the pattern and realization of zigbee -wi-fi wireless
Contents
1. IJRET International Journal of Research in Engineering and Technology ISSN 2319 1163 THE PATTERN AND REALIZATION OF ZIGBEE WI FI WIRELESS PATHWAY P Sasi Kala K Nishakar Assistant Professor Department Of ECE Abhinav Hi tech College Of Engg Hyderabad India kala smile gmail com Associate Professor Department Of ECE Vidhya Vikas Institute of Technology Hyderabad India Abstract The application of WSN ZigBee is having enormous growth and how to connect WSN ZigBee to the present standard network seamlessly is an issue what is worth studying In this paper it patters and realizes a ZigBee Wi Fi wireless pathway based on STM32W108 RF chip and embedded Wi Fi module In ZigBee network wireless pathway as a sink it receives information from sensor nodes and interacts with them In WLAN wireless pathway communicates with PC or network servers by means of AP Both the hardware scheme and software scheme of the wireless gateway are introduced Then the performance of the wireless pathway is tested and the result shows that it can be used for general purposes and the performance is stable The wireless pathway can realize communication effectively between ZigBee network and WLAN Index Terms STM32W108 ZigBee WI Fi Wireless gateway 1 INTRODUCTION sends commands from PC to ZigBee network Fig 1 displays the system operation model A wireless sensor network WSN consists of a number of distributed devices using sensors2. a that received from ZigBee network according to a certain format and transmits them to Wi Fi module For another Wi Fi module sends data to monitoring software on PC by means of AP In addition the Wi Fi module The hardware platform of wireless pathway is made up of two parts the RF chip STM32W 108 that integrates a 2 4 GHz IEEE 802 15 4 compliant transceiver and 32 bit ARM CortexTM M3 microprocessor and EMW 380 Wi Fi module The structure is demonstrated in Fig 2 zigBee WV 1 F 1 Wireless Gateway Fig 1 communication model between Zig Bee and Network Volume 01 Issue 03 Nov 2012 Available http www ijret org 373 IJRET International Journal of Research in Engineering and Technology TX RXD PB UART RXD RX_TXD B2 UART TXD CTS _RTS PB3 UART_RTS RTS CTS PB4 UART_CTS WAKEUP PAS Warki STATUS P A4 STATUS INT P A3 INT RESET2 PBS RESET STM32W108 EMW 380 W1 Fi Module Fig 2 Hardware of Wireless Gateway 2 1 STM32W108 STM32W108 is a fully integrated System on Chip SOC launched by STMicroelectronics recently It has 128 Kbytes of embedded Flash memory 8Kbytes of integrated RAM memory for data and program storage and peripherals like USART SPI TWI ADC general purpose timers and 24 GPIOs of use to designers of ZigBee based systems The processor can be operated at 12 MHz or 24 MHz when using the crystal oscillator or at 6 MHz or 12 MHz when using the integrated high freq
3. ansfer operative mode Then the module can send the data received from STM32W108 to monitoring software Besides the module will send the commands from monitoring software to STM32W 108 After finishing the work of EMW 380 Wi Fi module calling ember nit can complete the initialization of Ember Net ZigBee PRO Stack and RF module The network initialization is done by emberNetworkInit Furthermore the address table also should be initialized After entering into event loop emberFormAndJoinTick function can form network according to the given network parameters and join in it And then the permit joining flag becomes TRUE The application Tick function offers some services 1 checking timeout 2 sending a route request packet that creates routes from every node in ZigBee network back to wireless gateway 3 calling sink Advertise to send multicast message 4 detecting whether it have received data from EMW 380 Wi Fi 5 updating the address table 6 setting the time permitted join in network Of course the wireless gateway plays an important role in the communication model between ZigBee network and WLAN On the side of ZigBee network the wireless gateway takes charge of processing data on the application layer NWK and MAC layers are managed by EmberZNet ZigBee PRO Stack while STM32W108 handles with PHY layer From the point of view of WLAN wireless gateway also deals with data on the application layer and other layers li
4. e Wireless Gateway Design The application layer of wireless gateway software design is described in Fig 4 Start n p S Pd 4 A Initialize STM32W108 Initialize EMW 380 Configure and Launch EMW 380 Get EMW 380 s status N lt lt s TCP tarus TCPeonnected pi y l EMW 180 Enter DTU mode emberInit emberNetworkInit Enter Event Loop a Reset Watchdog N ember Lick application T ick Check PermitJoin Flag emberFormAndJomTick Fig 4 Application layer protocol wireless gateway software design When initializing STM32W108 INTERRUPTS_ON And hallnit are used to configure clock open system Timer and ISSN 2319 1163 turn on interruptions EM380C_fast_Init B AUDRATE provided by EMSP protocol API set can configure the interface between STM32W108 and EMW 380 Wi Fi module It will take about 1 2 seconds to completely initialize the module and then it will respond to the request sent by STM32W108 STM32W108 can query the INT pin of EMW 380 Wi Fi module to determine Whether the initialization is complete After finishing initialization JINT changes fromhigh to low EM380C_Set_Config amp parms can set the configuration parameters of the module And it will launch the module when using EM380C_StartupQ function Once the module has connected to monitoring software on PC as a client it will enter into transparent data tr
5. ice and WEP encryption which is suitable for small system with standard Wi Fi access 3 SOFTWARE DESIGN The software architecture of the wireless gateway includes System control software design of EMW 380 Wi Fi module software design of STM32W108 and wireless gateway application layer protocol The software architecture is shown in Fig 3 System control regulates hardware and application layer protocol of the wireless gateway System Control Applicaton Laver Protocol of Wireless Gateway EmberZNet ZigBee PRO EMSP Protocol sl M32W108 EMW 380 Wi Fi Fig3 Software Structure of Wireless gateway Tablel EMSP Protocol Format Protocol head Data field head data 3 1 EMW 380 Wi Fi Module Design EMW 380 Wi Fi module communicates with STM32W108 through UART and EMSP protocol And the EMSP protocol has nothing to do with the physical connection The module has two operative modes configuration mode and data transparent transmission mode In the configuration mode all the work is controlled by EMSP command In the data transparent transmission mode module encapsulates the received data into TCP UDP packets and sends them to remote end Furthermore it can send the TCP UDP packets that come from remote end to STM32W108 The data packet format of EMSP protocol is shown in Table1 It contains a protocol head 8 Bytes and data field maximum is 256 Bytes As shown in Table 1 all the request and response commands are chec
6. ke TCP IP 802 11 MAC and 802 11 PHY are regulated by EMW 380 Wi Fi module There are two directions of data communication in communication model between ZigBee network and WLAN 3 4 Data from Zigbee Network to Wlan In the ZigBee network after establishing a network by wireless gateway sensor nodes join in the network within the time that wireless gateway permits When the time expires sensor nodes can t join in the network anymore unless the button is pressed on route sensor nodes and then the permit joining flag becomes TRUE again But if the sensor node is the terminal node it can t allow other nodes to join in the network through itself So the size of the network can be dynamically changed and the extensibility of ZigBee network is good Every node has a Volume 01 Issue 03 Nov 2012 Available http www ijret org 375 IJRET International Journal of Research in Engineering and Technology unique NodeID assigned by wireless gateway once join process has completed After interacting with wireless gateway as shown in Fig 5 sensor nodes begin to send data to wireless gateway SINK_ADVERTISE is sent regularly and the time interval can be set by users And they will record each other s MAC address and NodeID in their address tables before exchanging data This interaction procedure can ensure that the data that sensor nodes send to wireless gateway is correct and integral When the sensor node is a sleep node it will enter i
7. ked to ensure the integrality and reliability The EMSP protocol consists of 12 commands to implement module control network control and network communication 3 2 STM32W108 Design Volume 01 Issue 03 Nov 2012 Available http www ijret org 374 IJRET International Journal of Research in Engineering and Technology From the point of ZigBee network the wireless gateway is a sink and gathers all kinds of data from sensor nodes The Ember Net ZigBee PRO provides users with a standard networking API based on the ZigBee specification across the STM32W108 platforms Users can just learn how to use API functions on the application layer and then can develop own projects Due to increasing flexibility and reliability of EmberZNet ZigBee PRO Stack it supports three types of mesh network topologies star network full mesh network and hybrid mesh network Aiming at the application design of the wireless gateway hybrid mesh network is used The stack mentioned above allows users to create own wireless personal area network WPAN The basic functions of stack contain network organization route discovery routing device discovery message relay and security Under the application layer of protocol stack is followed by transport layer application support layer and network Routing and discovery MAC and RF abstraction layer Physical RF and medium access provide hardware support for software design 3 3 Application Layer Protocol of Th
8. l of Research in Engineering and Technology on application layer As Fig 7 described x axis denotes the number of nodes in ZigBee network and y axis represents the average packet loss rate PLR of wireless gateway The four curves respectively show the change of PLR when the time interval of sending data is 80ms millisecond 100ms 120ms or 200ms mIn the above four cases ten tests are done respectively So the PLR is an average value of the ten tests As the time interval increases PLR drops If the time interval of sending a data packet is 1 second and there are 8 sensor nodes in the ZigBee network the PLR of wireless gateway drops to 0 The reason why PLR varies with the time interval of sending data packet is that PLR depends on three factors the number of sensor nodes N in ZigBee network the time interval of sending data packet T and the length of data packet L When N and L remain the same and T gets smaller the number of packet sent to the air per second increases and then the collision probability P raises when sending data packet Although there is data Retransmission mechanism in EmberZNet ZigBee RPO Stack and retransmission number is up to 3 the consecutive collision probability that is P3 would be substantially increased Therefore when time interval grows P gets smaller and PLR falls dramatically So T is an important influential factor to PLR Packet Loss Rate we a tn gt 4 5 N
9. nsor node and wireless gateway 3 5 Data from Wlan to Zigbee Network The way of transmitting data from WLAN to ZigBee network is almost the same The data from the WLAN is first transmitted to EMW 380 Wi Fi module It extracts the data from the TCP packet and transmits them to the application layer of wireless ISSN 2319 1163 gateway The application layer of wireless gateway parses the data according to the format in Table 2 and hands over the data to Ember Net ZigBee PRO Stack The stack will assemble them to IEEE 802 15 4 frame and send to destination node in ZigBee network The process includes the routing of the network so that the data sent to the specified node by the WLAN always reach the destination correctly Besides the node is identified by the NodeID When the node receives data then it handles with them further 4 RESULTS In this section result are discussed Hardware test environment includes wireless gateway TP LINK TL WN322G 54Mbps wireless USB network card PC several sensor nodes network sniffer produced by Mxchip Company and a network protocol analyzer for UNIX and Windows called Wire shark 4 1 Functional Test Firstly the function of wireless gateway is tested As shown in Fig 6 the monitoring software on PC is a server and its IP address is 192 168 4 7 While the IP address of wireless gateway is 192 168 4 53 and it is a client While the Wire shark software can capture the data packet that wireles
10. nto power save mode once it is idle If the sleep node misses the SINK _ADVERTISE sent by wireless gateway it can send SINK_QUERY message to wireless gateway asking for SINK_ADVERTISE and then start to send data to wireless gateway after finishing the interaction procedure in Fig 5 When wireless gateway receives data from ZigBee network it will parse data in terms of the type of monitoring data in application layer And then it again packages the monitoring data according to the format in Table 2 The start fields of data from ZigBee network to WLAN are 0x7E and 0x42 and the end field is Ox7E The Payload data contain MSG HEADER and MSG_DATA MSG_HEADER consists of the length of MSG DATA MAC frame control field destination PAN identifier destination address data type data command data response or command response and the group information of sensor nodes MSG_DATA includes NodeID and monitoring data while monitoring data will vary with different applications The check field is CCS checksum which is used to judge whether the data are correct TCP IP protocol embedded within EMW 380 Wi Fi module encapsulates the data that are from application layer of wireless gateway Then in transparent transmission mode it sends the encapsulated data to WLAN The monitoring software processes the received data and feedback to the users Gateway SINK_ADVERTISE Sensor node SENSOR_SELECT_SINK Fig 5 Communication procedure between se
11. s gateway sends to monitoring software Fila Help Fort fal Skap IF address 197 185 4 7 cow pa e E Febavnat Ou Wedald PurentI Statua Data 1eauntral Topology a 0 On TE4EL Oo On Mode Data deit i Oo BHS 0 On Node Id Temp Humi L5 Light Time a j mu 0 NULL NULL NULL Ox 184719 amiada Oo fh4t NULL NULL 05 M00 18 47 19 20101009 40212 NULL NULL D Del TEANG 210 1008 bands A O NULL e116 2070 1009 Od 18 47 09 2010 1009 hag AGO NUL 18 47 19 2 3755A NULL NULL W2 Od 18419 200 10 09 Fig 6 information shown by monitoring software For example the data that wireless gateway send to monitoring software are 7E 42 OC 00 00 2B 00 FF 00 FF 11 00 71 67 00 00 00 00 FF FF FF FF FF FF CD 00 00 00 58 A7 7E Among the 31 Bytes data CD and 00 are just light intensity value OxOOCD measured by sensor node Its NodeID is 26481 Comparing OxOOCD with the data of ZigBee network layer packet that captured by network sniffer the result is that they are same The decimal number of 0x00CD is 205 and it can be seen from Fig 6 4 2 Performance Test 1 Test scenario 1 Sensor nodes distribute randomly around the wireless gateway The rule is that each node sends only 1000 data packets to wireless gateway and then stop The length of each packet is 82 Bytes which is the maximum packet load length that users used Volume 01 Issue 03 Nov 2012 Available http www ijret org 376 IJRET International Journa
12. to cooperatively monitor physical or environmental conditions such as temperature 2 MODEL OF HARDWARE sound vibration or pressure at different locations ZigBee is a new IEEE802 15 4 standards based short distance low data rate and low power consumption wireless communication technology Moreover ZigBee specification has better compatibility between versions from earliest ZigBee 1 0 ZigBee 1 1 to ZigBee 2007 PRO With the constantly improving and maturing of ZigBee technology it is widely used in WSN Wi Fi is a most successful wireless local area network WLAN system that builds upon the IEEE 802 11 standards With the rapid development of Wi Fi in recent years infrastructure facilities have been improved What s more the coverage of wireless access points AP has already been very wide and the price is cheap Usually the bandwidth of WLAN is higher than the bandwidth of other types of internet connection such as ADSL GPRS and 3G and the transmission delay of WLAN is less than theirs In this paper a small in size low power low price and lightweight ZigBee Wi Fi wireless gateway is introduced It contains two functions For one thing in wireless sensor network based on ZigBee it is called ZigBee network for short terminal sensor nodes and route sensor nodes are responsible for collecting and processing data They will employ ZigBee technology to communicate with wireless pathway The wireless gateway encapsulates the dat
13. uency RC oscillator The difference between STM32W 108 and other 2 4GHz SOC chips are as follows 1 STM32W108 adopts 32 bit ARM Cortex IM M3 processor which can improve processing performance based on lower power consumption 2 It supports for external power amplifier and the output power is up to 7dBm 3 Different types of STM32W108 solidify different protocol stacks such as 802 15 4 MAC Ember Net ZigBee PRO and ZigBee RF4CE Users do not have to understand the network protocol development and they can directly exploit wireless networking products that comply with the relevant standards which can greatly simplify the development of the technical complexity products and shorten time to market In this paper the type of STM32W108 used integrates Ember Net ZigBee PRO Stack Meanwhile STM32W108 is responsible for wireless communication between wireless gateway and ZigBee sensor nodes 2 2 EMW 380 Wi Fi Module The wireless gateway adopts EMW 380 Wi Fi module to realize the WLAN capabilities It is an embedded Wi Fi 802 11b g applicable module The hardware is composed of ARM processor and Wi Fi RF chip The software integrates some network protocols such as Wi Fi TCP IP UDP and DHCP The module provides an SPI UART interface to connect with MCU A simple API command set is provided to implement link layer data services based on 802 3 frame formats The module ISSN 2319 1163 supports AP and Ad Hoc RF channel automatic cho
14. ulti communication methods J Chinese Journal of Sensor and Actuators 2008 21 1 169 172 5 Ali Khidir M Owens Thomas J Access mechanisms in Wi Fi networks state of art flaws and proposed solutions ICT Int Conf Telecommun Doha Qatar IEEE Computer Society 2010 pp 280 287 6 STMicroelectronics STM32W108HB STM32W108CB DataSheet http www st com mcu 2010 7 Ghasemi Abdorasoul Razavizadeh S Mohammad A simple MAC protocol for cognitive wireless networks IEICE Trans Commun Vol E92 B pp 3693 3700 2009 8 STMicroelectronics UM0923 User manual EmberZNet application developer guide http www st com mcu 2010 9 Shon Taeshik and Park Yongsuk Implementation of RF4CE Based Wireless Auto Configuration Architecture for Ubiquitous Smart Home CISIS Int Conf Complex Intelligent Softw Intensive Sys Krakow Poland IEEE Computer Society 2010 pp 779 783 10 Mixchip EMW 380_RM01040141 pdf http www mxchip com 2009 11 I Akyildiz X Wang W Wang Wireless mesh networks a survey Computer Networks 47 4 2005 pp 445 487 12 Xu Xiaotao and Wu Yanlin Technology and Application of Wireless Personal Area Network WPAN Beijing Posts amp Telecom press 2009 Volume 01 Issue 03 Nov 2012 Available http www ijret org 377
15. umbers of Node Fig 7 Data loss rate changes when different time interval used Packet Loss Rate te rI un Fig 8 Data loss rate changes when the length of packet varies CONCLUSIONS In this paper the ZigBee W1 Fi wireless pathway based on STM32W108 RF chip and EMW 380 Wi Fi module can connt the ZigBee network to standard network seamlessly From the result of performance test we can see that the performance and stability of wireless gateway suits the usual target of WSN application which is low real time demand small amount of data transmission and low bandwidth As applications expansion of WSN further research can focus on the low power design of ISSN 2319 1163 wireless gateway using wireless gateway ID to identify different deployment environments and adopting embedded Web Server technology enables users to visit different WSNs information REFERENCES 1 David Culler Deborab Esrtin Mani Sivastava Overview of sensor networks IEEE Computer Society August 2004 2 ZigBee Alliance Latest ZigBee specification including the PRO feature set http www zigbee org 2005 3 Hong jiang He Zhu qiang Yue and Xiao jie Wang Design and realization of wireless sensor network gateway based on ZigBee and GPRS Int Conf Inf Comput Sci ICIC Manchester United kingdom IEEE Computer Society 2009 pp 196 199 4 Cai Hao Feng Renjian and Wan Jiangwen Wireless sensor network gateway with m
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