85x1 only). Different members of the CC85xx family differ in the number of audio channels thatcan be streamed simultaneously and in USB audio support.

1SWRA440–November 2013 2.4 GHz Bi-Directional Audio Streaming with Karaoke for DVDs and Set TopBoxes using CC853xSubmit Documentation Feedback

Copyright © 2013, Texas Instruments Incorporated

http://www.go-dsp.com/forms/techdoc/doc_feedback.htm?litnum=SWRA440

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. Thesystem consists of IR remote, DVD or STB and an LCD TV. DVD or STB has an IR receiver that decodesIR commands transmitted by remote and controls the DVD operation. This IR system has the followinglimitations:• Range of control• Line of sight is required for control

3 Modified System to Establish Bi-Directional Audio LinkA 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 inputgoes to ADC and is converted to I2S digital audio, whereas the I2S digital audio received is converted toanalog audio by DAC and routed to the headphone output. I2S audio is interfaced with CC8531 that formsthe 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 2.4 GHz Bi-Directional Audio Streaming with Karaoke for DVDs and Set Top SWRA440–November 2013Boxes using CC853x Submit Documentation Feedback


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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 commandsfrom Remote

Pin of Audio codec on CC853x EVM

+

C1

1 µF

1G

ND

2V

S3

OU

T

U2TSOP312XX

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 toconfigure 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 stageamplifier, and fed to MICR input of Headset EVM located at the remote side.



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HPL pin

of audio codec on CC853x evm

R1

5

4.7

k

R16

5.6 kC10

10 µF

R21

10 kR22

220 k

R2

3

27

k

R2

4

4.7

k

C11

10 nF

1 2

U1-A74HCT14

3 4

U1-B

74HCT14

5 6

U1-C74HCT14

9 8

U1-D74HCT14

11 10

U1-E74HCT14

13 12

U1-F74HCT14

AK

D1

ML

ED

71

1

J3

R1

5.6 k

C1

560 pF

R2

4.7 k

1 2JMP1

1 2JMP2

D2

BA

T8

5

R3

22

0

R4

22

0

5 IN+

6IN- 7

OUT

U2-BLM393D

5V

HPL

5V

IR_OUT

Electret Mic

Q2

Q3

R5

4.7

k

R6

4.7

k

+C

3

1 µ

F

+C

4

R7

1k

R8

470 k

R9

1 k

R10

220

+C

5C

6

R11

220 k

R12

470 k

R13

1 k

C7

VBATVBAT

VBAT

1 µ

F

1 µ

F

R14

2.2

k

MICBIAS

IN1R of CodecMIC Jack

Karaoke Mic audiointo right channel

CC8531 Headset EVM

+

1 µ

F

10 µ

F

+

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. Thisenables the STB/DVD EVM to receive IR commands in RF format, and CC8531 converts the receivedsignal in digital I2S format. Audio codec on the EVM converts the digital audio to analog. This signal isconverted to 5-V logic level RC5 signal. A 36-kHz square wave is used to modulate RC5 and drive anIR LED. This IR LED, when kept in front of STB/DVD, will respond to IR commands without openingthe 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 digitalI2S. The digital I2S audio is converted back to analog output received at right Headphone channel, andis fed into TV audio along with STB/DVD audio. Hence, a karaoke effect is in place.



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Transmitted for remote side.

C5

1µ

F

C6

1µ

F

1

3

2

J4

STB_LOUT

STB_ROUT

MICL

MICR

C9

1 µF

R17

4.7 k

R18

4.7 k

R19

4.7 kR20

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-sideEVM. 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 connectedat the Headphone jack of the remote-side EVM. Thus, the person viewing a movie can listen to audioon 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. Twochannels, MIC and IR commands, are streamed from remote to STB/DVD, and two stereo audio channelsare streamed from STB/DVD side to Remote headphones. Throughout the demo, no software changeswere made either on the remote side or on the DVD/STB side.

4 ConclusionThe remote EVM can be hooked to any standard IR Remote. The STB EVM can be placed in front of anySTB/DVD and has the capability to communicate with the IR receiver inside. This demo can further beextended if a voice decoding engine is made on the STB side, and STB can be controlled by voicecommands from Remote. CC8531 can support wireless streaming of up to 4 audio channelssimultaneously. 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, wirelessloudspeakers and wireless 2.1 audio systems.

5 ReferencesUse 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)



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http://www.ti.com/lit/pdf/SWRS091

http://www.ti.com/lit/pdf/SWRU282

http://www.ti.com/lit/pdf/SWRU281

http://www.ti.com/litv/zip/swrr079


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

4.7

k

R6

4.7

k

+C

3

1µ

F+

C4

1µ

F

R7

1k

R8

47

0k

R9

1k

R1

0

22

0

+C

5

1µ

F

+C

6

1µ

F

R11

220k

R1

2

47

0k

R1

3

1k

1G

ND

2V

S3

OU

T

U2TSOP312XX

11

22

J3

CONN_1706358

+C

2

1µ

F

1 2

JMP1

12

JM

P2

R1

10k

R2

5.6

k

Q1

BC557

R3

1k

VBATVBAT

VBAT

VBAT

VBAT

MICR

VBAT

MICL

USB is used for testing.

www.ti.com Schematics

6 SchematicsFigure 10 and Figure 11 illustrate the Remote-side and STB-side schematics for audio streaming using CC853x.

Figure 10. Remote-Side Schematics



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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

1µ

F

R15

4.7

k

R16

5.6k

R17

4.7k

R18

4.7k

R19

4.7k

R20

4.7k

C10

10nF

R21

10k R22

220k

R23

27k

R24

4.7

k

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

AKD1

MLE

D71

1J3

R1

5.6k

C1

560pF

R2

4.7k

1 2

JMP1

1 2

JMP2

D2

BA

T85

R3

220

R4

220

3 IN+

2 IN-

1

OUT

8

VC

C

4

GN

D

U2-ALM393D

5 IN+

6 IN–7

OUT

U2-B

LM393D

C2

0.1

µF

R5

4.7

k

1IN

2

GND

3OUT

U3

MC7805CT

C3

10µF

C4

10µF

C5

1µ

F

C6

1µ

F

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



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