Remote Sensor and Controller System Employing RFID, ZigBee and IEEE Wireless Protocols

Transcription

1 Remote Sensor and Controller System Employing RFID, ZigBee and IEEE Wireless Protocols Nathan Brown March 1, 2008 Submitted to Prof. Lin & Dr. Rumsey

2 Problem Statement Process automation, control, and monitoring are all terms used every day in an industrial setting. Some modern homes may even have consumer oriented automation systems in place. Most of these systems are highly specialized, thus making them very expensive. The aim of this project is to create a platform for a system that is capable of monitoring and controlling a wide range of objects (devices, environment, people) from a central location by using low-power radio transceivers. Through the use of low power consuming radios, a wireless network is formed between all of the enabled devices and in turn, a user can control each of these devices from a personal computer or even a PDA via a local area network or even over the Internet. The possible use of this wireless controller and sensor system is virtually limitless. Any wirelessly enabled device could potentially be monitored or controlled. A vehicle's remote start system could be engaged while the driver is getting ready to leave the house in the morning. The same system installed in an assembly line can count of all products leaving the factory by tracking their RFID tags. The only differences are in the end-devices. The systemʼs structure is exactly the same. Having a central controller acting as a functional human interface and the gateway between a wired network and the wireless nodes that form the wireless infrastructure, a robust and scalable automation system is possible. These products exist, but they are either expensive, highly specialized, very simple, or simply inflexible.

3 Market Analysis Automation systems are definitely not new and there are several companies that provide solutions designed for the home and industrial uses. The common factor between these products is that they are usually specialized. The proposed system design would allow the end-user to configure the system for a wide variety of uses, whether they be for the household or targeted for industry. Similar products and their intended uses can been seen in the summary table. Product Comparison Table Product Description Uses INSTEON Z-Wave This is a wireless home automation system, with no central computer. All devices act as a repeater. Adapters are available to enable lighting fixtures or appliances. Wireless home automation, through monitors and controls. Devices can integrate Z-Wave technology, and all devices that have this technology, can communicate. A central computer allows customizations. X-10 Industry standard for device communication primarily uses the existing power lines. Most common application is electrical socket control. Home, lighting, appliance control, security systems. Home, automation, device integration Home, security camera, wall socket control. OleumTech Commercial & industrial monitoring products Pressure and fluid level monitoring SensiCast Wireless mesh network system for monitoring temperature, fluids, and other industrial environmental factors. Industry, harsh environments Both Z-Wave and this project are targeted for similar uses but Z-Wave is a proprietary technology with only a few members a part of itʼs alliance. ZigBee, the technology chosen for this project has over seventy members, with the most notable being Samsung, Freescale, Texas Instruments and many others. So the technology chosen definitely has a future. X-10 is an old technology that mainly uses the power lines, so itʼs strictly confined to a small pre-wired area. Also, this technology is proprietary, and its not scalable. Other products that are made for industrial applications must adhere to strict guidelines so they can withstand extreme environmental conditions. There is no reason why the end nodes to this project could not adhere to the same criteria. Since this system is scalable to different applications, certain end devices can meet different requirements depending on their intended use. The goal of this project is to develop a platform for a controller and sensor network, to increase efficiency in automation and other processes, at a lower cost that currently existing systems.

4 Requirements and Specifications This section will detail the physical pieces that the system will be composed of, as well as specifications, and requirements. This is a listing of requirements that the system needs to achieve: Radio operates in 2.4GHz ISM(Industrial/Scientific/Medical) Band PC for user interface and configuration Database access for information storage Range extends throughout a building C Language for programming ZigBee Communication Stack Physical Components The system will be divided into two main components each of which will have certain subcomponents necessary for operation. The brain of the system will be the Coordinator, and this device will structure all wireless network operations, and act as a human and data interface to the wireless network. The other portion of the system will be a network of wireless nodes, called Remotes, which will promote the range of the wireless network and function as controllers for devices or monitoring agents. The Coordinator will integrate a microcontroller, Ethernet, USB, IEEE transceiver & antenna, and general purpose I/O ports for attaching accessories. The Coordinator shall be a relatively small set-top box that can be placed on a desk or shelf. As with all wireless devices, they should always be set away from walls and other metal materials that can attenuate or interfere with the wireless signals. Power consumption will not be significant but since the Coordinator must always be on, it will need to be plugged into a wall outlet. Coordinatorspecific component details can be found in the table. Main Coordinator Components Component Description Specification NXP LPC2368 TI CC bit ARM7 based microcontroller. This device supports both USB and Ethernet with minimal external components. It also contains an SPI interface, which is necessary for connectivity to the ZigBee transceiver. Zigbee ( ) Transceiver with integrated ZigBee 2006 Protocol Stack Development tools are freely available, and the chip is programmable via Jtag interface. 2.4GHz ISM band radio transceiver. This device supports the ZigBee protocol stack, Z-Stack, provided by Texas Instruments. National DP83843 Ethernet PHY layer device. This provides the physical layer of Ethernet between the real-world and the microcontroller.

5 The Remote devices will also integrate a (different) micro-controller, and IEEE compliant transceiver & antenna, and general I/O. Other bulky and unnecessary features such as Ethernet and USB will not be integrated, as the Coordinator which has those features, acts as a gateway to the Remotes. Physically the remotes should not take up more than approximately 2-3 sq. in. of area. Their small size allows them to be placed inconspicuously or even carried around as a key fob. Power consumption will be kept to a minimum as most of the remotes will run off battery power; the batteries should last several months or years without having to be replaced. The technology used in the remotes can either be integrated into appliances and other electronic devices, or stand-alone remotes can be externally connected. The following table details the necessary components for the Remote devices. Remote Components Component Description Specification Silicon Labs C8050F120 TI CC2480 This 8-bit microcontroller is a low power device that has several general purpose inputs and output, as well as supporting the SPI interface for communication with the ZigBee transceiver. Zigbee ( ) Transceiver with integrated ZigBee 2006 Protocol Stack Development tools available from Keil, and the chip is programmable via Jtag interface. 2.4GHz ISM band radio transceiver. This device supports the ZigBee protocol stack, Z-Stack, provided by Texas Instruments.

6 Implementation Methods The procedure for implementing this design involves several steps. The first step involves defining the scope and goals of the project. The ultimate goal is to design a multipurpose and scalable system that can assist people or businesses in their daily tasks. Once the components have been chosen (see Trade-Off Study), prototype boards will need to be developed. The prototype boards allow experimentation with the hardware to be done, as to understand the hardware s operation and capabilities. This stage is the critical point at which a true sense can be attained of the limits of the system. Since the project has multiple components, multiple prototypes have to be created to understand how the devices communicate with each other. There is a blend of hardware design as well as software development. Prototyping is the first step in building the system. Schematic capture software is used to design the electrical circuits for the Coordinator and the Remotes. After the circuits have been drawn into the computer then, those drawings will be transferred into circuit design files. These files are loaded into another software application to design the physical layout of the circuit boards. Rapid prototyping machines are available to students turn the circuit board layouts into real boards. Companies also provide circuit board cutting services at a very low cost. The first prototype to be built is the Coordinator. This device has several components, including a microcontroller, ZigBee radio IC, Ethernet PHY IC, antenna, USB and Ethernet connectors, and various other passive components. This device will require more intensive software development and testing than the Remotes. A ZigBee development kit provided by Silicon Labs containing several ZigBee enabled remotes, with microcontrollers and antennas are going to be used for testing the Coordinator device. Once significant progress has been made with the Coordinator development, then Remote prototypes will be developed. The premade ZigBee remotes from Silicon Labs will greatly assist in the prototype, development and testing processes. Real-word device interfacing and integration is an important aspect of the system design. Some external projects are being developed to show off the capabilities of the overall system. An RFID security access panel will be ZigBee enabled to demonstrate how a database of users and access cards can be used to control access to a restricted area. Another demonstration will involve a remote vehicle lock and starter system. This will show how a vehicle parked near a remote can be controlled from a hand-held device (such as those that fit onto a keyring) or from a PC to see if the doors are locked. Both of these demonstrations show how that the system can be used in practical situations and there is no extra wiring necessary.

7 System Description The proposed project idea is a system of networked wireless sensors and controllers that communicate between each other to a central Coordinator. This Coordinator can communicate to a personal computer through a serial USB interface or directly to a network through an Ethernet connection. The system is divided into two primary functional components. The first of the two being the Coordinator which controls the entire system. It's functions include a means of human interface, network access for data storage and retrieval, and wireless communication with the wireless sensor and controller units, or Remotes. Each Remote is equipped with a small microcontroller and an IEEE compatible ZigBee transceiver. The ZigBee transceiver is capable of building a wireless mesh network with other transceivers in its range. The transceivers build the network infrastructure between the individual devices and the Coordinator. The figure illustrates the structure of the mesh network. Router End Node Coordinator

8 The Coordinator One goal of this system design is to give users the power to monitor or control devices without being constrained to their facility, whether it be the office, factory, or even their home. An important feature of the Coordinator is that it has USB and an Ethernet connectivity. The USB port allows the device to be plugged into any standard PC, and with the use of software, observe the Remotes on the network and control or monitor the devices attached to them. The software is able to communicate to the Coordinator because of the bi-directional capabilities of serial communication via the USB interface. The Ethernet connection provides a secondary means of user control since the Coordinator contains an integrated web (http) server. The web server hosts a site that allows the user to access functions necessary for monitoring and controlling devices attached to the remotes as well. Another purpose of the Ethernet connection is so the Coordinator has access to network resources, such at the time, or a database for storing information about the network. By allowing databases access, it helps reduce the storage limitations imposed by a small integrated device. A block diagram of the Coordinator can be seen in the figure. Power MCU ZigBee Transceiver ZigBee Protocol Ethernet PHY USB Plug Ethernet Jack

9 The Remote The Remotes are each equipped with a IEEE transceiver, and can function in one of two modes either as a router or an end node. Devices that are operating in the router mode, can retransmit traffic that it has received, just like a router used in a traditional network. The range of the network can be extended by having remotes function as remotes. Devices that are operating as an end node, do not have this 'routing' capability. The functions that the Remote are intended to perform include building the wireless network infrastructure, and to interface with real-word devices. The physical design of the remote will include a microcontroller, IEEE transceiver with antenna, and input/output ports. The Coordinator assigns unique network addresses to each of the remotes so each Remote can be accessed individually. The actual function of the remote, whether it will be monitoring an environment or controlling a device, will be programmed via the interface on the Coordinator. A block diagram of the Remote can be seen in the figure. Battery/Power Supply MCU ZigBee Transceiver ZigBee Protocol Analog/Digital IO

10 Regulatory Standards Several different technologies each with their own standards and regulations are to be used together to create the wireless sensor and controller system. All radio communications in the United States are regulated by the Federal Communications Commission (FCC). Other technologies like ZigBee, USB and Ethernet have their own compliance requirements and work with international standards groups, such as the IEEE. Radio Communications Under Title 47 within the Code of Federal Regulations, Part 15, Subpart 247 lists the regulations for the unlicensed frequency band that the radio transceivers will be operating in. Although this system will be using the unlicensed 2.4GHz (ISM) band, itʼs still necessary to conform to FCC regulatory standards for use in consumer or industrial products. The reference design for the TI CC2480 radio transceiver already compiles with the FCC CRF 47 Part 15. ZigBee The ZigBee Alliance has worked with the IEEE to form the IEEE standard. This defines the physical and MAC layers, as well as the high level communication protocol aptly named ZigBee. The radio transceiver, TI CC2480, has an integrated implementation of the ZigBee 2006 specification.

11 Trade-Off Study Many different solutions exist for accomplishing the requirements and goals of this project. Of the listed methods for both hardware and software, there are only a few that will work the best. The Assembly language gives the programmer the most flexibility with the target system but the code is practically not portable to any other platform. This is a problem because this ties the system design to one specific piece of hardware. The C programming language is standard for both PC and embedded applications and the ZigBee API is available from Texas Instruments in standard C libraries. The use of a microcontroller (MCU) is almost inevitable. These tiny integrated systems are powerful, flexible and make development much less of a chore. Making a choice for the appropriate chip is a tradeoff between the different criteria for the considered system component. A quantitative analysis is to be performed which will rank each of these criteria. The Coordinator device needs USB and Ethernet capabilities, so a MCU that has these features already integrated into the chip will rank higher. The Remotes need to be small and consume little power, so a much simpler MCU is needed. As always, the ability to develop for the chip is a critical decision factor. A chip may possess the perfect characteristics, but if development tools are too costly or difficult to use, then an alternative must be found. Programming Language Trade-Off Comparison Language Portable Difficulty Libraries Flexibility Best Choice? C Yes Moderate Available Mostly X Assembly No Hard None Completely - ZigBee Radio Transceiver Trade-Off Comparison ZigBee Transceiver Interface Integrated MCU Z-Stack Compatible Transceiver Only? Simple ZigBee API? Best Choice? TI CC2430 SPI Yes Yes No No - TI CC2480 SPI/UART No Yes Yes Yes X TI CC2520 SPI No Yes Yes No - Freescale MC13203 SPI No Yes Yes No -

12 Microcontroller Trade-Off Comparison MCU Core Ethernet USB UART SPI Low Power Development Tools Intended Use NXP LPC2368 ARM7 Yes Yes Yes Yes No JTAG, Free Software Coordinator TI MSP No Yes Yes Yes Yes Remote SiLabs C8051F No No Yes Yes Yes JTAG Remote

13 Required Resources There are a number of resources required to complete this project. These resources range from physical devices to knowledgeable individuals. This section will outline the resources that have been used and others that will be required. People The knowledgeable professors at Indiana University Purdue University Fort Wayne have been a great help so far in giving suggestions and advice related to this project. So far advice has been received from the following professors: Prof. Paul Lin, Dr. Steve Walter, Prof. Gary Steffen, Prof. Peter Goodman, and Dr. Suzanne Rumsey. Hardware ZigBee transceiver - CC2480 Microcontroller Microcontroller - MSP430 or SiLabs 8051 (for remotes) - LPC2368 (for controller) Flash programmer, PCB Prototyping tools, ZigBee Development kit Software C Language and Integrated Development Environment ZigBee API Facilities The IPFW campus computer labs have been used for research and the available test equipment may need to be used for future testing.

14 Project Schedule This Gantt chart outlines the schedule for task completion for Senior Design Phase I. The schedule for the Project Development is still being created.

15 Estimated Cost The development of this project will not require a large investment. Most of the electrical components that will be used typically only cost several pennies each--some a few dollars. But, most of the companies that produce these products are willing to give out free samples in large enough quantities to build a fully working prototype. Microcontrollers - All have been provide free of charge from companies such as Silicon Labs, Texas Instruments, and NXP Semiconductors. ZigBee Transceivers - All have been provide free of charge from companies such as Texas Instruments and Free Scale. Development Tools - A JTAG programmer has been purchased for $50 for an ARM7 based microcontroller. Development Kits - A ZigBee development kit has been provided by Professor Lin.

16 Return of Investment and Benefits Since there are no stakeholders involved such as companies or clients, there are no direct monetary benefits to the completion of this system. Although, the system design does have its own other benefits. The wireless sensor and controller system is an excellent idea for a scalable platform. Potential clients can easily deploy the system in almost any environment and tailor the system to suit their needs. Because the design does not assume anything about what the user will be using it for, itʼs designed in such a way so the Remote wireless units can be connected to a wide variety of real-world devices, both analog and digital. The user interface, which is accessed through the Coordinator device allows the user to program the remotes to describe how they are to be used. Lighting control and automation in the home, versus monitoring the operating temperature of a machine in a factory would normally take two completely different systems; the two have completely different requirements and goals. A unified platform for automation and control systems could significantly reduce end-user costs, and ultimately improve efficiency wherever these devices are used. Another example would be knowing which lights are on in a building without traversing every room and how that could have a significant impact in reducing energy consumption. As system designers, invaluable knowledge is gained though managing a project such as this one, as well as gaining experience physical hardware and software development. New technologies such as RFID and ZigBee have many uses and will be used in many products in the future.

17 Risk Analysis This section deals with identifying the risks associated with the project design and development process, ranking the risks according to severity and probability, and how to go about minimizing those risks. The first step in risk analysis is to identify the appropriate risks, and the next step involves analyzing those risks. Risk Identification Performance Risk System will suffer interference Insufficient range System Inflexibility Management Wrong components ordered Goals arenʼt reachable Requirements arenʼt reachable Schedule Parts arrive late Objectives not met by deadline Risk Severity-Probability, Quantitative Rankings III (Most Severe, Not Probable) IV (Most Severe, Medium Probability) V (Most Severe, Most Probable) Severity I (Medium Severe, Not Probable) II (Medium Severe, Medium Probability) IV (Medium Severe, Most Probable) 0 (Not Severe, No Probable) I (Not Severe, Medium Probability) III (Not Severe, Most Probable) Probability

18 Qualitative and Quantitative Assessment This table lists the possible risks associated with this project. The qualitative analysis is a description of what the risk involves, and the quantitative analysis is a numerical ranking based off the matrix plot of the severity of the risk vs. probability of the risk occurring. Qualitative Quantitative 1 System will suffer interference The 2.4GHz ISM band is used for a wide range of consumer devices. WiFi, Bluetooth, cordless phones, and even microwave ovens use this band. The ZigBee Alliance has done a study and assures that the IEEE standard will work harmoniously with these devices. III 2 Insufficient range ZigBee was designed for radios to consume little power so devices can run off battery power for extended periods of time. Most facilities such as businesses, schools, and industrial environments are built with concrete and steel. These materials will attenuate radio signals significantly, so range is definitely an issue. IV 3 System Inflexibility The flexibility of the system depends on how general the Remotes can be designed. The ability for the Remotes to interface with a wide range of real-world devices is being researched. There must also be a way for the user to control each remote. The software interface should be customizable to provide this functionality. III 4 Wrong components ordered Ordering the correct components is dependent on identifying the correct components that are needed, as well as ordering the intended part. II 5 Requirements arenʼt reachable The requirements are a minimal set of criteria the system must meet to be considered completed or successful. The requirements basis of the core functionality. V 6 Goals arenʼt reachable Goals are a set of desired requirements. So, they arenʼt required at all. But if resources are available, then the goals should be met. I Risk Matrix Probability vs. Severity 1&

19 Teaming Factors This project is a team effort between Nathan Brown and Carol Van Houtin. All research and project planning are to be worked on together. The two main segments of the project development are hardware and software. Nathan will specialize in the software engineering aspect whereas Carol will specialize in the hardware/circuit design. Although, both team members will collaborate together on both segments.