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1. User interface The SmartRFO4EB includes an LCD panel two pushbuttons one joystick and 2 LEDs to help developers get the intuitive feedback from hardware during the development A potentiometer is built in for analog measurement the board is also featured with an audio filter and amplifier enabling transmission and reception of audio signals 10 In Circuit Emulator For more efficient development the CC2430 includes an on chip real time In Circuit Emulator ICE SmartRFO4EB controls the emulator via the USB interface mar iA Fase 14 icd jo i Figure 2 Picture of Development board 28 11 CHAPTER 3 SENSOR DATA COLLECTING SUBSYSTEM 3 1 Overview Sensor data collecting subsystem enable the sensor board to sample and capture the analog data from sensors and convert the analog data to digital value which will be delivered up to application Firstly the hardware background is given then we present the implementation regarding to control sensors A D channels and deliver data to the application level 3 2 Relevant Hardware CC2430 has a built in analog temperature sensor the measurement parameter is 0 763V at 0 C and 2 44mV C 12 The A D conversion channel is provided to sample the temperature convert the sampled data to digital data and output data to the certain pin port of the chipset and then the application is able to access the pin port and get the value On the other hand there is also a potm
2. it has the features to transmit data transparently between TCP IP and serial port Once SerProxy is startup it listens on specified TCP port once some data come in it is able to redirect the data transparently to the serial port With the help of SerProxy we configure a proxy setting of browser to the machine where SerProxy is 40 running on the port the SerProxy is listening The browser will send the http request to the SerProxy which will redirect what it receives to the serial port When all these are ready a web server is supposed to be running on to the sensor node to accept these http requests from the serial port interface connected by SerProxy 7 4 Processing within ZigBee network A web server is very import in our system currently it is running onto the sensor node with specified functionality It is called manager node it acts like a bridge to connect serials port to the query subsystem and RF communication subsystem It includes the following components 1 HTTP parser HTTP parser is featured to parse the http request coming from serial port it analysis the http request header get the exact query command from the header and it also need to parser the address information from the http request to make clear onto which node the request is expecting to look up After that the parser will invoke the query starter to transfer the query out and wait for the query result to come Once the response of the query is coming bac
3. industry quickly such as Wi Fi and Bluetooth Both of them and ZigBee have the function to communicate remote devices wirelessly but each of them has the specific functionalities and performance benchmarks Table 1 shows the traits comparison within Wi Fi Bluetooth and ZigBee 27 Table 1 Comparison within Wi Fi Bluetooth and ZigBee 9 Bri w i E Cable Web Email Application Monitoring and control replacement more than more than System resources 4KB 32KB 250KB Battery life days more than 1000 Fi 2 00 Network size MEE P uh bii ow qp s in reality 7 Bandwidth KB s 54000 Transmission range 30 70 10 1 meters Power consumption TX more than node iiid 400 mA Power consumption 3 uA 200 pA 20 mA Standby mode The main advantages of ZigBee compared to Bluetooth and Wi Fi are the very low power consumption in sleeping mode and the small footprint of the ZigBee stack protocol which make it possible to provide components with very low cost What s the relationship of IEEE 802 15 4 and ZigBee We might consider the 802 15 4 as physical radio and ZigBee as the logical network and application software According to OSI Open system Interconnection reference model IEEE 802 15 4 ZigBee covers three layers the lowest two layers physical PHY and media access layer MAC belong to IEEE 802 15 4 standard the layer above these two are defined by ZigBee standard 8 In 802 15 4 four basic frame ty
4. or 64 bit IEEE address Both of them are not compatible with the most widely used IP address which means ZigBee network is not able to be a part of Internet can not join the IP network and be located directly from outside the ZigBee network without the help of specific designed gateway 3 Most of sensor node didn t largely store the history data They either don t store history data at all only keep the current sampled data in their storage system or do some aggregations or compressions real timely without storing the history data piece by piece as they were They do so because there are restrictions in memory space in the earlier sensor node Our system built on ChipCon 2430 which has 128K byte flash memory and 8K byte RAM in some extent it lifts the burden of storing more details that we got So figuring out a storage system to keep the data in permanent storage efficiently and reliably is one of the main challenge that we are facing 4 With a existence of challenge No 3 we can easily expected further that there are not many query algorithms and implementations available for system builder to query the data within this large amount of sensor data One of important task for us is to get this question over with 5 To design a system which is scalable and extendable be good modularization These features are critical at the beginning stage of design procedure a well designed architecture in these aspects will place solid and flexible
5. the programmer designed the running schedule for them First A runs after A is done A transfers the CPU time to Task C B has to wait then Task C is start and run when C finishes his job he let Task B to take over then it s B s turn to run likewise when B has done his duty the CPU time will be handed over to Task A this processing will repeat again and again if these three tasks cooperate with each other in a certain way that all of them comply with they are able to run smoothly and share the CPU time with no delay and blocking 16 gives a similar introduction on Cooperative mode The major components inside RTX51 tiny kernel are illustrate as the software structure diagram below 47 Global Table of Task Task information T Ti mer State delay block Poi nters bit System Registers Pragram cownter System STACK y Y Register PC Figure 8 Software structure in RTX51 tiny System STACK Stored into the IDATA segment the maximum address of STACK is defined by macro RAMTOP System Registers all running state related registers including ACC PSW B RO R7 DPH DPL Program Counter Core register that stored the code address of current running program Global Information Block Stored into the Bank registers It s a global buffer to hold the crucial and frequently updated task information The Block consists of saveacc tem
6. those networks will overlap with each other or face the need of interacting with each other to interchange data To interact with all these remote sensor devices and sensor networks there should be an industry standard to represent the comprehensive requirements in personal area network and let the manufactures comply with it Only in this way the sensor network world can be unified to a healthy growing way One of the most promising protocols is ZigBee a software layer based on the TEEE 802 15 4 standard ZigBee is designed to satisfy the market s need for a cost effective wireless home area network that supports low data rates low power consumption simplicity security and reliability 1 2 3 introduce the standard specification of IEEE 802 15 4 4 5 6 presented ZigBee in terms of concepts and protocols In the previous experiences there are some challenges in different aspects that we met when people were trying to create a software architecture or system to manage the sensor data of ZigBee network They are shown below 1 ZigBee protocol lacks of traffic intended consideration even though ZigBee is designed to be with low data rate low power consumption simplicity and security The capability of transmitting data is not strong enough to make it carry the large amount of traffic like stream data large amount data generated sensor like video camera 2 The Address used to identify a node in ZigBee networks are a 16 bit number
7. Area for Task 2 Unused Space by Task 0 Stack Start Task 0 is running Figure 9 Stack Management in RTX51 tiny 8 6 Initialization of RTX51 tiny Stack Area for Task 1 Used space by Task 0 Step two gt RAMI OP Unused Space SP Stack Start Stack Area for Task 2 Stack Area for Task 1 Used space by Task 0 Stack Start Task 2 is running After the embedded system is booted up the initialization module of RTX51 will be called by the boot loader and do initialization works to prepare the data structures and get some vital peripheral ready A list of sequential steps will be accomplished during the initialization procedure 1 Initialize the table of Stack Pointer the stack pointer table is at the location starting from the next byte of SP register SP 1 Each item in stack pointer table will be filled with RAMTOP 255 Initialize the table of task timer state The first item in table will be set non zero value indicating the first task is at active and ready states The other items are filled with zero 3 Push the code address of first task into stack 50 4 Configure the Timerl with modulo mode enable the timer interrupt and start the timer 5 Enable the global interrupt and call RET after that the program counter will fetch the first two byte in stack so enable the CPU to go to the code space to run the first task 8 7 Process
8. Network wireless networking solution that supports low data rates low power consumption and security promoted by ZigBee Alliance ZigBee is based on the IEEE 802 15 4 specification which was ratified in May 26 2003 ZigBee is designed specifically to replace the proliferation of individual remote controls and sensor devices 5 6 A home area network covers an areas of 30 70 meters consists of one or more kinds of electronic devices including sensors actuators appliances and asset tracking device security surveillance equipments and so on ZigBee is a protocol stack to standardize the behaviors on the wireless communication within these diversified devices If we do some survey into the HAN network we will notice that the wireless payloads circulating within the network sent and received by most of the devices are small packets they carry the control commands the running status that need to be monitored For some widely used applications for example the smoke detector installed in every kitchen at most of the time the detector is in deep sleep mode only generate a burst of alarm information in case of the trigger event heavy smoke detected happening So some characteristics are necessary for the device in HAN networks Allow long sleeping time Very low power consumption In the previous couple of years WLAN Wireless Local Area Network technologies were invented gain the explosive progress and own their space in the
9. Network Stream Mode in Bad Network Figure 12 Reliability comparisons in four scenarios These four histogram illustrate that 58 1 The ZigBee networks work well when the traffic is light and the network status is healthy But along with the traffic in the network increase a number of packets lost during the transmission 22 The number of packets that are received successfully dramatically decreases when the statuses of ZigBee networks are week This and the above phenomena prove that the ZigBee networks lack of traffic intended consideration and is not capable of dealing with the large amount of data transmission and weak signal situations 3 TCP IP ZigBee network in our system work very well in all kinds of situations no matter in heavy traffic situations or in weak signal situations no packet is lost and the reliability of RF communication is guaranteed 4 Packet model provide higher percentage of receiving packets than stream mode does when the packets are transmitted in ZigBee network An integrated comparison is given below in a more intuitional point of view 59 Percentage Communication Reliability Figure 13 Reliability comparisons between TCP IP ZigBee network and ZigBee network 60 TCP amp ZigBee ZigBee Pack et Mode ZigBee Stre am CHAPTER 10 CONCLUSION AND FUTURE WORK ZigBee is promising protocol stack designed specially to unify the diversified electronic device running within a P
10. RTX TS DELAY flag RET Figure 11 Processing Diagram of Task Scheduling in RTX51 tiny Part IT 53 CHAPTER 9 PERFORMANCE TEST ON NETWORK COMMUNICATIONS 9 1 Overview This chapter will take a performance test on performance and reliability of network communications Two participants involved inside this test are ZigBee network and combination of TCP IP and ZigBee network The test result will tell us the improvement that TCP IP gives to our network when it is built onto ZigBee network 9 2 Test Environment and terms Two participants that were tested are Pure ZigBee networks and TCP IP ZigBee networks Some prerequisite terms are explained below Network Hardware Network hardware includes two Chipcon 2430 development board with CC2430 chipset built in Status of Network Communication It means how well the communications can be performance Two network status will be considered Good and Bad network status Good network means two sensor board are close without any physical obstacles between them Bad network means two sensor nodes are far apart 20 meters with a couple of physical obstacles 6 7 walls and metal box 54 Test Payload It represents how many bytes of application data that every transmitted packet will carry Data payload used during the test can be divided into three scenarios light middle and heavy where light payload means 10 bytes data middle one means 30 bytes and heavy means 60 bytes Transmis
11. Technology Wireless Control that Simply Works Kinney Consulting LLC Whitepaper 2 10 2003 Baker N ZigBee and Bluetooth strengths and weaknesses for industrial applications in Computing amp Control Engineering Journal April May 2005 Mikhail Galeev Home networking with Zigbee http www embedded com show Article jhtml articleID 18902431 Bluetooth Wi Fi or ZIGBEE http www embeddedtouch com et client 041 129846391 php lg en Introduction of SerProxy http www Ispace nildram co uk freeware html Chipcon CC2430 Product Information A true ZigBee low cost low power System on chip SoC solution http www chipcon com index cfm kat_id 2 amp subkat_id 12 amp dok_id 245 Chipcon data sheet 63 13 14 15 16 17 18 19 20 21 22 23 24 25 http www chipcon com files CC2430_Data_Sheet_rev1p03 pdf CC2430 features http www chipcon com index cfm kat_id 2 amp subkat_id 12 amp dok_id 240 RTXS1 tiny Introduction http www keil com c5 1 rtx5 1tiny Round Robin Mechanism in RTX51 tiny http www keil com support man docs tr5 1 tr51_rrobin htm Cooperative task scheduling in RTX51 tiny http www keil com support man docs tr5 1 tr5 1_coop htm The uIP Embedded TCP IP Stack http www sics se adam uip TCP Tutorial http www ssfnet org Exchange tcp tcpTutorialNotes html Transmission Control Protocol TCP RFC 793 http rfc net rfc793 html A TCP IP Tutori
12. The beacon mode is able to control the power consumption in whole network and extended network In this mode the two way network is managed by 29 central dispatcher in terms of controlling the channels and manager the calls by which it optimized the power consumption of whole network Non beacon mode is typically deployed as security systems where ZigBee end devices like intrusion sensors sleep most of the time They wake up on a regular interval might be long time period to announce their presence in the network When an event shows up the sensor is triggered and wakes up immediately and sent the alert Somebody s entered the front gate The network coordinator listens to the network all the time and can therefore wait to hear from each of these end devices Due to fact that network coordinator has enough power supply it can allow clients to sleep for unlimited periods of time non beacon mode enables the slave nodes to save power On the contrary beacon mode is fitter to be used if the network coordinator has limited power supply The side to listen is end devices they listen for the network coordinator s beacon broadcast at certain interval An end device registers with the coordinator and looks for any messages to itself If no messages are pending the client returns to sleep awaking on a schedule specified by the coordinator to listen to beacon coming next Once the end device communications are completed the coordina
13. a detailed illustration on B or B tree which is suitable to handle the case in which huge numbers of data were contained but the balancing operation is a extremely tedious and will turn into be overloaded workload at some extent Plus the memory allocation mechanism is required as prerequisite if B tree is consider to be used In some embedded system operating system this mechanism is not provided due to the simplicity sake Skip list owns a good balance between performance and simplicity 26 it uses multi linked list to accelerate the search the search process will go through those multi linked list from top layer to the bottom but stick to the one direction making the searching happens like jumping among several link list to get to the desired destination finally Skip list has to generate a random number to decide the layer number for the new added item which at the same time disables it to guarantee time complexity in terms of search operation in the worst cases the search operation will be identical to 20 the linear search One more thing is the same to B tree the memory allocation mechanism is also a base requirement 25 Binary Search is significantly fast search algorithm with O logoN time complexity The key of data stored by binary search algorithm is required to be in order ascending or descending order No matter using static memory allocation or dynamic memory allocation binary search will work well and show the s
14. as a software engineer in AsiaInfo Technologies He joined University of Texas at Arlington as a Master s student in Computer Science and Engineering department in Fall 2004 In Spring 2006 and Summer 2006 he worked as a software engineer internship in Sipera Dallas TX and Google Mountain View CA respectively His current research interests include embedded development Sensor network TCP IP Stack Distributed computing etc He received M S in Computer Science and Engineering from UTA in 2006 66
15. groundwork for the upper applications in the future accommodate the problem revising and future upgrade with no need to rebuild the original designed architecture 6 Select and run a real time operating system onto our specific sensor nodes Chipcon2430 is quite new hardware released on the market plus the fact that Chipcon Corp doesn t have its own RTOS solution both of issues lead to the fact that so far there is no corresponding operating system for education purpose 7 Providing the users a convenient access window to the users Many sensor network need uses install their own software onto users computers before their functionalities can take effect there should be a way to release the burden to the users on this Facing these challenges in this thesis we proposed our corresponding solutions to above challenges in respective chapter all these solutions and other necessary components make up of a distributed sensor data management software infrastructure For the challenge No 1 and 2 we build a TCP IP stack on top of ZigBee stack offer the feature of reliable connection oriented data transmission into our ZigBee networks strengthen largely their capability to couple with the data traffic situations The retransmission and reassembly feature offered by TCP IP also make our ZigBee networks now are ideal to carry stream data On the other hand the IP stack identify every sensor node with an unique IP address the ZigBee network
16. how many pages were used to store data The following figure illustrate how cyclic queue works 15 HeadPage Medi anPage Rear Page Figure 3 Cyclic Queue When the cache page in RAM is full the content of whole page will be dump into the cycle queue here two scenarios will occur one is the cycle queue is not full the other is the cycle queue is full right before the dumping processing In the first case the system will locate the right page position to save the page from cache it should be the rear of the cycle queue the location will be figured out by adding two parameters the size of the queue and the head pageID HeadPageID PageUsedCount one situation has to be concerned with is that when the HeadPage is behind the rear page the sum of this two parameters is not right due to the fact that the part beyond the end of queue has to be wrapped back to the start of the queue The following figure gives us an intuitional image 16 UsedPageCount 9 UsedPageCount 10 HeadPage UsedPageCount 11 HeadPage Figure 4 Insertion operation of cyclic queue In the second case full queue is never unlikely in the queue operations generally speaking two measures we can take deny the insertion or
17. in RIAL ois e nee rper i htt te svoneteinestDeukwenstes 48 9 Stack Management m RTX51 tiny st tii di as 50 10 Processing Diagram of Task Scheduling in RTX51 tiny Part I 52 11 Processing Diagram of Task Scheduling in RTX51 tiny Part ID 53 12 Reliability comparisons in four scenarios eee 58 13 Reliability comparisons between TCP IP ZigBee and ZigBee network 60 ix Table LIST OF TABLES Page Comparison within Wi Fi Bluetooth and ZigBee sess 28 Categories or ZigBee MEVICES acini ient tex tv eavabsiidsseAeaeuuensabaiwatasbdcclsdeens 29 Important APIs in PHY amp MAC layer libraries in Chipcon CC2430 ZigBee A A A eot va butudt 33 Difference between 8051 and CC2430 in controlling time tick timer 45 Experiment result when payload is 10 bytes 56 Experiment result when payload is 30 bytes esee 56 Experiment result when payload is 60 bytes esee 57 CHAPTER 1 INTRODUCTION In the recent few years the applications of sensor devices have been explosively expanded in many areas like house appliances automatic surveillance environment protection and military reconnaissance etc They come with not only a lot of diversified sensor networks made by different manufactures but also all kinds of different private communication protocols As there are more and more sensor networks being deployed to the market sooner or later
18. or modification O Well documented and well commented source code uIP s source code also includes the low level driver under TCP IP in the most of version the driver included is the most typical Ethernet driver Our hardware system does not have Ethernet network card and related interface the driver come with uIP source code is not required at all we have to replace it with the driver suitable to our hardware environment According to the OSI reference model our TCP IP stack should be built on top of ZigBee protocol the Chipcon Corporation does not have any software solution for that temporally so providing such a solution by ourselves is our choice The development mainly focuses on 1 Making such a driver based on ZigBee s protocol stack this driver should implement the data transmission by using the programming interface provided by PHY and MAC layers Some features are tightly coupled to Ethernet network such as ARP will be removed since the ZigBee network hardware is not feasible to broadcast the IP address to the network and try to get the corresponding MAC address ZigBee network has the at least one FFD to be the coordinator when the end device start the connection and try to associate to the network the coordinator will catch the request assigned the unused ZigBee address IEEE 64bit format or 16bit short format to that end device initialize the channel allocate the network resources specify the param
19. overwrite the head of queue Since we have ceaseless sensor data coming along time passing it is unreasonable to deny the new data and keep the old data in the queue So overwriting the head page is our choice The process of this is to locate the rear page ID firstly and move one page further so as to get the head page overwrite this page and change the HeadPageID to point to next page of original head page and the size of queue PageUsedCount keep unchanged 17 4 4 Caching and flashing The drawback of flash memory is also obvious we surely can not do modification frequently to flash memory Like we mentioned before ahead of inserting page to cycle queue we use a region in RAM to cache the newest data from A D channel the region with same size to the page size in flash memory is efficient and straightforward So a fix addressed RAM space is appointed as the cache space sensor data got freshly from A D channel will be put into the cache first the subsequent data will be appended to the cache space until the cache page is out of space when the whole cache page will be dumped to the cycle queue in flash memory 18 CHAPTER 5 SENSOR DATA QUERY SUB SYSTEM 5 1 Overview As we mentioned in the previous chapter the storage subsystem is capable to store large number of sensor data into the flash memory It raises a challenge that how to locate a specified data in the middle of the sensor data efficiently We propose an alternative bin
20. zero trigger a hardware interrupt then trigger a hardware interrupt Control 2 When timer interrupt happens the counter value stored in T1CCOL TICCOH will be turned back to preset value automatically 8 4 Basic software architecture of RTX51 tiny RTX5 tiny on our system use the timer 1 Modulo mode interrupt to implement the task scheduling mechanism RTX51 rewrite the Interrupt vector of Timer 1 let it point to the code defined in RTX51 tiny The interrupt of timerl is called Timer tick which is the base measurement unit for all other timeout and interval used in 46 RTXS1 after The timeout value can be configured at the compiling time RTX51 can schedule the tasks with two modes Round Robin mode Each task running on the RTOS will be assigned a fix time slice when the task was assigned it will own the privilege to control hardware CPU Memory DMA etc But once the time slice is running out the CPU will switch the control privilege to another task that is in Ready status As what is mentioned in 15 in Round Robin mode each task has the same time slice every task in Ready status will be run in turn Cooperative mode In this mode no time slice is assigned to the tasks the task scheduling logic is put into the tasks themselves the task is not running in turn any more They cooperate with each other and decide who will be the next to run For example There are Task A Task B Task C is running
21. 128 the number behind F means the size of the flash memory The one that we use in the development is CC2430 F128 which includes 128 K bytes flash memory The CC2430 is a true System on Chip SoC solution specifically designed the requirement of IEEE 802 15 4 and ZigBee applications The CC2430 is equipped with an industry standard enhanced 8051 MCU 8K bytes RAM and 128K bytes flash memory A high performance radio frequency transceiver is also built in the chip Featured with various operating modes CC2430 is suited for systems where ultra low power consumption is required Some important hardware features are listed below 11 12 13 High performance and low power 8051 microcontroller core 2 4 GHz IEEE 802 15 4 compliant RF transceiver in radio core 128 KB in system programmable flash 8 KB on chip RAM 4 KB with data retention in all power modes CSMA CA hardware support Digital RSSI LOI support Battery monitor and temperature sensor 8 14 bits ADC with up to eight inputs AES security coprocessor Two powerful USARTS with support for several serial protocols One IEEE 802 15 4 MAC Timer one general 16 bit timer and two 8 bit timers 2 general I O pins two with 20mA sink source capability 2 3 Hardware summary of development board SmartRFO4EB is the name of the development board SmartRFO4EB is the platform for development and testing on both hardware and software Some important features are worth to be mentioned 28
22. A Link quality measurements O Data Transfer O Retransmission O Fame acknowledgement Association Disassociation O Beacon notification The software of MAC and PHY layer has plenty of interfaces for developers to control and manage the diversified elements in ZigBee network The most frequently used API is shown below in Table 3 32 Table 3 Important APIs in PHY amp MAC layer libraries in Chipcon CC2430 ZigBee solution API Features Where to apply Setup MAC framework and DB Coordinator or MAC_INIT peripherals devices Coordinator or mpmSetRequest Power up MAC sublayer devices Set the PIB attributes The MAC PIB contains the attributes Coordinator or mlmeSetRequest required to manage the MAC sublayer Devices of a device mlmesStartRequest Start service of the coordinator Coordinator Scan the network for existing mlmeScanRequest Devices coordinator mlmeAssociateRequest Associate with the specified coordinator Devices Coordinator or mcpsDataRequest Send out the data Device Call back function called by the MAC layer when a packet transmission Coordinator mcpsDataConfirm initiated by Device mcpsDataRequest has succeeded or failed is used to request pending data mlmePollRequest transmitted using indirect data Device transmission from the coordinator 33 Table 3 Continued Call back function called by MAC layer mlmePollConfirm to report the
23. A DISTRIBUTED SENSOR DATA MANAGEMENT INFRASTRUCTURE BASED ON 802 15 4 ZIGBEE NETWORKS by TIANQIANG LI Presented to the Faculty of the Graduate School of The University of Texas at Arlington in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE IN COMPUTER SCIENCE AND ENGINEERING THE UNIVERSITY OF TEXAS AT ARLINGTON December 2006 ACKNOWLEDGEMENTS I would like to take the opportunity to express my appreciation to my supervising professor Dr Yonghe Liu for his constantly motivating and encouraging me and for his invaluable advices during the course of my master thesis studies And he also keeps giving me the considerate and comprehensive supports on my requirements regarding to hardware software technical support and communications All of these are the strong momentums that greatly drive me to overcome many difficulties that I met during the course of thesis and get the research done on time I wish to thank Dr Sajal K Das and Dr Ramez Elmasri for their interests in my research to be my thesis committee and assign their precious time to evaluate my research I also wish to thank my teammate PhD candidate Jun Luo for his interests in my research and for the helpful discussions and invaluable comments which help me find the correct direction in my research and make the progresses faster Special thanks should be given to my friends help me in many ways Finally I would like to express my deep g
24. AN network IEEES802 15 4 ZigBee has been steadily accepted by the industry as a de facto industry standard more and more manufactories produce the ZigBee compatible devices It offers people a large momentum to develop from hardware to software product compliant to the ZigBee Under this background in this thesis a software solution for distributed sensor data management based on IEEE 802 15 4 ZigBee network has been proposed It guarantees the reliable data transmissions and enables people to manage the data generated by distributed sensor nodes efficiently It takes advantage of the features offered by hardware CC2430 CPU and development board accomplishes the functionalities from collecting and storing sensor data providing efficient search approach to locate sensor data rapidly communicating with other node of ZigBee network in standard TCP IP protocol offering users a browser based management interface to connect their personal computer to ZigBee network and initiate the query request And experimental solution regarding to Real Time Operating System is also provided in the software system As ongoing effort new sensor is about to be installed onto the sensor board and some peripheral interface like flash memory card are also under consideration so the software should be improved by enriching the driver library to satisfy the requirement 61 of hardware Compiler is tightly related with our development specially when RTOS is appl
25. E ATE ix LISTOPTABEBS aunando T E Dados x Chapter Page US TINGE OE WC ULP PD p 1 IM ES a ET T7 2 HARDWARE ENVIRONMEN Lisa a ai 9 LUE AUI P 9 2 2 Hardware Summary on Chip Set acus ege tad dede Adie 9 2 3 Hardware summary of development board sese 10 3 SENSOR DATA COLLECTING SUBSYSTEM eeeeeeeee eee eenen attese nttnnin 12 LONA id elisa 12 32 Relevant Hardware dt ii lb 12 3 3 Software Ip tai 12 4 SENSOR DATA STORAGE SUBSYSTEM 0 cccssssscssscossessesssesssecssesssesesesonees 14 AN OVERVIEW MM Nash E AA e P RE 14 A A a sess Ra RRE 14 4 3 Page Accessing and Cycle OU do 15 44 Caecbhing and flashing ii ii a eu Salad ep 18 5 SENSOR DATA QUERY SUB SYSTEM b eeeessessesesesesssesesseesesseesesseessesessesessesess 19 A E E E E TTE ESS 19 5 2 Comparison of searching algorithms aii penat Corte ou ra pava se er tob dau Pone 19 5 3 Dynamic and static binary Seateliccu deas o eati toute Da ou petiuit ee obe dut totes 21 6 RADIO FREQUENCY COMMUNICATION SUBSYSTEM cece 26 A RE 26 6 2 Overview of IBEE 802 15 4 and ZIGBBBE ritirare nannte 26 6 3 Specification in CC2430 and Physics and MAC Layer sess 3l 64 TCP IP Protocol Implementation tt 34 T USBR INTEREACE SUBSYSTEM eheu iii id 39 QE RVC A 39 1 2 Browser based mterface e rece tr ta 39 Dace WN WO GORI passat TM 40 TA Processing within Zig Bee
26. OOL LocateLog INT16 time UINTS val Where Time is the key to search val is the pointer of memory specified by invoker to store the result data Return value TRUE if key is found FALSE otherwise 25 CHAPTER 6 RADIO FREQUENCY COMMUNICATION SUBSYSTEM 6 1 Overview ZigBee network lacks of data traffic intended consideration since its major designing purpose doesn t lie on this ZigBee protocol is not ideal to carry the large amount of payload In an attempt to compensate this gap we build a TCP IP stack on top of ZigBee stacks strengthen largely their capability to couple with the data traffic situations The retransmission and reassembly features offered by TCP IP also make our ZigBee networks now are suitable to carry stream data On the other hand the IP stack enables the ZigBee network can be part of the Internet the sensor node is able to be accessible and located by using the standard IP routing protocol This chapter mainly depicts the how our system accomplishes radio frequency communication based on 802 15 4 ZigBee standard Some detailed introductions regarding IEEE 802 15 4 and ZigBee protocol stack will be found in this chapter the features and usages of software library of PHY and MAC layer is discussed lastly the a light weighted but richly featured TCP IP implementation specific to our system on top of ZigBee protocol stack is gone through 6 2 Overview of IEEE 802 15 4 and ZIGBEE ZigBee is a PAN Personal Area
27. S Swi YES ch_Task e Pe a NG 0 gt TI MESHA a SET TS LAY bit Y Table o fin Scan Status item try from current task bit is set otherwise keep cycling one with K Ready Y Adjust Stack conte pointer table af register pointers that is for t task switch to nt and the stack ter that the SP to the position e next ready another task v RTX Robi nTi me FTI MESHARI NG Next task s TI MESHARI NG 0 aoe Se m d lm set K ROBIN bit C RET Figure 10 Processing Diagram of Task Scheduling in RTX51 tiny Part I 32 Signal Off ext task s K ROBIN bit TS set NO fask is waiting for signal and receive a signal later YES Robi nON Signa NoEve ask is waiting for ti meo event and timeou occurs later YES On NO nt Clear K Ready K TMO and K SIG bits XCH A RO Save to Status Table v SETB EA v Clear all bits but Keep K READAY bit Y ORL AR7 A v Clear RTX TS DELAY flag Ti meout ON YES C RET y R7 TMO_EVENT Y Clear K SIG K TMO TMO EVENT bits gt Save new state to State Table v SETB EA v POP AR7 ARO DPL DPH B PSW ACC from the system STACK v Clear
28. TOS running on Intel 8051 architecture it provide the features including priority based task scheduling stack management and interrupt management etc But the footprint of it is around 6K bytes which is quite large comparing the 8K RAM totally on CC2430 and RTX requires quite a few RAM RTX5 tiny is compact version of RTX51 only support a subset of features and functionalities of RTX51 but consume less RAM and offer the much less binary footprint around 900 bytes meanwhile it also support some important features well shown below as 14 which make it one of the most practical and efficient RTOS in the industry O Flexible multi task scheduling including Round Robin scheduling and Cooperative Scheduling Efficient stack management Explicit task management feature create delete switch task make task sleep set task status send signal between tasks User code support in Timer Interrupt e CPU Idle mode 8 3 Migrate to our system Though RTX51 tiny supports various 8051 series CPU but CC2430 is a kind of enhanced 8051 CPU it is not fully compatible to industry standard 8051 CPU so the 44 source code Assembly language of RTX51 tiny does not take effect due to the incompatibility In the attempt to deploy RTX51 tiny to CC2430 hardware we have to port a new version that is adapted to CC2430 by revising some parts of code within the incompatible module One of the most vital modules that are not compatible is the tim
29. a collected by collecting subsystem This subsystem is capable to store large amount of logs of sensor data We build up this subsystem enhanced with a couple of algorithms and technologies which include RAM Flash two layered storage structure cyclic queue page accessing etc The storage subsystem is able to store at most 47K sample data Considering the RAM and flash memory offer distinct virtues on store data as well as their distinct flaws firstly we briefly discuss about what can RAM and flash memory can do and not do secondly a two layer structure caching and flashing structure is presented on how to combine the merits of both RAM and flash memory to make the data to be stored reliably and efficiently The third in the flash memory part the cycle queue data structure will be discussed as well as the page accessing mechanism 4 2 RAM and Flash memory Data storage subsystem is used to save the data that sensors have sampled into CC2430 s memory space as sort of log data for the later usage There are 8K bytes of RAM and 128K bytes Flash memory in CC2430 RAM owns the fast accessing operation but it is sort of vulnerable storage only maintains data when the power is on on the other hand flash memory has slow accessing speed but possess the functionality 14 for reliable storage even without the power supply Most of modern computer architectures make use of the merits of both of them to pursue the balance the accessing per
30. a reliability by using the RAM as the first level cache and Flash Memory as the permanent storage space under the cache to flash synchronization algorithm the data will be save with efficiency and consistency The cyclic queue data structure enhances the storage subsystem with higher data utility ratio in limited Flash memory spaces it also place a solid foundation under the data query subsystem which is implemented by using the cyclic binary search algorithm The support of 802 15 4 ZigBee makes it easier and convenient to interchange data and interact with other ZigBee network The TCP IP feature on this system makes the connection oriented reliable packet transportation and flow control possible Based on it plenty of network applications like http web server DHCP FTP SNMP are applicable with no difficulties 1 1 Outline Chapter 2 gives an overview regarding to the hardware environment including the features of the chip set ChipCon 2430 and his development board Chapter 3 describes the sensor data collecting subsystem which will enable the sensor board to sample and capture the analog data from sensor and use some mechanisms to notice the application Chapter 4 depicts how sensor data storage subsystem works some important components and implementation approaches are illustrated such as the cycle queue and cache buffer Chapter 5 presents the algorithms and data structures that sensor data query subsystem uses and the implementatio
31. al RFC 1180 http rfc net rfc1180 html Internet Protocol RFC 791 http rfc net rfc79 1 html Ramez Elmasri and Sham Navathe Fundamentals of Database Systems 4th edition published by Addison Wesley July 2003 Dennis Chester Smolarski The Essentials of Data Structures I published by Research amp Education Assoc Mar 1990 James Andrew Storer An Introduction to Data Structures and Algorithms published by Springer Jan 2002 Mikhail J EDT Atallah Algorithms and Theory of Computation Handbook published by CRC Press Oct 1999 64 26 27 28 29 30 31 William Pugh Skip Lists A Probabilistic Alternative to Balanced Trees Communication of ACM June 1990 RTXS1 tiny Introduction http www keil com c51 rtx51 CC2430DK Development Kit ChipCon Products From TI White paper http www chipcon com files CC2430DK 20Development 20kit 20descripti on_rev_A pdf HAL_CUL_EB Software User Manual http www chipcon com files HAL_CUL_EB_Software_ 20User_Manual_1_ 1 pdf CC2430 IEEE 802 15 4 MAC PHY software layers Technical Paper of Chipcon Corp Confidential Stack Management in RTX51 tiny http www keil com support man docs tr51 tr51 stackmgmt htm 65 BIOGRAPHICAL INFORMATION Tianqiang Li received his Bachelor of Science degree from Jinan University China P R 1998 After his graduation he worked as a software engineer in Suntek Technologies until 2000 from 2000 to 2004 he worked
32. ame search performance So far due to the dynamic memory allocation mechanism is temporarily not available in our operating system running on our sensor node plus the maturity that binary search owns and code complexity which will affect the footprint of our executable program the smaller the better We figure binary search is the best choice so far according to what we have on the aspect of hardware environment and the software development kits 5 3 Dynamic and static binary search Like the last chapter mentioned the flash memory accessing mechanism designed by CC2430 is not identical in the aspects of reading and writing Block writing has to be applied when writing request happened But reading operation is performed in same way with doing regular external memory reading which is byte level Since search operation is a kind of read only operation we can search and examine to the level of item in the cycle queue At the same time in the scenario where the specified data locates into the cache instead of in the cycle queue binary search is also feasible to be applied to the RAM space only difference between them is that in cache page the search range is fix from the beginning of the page to the end of page we call it static 2 binary search meanwhile in cycle queue the range that contains stored data is various from time to time depending on the frequency of the insertion requests That means the search range is movable continuo
33. ary search algorithm running on two layered structure of storage subsystem which is able to reduce the time complexity to O logoN Firstly we will give a comparison of several candidate query algorithms Secondly we make our choice and explain the reasons that we choose binary search Thirdly the dynamic binary search and static binary search two derived from binary search are applied to our system and make our solution fast and satisfy the searching requirements in both cache area and cycle queue 5 2 Comparison of searching algorithms Quite a few mature and widely used search algorithms are there in the software industry to cope with this question Linear Search Binary Search Hash Table Search B or B tree Skip List etc are the most well known techniques in the search areas None of them are perfect for all cases they have their merits and drawbacks 22 23 24 25 19 Linear search is easiest one to be implemented but with no efficient performance when the data set is large the performance is unacceptable due to low CPU benchmark and lack of memory on embedded system Hash table search technically is the fastest algorithm but it has to take much more concerns and energies onto solving the conflict problem along with more and more items were added into the hash table 24 one other drawback of hash table search is it is not capable to do the range search quickly search data that falls into the specified range 22 gives us
34. can be part of the Internet or a subnet of Internet the individual sensor node is able to be accessible and located by using the standard IP routing protocol Chapter 6 will give us detailed descriptions regarding these Chapter 9 gives readers a practical experiment in aspect of performance on both TCP IP ZigBee network and pure ZigBee some statistics data are shown in this chapter illustrating how TCP IP offer the virtues to ZigBee networks To overcome the challenge No 3 we build up a storage subsystem enhanced with a couple of algorithms and technologies which include RAM Flash two layered storage structure cyclic queue page accessing etc The storage subsystem is able to store at most 47K sample data Chapter 4 will explain specifically these issues The point to solve challenge No 4 lies in designing an efficient algorithm coupled tightly with storage subsystem We proposed an alternative binary search algorithm running on two layered structure of storage subsystem which is able to reduce the time complexity to O log2N For more details please reference Chapter 5 In terms of Challenge No 5 we introduce a well modularized extendable software framework to manage the sensor data across the network It consists of 5 subsystems which interact with each other cooperatively but with their own distinct design functionalities the applications are able to easily hook up to the existing system and start to run such a framework place a solid
35. e packet should finally reach By confirmed with the ZigBee destination address the PHY and MAC layer will do their duty to deliver the packet right to the end device One issue that we should pay attention to is The ATT address translation table is mostly only necessary onto the coordinator in most of the cases end devices don t require ATT this is decided by the center coordinator management mechanism 37 specified on ZigBee network The only part that end devices need is the its source IP address and the destination IP address where the packet is supposed to reach Unlike the IP routing and ARP structure in Ethernet network end devices in ZigBee network don t have to know the MAC address of the destination because they have the only single point the coordinator to contact packet will be transmitted to the coordinator the coordinator will look the MAC address ZigBee address up given by the packet s destination IP address If the TCP IP communication occurs within one PAN Personal Area Network one coordinator might be enough but if more than one PAN are deployed the packet might be needed to be sent to the some devices that are not belong to the PAN where the source end device lies Here some routing functionalities are needed in ZigBee network the network topology consists of a number of PANs and the routers The PAN ID and device address are both needed when we address the unique device inside the whole ZigBee netwo
36. ented in an attempt to fill the gaps in functionalities of ZigBee networks such as TCP IP stacks built onto ZigBee protocols Some advanced design ideas are also presented such as browser based user interface communication via standard protocol HTTP Some software implementations are accomplished for the first time without former references such as the immigrating the RTX51 tiny from standard 8051 CPU to ChipCon2430 CPU The infrastructure that we proposed consists of the sensor data collecting subsystem data storing subsystem data query algorithm and subsystem radio frequency intercommunication subsystem and browser based user accessing interface Sensor data collection and storing system will periodically save the sampled value from sensor to the memory system and later to the permanent flash memory Data query subsystem will provide an efficient approach to locate the data to be queried among large number of stored data Radio frequency intercommunication subsystem is in charge of the radio frequency communication between devices to delivery back and forth for the query request and response is the one of the major duties in this subsystem iv The user accessing interface supports the users to submit query requests in the browser with the standard http link address in users personal computer TABLE OF CONTENTS ACKNOWLEDGEMENTS a e ra E gode rd Aae R A S eaaa eq Tra as ii PS RAC oh E E E E AE AE iii LISTOPIELUSTRATIONS 600 a A T E
37. er click module RTX51 Tiny leverages the standard 8051 Timer to generate a periodic interrupt which is called RTX51 Tiny Timer Tick Other Timeout and interval values specified for the RTX51 Tiny are based on timer tick which means they are all measured by using the Timer Tick Standard 8051 CPUs function some built in registers to provide the timer tick there are one to four timer available in 8051 CPU depending on the model of hardware in the most common scenario the first timer will be used to generate the timer click RTX51 tiny uses the standard 8051 Timer 0 mode 1 to generate the timer tick but in CC2430 the counterpart is Timer 1 Modulo Mode The differences between them are listed below Table 4 Difference between 8051 and CC2430 in controlling time tick timer Standard 8051 CC2430 Name of TimerO Timer 1 Timer Node Magee Modulo Mode 45 Table 4 Continued TMOD Mode selection T1CTL Mode selection and enable disable timer TIMIF overflow interrupt mask 2 When timer interrupt happens the counter value need to be reset to TLO and THO Relevant TLO low byte of counter value T1CCOL low byte of counter Registers THO high byte of counter value T1CCOH high byte of counter TRO enable disable of timer T1IE Timerl interrupt enable disable 1 Counter value is set to zero and 1 Counter value is set to preset increments to the preset value then value and decrements to
38. eter at the Evaluation Board when the potmeter is turns on the voltage will be sampled converted by controlling the A D channels 3 3 Software Implementation In order to enable the A D channel the SFR Special Function Register ADCCFG is required to be initialized correctly then the next step is to select the ADC 12 conversion sequence by set the corresponding bits in register ADCCON To start the sampling certain bit has to be set in ADCCON if the hardware level sample has been done certain bit in ADCCON will be set to indicate this issue and the data after A D conversion will be put into register ADCH which is addressable for application 12 In the common cases people would like to get the sensor node doing sampling periodically instead of doing it manually or single time The best way to put the sampling and A D conversion to run in a fixed interval is using interrupt There are there timers in CC2430 for us to use after users set the timer correctly and run when the time out event occurs an interrupt event will be triggered then the interrupt routine corresponding to the timer will be called by the kernel Users can customize specific operations that will be performed into the interrupt routine and update the system interrupt vector by changing the value of timer routine entry to customized function address 13 CHAPTER 4 SENSOR DATA STORAGE SUBSYSTEM 4 1 Overview This chapter describes how our system store the dat
39. eter of the new connection and finally send address back to the end device on the other hand ZigBee routers do not have to associate to certain coordinator 36 and other devices that communicate with it are the ZigBee routers too their addresses are static and pre configurated during planning and constructing the ZigBee network Above two scenarios prove that ARP is not necessary in ZigBee network according to the current IEEE specification 3 An alternative DHCP mechanism is necessary to provided on coordinators since the PHY amp MAC address of ZigBee network is IEEE 64bit format or 16 bit short format TCP IP use IP address to locate the machine we need to have some translation operations from IP address to ZigBee address when a packet is being sent out Since ARP protocol is not ideal for ZigBee network we consider the new protocol like below When an end devices file the request to associate to the coordinator the coordinator in charge of not only assigning the ZigBee address for the end device but also assigning the IP address for it and record down the matching relationship of this ZigBee IP addresses pair into its address translation table When the client end device send a packet to coordinator the IP layer will extract the destination IP address inside the IP header and look it up within the translation table if item is found the value that pairs with the IP address will be the ZigBee address that points out the where th
40. formance and the reliability by applying a two layer structure use RAM as the cache to store the most recent and most dynamic data and use flash memory to store the less recently or used data In our system the similar approach is adopted to increase the software response speed and provide the permanent storage at the same time 4 3 Page Accessing and Cycle Queue In addition in CC2430 the write operation is different to the read operation The smallest accessing unit in reading flash memory in our system is byte but the counterpart in writing flash memory is block with size of 2k bytes So the best way for us to manage the flash memory is block accessing 12 29 With the limited flash memory size we create a cycle queue in Flash memory space as the container for the sensor data which is being generated periodically The operating unit to the cycle queue is a page block of size 2k bytes this is accordant to the traits of flash memory that the size of single writing operation is 2k bytes Every page will be assigned an page ID in an ascending order from O to N 1 N is the total page number of the queue In an attempt to indicate the current starting location of the queue head of the queue the Head PageID is maintain for this purpose meaning the head page ID it also means that the data stored in this page are the least recent data in the whole queue Another variable called UsedPageCount is used to monitor the size of the queue it tells the
41. great needs TCP IP protocol stack is de facto standard and overwhelmingly the most popular network interconnecting protocol it is reliable connection oriented data transmission with flow control make it ideal to be the carrier of stream data 18 19 20 There are lots of implementations for TCP IP protocol stacks but it is not every implementation is ideal to be deployed onto an embedded system Embedded systems are not like large scale computer architecture and mature personal computer PC they lack of memory Mostly RAM less than 10K ROM less than 256K CPU performance is much weaker than main stream computers these lead to the code footprint RAM requirement and code complexity are three vital factors for the program running on embedded systems Based on consideration above we choose the uIP as our solution From 17 uIP is a compact implementation of the TCP IP protocol stack designed for small 8 bit and 16 bit microcontrollers It supports the RFC compliant protocols for network communication with a very small binary footprint and RAM usage uIP code size is a few kilobytes and RAM usage is a few hundred bytes Some extra good features of it are shown below O RFC standard TCP and IP protocol implementations including flow control fragment reassembly and retransmission time out estimation Unlimited number of listening TCP connections maximum amount is configurable 35 O Free for both commercial and non commercial use
42. groundwork for future applications developments by provide a serials of API fully covering the necessary features to upper layers programs Based on them the developers will feel easier to get in convenient to develop and shorten the development period greatly We discover a solution to Challenge No 6 to implement it successfully Even though there is no existing example that we could reference we immigrate the RTX51 tiny RTOS to our sensor nodes successfully There are no technical support for such a porting we first look through and understand all the source code of RTX51 tiny and make some necessary change to the code and port our version to our sensor nodes Chapter No 8 is right place for reader to look into these questions We select the browser based solution to solve Challenge No 7 furthermore The HTTP protocol are used as the protocol when communications occur between User interface subsystem and the RF communication subsystem Both of issues enable users to not install any software onto their desktop merely use browser and type the specified link and then the whole processing can be started and done within the browser Reader will see more details in Chapter No 7 Below is a brief introduction to the whole system sensor data management infrastructure based on the hardware environment of 801 15 4 ZigBee sensor network A system diagram below depicts how the system is constructed RF communication Subsystem C
43. ied every compiler has its advantage and limitation more study need to be put on how to provide a efficient and integrated development solution by choosing the appropriate Compiler or related software to compile the RTOS and application code or doing some immigration work on RTOS and application code So far the management node is required to deliver the query request to the destination node in the future a better infrastructure will be removing the management node and let each node is able to be hooked up by the personal PC A more comprehensive web server is needed since there will be more requirement such as file downloading Security Socket Layer SSL etc A File system will be able to enhance current storage mechanism to a more flexible and manageable level 62 1 2 3 4 5 6 7 8 9 10 11 12 REFERENCES Ed Callaway P Gorday L Hester J A Gutierrez M Neave B Heile V Bahl Home networking with IEEE 802 15 4 A developing standard for low rate wireless personal area networks IEEE Communication Magazine August 2002 IEEE 802 15 WPAN Task Group 4 TG4 http www ieee802 org 15 pub TG4 html IEEE 802 15 on Wikipedia http en wikipedia org wiki IEEE_802 15 Homepage of ZigBee Alliance http www zigbee org William C Craig Program Manager Wireless Communications ZMD America Inc Zigbee Wireless Control That Simply Works White Paper P Kinney ZigBee
44. ing Diagram of Task Scheduling in RTX51 Tiny 51 Start Mea Y Set Interrupt vector for Tl JMP TI MERI NT RTX_STACKERROR h d Stack Error Handling v HW TIMER RETI TI MERI NT Y Call HW TI MER Y Save PSW to RTX SAVEPSW y 0 PSW 0x01 select Bank one y Save ACC to saveacc j Reset the timer0 counter TI ME LOOP Stack space enough A YES No Wait Ti meout NoTi meout Laas er heck next task hit Taste item in table 7 RUNE From decrements the timer count for every Y the top of the task state table task Timer Counter us utl Ea al _ A T CLR EA Lens currently waiting fer Timeout event YES v Set Ready TMO EV NT bits save new status back to STAT TABLE SETB EA LZ E YES y SEE ae NO y Restore ACC from saveace Restore PSW from SavePSW ee _ A AE es NO Decrement R X ROBI NTI ME lt 7 PRIX ROBINTIME 0 gt gt RTX TaskSwitchi ng YES y PUSH ACC PSW B DPH DPL ARO AR7 into Stack Deal with current task Y Get current status of current running task Y CLR EA Y Set its K Robin bit and save back Y SETB EA 08 Swi 0
45. k it will create the response message in standard HTTP format and send it back to the SerProxy via the serial port SerProxy will transfer intact response back to the browser then the query result will be shown up into browser 2 Query starter Query starter is called by web server when the HTTP parser s job is done at this moment the query string is extracted the address information IP address is also 41 present both of them will be passed as the parameter to Query Starter which will reformat the query string into the private protocol as the packet payload next either look up the Address Translation table and then forward the packet to the right destination Coordinator or post the packet directly to the coordinator end device The query processing continues on the other side after the query string has been send to the destination over TCP IP here management node is acting like a client send request to the server which means the destination node The destination node receive the query string from the network then call the local query subsystem mentioned at Chapter 5 by passing the query parameters When the query operation is accomplished the result will be send back tracing back from the way that the query request came 42 CHAPTER 8 RESEARCH OF EMBEDDED OPERATING SYSTEM 8 1 Overview Chipcon2430 is quite new hardware compared with the other 8051 chipset in the current market plus the fact that Chipcon Corp d
46. lient Query Subsystem Storage Subsystem Collecting Subsystem Hardware of sensor node IEEE 802 15 4 ZigBee Network RF communication Subsystem Man v 3 age Node User Interface Subsytem The sensor network hardware consists of a couple of development board with CPU ChipCon2430 a system on chip radio frequency chipset supporting 2 4G Hz IEEE 802 15 4 ZigBee application An 8k byte RAM and 128K bytes Flash memory are build in into the chipset as well as a high performance radio transceiver A temperature sensor is also included inside the chipset 11 12 13 Based on hardware supports a software system is developed in an attempt to collect the data sampled by sensor store them to the permanent memory space remotely look up the specific data we need from the storage of remote nodes with high efficiency by using the high performance search algorithm and radio frequency communication provide friendly query interface to the non professional users support the TCP IP protocol stack 19 Figure 1 System Architecture 6 21 on top of IEEE 802 15 4 MAC and physical layer 2 3 This software system is comprehensive solution which empowers users to file a search request from a browser in users PC and the query result will be returned and displayed by the browser The data storage subsystem takes care on both aspects of efficiency and dat
47. mic binary search tree Def DynamicBinSearch key val HeadPage LogSummaryCache Head_PageNumber For the cycle queue structure RearPage HeadPage LogSummaryCache PageUsedCount 1 MAX_PAGE Every page contain 512 items OrgHead HeadPage 512 OrgRear RearPage 1 512 1 head OrgHead rear OrgRear Flag to mark if the head pointer is ahead of rear pointer originally used to determine if the search processing should stop or not OrgState head gt rear 23 Size of the window distance rear head in case of head lt rear OR 512 MAX_PAGE head rear in case of head gt rear The median location of window dobber head distance 2 MAX_PAGE 512 Process to shrink the window For head rear or head gt rear OrgState if time gt item at dobber time head dobber 1 Jelse if time lt item at dobber time rear dobber 1 Jelse Found the specified key val PageLog dobber val 1 return TRUE Adjust the size of window Distance rear head in case of head lt rear 24 OR 512MAX PAGE head rear in case of head gt rear Caculate the new median location in new window Dobber head distance 2 MAX_PAGE 5 12 At last with all this preparation works being ready the API Application Programming Interfac is given for the developer to search the specified key inside sensor data storage system B
48. n details to guarantee it to be a rapid solution compared to other solutions Chapter 6 explains the approaches that are leveraged by radio frequency communication subsystem Some detailed introductions regarding IEEE 802 15 4 and ZigBee will be found in this chapter the features and usages of software library of PHY and MAC layer is discussed as well as the TCP IP implementation on top of ZigBee protocol stack Chapter 7 discusses the user interface subsystem in terms of how it is built and the major technologies and software modules involved Chapter 8 provides a research report on real time operating system for embedded system The typical RTOS system called RTX51 tiny is introduced in comprehensive aspects 0066rom task scheduling timer tick to stack management Also some processing logics within the kernel of RTX51 tiny are also analyzed Chapter 9 give us an practical experiment on how TCP IP protocol stack improves the ZigBee Network s capabilities on handling heavy data traffic situations CHAPTER 2 HARDWARE ENVIRONMENT 2 1 Overview There development environment in terms of hardware mainly consists of two components The chipset module plug in board and the development main board Some tightly related parameters regarding to the functionalities of these two components will be introduced in the following sections 2 2 Hardware Summary on Chip Set There are three versions in the family of Chipcon 2430 they are CC2430 F32 F64 and F
49. niet Work aeree nseries nine onn mantra peur cra 41 8 RESEARCH OF EMBEDDED OPERATING SYSTEM e 43 S I OVE VIE Was pns A aia 43 8 2 Overview of Embedded Operating System sse 43 8 3 Mierat TU QUE SY SIG oor odo erras NO E 44 8 4 Basic software architecture of RTX51 tiny eese 46 8 5 Stack Management in R TX51 tiny deseen reget erede ta Sumber p adt 49 vii 8 6 Initialization of RTX51 MV dia eain 50 8 7 Processing Diagram of Task Scheduling in RTX51 Tiny 51 9 PERFORMANCE TEST ON NETWORK COMMUNICATIONS 54 E A A 54 9 2 Test ENVIFON Ent and Ter Pls erica artesa 54 e AA O A tat Hale idi ripeto dra 55 DATES CREU it ata 55 9 5 Experiment Ana SiS e aiaa e a ra iii 57 10 CONCLUSION AND FUTURE WORK eerte en eene 61 REFERENCES ito MES 63 BIOGRAPHICAL INFORMATION cti iaa 66 viii LIST OF ILLUSTRATIONS Figure Page I System Arc IIIS CHINE retinas Utero 6 2 Picture or Development board serrat load 11 3 Cyclic ri MMC EE 16 4 Insertion operation or Cyclic queue vecino rescindir 17 5 Two cases in Splitting the window in cyclic queue esee 23 6 ZipBeenetwork model iiie eee ditas ciastenseceiwcnsecedssassesecddieeteseseuanatssiacienrese 31 7 Structure of User Interface Subsystem sv cicncoccccsetssussassasssdacengucesscseversecsacediacavecavees 39 8 Software structure
50. oesn t provide customers its own RTOS solution which lead to the fact that there is no corresponding operating system solution on this chipset for education purpose We migrate the RTX51 tiny RTOS to our sensor nodes successfully even though there is no existing example that we could reference Embed OS specially the real time operating system is major attention in this chapter Some basic concepts are introduced firstly followed by the fact that we choose RTXS1 tiny as our RTOS thirdly we migrate RTX51 tiny to our system ChipCon2430 and the distinctions on implementation details between 8051 standard CPU and Chipcon2430 followed finally we analysis and illustrate technologies used at some vital parts of RTX51 tiny including the stack management task scheduling and initialization procedure 8 2 Overview of Embedded Operating System Along with the more and more powerful hardware equipped to the embedded system more and more hardware features are provided it also means the corresponding software running on embedded system proliferate rapidly The architecture of single task assisted with interrupt mechanism become incapable to handle all these hardware 43 events or software tasks to run within the same embedded system So far the trend of Real Time Operating System RTOS is more and more popular RTOS is capable to manage more than one programs running simultaneously as described in 14 15 16 RTX51 is one of the widely used R
51. payload is 30 bytes Payload 30 bytes Network ZigBee TCP IP ZigBee Network Status Good Bad Good Bad Packet Finish Packet Finish Packet Finish Packet Finish Received Time Received Time Received Time Received Time 10000 53 10000 56 Packet Mode 10000 52 9748 Null 56 Table 6 Continued 9996 Null 9989 Null 9995 Null 9961 Null 10000 167 10000 170 Stream Mode 9996 Null 9947 Null 10000 168 10000 171 10000 51 9999 Null 10000 167 10000 171 Table 7 Experiment result when payload is 60 bytes Payload 60 bytes Network ZigBee TCP IP ZigBee Network Status Good Bad Good Bad Packet Finish Packet Finish Packet Finish Packet Finish Received Time Received Time Received Time Received Time 10000 68 9532 Null Packet Mode 9998 Null 8689 Null 10000 68 9978 Null 9998 Null 9912 Null 10000 181 10000 184 Stream Mode 9998 Null 9891 Null 10000 184 10000 186 10000 62 9697 Null 10000 182 10000 184 9 5 Experiment Analysis Some statistics histograms give us the summary of the table above 57 100 99 995 99 99 packs 99 985 99 98 99 975 add TCP amp ZigBee ZigBee TCP amp ZigBee ZigBee Packet Mode in Good Network Stream Mode in Good Network Recv Packet 2 TCP amp ZigBee ZigBee Packet Mode in Bad
52. pes are defined Data ACK MAC command Beacon Data Frames supports a payload with size of 104 bytes with unique frame ID 28 for tracking purposes ACK frame acknowledges the packet has been received by the destination node correctly MAC command frame are used to control and configure the client node by coordinator Beacon frame is like notice message for the client nodes client nodes are wake up by the beacon frame They listen on the PAN network and will go back to the sleep mode if no beacon frame is received ZigBee devices can be divided by three kinds of categories Table 2 Categories of ZigBee devices 8 Device type Characteristics Role in the network Maintain the overall network information Coordinator requires the most memory and computing Pan network manager power Full function Coordinator or device FFD Per eee Oe network router Reduced function Limited functionality Network edge device device RFD ZigBee networks are designed to conserve the power of the slave nodes For most of the time a slave device is in sleeping mode and wakes up only for a fraction of a second to let the coordinator know its presence in the network ZigBee network can run under Beacon or non beacon strategies Basically in non beacon mode each client is autonomous acting like two way radio network can establish a conversation at will but the conversation perhaps will be disturbed by others occasionally
53. porary buffer for ACC 1 byte savepsw temporary buffer for PSW 1 byte currenttask Task ID of current running task 1 byte 48 Table of stack pointers Lies in IDATA segment a table storing the stack pointers SP with respect to each task running on the system Table of Task Timer State Allocated in IDATA segment a table to store each task s left time slick and task state Task delay bit a bit to be a flag which is used to indicate if the task switching is running after timer interrupt occur if this bit is set the new coming timer interrupt routine will be ignored 8 5 Stack Management in RTX51 tiny The Stack space in RTX51 tiny is located in internal memory IDATA all the running tasks share the stack space together The management mechanism is The task that is running owns the CPU time has as much amount of available stack space as possible to use When this task is switch out its stack space will be shrunk and relocated in other words the used stack space used by this task will be relocated and the unused space will be merged into the stack space used by new task that is switched in So the switched in task is expanded that guarantee the current task has the maximum stack spaces as possible to use there is a brief explanation represented in 31 49 RAMI OP Stack Area for Task 2 Stack Area for Task 1 Unused Space by Task 0 Used space by Task 0 Step one gt AMT OP Stack
54. ratitude to my parents and brother for their encouragement patience and thoughtful concern November 9 2006 11 ABSTRACT A DISTRIBUTED SENSOR DATA MANAGEMENT INFRASTRUCTURE BASED ON 802 15 4 ZIGBEE NETWORKS Publication No Tianqiang Li M S The University of Texas at Arlington 2006 Supervising Professor Yonghe Liu Wireless sensor networks consist of a certain number of autonomous devices with sensor every device has certain detection functionality like light temperature pressure etc Communication by using the radio frequency make these spatially distributed devices feasible to oversee the activities in a large scale of area space 802 15 4 ZigBee networks are slated to run in the unlicensed frequencies It is a packet based radio protocol aimed at very low cost battery operated widgets and sensors that can intercommunicate and send low bandwidth data to each other iii This thesis covers the content of a software solution of data management for an 802 15 4 networks Its main contribution lies in it grounds a scalable and extendable infrastructure for current and future developments to depend on enabling users to manage the distributed sensor data across the diversified and spacious ZigBee network Some unique technologies are proposed according to the specific hardware embedded environment such as cyclic queue storage structure of RAM Flash memory Dynamic binary search etc Some improvement solutions are also implem
55. result of calling Device mlmePollRequest Call back function that is invoked by Coordinator or mcpsDatalndication the MAC layer when a data frame is Device successfully received Callback generated by the MAC mlmeDisassociateIndica sublayer to the higher layer upon Coordinator reception of a disassociation notification tion command frame 6 4 TCP IP Protocol Implementation TEEE 802 15 4 defines the PHY layer and MAC layer ZigBee defines above layers like Network layers NWK and part of application layer E X application profiles The current standard enables the devices defined in same profile category can interact the control commands and exchange data even devices are made by different manufactures But control commands compatible to devices in same profile category does not satisfy all the requirements from HAN network for example once the ZigBee remote control A is able to hook up to ZigBee monitor B and control B once this control commands are done the part coming next is to fetch exchange and synchronize what the monitor has captured Sensor data flow is the vital part of ZigBee network also is the source for later data exploitation Sensor data flow is sort of data stream that 34 were continuously generated with large data payload which is not like control commands with small payload body Facing to these the reliable data transmission which is suitable for stream data transportation is in
56. rize At the same time some GUI interfaces would be helpful 39 We choose use the Internet browser to be the most frontal interface to face the users Its compliancy to the RFC Internet standard HTTP HTML XML DHTML etc make the Internet communication is much more convenient than other GUI interfaces furthermore it is probably the software that people can the most easily get for free Every modern operating system comes with browser 7 3 Way to hookup The browsers are used onto users desktop or laptop a way that let the PC hook up to ZigBee network has to be figured out otherwise the communication can not be accomplished There are a couple of channels available to be used to interact with the outside devices such as Serial port RS232 USB Radio Frequency We choose the serial port communication as our approach to hook the PC up to the sensor network in the current version of system This kind of mature technology is widely accepted by the industry and convenient for developer to build the communication work up The next step of work is how to get the browsers send their data through the serial port Generally speaking browsers work based on the TCP IP network environment such as Ethernet and Wi Fi they send data up to the network that PC attached instead of the serial port In this situation a proxy is an ideal software to make our requirement come true We use a proxy software called SerProxy can be downloaded in 10
57. rk Remember what we mention in the last paragraph Only IP ZigBee address pair are recorded we should modify the ATT and put PAN ID into the ATT to guarantee the capability that enables the global ZigBee network data transmission The routing mechanism is very similar to the one in TCP IP protocol so we take advantage of the routing module in uIP software to implement the TCP IP routing on ZigBee network 38 CHAPTER 7 USER INTERFACE SUBSYSTEM 7 1 Overview This chapter is going to give a big pictures and implementation details on how the users do the sensor data query against the ZigBee network The major steps in the procedure is that Send http query request from browser which will deliver the request through a proxy to the serial port RS232 the web server on management node will phase the http request and send the query request to the destination node the query response will be send back following the same route reversely The architecture of this module is shown below Private A ce HTTP Protocol BN pl AA Cung IEEE 802 15 4 2 Browser focal Net wor SerProxy RS232 Manage Node K ZigBee i ZigBee Net work j u c HTTP Figure 7 Structure of User Interface Subsystem 7 2 Browser based interface The user interface is supposed to be designed for less professional or non professional people so it should not have lots command lines for users to type or a large keyword set to memo
58. sion model It means how sensor nodes send out the packets Two categories will be considered which are packet mode and stream mode Packet mode stands for the next packet has to be sent after having got the acknowledgement of last packet Stream mode represent the packet are sent in a asynchronous mode without having to wait until the acknowledgement of previous sent packet arrives 9 3 Test Procedure Two sensor nodes will be involved one is the sender the other is receiver Sender will transmit 10000 packets with three possible payloads respectively light middle and heavy under two network status Good and bad respectively The time used to finish the transmission and the number of packet that were received successfully by the receiver node will be recorded 9 4 Test Result Here are the tables that record the experiment result 55 Table 5 Experiment result when payload is 10 bytes Payload 10 bytes Network ZigBee TCP IP ZigBee Network Status Good Bad Good Bad Packet Finish Packet Finish Packet Finish Packet Finish Received Time Received Time Received Time Received Time 10000 40 10000 44 Packet Mode 10000 40 9748 Null 9994 Null 9989 Null 9994 Null 9993 Null 10000 157 10000 160 Stream Mode 10000 39 8429 Null 10000 156 10000 159 9994 Null 9994 Null 10000 157 10000 161 Table 6 Experiment result when
59. tor itself returns to sleep for the sake to lower power consumption The NWK layer is in charge to associate or dissociate devices through the network coordinator routes frames to their destination and perform security In addition the NWK layer of the network coordinator also in charge of starting a new network and assigning an address to newly associated devices 30 The NWK layer specifies multiple network topologies including star cluster tree and mesh which are shown in Figure below e ZigBee coordinator FFD Z gBee router FFD ZigBee end device RFD or FFD lt gt Mesh link lt gt Star link In the star topology one of the FFD type devices will play the role of network coordinator and is used for initiating and maintaining the devices on the network All other end devices communicate with the coordinator directly In the mesh topology like in star topology the ZigBee coordinator is responsible for starting the network and for choosing key network parameters but the network can be expanded and interact with network outside via the use of ZigBee routers 6 3 Specification in CC2430 and Physics and MAC Layer The CC2430 IEEE 802 15 4 MAC and PHY software implements the functionality as specified by the IEEE 802 15 4 specifications The MAC software may run by using a CC2430EB development kit 31 Functionality of the MAC and PHY layers include following features as described in 30 CSMA C
60. usly we are required to revise the static search algorithm slightly and put some more control logic into it and generate an upgraded version that we call dynamic binary search algorithm The key part of binary search is to select the search window then locate the median item right inside the window compare the value to be search and the value of the median item then determine which half of the window we should go further that half of window will turn into be new search window similar processing are repeated until the value is found The range containing data in the cycle queue is various the pointer HeadPageID and queue size PageUsedCount are used to monitor the variance of this range Let s make definition for some terms here in order to illustrate the search procedure intuitively later an figure also depicts how to locate and split the window Definitions HeadPage First page ID of the queue that stores data RearPage The last page ID of the queue that stores data OrgHead The first item that stores the oldest data OrgRear The last item that stores the most recent data Distance The size in items of the search window 22 HeadPage Medi anPage Rear Page Medi anPage RearPage HeadPage Figure 5 Two cases in splitting the window in cyclic queue The ADT abstract data type description for the dyna

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