Wireless Audio Hardware JN-RM-2033 Revision 1.4 11-Jan-2008
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Wireless Audio Hardware Jennic Contents About this Manual 4 Organisation 4 Conventions 4 Acronyms and Abbreviations 4 Related Documents 4 Feedback Address 5 1 The Reference Design 7 1.1 Design Features 8 1.2 Pre-requisites 9 1.3 Board Set-up 9 1.3.1 Connecting External Audio Devices 9 1.3.2 Using the Surface Mount Microphone 10 1.3.3 Using an External 5V Speaker Supply (SPKVDD) 10 1.4 Operation 11 1.4.1 Pairing 11 1.4.2 Test Tone 11 1.4.3 Digital Volume Control 11 1.4.4 Push-To-Talk Facility 11 1.4.5 Sample Rate Switch 12 1.4.6 Security 12 1.5 Features Summary 12 1.6 Data Rates 13 2 Hardware 15 2.1 Microphone Bias 15 2.2 Outputs 15 2.3 Control and Audio Interfaces 15 2.4 Additional CODEC Features 16 2.5 Performance 16 2.6 Pinout 17 2.7 Schematic 18 2.8 Component List 19 2.9 Component Placement 20 3 Software 21 3.1 Binary Files and Communication Modes 21 3.2 Association and Pairing 22 Appendix: Association and Pairing 23 JN-RM-2033 v1.4 Jennic 2008 3
Jennic Wireless Audio Hardware About this Manual This manual describes a reference design for an IEEE802.15.4 compliant, voice quality, audio link based around a Jennic JN513x series wireless microcontroller. Organisation This manual consists of 3 chapters and an appendix, as follows: Chapter 1 introduces the reference design, and describes board set-up, operation, features and performance Chapter 2 provides hardware information on the design Chapter 3 introduces the supplied application software The appendix contains a flow diagram that illustrates association and pairing Conventions Files, folders, functions and parameter types are represented in bold type. Function parameters are represented in italics type. Code fragments are represented in the Courier typeface. Acronyms and Abbreviations ADC ADPCM ALC API DAC PTT Analogue to Digital Converter Adaptive Differential Pulse Code Modulation Automatic Level Control Application Programming Interface Digital to Analogue Converter Push-To-Talk Related Documents [1] Jennic JN513x Wireless Microcontroller Datasheet (JN-DS-JN513x) [2] Jennic Integrated Peripherals API (JN-RM-2001) [3] Jennic 802.15.4 Stack API (JN-RM-2002) [4] Jennic Application Queue API (JN-RM-2025) [5] Wolfson WM8510 Data Sheet 4 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic Feedback Address If you wish to comment on this manual, or any other Jennic user documentation, please provide your feedback by writing to us (quoting the manual reference number and version) at the following postal address or e-mail address: Applications Jennic Ltd Furnival Street Sheffield S1 4QT United Kingdom doc@jennic.com JN-RM-2033 v1.4 Jennic 2008 5
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Wireless Audio Hardware Jennic 1 The Reference Design Jennic s Audio Reference Design provides the necessary information to build a mezzanine board to achieve wireless audio transmissions using the IEEE 802.15.4 protocol. The design allows voice-quality audio applications to be evaluated and developed for the Jennic JN513x wireless microcontroller. The reference design package includes the following items: Schematics and PCB data for an audio reference board Sample.wav sound files to demonstrate audio quality for voice transmissions at 16-kHz and 8-kHz sample rates Separate software binaries for each of the communication modes, as described in Section 3.1 The audio reference board can be evaluated with carrier boards from a Jennic JN5139 evaluation kit (JN5139-EK000 or JN5139-EK010). The audio board is connected to a sensor board of the evaluation kit via the 40-way expansion header (see Figure 1 below). The voice-quality wireless audio link can be assessed using two audio boards, each connected to the necessary audio peripherals such as microphones, speakers and headphones. Simplex, half-duplex or full-duplex audio links can be configured using the supplied software. Figure 1: Audio Reference Board Mounted on a Sensor Board JN-RM-2033 v1.4 Jennic 2008 7
Jennic Wireless Audio Hardware 1.1 Design Features The audio reference board has the following features: Wireless audio, 2.4-GHz IEEE 802.15.4 compliant Simplex, half-duplex and full-duplex options 3.5-mm headphone and microphone jacks Line input Speaker output capable of driving 0.8W into 8Ω at 5V Headphone output capable of driving 40mW into 16Ω at 3.3V Programmable sample rates of 6, 8, 11.025 and 16 khz 16-bit ADC and DAC Software based ADPCM compression Intelligent channel agility Pairing facility LOS Range > 200 m Secure 128-bit AES transmission PTT (Push-To-Talk) capability Digital volume control RF signal quality indication Low battery indication Out-of-range indication Low power Low BOM with cap-less connect headphone output Input signal automatic level control Low-noise microphone bias Low voltage operation (2.5V to 3.6V) Industrial temperature range (-20 C to +70 C) 8 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic 1.2 Pre-requisites The sections that follow make the following assumptions: You have at least two audio reference boards (which can be constructed with the aid of the hardware information provided in Chapter 2, and the schematics and gerbers packaged with the reference design). You have two sensor boards from a Jennic JN5139 evaluation kit. You have downloaded the relevant application binaries, one to each sensor board, using the JN51xx Flash Programmer (for further details of the supplied binary files, refer to Section 3.1). 1.3 Board Set-up This section describes how to set up a system for evaluating a wireless audio link that uses the audio reference boards. Connect each audio board to a sensor board from the evaluation kit, as follows: 1. Plug the audio board onto the sensor board s 40-way expansion connector, as illustrated in Figure 1. 2. Insert batteries into the sensor board (correct orientation is indicated on the board). 3. Ensure J2 on the sensor board is located in position J2(1-2), where pin 1 is located nearest the fuse. 4. Ensure J13 on the audio reference board is located in position J13(1-2), where pin 1 is located nearest the green 3.5-mm jack. 5. Connect the required input (microphone or line input) and output (speaker or headphones) to the audio board, as detailed in the sections below. 1.3.1 Connecting External Audio Devices The following input/output connectivity is provided on the audio reference board: Inputs: A microphone input is provided, along with a line input for connecting other audio equipment. Outputs: Speaker terminals and a 3.5-mm headphone socket are provided: The audio reference board can drive an 8-Ω speaker (bridge-tied load configuration). The hardware includes a jack insert detect function which automatically mutes the speaker output when a headphone jack is inserted. The above connectivity is illustrated in Figure 2 below. JN-RM-2033 v1.4 Jennic 2008 9
Jennic Wireless Audio Hardware Audio Reference Board Two Wire Control Interface Mono Audio Codec Control Interface Volume Up/Down I2S Audio Interface 40 Way Expansion Header 1 Digital Filter DAC J5 ADC Digital Filter Mic Microphone Jack Line Input Headphone Jack BTL Speaker Output + - V - + SPKVDD (5V) Figure 2: Audio Reference Board Connection Diagram Note: To keep noise to a minimum, headphones and/or a speaker must be connected. 1.3.2 Using the Surface Mount Microphone In addition to the 3.5-mm jack microphone input, a surface mount microphone is available on the board. This microphone can be enabled as follows: 1. Ensure J11 is fitted. 2. Ensure J13 is located in position J13(2-3). 1.3.3 Using an External 5V Speaker Supply (SPKVDD) The power supply for the speaker and headphone output drivers is connected to VDD on the board, by default. To achieve higher volume, lower distortion headphone and speaker outputs, SPKVDD can be supplied from an external source on jumper J5 (5.5V maximum) - see Figure 4: Audio Reference Design Schematic. Note: R6 must be removed when supplying SPKVDD externally. 10 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic 1.4 Operation This section describes how to operate the audio reference boards once they have been programmed with simplex, half-duplex or full-duplex software. Note that some of the features described are not available with all of these software configurations, as noted below. 1.4.1 Pairing Befo re audio communication between two devices can commence, the two boards must be paired. To do this: 1. Turn on the sensor boards. LED D1 on both boards should start to flash rapidly, indicating that both boards have detected each other. If D1 flashes slowly, reset both boards using the reset button. 2. To pair the boards, press and hold switches SW1 and SW2 on both sensor boards. If pairing has been successful, LED D1 will remain illuminated. LED D2 will toggle every time a packet is received. For further information, refer to Section 3.2 Association and Pairing. Note: Pairing information is cleared when a device is turned off. 1.4.2 Test Tone A 400-Hz test tone can be transmitted by pressing the switch SW1 on the sensor board. 1.4.3 Digital Volume Control The speaker output volume can be adjusted up and down by pressing switches S1 and S2 respectively on the audio reference board. 1.4.4 Push-To-Talk Facility The Push-To-Talk (PTT) function is assigned to switch SW2 on the sensor board. When SW2 is pressed, the radio changes from receive to transmit mode. Note: This function is only available in half-duplex mode. JN-RM-2033 v1.4 Jennic 2008 11
Jennic Wireless Audio Hardware 1.4.5 Sample Rate Switch The sample rate can be switched between 8 khz and 16 khz by pressing and holding down switches S1 and S2 simultaneously on the audio board. When LED D1 illuminates, this indicates a sample frequency of 16 khz. This operation must be done at both ends of the link. Note: This function is not available when operating in full-duplex mode (sample rate is fixed at 8 khz). 1.4.6 Security When secured mode transmission is enabled, security is applied to data frames using AES-CCM* 128-bit encryption, as defined in the IEEE 802.15.4-2006 specification. The encryption and decryption operations are performed on-the-fly using the JN513x hardware co-processor. This alleviates the need for software support and ensures that the encryption and decryption process is transparent to the CPU. 1.5 Features Summary The following table summarises the main features of the audio reference boards. Feature Link Type Simplex Half-Duplex Full-Duplex Sample Rate Switch Yes Yes No PTT No Yes No Volume Control Yes Yes Yes Channel Agility Yes No Yes Test Tone Yes Yes Yes Security* Yes Yes Yes Table 1: Feature Summary 12 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic 1.6 Data Rates The software-based compression running on the JN513x greatly reduces the amount of data that must be transmitted by the radio. The following table illustrates the raw and on-air data rates at 16-bit resolution. Sampling Rate (khz) Resolution (bits) Raw Data Rate Simplex Radio Data Rate Half-Duplex Radio Data Rate Full-Duplex Radio Data Rate 8 16 128 kbps 32 kbps 32 kbps 64 kbps 16 16 256 kbps 64 kbps 64 kbps Not applicable Table 2: Data Rates JN-RM-2033 v1.4 Jennic 2008 13
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Wireless Audio Hardware Jennic 2 Hardware The audio reference board includes the Wolfson WM8510 Mono Audio CODEC that performs all the necessary audio filtering, signal amplification and output drivers. The solution operates down to 2.5V, with a maximum VDD of 3.6V (5.5V SPKVDD), and has an operating temperature range of -25 C to +85 C. A number of features are provided which simplify the system design and reduce the component count. 2.1 Microphone Bias The microphone bias output provides a low-noise reference circuit suitable for biasing electret type microphones and their associated external resistor bias network. The MICBIAS source current is limited to 3 ma maximum. 2.2 Outputs The headphone output can drive loads of 16 Ω or 32 Ω, and is configured with DC blocking capacitors. The DC blocking capacitance in conjunction with the headphone load resistance determine the lower cut-off frequency of the audio output. The reference design is fitted with a 100-µF DC blocking capacitor (C7), which gives a 100-Hz cut-off, assuming a 16-Ω load that is: f c ( 2π 16Ω μf ) = 1 2π R C1 = 1 100 where the output is driving two 32-Ω loads in parallel. load Note: The WM8510 Mono Audio CODEC can also be configured to provide a cap-less headphone output drive. In this configuration, DC blocking capacitors are not required, thus reducing the BOM cost significantly. Please refer to the Wolfson WM8510 data sheet for further details. The outputs can provide up to 40 mw into 16 Ω, and are capable of driving up to 1.5V RMS. The speaker output can drive up to 0.8 W into an 8-Ω bridge-tied load speaker configuration. 2.3 Control and Audio Interfaces The JN513x includes an industry standard 2-wire synchronous serial interface. With the WM8510 operating as a slave device, the JN513x wireless microcontroller writes to the WM8510 register set and controls the device through this control interface. The flexibility of the JN513x Serial Peripheral Interface (SPI) allows this port to be configured to interface with the WM8510 digital audio interface. To achieve compatibility, the WM8510 audio interface is configured to support the left justified audio data format and operate as a slave device. With the JN513x SPI port JN-RM-2033 v1.4 Jennic 2008 15
Jennic Wireless Audio Hardware configured for the desired transaction size and clock edge polarity, the automatic slave select functionality allows the SPI select signal to be used as the audio interface FRAME signal. Thus, high-speed synchronous data transfer between the JN513x and WM8510 is achieved without the need for software intervention. 2.4 Additional CODEC Features Application-specific filters are also available on the WM8510 to help reduce the effects of specific noise sources, such as wind. These filters include a programmable high-pass filter and notch filter. Full details of the CODEC s electrical characteristics, and additional features such as ALC, can be obtained from the Wolfson data sheet, available for download from the Wolfson Microelectronics web site (www.wolfsonmicro.com). 2.5 Performance The THD+N performance has been measured on a single board in loopback configuration, and also for an over-the-air end-to-end link. The moderate effect of the ADPCM compression (only applied in the over-the-air link) can be seen to impact the performance at high audio levels. Harmonic distortion increases, as expected, at high output levels. dbr THD + Noise (A-weighted) 0-20 -40-60 -80-100 -120-80 -40 0 Output (dbv) Loopback Over air link Figure 3: Audio Link THD+N Results 16 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic 2.6 Pinout The table below summarises the pinout of the board s 40-way connector. Pins Signal Function Alternate Function 1 DIO0 WM8510 Audio Interface (FRAME) 2 DIO1 U2 Buffer IC Output Enable 3-8 DIO2-7 Not Connected 9 DIO8 LED D1 Control 10 DIO9 Not Connected 11 DIO10 Not Connected WM8510 Audio Interface (MCLK) when R11 fitted 12 DIO11 Not Connected 13 DIO12 Not Connected 14 DIO13 WM8510 Audio Interface (MCLK) 15 DIO14 WM8510 Control Interface (SCLK) 16 DIO15 WM8510 Control Interface (SDIN) 17 DIO16 Not Connected 18 DIO17 Not Connected 19 DIO18 Switch S1 Control 20 DIO19 LED D2 Control 21 DIO20 Switch S2 Control 22 SCLK WM8510 Audio Interface (BCLK) 23 MISO WM8510 Audio Interface (ADCDAT) 24 MOSI WM8510 Audio Interface (DACDAT) 25-40 - Not Connected Table 3: 40-way Connector Pinout JN-RM-2033 v1.4 Jennic 2008 17
Jennic Wireless Audio Hardware 2.7 Schematic Figure 4: Audio Reference Design Schematic 18 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic 2.8 Component List The audio reference design presented in this manual consists of the following components mounted on a 2-layer PCB: Item Ref Part Manufacturer Part Number 1 J4 5-pole 3.5-mm audio socket (Green) KYCON STX-3120-5B-577C 2 J7 5-pole 3.5-mm audio socket (Blue) KYCON STX-3120-5B-284C 3 J8 5-pole 3.5-mm audio socket (Pink) KYCON STX-3120-5B-701C 4 C1 100-nF 603 X7R 16V Phycomp 2238-786-15649 5 C4, C6, C19 1-µF 0603 Y5V 16V Flint CC0603CY5V105ZTR 6 C2, C5, C8, C10, C11, C17, C18 7 C3, C9, C12, C13, C14, C15, C16 220-nF 0603 X7R 10V Farnell InOne 335-2020 4.7-µF 0603 X5R 6.3V Farnell InOne 922-7784 8 C7 100-µF 6.3V Tant AVX TAJB107K006R 9 J5, J6, J11 Header 2-Way 2.54-mm pitch HARWIN M20-9990246 10 J1 Header 40-way 2.54-mm pitch Farnell InOne 359-970 11 R2, R6, R9, R19 0R 0603 1% ROHM MCR03EZP000 12 R7, R10, R12 10K 0603 1% Phycomp 232270461003 13 R13, R14 2K2 0603 1% Phycomp 232270260222 14 R8 33K 0603 1% Farnell InOne 933-1034 15 R3, R5 43K 0603 1% Farnell InOne 357-1592 16 R4, R15, R16 680R 0603 1% ROHM MCR03EZPFX6800 17 S1-2 Switch push button SW-SPST Farnell InOne 947-1677 18 U1 IC CODEC Wolfson WM8510 19 J13 Header 3-Way 2.54mm pitch HARWIN M20-9990346 20 U2 IC, SM Logic Buffer TI SN74AHC1G125DBVR 21 - Jumper 10-mm VISHAY TLMC3100-GS08 22 D1, D2 SMD LED PLCC-2 GREEN HARWIN M7687-05 22 M1 Surface Mount Microphone Knowles Acoustics SPM0204HE5-2 JN-RM-2033 v1.4 Jennic 2008 19
Jennic Wireless Audio Hardware 2.9 Component Placement Figure 5: Top Silk Screen 20 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic 3 Software This chapter describes the basic functionality of the binaries supplied with the reference design. 3.1 Binary Files and Communication Modes Pre-built application binary files are supplied in the reference design package. There are two applications: audio_master which must be downloaded to and run on the sensor board that will act as the master device (as well as the network Co-ordinator). audio_slave which must be downloaded to and run on the sensor board that will act as the slave device (as well as a network End Device). These applications have been built for the three different link types: simplex, halfduplex and full-duplex. Full-duplex allows communication in both directions, with both ends able to transmit and receive simultaneously. Half-duplex allows communication in both directions, but NOT simultaneously. By default, both ends are in receive mode. When the Push-To-Talk (PTT) button is pressed, the device switches into transmit mode. Simplex allows communication only in one direction (with the slave board as the transmitter and the master board as the receiver). A performance summary of the available link types can be found in Table 1 and Table 2. Separate pairs of binary files are provided for the different link types. Each pair of application binaries is supplied in a separate folder, as illustrated below. Binaries/<Version>/ Simplex/ Half Duplex/ Full Duplex/ audio_master.bin audio_slave.bin audio_master.bin audio_slave.bin audio_master.bin audio_slave.bin JN-RM-2033 v1.4 Jennic 2008 21
Jennic Wireless Audio Hardware 3.2 Association and Pairing When the network is first formed, the two devices must associate as follows (also refer to Figure 6 below): 1. When powered on, the Co-ordinator (running audio_master) initiates an energy scan to determine the quietest channel on which to establish the network. 2. When powered on, the End Device (running audio_slave) initiates an active scan to find a Co-ordinator with a specific PAN ID. 3. Once the Co-ordinator has been detected, the End Device initiates an association request for the Co-ordinator. 4. On receiving this request, the Co-ordinator reads the extended address of the End Device and returns a response. 5. On receiving the Co-ordinator s response, the End Device reads the extended address of the Co-ordinator. 6. LED D1 on both boards now flash rapidly, indicating successful association (further association requests received by the Co-ordinator are refused). In the case where two or more separate audio links are being established simultaneously, an additional manual pairing routine is performed to ensure the End Device has associated with the intended Co-ordinator (see the figures below). C C C x C ED ED ED ED Association Transmission Successfull PairingTransmission Association Transmission Unsuccessfull PairingTransmission Figure 6: Correct Association and Pairing Figure 7: Cross Association and Failed Pairing To establish the audio link, the two devices must now be paired, as follows: 1. When the sensor board switches SW1 and SW2 on the End Device are held down, a pair request command frame is transmitted to the Co-ordinator. 2. If the sensor board switches SW1 and SW2 on the Co-ordinator are also being held down, the Co-ordinator will then send a pair response command frame back to the End Device. This process is illustrated in the Appendix. 22 Jennic 2008 JN-RM-2033 v1.4
Wireless Audio Hardware Jennic Appendix: Association and Pairing Association C ED Slow Flash LED SW1 E_STATE_IDLE E_STATE_IDLE SW1 Slow Flash LED vstartenergyscan() vstartactivescan() E_STATE_ENERGYSCANNING E_STATE_ACTIVESCANNING vhandleenergyscanresponse() vhandleactivescanresponse() vstartcoordinator() E_STATE_COORDINATOR_STARTED vstartassociate() vhandlenodeassociation() Association Request E_STATE_ASSOCIATING Rapid Flash LED SW1 E_STATE_ASSOCIATED Association Response vhandleassociateresponse() Pairing E_STATE_ASSOCIATED SW1 Rapid Flash LED vreadpairswitch() vreadpairswitch() E_STATE_PAIRING vhandlemcpsdataind() Pair Request Command Frame E_STATE_PAIRING No E_STATE_PAIRING? Yes vhandlecommandframe() vhandlemcpsdatadcfm() Pair Response Command Frame Ack vhandlemcpsdataind() vhandlecommandframe() LED On E_STATE_WAITING_PAIR_SW_RELEASE E_STATE_WAITING_PAIR_SW_RELEASE LED On SW2 SW2 vreadpairswitch() vreadpairswitch() E_STATE_PAIRED E_STATE_PAIRED JN-RM-2033 v1.4 Jennic 2008 23
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Wireless Audio Hardware Revision History Jennic Version Date Description 1.0 20-June-2007 First release 1.1 29-June-2007 Software descriptions updated 1.2 08-Aug-2007 Security description added 1.3 14-Aug-2007 Figure 2 updated 1.4 11-Jan-2008 Design features list updated to include ifa and 6KHz sampling JN-RM-2033 v1.4 Jennic 2008 25
Jennic Wireless Audio Hardware Important Notice Jennic reserves the right to make corrections, modifications, enhancements, improvements and other changes to its products and services at any time, and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders, and should verify that such information is current and complete. All products are sold subject to Jennic s terms and conditions of sale, supplied at the time of order acknowledgment. Information relating to device applications, and the like, is intended as suggestion only and may be superseded by updates. It is the customer s responsibility to ensure that their application meets their own specifications. Jennic makes no representation and gives no warranty relating to advice, support or customer product design. Jennic assumes no responsibility or liability for the use of any of its products, conveys no license or title under any patent, copyright or mask work rights to these products, and makes no representations or warranties that these products are free from patent, copyright or mask work infringement, unless otherwise specified. Jennic products are not intended for use in life support systems/appliances or any systems where product malfunction can reasonably be expected to result in personal injury, death, severe property damage or environmental damage. Jennic customers using or selling Jennic products for use in such applications do so at their own risk and agree to fully indemnify Jennic for any damages resulting from such use. All trademarks are the property of their respective owners. Corporate Headquarters Furnival Street Sheffield S1 4QT United Kingdom Tel +44 (0)114 281 2655 Fax +44 (0)114 281 2951 E-mail info@jennic.com Japan Sales Office Osakaya building 4F 1-11-8 Higashigotanda Shinagawa-ku, Tokyo 141-0022, Japan Tel +81 3 5449 7501 Fax +81 3 5449 0741 E-mail info@jp.jennic.com Taiwan Sales Office 19F-1, 182, Sec.2 Tun Hwa S. Road Taipei 106 Taiwan Tel +886 2 2735 7357 Fax +886 2 2739 5687 E-mail info@tw.jennic.com United States Sales Office 1060 First Avenue, Suite 400 King of Prussia PA 19406 USA Tel +1 619 223 2215 Fax +1 619 223 2081 E-mail info@us.jennic.com Korean Sales Office 601, Bethel B/D, #324-1 Yangjae-dong Seocho-gu Seoul 137-897 Korea Tel +82 2 552 5325 Fax +82 2 577 9130 E-mail info@kr.jennic.com 26 Jennic 2008 JN-RM-2033 v1.4