Procedia Engineering 15 (2011) 3567 – 3571

1877-7058 © 2011 Published by Elsevier Ltd.doi:10.1016/j.proeng.2011.08.668

Available online at www.sciencedirect.comAvailable online at www.sciencedirect.com

ProcediaEngineering

Procedia Engineering 00 (2011) 000–000

www.elsevier.com/locate/procedia

Advanced in Control Engineeringand Information Science

A Kind of Sensor the Wireless Network Nodes Design and Implementation of the ARM

Yun-Juan Li a，b，Yan-jun Fang b ， ling Chen a a*aKunming University,Kunming and 650214,China

b Wuhan University, Wuhan and 430072,China

Abstract

The application in the Underwater Wireless Sensor Network is increasing extensive and the Present situation of the real-time processing of networks nods is very limited.This paper put forward a new solution,which is the novel node design with ARM in the Underwater Wireless Sensor Network.. Flexible direct digital synthesis of the signal returned willl be calculated with the ARM’s characteristics of data processing capabilities, embedded systems migration. Give full play to the advantage of both to complete an efficient design of underwater wireless sensor network node.

© 2011 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of [CEIS 2011]

Keywords- Wireless network ； ARM ；Underwater communication ；numbers resulting directly

1. INTRODUCTION

With the rapid development of modern technology, a combination of modern sensors, electronics, communications, embedded computing and distributed information processing and other related disciplines, wireless sensor network technology is increasingly integrated into people's daily life. Underwater wireless sensor network, referred to as UWSN, as a special case of WSN in the special environment in the underwater environment, information collection, detection of water pollutants, abnormal ocean currents trends in the fields of biological communities have broad prospects [1]. Especially in the domestic Chinese Academy of Sciences Institute of Acoustics, Xiamen University, Harbin Engineering University and other research institutions in the production of underwater acoustic communication with the node has made great progress. Foreign Benthos, Aquatec Group, EvoLogies,

* Corresponding author. Tel.:13638633308; fax:027-68772271. E-mail address linda220603@126.com:.

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LinkQuest other companies also offer a mature commercial underwater acoustic communication nodes in the underwater environment for the UWSN provide the basis for the application [2]. Underwater wireless sensor networks as the core network nodes, in the face of the special environment and broad areas of application, its data processing capabilities and flexibility there is some limitations, especially in mature Wangluo protocol node transplantation in facing great Challenges. This article UWSN an open hardware design of the node, select the DDS (Direct Digital Synthesis) technology as a way to signal, S3C2440 as the DS-QPSK modulation and demodulation system and embedded vxWorks operating system platform migration, the advantages of the two Combine the advantages of achieving a more modem system network nodes [3].

2. COMPOSED OF SENSOR NODES

This design of the underwater network node specific modulation and demodulation system structure shown in Figure 1.

Fig. 1. network node hardware structure

Consists mainly of ultrasonic transceiver module, data processing module of two parts: the AD9850 chip as the core of the design and conduct of the ultrasonic transceiver module real time data processing module ARM core board (signal S3C2440). Mainly by the ultrasonic transceiver DDS chip AD9850. Amplifier chip TL72, OP820, AD603, AD8397 filter chip MAX262 driver chip components to complete the signal waveform generation, voltage amplifier, power amplifier, impedance matching of the ultrasonic emission process; while achieving the process of Ultrasonic receiver voltage follower, an amplification, band-pass filter , Automatic gain control, analog-digital conversion and other steps; to achieve signal data transceiver.

The ARM data processing board in the complete system hardware configuration and software development, the use of implants to achieve node vxWorks system data conversion, coding, processing, network protocols transplantation.

3. ULTRASONIC TRANSCEIVER MODULE

For underwater wireless sensor networks, there is no uniform way as terrestrial wireless network protocol standards, and to ultrasound as a means of underwater transmission channel and receiving treatment on the energy output with the high demands put forward [4].This selection technique based on frequency of occurrence of DDS chip AD9850 as the basis for the transmitter circuit, in this based on the amplification and power match, the DDS generated MFSK signal or BPSK signal is converted to ultrasonic transducer driving current signal.

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AD9850 digital synthesizer is a highly integrated device that uses advanced DDS technology, chip integrates two high-speed, high performance quadrature D / A converter can be programmed via digital output I, Q two synthesized signal. With 48-bit frequency resolution, two 14-bit phase registers and BPSK pin, while the phase register can be configured to achieve higher order PSK modulation, the AD9850 circuit module of the node shown in Figure 2.

104C1

104

C2

104

C3

104

C4

104

C5

VCC

P2

BNCSIN

Q-Q

FQ_UDWCLK

123456789

10111213141516

P1

Header 16H

VCC

RST

D7D6

D4D5

D3D2D1D0

CLK_IN9

RESET22

FQ_UD8

WCLK7

D725

D626

D527

D428

D329

D230

D131

D032

DACBL17

AVDD11

AVDD18

DVDD23

PVCC6

RSET 12

VOUTP 14

VOUTN 13

VNN 15

VNP 16

IOUB 20

IOUT 21

AGND 19

AGND 10

DGND 24

PGND 5

U1

AD9850

F1

500mAD14007 10uF

C6

104C7

1KR1

DS1LED0

CLK3.9K

R3

Q

Q-

1KR4

1KR5

100R6

D0D1

D3D2

D4D5D6D7

FQ_UDWCLK

200R2

VCC

1

C8

5.6

C9

4.7

C10

470n

L1

390n

L2

390n

L3

22C11

22C12

22C13

22C14

200R7

SIN

1 23 4

U2

30M VCC

CLK

Fig. 2. AD9850 block diagramS3C2440 according to the emission of signals, signal coding and data conversion, control, analog

signals generated by AD9850; high-fidelity op amp TL072 by linear amplification, and then there MCP41010 Digital Potentiometer 256 power options; emitter follower and the track To-rail voltage output amplifier AD8397 Class D with only isolated from the multi-level interaction between amplifier and enhanced signal drive capability [5]; the end is the ultrasonic transmitter circuit matching networks and transformer, amplifier and transducer to achieve between Impedance matching.

Complete the receiving transducer the sound signal - electric converted by the amplifier (op37, op820) amplification, through the band pass filter (max262) to achieve interference signal filtering. Through the AGC circuit (AD603) to the appropriate signal gain and attenuation. AD-chip 10-bit high speed through the TLC5540, get 1MSPS signal sampling rate for the S3C2440 to achieve subsequent demodulation, decoding, reduction and other steps, and the collected signal into the computer for analysis.

4. ARM CORE BOARD TO ACHIEVE ACOUSTIC COMMUNICATION

ARM embedded systems in recent years as the fastest-growing architecture, there are many ready-

made research and application of the results can be applied in the above. Especially as many of the wireless sensor network protocols have developed a support package for the ARM, allows us to further develop the BSP is possible, especially in the network layer can learn a lot of research experience in terrestrial wireless networks [6]. The underwater environment also requires multi-tasking real-time embedded operating system, the coordination and processing. The design is by transplantation vxWorks S3C2440 system and its driver, to achieve QPSK modulation and demodulation tasks.

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4.1 vxWorks system migration

The design of the Window XP installed Tornado2.2 cross compiler to build vxWorks environment; install winML achieve ARM Smart Link input and output devices and image interface; by Tftpd32 ARM host and client to achieve the shared communication. vxWorks transplantation includes hardware and software design, flow chart shown in Figure 3:

Figure 3. vxWorks migration process

Hardware design completed by the ISE and EDK software programming in Tornado2.2 to complete, the figure rectangle represents the hardware initialization, with emphasis on the mapping of the interrupt system, heart clock, support the realization of the clock, serial port driver; oval on behalf of the operating system Level work completed, including the FLASH drive, block device drivers, file system and winML GUI realization. vxWorks kernel version support package through the (BSP) to obtain hardware information [7], finally got the driver compiled by U-boot kernel file downloaded to the Nor FLASH manner, the realization of system operation.

4.2vxWorks software development

Figure 4QPSK modulation software flow chart Figure 5 QPSK demodulation software flow chart

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In vxWorks by taskSpawn () function to create transmit and receive two tasks, and set priority 10. Launching the original letter code and pseudo random code PN spread spectrum modulation to do, the modulated coded into the chip through the DDS phase signal; receiving task to create two interrupts [8], when the interrupt signal is detected simultaneously began to receive Waveform for AD sampling, when sampling is completed, the data in the array correlation operation, the digital phase modulation, demodulation, and ultimately restore the symbol, the specific software flow chart shown in Figure 4,5. VxWorks transmitting and receiving, in addition to the two most important tasks, there are the corresponding power supply monitoring, acoustic testing, the PC parallel execution of multiple tasks such as communication, task priorities are lower than the transmitter and receiver tasks, to ensure less loss of signal . In practice, when the S3C2440 running at 400Mhz, the communication speed up to 1200bps. (5w transducer, distance 50m)

5.CONCLUSION

This article describes the kind of DS-QPSK modulation section of underwater wireless sensor networks and its implementation scheme based on ARM platform. VxWorks embedded operating system to achieve the introduction of interrupt management and multi-threading mechanism to achieve the system's simple and efficient and good real-time; full play the advantages of DDS technology, to achieve better emission wave effect, the node can be used in practical underwater Sensor network environment.

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