2.4 GHz Digital Wireless Dual Microphones with USB … · 2.4 GHz Digital Wireless Dual Microphones with USB ... 2 System Description This solution implements a set of 2.4-G wireless
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LED
LED
LED
LEDCC2590CC8531
MSP430G2453 ADC3101
CC2590
USB AudioInput Device
SFlash CC8531
MSP430G2453
Dongle
SPII2S
I2C
SPI
I2C I2S
Buttons
Microphone
Speaker
PCM5102
TI Designs2.4 GHz Digital Wireless Dual Microphones with USBReceiver
TI Designs Design FeaturesTI Designs provide the foundation that you need • High-Performance 2.4-GHz Digital Wireless Stereoincluding methodology, testing, and design files to Microphonesquickly evaluate and customize the system. TI Designs • Automatic or Manual Pairing Between thehelp you accelerate your time to market. Microphone and the Dongle
• Automatic Volume Gain Control with the ADC ChipDesign Resources• The Dongle Works as an Analog Input to the Mixer
TIDM-WIRELESS- or as a USB Audio Input DeviceTool Folder Containing Design FilesMICROPHONE • Working Range Over 100 mMSP430G2453 Product Folder
• Include the Configuration Files for the CC8531 andCC8531 Product Folderthe MCU Source CodeCC2590 Product Folder
TLV320ADC3101 Product Folder Featured ApplicationsPCM5102 Product Folder
An IMPORTANT NOTICE at the end of this TI reference design addresses authorized use, intellectual property matters and otherimportant disclaimers and information.
All trademarks are the property of their respective owners.
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Latency 14 msPower supply current (Microphone) 45 mA
Power supply current (Dongle) 55 mAWorking range 100 m (line of sight)
2 System DescriptionThis solution implements a set of 2.4-G wireless dual microphones with a USB receiver system. Thisdesign is built using one CC8531 RF master, two CC8531 RF slaves, and the MSP430G2453 controller.This solution could be used in a professional audio-amplifier system, a karaoke system, or other systems.With TI's ultra-low-power MCU controlling the power supply of the microphone, the battery life is longer.To ensure longer battery life, the wireless microphone will enter into standby mode when no wirelesssignal is detected for more than one minute. The wireless microphone could be paired to the receiverautomatically or manually. The volume can be manually changed with the key, and the power andconnection statuses are indicated with color LEDs.
2.1 CC8531The CC8531 is a 2.4-GHz RF SoC for wireless digital audio streaming. The CC8531 converts between theRF audio data and the I2S digital audio data. The CC8531 supports up to four audio channels as well as afull-speed USB audio device. However, only one kind of application can be chosen at a time. In thissolution, the master CC8531 will be configured as a USB audio device when it is plugged into a USB slotin the PC, and as an analog receiver when it is plugged in to a speaker.
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2.2 MSP430G2453The MSP430G2453 is an ultra-low-power mixed-signal microcontroller with built-in 16-bit timers, up to 24I/O capacitive-touch enabled pins, a versatile analog comparator, and a built-in communication capabilityusing the universal serial communication interface. In addition, the MSP430G2453 has a 10-bit analog-to-digital (A/D) converter with eight channels.
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2.3 TLV320ADC3101TLV320ADC3101 is a low-power stereo ADC with an embedded miniDSP for wireless handsets andportable audio. This ADC supports sampling rates from 8 kHz to 96 kHz with an integrated programmable-gain amplifier providing up to 40 dB analog gain or AGC. Front-end input coarse attenuation of 0 dB, –6dB, or off, is also provided. The inputs are programmable in a combination of single-ended or fullydifferential configurations. Extensive register-based power control is available via an inter-integrated circuit(I2C) interface, enabling mono or stereo recording. Low power consumption makes the TLV320ADC3101ideal for battery-powered portable equipment.
Figure 4. Typical Circuit Connections
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The TLV320ADC3101 includes automatic gain control (AGC) for ADC recording. AGC can maintain anominally constant output level when recording speech. In AGC mode, the circuitry automatically adjuststhe PGA gain as the input signal becomes overly loud or very weak, such as when a person speaking intoa microphone moves closer to or farther from the microphone. The AGC algorithm has severalprogramable parameters, including target gain, attack and decay time constants, noise threshold, andmaximum PGA applicable, that allow the algorithm to be fine-tuned for any application. The algorithm usesthe absolute average of the signal (which is the average of the absolute value of the signal) as a measureof the nominal amplitude of the output signal. Because the gain can be changed at the sample intervaltime, the AGC algorithm operates at the ADC sample rate.
Figure 5. AGC Characteristics
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3.1 The Block Diagram of the Dongle (Receiver)The block diagram of the dongle is shown in Figure 7, and the power supply diagram is shown in Figure 8.CC8531 is the RF audio transceiver center, and CC2590 is the RF range extender. The SFlash stores theconfiguration codes of different modes for CC8531, and the MSP430G2453 detects the connection targetand programs the CC8531 with the desired configuration code. The MSP430G2453 also controls thestatus of the LED display. PCM5102 is the DAC chip and is only useful when the dongle works in analogmode. When the dongle works in USB mode, the USB audio data transmits from the CC8531 to theplugged device (such as a PC).
Figure 6. Board Photo of the Dongle
Figure 7. System Diagram of the Dongle
The dongle is powered by the external 5-V power supply or the 5-V power USB. TLV70033DDCRconverts the 5-V input to a 3.3-V power supply for the devices on the board. The block diagram of thepower supply for the dongle is shown in Figure 8.
Figure 8. Power Supply for the Dongle
NOTE: Do not program the CC8531 too many times because its program life is 1000 cycles.
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3.2 The Block Diagram of the Microphone (Transmitter)The block diagram of the microphone is shown in Figure 10, and the power supply diagram is shown inFigure 11. CC8531 is the RF audio transceiver center, and CC2590 is the RF range extender. The MCUof MSP430G2453 detects the button status, controls the CC8531 for pairing, and controls the ADC3101 toadjust the volume.
Figure 9. The Board Photo of the Receiver
Figure 10. The System Diagram of the Microphone
The microphone is powered by two 5# dry batteries. The 3.3-V voltage input is converted to 1.8 V for low-power supply in ADC3101. The block diagram for the power supply of the microphone is shown inFigure 11.
Figure 11. Power Supply for the Microphone
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4.1 Input and Output InterfaceThe microphone has two buttons: a (DN) VOLUME button to mute or turn down the volume, and an (UP) VOLUME button to turn on, unmute, and turn up the volume. Each microphone has a power/statusLED that indicates the power and the link status. For the dongle, the power and the audio signal are allinput or output from the USB connector. The dongle has one wireless link-status LED and one work-modeLED.
4.2 Operation Manual
1. Press and hold the button to power on the wireless microphones.2. Connect the wireless receiver to the wireless-only USB connector on the wireless-enabled device or to
a USB port on a computer. Put the wireless microphones closely to the receiver; the microphones willautomatically sync to the receiver.
3. Use the and buttons on the wireless microphones to adjust the volume.4. Press and hold the button for 1.5 seconds to mute the microphone volume.5. Press the button to unmute the volume of the wireless microphones if the volume has been muted.6. If the wireless receiver is removed from the USB port, the wireless microphones will power off (the
MCU enters into standby mode) when no wireless signal is detected for more than one minute.7. Press and hold the and buttons simultaneously for 1.5 seconds on each wireless microphone to
pair the microphone with another receiver.
4.3 State MachineIn a wireless audio network, the CC8531 on the dongle board works as the master, and the CC8531 onthe microphone board works as the slave. The slave must be paired with the master before connectingwith the master.
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4.3.1 State Machine of the MicrophoneThe microphone has the following states in its life cycle:• Powered: The microphone is powered on with two 5# batteries.• Paired: The CC8531 on the microphone is paired with the master and can connect with the master.• Not Paired: The microphone is not paired with the master and cannot connect with the master. If the
microphone is powered on from this state, its status will be No Link, and the status LED will blink.• Standby: The MCU is in low-power mode and the CC8531 is inactive. The status LED is off.• Work: The slave CC8531 can connect with the master CC8531, and the microphones work normally.
In this state, the status LED is on.• No Link: The MCU is in normal mode and the slave CC8531 cannot connect with the master CC8531.
In this state, the status LED will blink at 0.3 Hz.• Mute: The MCU is in normal mode and the CC8531 connection is good, but the volume is mute. In this
state, the status LED will blink at 1 Hz.
Figure 12. State Machine of the Microphone
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4.3.2 State Machine of the DongleThe dongle has following states in its life cycle:
• Paired: The CC8531 on the dongle is paired with the slave and can connect with the slave. The pairedstatus is memorized even when the dongle is not powered on.
• Not Paired: No microphone is paired with the dongle.• Work: The slave CC8531 can connect with the master CC8531, and the microphones work normally.
In this state, the status LED is on.• No Link: The MCU is in normal mode and the slave CC8531 cannot connect with the master CC8531.
In this state, the status LED will blink at 0.3 Hz.
Figure 13. State Machine of the Dongle
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5 Getting Started HardwareTo debug the system, the necessary test points are designed on the bottom side of the board as shown inFigure 14 and Figure 15. The testing wire should be welded to these points to connect with the debuggingtools.
Figure 14. Bottom Side of the Receiver Board Figure 15. Bottom Side of the Slave Board
5.1 MSP430 USB Debugging InterfaceThe MSP430-FET430UIF, which is shown in Figure 16, debugs the firmware on the MCU.
Figure 16. MSP430-FET430UIF
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A If a local target power supply is used, make connection J1. If power from the debug or programming adapter is used,
make connection J2.
Getting Started Hardware www.ti.com
To debug the MCU software, connect the following four points on the board to the debugger: VCC, GND,RST, and TEST. The connection should follow the illustration in Figure 17.
Figure 17. Spy-Bi-Wire Connection
5.2 CC DebuggerThe CC Debugger (Figure 18) programs Flash on the software running on CC8531. The manual of the CCDebugger can be downloaded here: http://www.ti.com/lit/ug/swru197h/swru197h.pdf. To flash the firmwareto the CC8531, connect the GND, Target Voltage Sense, Csn, SCLK, RESETn, MOSI, and MISO pins tothe corresponding test points as shown in Figure 19.
Figure 18. CC Debugger Figure 19. Target Connector Pin-Out
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6 Getting Started FirmwareTo develop the firmware for the MCU, download and install Code Composer Studio 5.5.0. To flash theconfiguration firmware to the CC8531, download and install PurePath Wireless Configurator.
6.1 Necessary Tool softwareThe site to download the Code Composer Studio 5.5.0:http://processors.wiki.ti.com/index.php/Download_CCS#Code_Composer_Studio_Version_5_Downloads
The site to download the PurePath Wireless Configurator 1.4.2: http://www.ti.com/tool/purepath-wlcfg?keyMatch=purepath%20wireless%20configurator&tisearch=Search-EN
The design software is in the package WP_SoftwarePackage.zip.
6.2 The firmware for the CC8531After the WP_SoftwarePackage.zip is extracted, two folders will appear as shown in Figure 20. Thedirectory WP_CC8531_ppwCfg_V1_0 contains the firmware for CC8531.
Figure 20. Folders in the WP_SoftwarePackage.zip Figure 21. Directory Including Configuration Files forCC8531
The UI of the PurePath Wireless Configurator is shown in Figure 22.
Figure 22. PurePath Wireless Configurator
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To open the project file, click the "open" icon, find the configuration directory in the opened dialog, anddouble-click the desired project file name (as shown in Figure 21). The files in the directoryHost_Master_Customer are for the analog master mode. The files in the directory USB_Master_Customerare for the USB-audio-device master mode. The configuration for the slave is the same in both analogmode and USB-audio-device mode.
Figure 23. Open PPW Project Dialog
After the ppwprj file is opened, the configuration items will be displayed. To switch the display betweenitems for the master, items for the slave, and flash programming, click the caption in the left window asshown in Figure 24, Figure 25, and Figure 26.
Figure 24. UI for the Master Configuration
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To program the flash for CC8531, use the CC Debugger to connect the PC and the target board. After theestablishing the connection, press the reset button on the CC Debugger. The device name will be listed inthe “Connected devices” field of the PPW configurator as shown in Figure 26. Select the project file to beflashed in the “Current project” field, then click the bottom “Program CC85xx device” button to finish theprogramming.
For more details about how to use the configurator, please access the configurator's integrated helpsystem and refer to the CC85xx Family User’s Guide.
6.3 The CCS projects and source code for the MCUAfter the WP_SoftwarePackage.zip is extracted, folder WP_MCU_SW_V1_0 will be available. Thisdirectory contains the source code and the CCS project for the master and the slave.
Figure 27. WP_MCU_SW_V1_0 Directory
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The "proj" directory contains five projects: CC85xx_EHIF_lib, WP_master, WP_slave,WP_master_FCCTest and WP_slave_FCCTest. To open these projects, open the Code Composer StudioV5.5.0, then from the menu click “project → import the CCS Eclipse projects” to import the projects fromthe directory “WP_MCU_SW_V1_0\MSP430G2453\proj”. Figure 28 shows this data.
Figure 28. Import the CCS Projects Figure 29. Active Debug
For each project, set debug as active as shown in Figure 29, and build the project. The corresponding .outfile will be generated in the "Debug" and "Binaries" folders if no compiling errors occur. The .out file is theexecutable file that should be downloaded to the MCU. Connect the target board and the PC with theMSP430-FET430UIF to download the .out file to the flash of the MCU.
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6.4 Work as the USB Recording DeviceIf the dongle is plugged into the USB port of the PC, the dongle will be identified as a USB recordingdevice as shown in Figure 30. The device name can be found by clicking “Device identification → Productname”, which is set in the PPW configurator as shown in Figure 31.
Figure 30. Device Name Listed in the Recording Devices
Figure 31. Device Name Setting in the PPW Configurator
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7 Test SetupFor FCC RF certification testing, all of the devices should pass the eight RF testing items. A spectrumanalyzer is required for the testing. The antenna on the board should be broken down and replaced with acable to the instrument.
Figure 32. FCC Test Setup
Setup Procedure:1. Connect the instrument and test board as shown in Figure 32.2. For the dongle board, press the power-on button to change the testing content to the next testing
content as shown in Table 2. For the microphone board, press the UP button to change the testingcontent to the next one.
3. Measure the RF signal on the spectrum analyzer to confirm the RF signal programmed on the testboard.
8 Test DataFor FCC RF certification testing, all of the devices should pass the eight RF testing items. With the testingfirmware, the eight items have been tested and the result is in Table 2:
Table 2. FCC Test Result
NO. TESTING CONTENT RESULT1 Outputs a continuous-wave RF signal at 2406 MHz. PASS2 Outputs a continuous-wave RF signal at 2438 MHz. PASS3 Outputs a continuous-wave RF signal at 2474 MHz. PASS4 Outputs a pseudo-random modulated RF signal at 2406 MHz. PASS5 Outputs a pseudo-random modulated RF signal at 2438 MHz. PASS6 Outputs a pseudo-random modulated RF signal at 2474 MHz. PASS7 Receiver only mode. PASS8 Transmitter only mode with the packet error rate test. PASS
9 Design Files
9.1 SchematicsTo download the schematics, see the design files at TIDM-WIRELESS-MICROPHONE.
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40 10 C5, C23, C27, C35, 2.2 uF; 6.3 V CAP CER SMD402C37, C39, C42, C45,C49, C52
41 2 C16, C19 2nF2; 50 V CAP CER SMT60342 1 C10 1pF2; 50 V CAP CER SMT40243 1 C20 1pF8; 50 V CAP CER SMT40244 1 C17 6pF8; 50 V CAP CER SMT40245 1 C1 18 pF; 50 V CAP CER SMT40246 1 C11 27 pF; 50 V CAP CER SMT40247 2 C21, C24 33 pF; 50 V CAP CER SMT40248 2 C29, C30 47 pF; 50 V CAP CER SMT40249 1 C13 220 pF; 50 V CAP CER SMT40250 1 C28 10 uF; 10 V CAP TANTAL SMD080551 1 C36 47 uF; 10 V CAP TANTAL SMD080552 5 C43, C44, C46, C47, 220 uF; 6.3 V CAP TANTAL SMD1206
11 About the AuthorJEANNE YI is a Systems Application Engineer at Texas Instruments, where she is responsible fordeveloping system design solutions for the industrial segment. Jeanne brings to this role her extensiveexperience in high-speed digital, low-noise analog, and RF system-level design expertise. Jeanne earnedher Bachelor of Engineering in Automation from Shanghai Tiedao University in Shanghai, China.
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