Design of a Smart Classroom Broadcasting System Based on WSN He Gong a, Zhu Wen b, Ziyu Wu b, Manhua Yu b

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1 Advanced Materials Research Online: ISSN: , Vols , pp doi: / Trans Tech Publications, Switzerland Design of a Smart Classroom Broadcasting System Based on WSN He Gong a, Zhu Wen b, Ziyu Wu b, Manhua Yu b &Technology College, Jilin Agricultural University, Changchun , China a gonghe0001@163.com, b wz00745@sina.com Keywords: WSN, JN5148, Broadcasting System, Speech Synthesis. Abstract. This paper presents a smart classroom broadcasting system using WSN technology. Different from other online broadcasting systems, it adopted ZigBee module JN5148 as microcontroller. Text or audio files were sent to the radio terminal in network data packets through the coordinator. It has achieved wireless transmission and intelligent release of personalized voice and ringtone, real-time control of fire alarm and security monitoring. Test results show that ZigBee network operates stably, the broadcasting system embeded ZigBee techology does not need complex wiring installation.the whole system is easy to maintain. It also meets the the application requirements for current broadcast technology. Introduction With the continuous development of modern information technology, school multimedia teaching grows popularity, the requirement that using broadcasting system to teach is constantly increasing. In particular, the popularity of music ringtones and the implementation of the English listening test,etc are all putting forward higher demands for current school broadcasting system in funtion, capacity, quality,intelligent level, etc. Today's public broadcast technology is mainly divided into three kinds. They are analog broadcasting system, digital broadcasting system and network digital broadcasting system. The traditional analog audio broadcast system is often influenced by factors such as voltage, power and so on. Transmission distance is short and the analog signal is susceptible to interference.the system scalability is bad and analog transmission can not be controlled in separate zones [1].The digital broadcase technology is controlled by computer, it can realize zone control. It upgrades local analog devices of analog broadcasting system digitally. But it needs complex wiring installation, the power of each partition needs careful calculation [2]. Network digital broadcase system deals with the problems like sound quality, interference, real-time transmission,etc. But this mothod costs high, needs faster network speed and higher bandwidth [3]. In this research, we apply WSN technology to the broadcast system.we design this new system for classrooms of school. Comparing with other broadcasting systems, this system can report different content in different classroom. It can real-time report text messages, storage and play music, and intelligent monitoring firefighting and security status. This system does not depend on any form of network, installs easily and can be humanized managed. The Characteristics of the Smart Classroom Broadcasting System The intelligent classroom broadcasting system based on WSN (Wireless Sensor Network) has many advantages.1) Stationing flexibly. The broadcast terminal can be placed in any position and dose not need comples wiring. Because ZigBee network itself is a flesible self-organized network [4]. 2) Zone control. It can report different orders relying on different classroom states. For example, Room 101 is having classes, reporting bell for classes. Room 102 is having an exam, reporting the rule of the exam. 3) Intelligent monitoring environment, smoke and security states. When anomalies happened, the alarm sounds immediately. It will report escape routes to all rooms when a fire occurs.4) Easy to manage. Users can manage all nodes through the PC software platform. It can aquire any classroom s state from database and sent different orders.so we call it a smart broadcasting system. All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (# , Pennsylvania State University, University Park, USA-19/09/16,09:33:30)

2 Advanced Materials Research Vols The Overall Design of the System In the role assignment of the smart classroom broadcasting system, there exists one coordinator, multiple routing nodes and a few end notes.they make up a tree network.fig.1 shows the floor plans of teaching building in Jilin Agricultural University and the nodes deployment situation. The coordinator connects with the computer through UART. It builds the whole network, gathers the information all nodes update and sends the text and audio files to the radio terminal to storage or play. All files are sent in data packets in accordance with the ZigBee network protocol. Router and ending nodes are all broadcasting terminals, timing acquire environment, smoke, security information to update to the coordinator. When receiving audio files, they storage them and decode them to play. To make sure stability and communication efficiency of the Network, most of nodes in the building is router nodes. Only nodes in the end of the floor are ending nodes.some relay nodes, also called router, are installed in the place where the channel characteristic is bad. In the design of coordinator, we reserve the ethernet interface, so it can easily communicate with the campus network. The Hardware Design of the System Fig. 1 The Network Structure Radio terminal hardware is mainly divided into three parts, information acquisition, main controller and radio output. acquisition is responsible for collecting temprature and humidity, smoke and security information.the main controller is the core of the broadcasting system, it is in charge of completing each module s reset and initialization on the circuit board. It sends the acquired information to the coordinator. It also reads the information from the SD card and controls the speech synthesis module to broadcast text messages and the decoding module to play music. Radio output comprises of audio decoder, speech synthesis module and an audio signal switching module. The system broadcasts information via the15w active amplifier. Fig. 2 shows the hardware structure diagram. Temp&Humi Sensor Smoke Sensor JN5148 VS1003 Decoder Speech Synthesis Module Audio Signal Switching Module Amplifier Security Sensor External Memory Fig. 2 The Hardware Structure Diagram

3 522 Advances in Applied Sciences and Manufacturing Main Processor The system chooses JN M04 which is NXP Company launched as the main processor. The device features an enhanced 32-bit RISC processor and includes a 2.4GHz IEEE compliant transceiver, 128kB of ROM, 128kB of RAM, and a rich mix of analogue and digital peripherals, including I 2 C, SPI, ADC interface and so on. Four-wire I 2 S audio interface can connect with the main trend decodes directly [5]. The highest transmission distance can achieve 1000m. The signal attenuation is not obvious between two or three walls [6]. In software development, Jennic provides a wealth of routine and code, making software relatively easy to develop. Speech Module The speech synthesis chip comes from Beijing Yu tong world Technology Co., Ltd. It has two communication modes, UART or SPI, receives the synthetic text data, and converts the text to speech (or TTS voice). It can send a maximum length of 4 k bytes of data. JN5148 sends control orders and text to SYN6658 through UART1. SYN6658 converts the received text data to voice output. We can choose five different human voices and adjust the voice tone and speed. There are many message alert tones in the chip. It can automatically identify text and symbols. So we do not record the content of the speech in advance, it can realize the function of the voice broadcast. Fig. 3 shows the SYN6658 circuit principle diagram. Audio Module Fig. 3 The SYN6658 Circuit Principle Diagram VS1003 is a single-chip MP3/WMA/MIDI audio decoder and ADPCM encoder. It contains a high-performance, proprietary low-power DSP processor core VS_DSP, working data memory, 5 KiB instruction RAM and 0.5 KiB data RAM for user applications, serial control and input data interfaces, 4 general purpose I/O pins, an UART, as well as a high-quality variable sample-rate mono ADC and stereo DAC, followed by an earphone amplifier and a common buffer [7]. Fig. 4 shows the VS1003 circuit principle diagram.

4 Error Log System Setting Classroom Management Schedule Setting Network Status Smoke Security Environment Music Editor Text Editor Music playing Voice Playing Advanced Materials Research Vols XT1 R1 RXD X1 C1 33p M R6 R2 R3 R4 R5 C2 33p RESET IO0 IO1 IO2 IO3 DIO18 DIO13 DIO17 DIO12 RESET XT1 IO0 IO1 IO2 IO U1 SO SI SCLK xcs xreset DREQ xdcs/bsync XT1/MCLK VCO GPIO0 GPIO1 GPIO2/DCLK GPIO3/SDATA TEST CVDD RX TX DGND AVDD AVDD LEFT RIGHT GBUF MICP MICN AGND 6,1 4,1 9 5,7,24,31 CVDD 26 RXD 27 TXD 4,1 6,2 0,21,22 GND 38,43, LOUT ROUT GBUF MINCP MICN 44 37,40,41,4 7 AGND C3 1u C4 103 VS1003 Fig. 4 The VS1003 Circuit Principle Diagram External Storage Module To storage the text and audio files, we save the received data packets to the SD card. SD card is developed on the basis of the MMC and is a new generation memory devices based on semiconductor flash memory device. It is widely used in portable devices. The capacity of a SD card is up to 32G now. It can completely meet the requirements of large capacity storage. We use FATFS file system to manage the SD card to realize the function of reading and writing SD card. In this design, the SD card communicates with JN5148 via SPI interface. The Software Design The system software platform adopts C/S architecture, applies Java 1.6 and Oracle database to develop it. It has three functions, intelligent broadcasting, and status query and system maintenance. Users can choose which song to play or which text to speech in intelligent radio interface. At the same time we can change music and edit the text content of speech. In status query interface, we can see the real-time information, including temp&humi situation, smoke and security information and the network running status. We can also open or close the security function. If the sensor detects anomalies, we will immediately receive prompt messages and an alarm sounds in the classroom. In system maintenance interface, we can set the schedule to tell the terminal which time to ring the bell and add the new classroom which has a now node. Safety management is mainly supervising the users, such as changing personal information, changing password. The error log records the running status of the whole ZigBee network and the hardware station of nodes. Users can query which nodes leave the network, join the network again or lose the network. We can better handle failures and improve the further project according to the error log. Fig. 5 shows the software structure. Intelligent Classroom Broadcasting System Software Platform Intelligent Broadcast Status Query System Maintenance Fig. 5 The Software Structure Diagram

5 524 Advances in Applied Sciences and Manufacturing Summary In order to ensure the stable operation of the system, we do the test about the transmission of audio files and network running status, including playing music or speech in the designated terminal, starting, stopping, adjusting volume of the designated terminal. We can see the running status of radio terminals through the PC software platform. Test times are 200 times. Radio terminal nodes state diagram is shown as Fig. 6. The successful networking nodes operate normally, they can perfectly play audio files and the audio output has little distortion. For failing networking nodes, the error log records that the nodes rejoin network happen at No.102 times and No.198 times. Maybe they are outage or wireless signal is affected. It is within the limits of failures the network allows. Fig. 6 The Radio Terminal Nodes State Diagram The system also needs to be improved in the following aspects. One is the improvement of network transmission protocol. For ZigBee network transmission capacity is limited, the large capacity audio or test files cannot be transmit at one time. We can only adopt subsection data transport way to solve this problem, which creates too long delay time. So it cannot be used in the higher real-time occasion. The other one is improving the audio performance. Improving the transmission way of high-quality audio formats, it will make this system can be applied in the occasion which needs high-quality requirements. Acknowledgements This work was financially supported by Changchun technology project The research and application of quality monitoring technology of deer products based on IOT. (12SF31) References [1] L. Chen: Computer & Digital Engineering, vol. 37 (2009) No.7, P.96. (In Chinese) [2] H.L. Zeng, D.T. Liu: Audio Engineering, vol. 34 (2010) No.12, P.78. (In Chinese) [3] C. Wang: Design and Implementation of Network Digital Audio Broadcasting Terminal Based on ARM Cortex-M3 (MS., XIAN University of Science and Technology, China, 2012), p. 28. [4] D.Q. Rao, W.C. Zhang: Electronic Design Engineering, vol. 20 (2012) No.23, p (In Chinese) [5] on [6] P. He: Research of Building Structure Monitoring System Based on Wireless Sensor Network (MS., Jiangnan University, 2012), p.46. [7] on