The Design and Implementation of ZigBee-Wi
Contents
1. ICT Int Conf Telecommun Doha Qatar EEE 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 20092. While the IP address of wireless gateway is 192 168 4 53 and it is a client While the Wireshark software can capture the data packet that wireless gateway sends to monitoring software 100 IJCSNS International Journal of Computer Science and Network Security VOL 15 No 1 January 2015 File Telp r Slop IF sire pae IES dT Pori pow Ca j i E Pakarnat Date Ledtantrel Torlar Mode Data BAHI a z u NULL MULL NULE Msi TRAATI 20a yd x755 a Or 76481 MULL MULL 04 Cet TEA FOTO US 4071 NUL HULL O Mai WEDA EAE Baias 2T 57 NULL Osi arb 201 ofl oyna W153 0 FFL Eii NULL 1ean aa e0 as 54157 aT 84 NULI Dstt DACA T S hs MULL MLILL 117 cect TAT FOTOS Figure 6 The data are 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 OxOOCD is 205 and it can be seen from Fig 6 Moreover users can observe and analyze all the data that measured by sensor nodes as shown in Fig 6 B Performance Test 1 Test scenario 1 Sensor nodes distribute randomly around the wireless gateway The rule is that each node s
3. start field MSG_HEADER MSG_DATA checklend field SENSOR_SELECT SINK Figure 5 The interaction procedure between sensor node and wireless gateway 2 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 gateway The application layer of wireless gateway parses the data according to the format in Table 2 and hands over the data to EmberZNet 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 PERFORMANCE EVALUATION In this section performance evaluation and its 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 Wireshark A 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
4. Fi module can connect 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 IJCSNS International Journal of Computer Science and Network Security VOL 15 No 1 January 2015 101 the low power design of 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 multi 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
5. layer protocol The software architecture is shown in Fig 3 System control regulates hardware and application layer protocol of the wireless System Control gateway Application Layer Protocol of Wireless Gateway EmberZNet ZigBee PRO EMSP Protocol ST M32W108 EMW 380 W1 Fi Figure 3 The software architecture of wireless gateway TABLE I EMSP PROTOCOL FORMAT Protocol head Data field head data commandilengthlresult data hecksum hecksum A EMW 380 Wi Fi Module Software Design EMW 380 Wi Fi module communicates with STM32W 108 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 Table 1 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 checked to ensure the integrality and reliability The EMSP protocol consists of 12 commands to implement module control network control and network communication They are EMSP_CMD_RESET EMSP_CMD_GET_COMNFIG EMSP_CMD
6. node it will enter into 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 Ox7E 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 TABLE I THE FORMAT OF DATA FROM ZIGBEE NETWORK TO WLAN Data Packet Format Field
7. power is up to 7dBm 3 Different types of STM32W108 solidify different protocol stacks such as 802 15 4 MAC 7 EmberZNet ZigBee PRO 8 and ZigBee RF4CE 9 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 EmberZNet ZigBee PRO Stack Meanwhile STM32W108 is responsible for wireless communication between wireless gateway and ZigBee sensor nodes B EMW 380 Wi Fi Module The wireless gateway adopts EMW 380 Wi Fi module 10 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 supports AP and Ad Hoc RF channel automatic choice and WEP encryption which is suitable for small system with standard W1 Fi access 3 SOFTWARE DESIGN SCHEME 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
8. 96 IJCSNS International Journal of Computer Science and Network Security VOL 15 No 1 January 2015 The Design and Implementation of ZigBee Wi F1 Wireless Gateway Rakesh Manukonda and Suresh Nakkala M Tech in VLSI amp ES MLEC Singarayakonda JNTU Kakinada Abstract The application of WSN ZigBee is growing popularity and how to connect WSN ZigBee to the present standard network seamlessly is an issue what is worth studying In this paper it designs and realizes a ZigBee W1 Fi wireless gateway based on STM32W108 RF chip and embedded Wi Fi module In ZigBee network wireless gateway as a sink it receives data from sensor nodes and interacts with them In WLAN wireless gateway 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 gateway is tested and the result shows that it can be used for general purposes and the performance is stable The wireless gateway can realize communication effectively between ZigBee network and WLAN Keywords ZigBee Wi Fi wireless gateway STM32W108 1 INTRODUCTION A wireless sensor network WSN 1 consists of a number of distributed devices using sensors to cooperatively monitor physical or environmental conditions such as temperature sound vibration or pressure at different locations ZigBee 2 is a new IEEE802 15 4 standards based short distance low data rate and lo
9. _SET_CONFIG EMSP_CMD_GET_STATUS EMSP_CMD_RECV_DATA EMSP_CMD_SEND_DATA EMSP_CMD_SCAN_AP EMSP_CMD_GET_MF_INFO EMSP_CMD_GET_RF_POWER EMSP_CMD_GET_VER EMSP_CMD_START and EMSP_CMD_SET_RF_POWER From the angle of implementation different commands of EMSP protocol have different response time 98 IJCSNS International Journal of Computer Science and Network Security VOL 15 No 1 January 2015 B STM32W108 Software Design From the point of ZigBee network the wireless gateway is a sink and gathers all kinds of data from sensor nodes The EmberZNet 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 11 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 12 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 network routing and discovery MAC and RF abstraction layer Physica
10. e on PC as a client it will enter into transparent data transfer operative mode Then the module can send the data received from STM32W 108 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 emberInit can complete the initialization of EmberZNet 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 applicationTick 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 sinkAdvertise 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 to 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 als
11. ends 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 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 In 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 S
12. g software on PC by means of AP In addition the Wi Fi module sends commands from PC to ZigBee network Fig 1 displays the system operation model 2 HARDWARE DESIGN SCHEME The hardware platform of wireless gateway is made up of two parts the RF chip STM32W108 6 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 CTS RPS PBS RTS CTS PH WAREUP PAS SI MOZW10 EMW 390 Wi Fi Module Figure 2 The hardware structure of wireless gateway IJCSNS International Journal of Computer Science and Network Security VOL 15 No 1 January 2015 97 A STM32W 108 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 frequency RC oscillator The difference between STM32W108 and other 2 4GHz SoC chips are as follows 1 STM32W108 adopts 32 bit ARM CortexTM M3 processor which can improve processing performance based on lower power consumption 2 It supports for external power amplifier and the output
13. l RF and medium access provide hardware support for software design C Application Layer Protocol of the Wireless Gateway Design The application layer of wireless gateway software design is described in Fig 4 r w Start P Tokiakise STMOIWIOE Intialize ETW 80 Configure md Launch EATW 380 Get EMW J60 s staha T _ ae LP ocd nem f FMW 320 Enter OTU mode E envberindii J embertvetwrdrkind Enier Event Loop Reset Watchdog Ss a T g s embe Teki pplscatsonT cki m emberFermAndIoinTick Cheek Perini Tots Fag Figure 4 Application layer protocol of the wireless gateway software design When initializing STM32W108 INTERRUPTS_ONQ and halInitQ are used to configure clock open system timer and turn on interruptions EM380C_fast_Ini BAUDRATE 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 STM32W 108 can query the INT pin of EMW 380 Wi Fi module to determine whether the initialization is complete After finishing initialization INT changes from high to low EM380C_Set_Config amp parms can set the configuration parameters of the module And it will launch the module when using EM380C_Startup function Once the module has connected to monitoring softwar
14. o T is an important influential factor to PLR 2 Test scenario 2 The test scenario is similar to test scenario 1 but the T is 100ms and changes in L The four curves in Fig 8 respectively show the changes of PLR when the L is 82 Bytes 62 Bytes 42 Bytes and 22 Bytes In the above four cases ten tests are also done respectively And the PLR also is an average value As shown in the Fig 8 when L grows bigger PLR increases accordingly Under the condition that N and T are invariable and L becomes bigger the time of cost in sending a data packet is increasing And the time that data packet occupies the channel will corresponding grow longer Therefore when P grows it causes PLR upwards The reason four curves in Fig 8 are close to each other is because the time of sending a data packet successfully is nearly unchanged although L changes The time mentioned above includes the propagation delay and transmission delay When L varies PLR will change but the changes are not very obvious i amp Packed Loss Hale it S 7 4 q f Numbers of ode Figure 7 Packet loss rate changes when different time interval used i ipa e al Ryba Packed Liis Kate 5 kd B aF i A T F P 7 T E E Li Simbers of N adt Figure 8 Packet loss rate changes when the length of packet varies 5 CONCLUSION In this paper the ZigBee W1 Fi wireless gateway based on STM32W108 RF chip and EMW 380 Wi
15. o deals with data on the application layer and other layers like 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 1 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 any more unless the button is pressed on route sensor nodes and then the permit joining flag becomes TRUE again But if the IJCSNS International Journal of Computer Science and Network Security VOL 15 No 1 January 2015 99 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 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
16. w 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 3 4 Wi Fi 5 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 W1 Fi wireless gateway is introduced It contains two functions For one thing in wireless sensor Manuscript received January 5 2015 Manuscript revised January 20 2015 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 gateway The wireless gateway encapsulates the data 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 monitorin
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