28-03-2011, 02:58 PM
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INTRODUCTION
When you hold the TV remote and wish to use it you have to necessarily point your control at the device. This one-way, line-of-sight, short-range communication uses infrared (IR) sensors to enable communication and control and it is possible to operate the TV remotely only with its control unit.
Add other home theatre modules, an air- conditioner and remotely enabled fans and lights to your room, and you become a juggler who has to handle not only these remotes, but also more numbers that will accompany other home appliances you are likely to use.
Some remotes do serve to control more than one device after ‘memorizing' access codes, but this interoperability is restricted to LOS, that too only for a set of related equipment, like the different units of a home entertainment system
Now picture a home with entertainment units, security systems including fire alarm, smoke detector and burglar alarm, air-conditioners and kitchen appliances all within whispering distance from each other and imagine a single unit that talks with all the devices, no longer depending on line-of-sight, and traffic no longer being one-way.
This means that the devices and the control unit would all need a common standard to enable intelligible communication. ZigBee is such a standard for embedded application software and has been ratified in late 2004 under IEEE 802.15.4 Wireless Networking Standards.
ZigBee is an established set of specifications for wireless personal area networking (WPAN), i.e., digital radio connections between computers and related devices. This kind of network eliminates use of physical data buses like USB and Ethernet cables. The devices could include telephones, hand-held digital assistants, sensors and controls located within a few meters of each other.
ZigBee is one of the global standards of communication protocol formulated by the relevant task force under the IEEE 802.15 working group. The fourth in the series, WPAN Low Rate/ZigBee is the newest and provides specifications for devices that have low data rates, consume very low power and are thus characterized by long battery life. Other standards like Bluetooth and IrDA address high data rate applications such as voice, video and LAN communications.
Device Types:
There are three different ZigBee device types that operate on these layers in any self-organizing application network.
These devices have 64-bit IEEE addresses, with option to enable shorter addresses to reduce packet size, and work in either of two addressing modes – star and peer-to-peer.
1. The ZigBee coordinator node : There is one, and only one, ZigBee coordinator in each network to act as the router to other networks, and can be likened to the root of a (network) tree. It is designed to store information about the network.
2. The full function device FFD : The FFD is an intermediary router transmitting data from other devices. It needs lesser memory than the ZigBee coordinator node, and entails lesser manufacturing costs. It can operate in all topologies and can act as a coordinator.
3. The reduced function device RFD : This device is just capable of talking in the network; it cannot relay data from other devices. Requiring even less memory, (no flash, very little ROM and RAM), an RFD will thus be cheaper than an FFD. This device talks only to a network coordinator and can be implemented very simply in star topology.
ZigBee Characteristics:
The focus of network applications under the IEEE 802.15.4 / ZigBee standard include the features of low power consumption, needed for only two major modes (Tx/Rx or Sleep), high density of nodes per network, low costs and simple implementation.
These features are enabled by the following characteristics. 2.4GHz and 868/915 MHz dual PHY modes. This represents three license-free bands: 2.4-2.4835 GHz, 868-870 MHz and 902-928 MHz. The number of channels allotted to each frequency band is fixed at sixteen (numbered 11-26), one (numbered 0) and ten (numbered 1-10) respectively. The higher frequency band is applicable worldwide, and the lower band in the areas of North America, Europe, Australia and New Zealand .
• Low power consumption, with battery life ranging from months to years. Considering the number of devices with remotes in use at present, it is easy to see that more numbers of batteries need to be provisioned every so often, entailing regular (as well as timely), recurring expenditure. In the ZigBee standard, longer battery life is achievable by either of two means: continuous network connection and slow but sure battery drain, or intermittent connection and even slower battery drain.
• Maximum data rates allowed for each of these frequency bands are fixed as 250 kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz.
• High throughput and low latency for low duty-cycle applications (<0.1%)
• Channel access using Carrier Sense Multiple Access with Collision Avoidance (CSMA - CA)
• Addressing space of up to 64 bit IEEE address devices, 65,535 networks
• 50m typical range
• Fully reliable “hand-shaked” data transfer protocol.
• Different topologies as illustrated below: star, peer-to-peer, mesh
Technology Comparisons:
The “Why ZigBee” question has always had an implied, but never quite worded follower phrase “…when there is Bluetooth”. A comparative study of the two can be found in The bandwidth of Bluetooth is 1 Mbps, ZigBee's is one-fourth of this value. The strength of Bluetooth lies in its ability to allow interoperability and replacement of cables, ZigBee's, of course, is low costs and long battery life.
In terms of protocol stack size, ZigBee's 32 KB is about one-third of the stack size necessary in other wireless technologies (for limited capability end devices, the stack size is as low as 4 KB).
Most important in any meaningful comparison are the diverse application areas of all the different wireless technologies. Bluetooth is meant for such target areas as wireless USB's, handsets and headsets, whereas ZigBee is meant to cater to the sensors and remote controls market and other battery operated products.
The IEEE 802.15.4–based ZigBee is designed for remote controls and sensors, which are very many in number, but need only small data packets and, mainly, extremely low power consumption for (long) life. Therefore they are naturally different in their approach to their respective application arenas.
ZigBee Applications:
The ZigBee Alliance targets applications "across consumer, commercial, industrial and government markets worldwide".
Unwired applications are highly sought after in many networks that are characterized by numerous nodes consuming minimum power and enjoying long battery lives.
ZigBee technology is designed to best suit these applications, for the reason that it enables reduced costs of development, very fast market adoption, and rapid ROI.
Airbee Wireless Inc has tied up with Radio crafts AS to deliver "out-of-the-box" ZigBee-ready solutions; the former supplying the software and the latter making the module platforms. With even light controls and thermostat producers joining the ZigBee Alliance, the list is growing healthily and includes big OEM names like HP, Philips, Motorola and Intel.
With ZigBee designed to enable two-way communications, not only will the consumer be able to monitor and keep track of domestic utilities usage, but also feed it to a computer system for data analysis.
A recent analyst report issued by West Technology Research Solutions estimates that by the year 2008, "annual shipments for ZigBee chipsets into the home automation segment alone will exceed 339 million units," and will show up in "light switches, fire and smoke detectors, thermostats, appliances in the kitchen, video and audio remote controls, landscaping, and security systems."
Futurists are sure to hold ZigBee up and say, "See, I told you so". The ZigBee Alliance is nearly 200 strong and growing, with more OEM's signing up. This means that more and more products and even later, all devices and their controls will be based on this standard.
1.2 SCOPE OF THE PROJECT
The application is aimed at providing up to channeled data from various sensors. Each module is a part of the proposed star/mesh network. The module for demonstration purpose digitizes …
1) Temperature
2) Fire
3) LDR
4) Logical switching
1.3 ORGANISATION OF MCU AND ZIGBEE MODULE
The XBee/XBee-PRO OEM RF Modules interface to a host device through a logic-level asynchronous serial port. Through its serial port, the module can communicate with any logic and voltage compatible UART; or through a level translator to any serial device (For example: Through a Max-Stream proprietary RS-232 or USB interface board).
2. Block Diagram
Zigbee tranceiver
Block diagram Explanation:
The microcontroller is interfaced with different sensor, devices and a ZigBee module. The sensors and devices will give status to the controller; this status information is fed to the main control unit through the ZigBee modules. In the MCU the devices are monitored, if needed it can control the operations through microcontroller via ZigBee module. The functionality of each module is given below.
INTRODUCTION
When you hold the TV remote and wish to use it you have to necessarily point your control at the device. This one-way, line-of-sight, short-range communication uses infrared (IR) sensors to enable communication and control and it is possible to operate the TV remotely only with its control unit.
Add other home theatre modules, an air- conditioner and remotely enabled fans and lights to your room, and you become a juggler who has to handle not only these remotes, but also more numbers that will accompany other home appliances you are likely to use.
Some remotes do serve to control more than one device after ‘memorizing' access codes, but this interoperability is restricted to LOS, that too only for a set of related equipment, like the different units of a home entertainment system
Now picture a home with entertainment units, security systems including fire alarm, smoke detector and burglar alarm, air-conditioners and kitchen appliances all within whispering distance from each other and imagine a single unit that talks with all the devices, no longer depending on line-of-sight, and traffic no longer being one-way.
This means that the devices and the control unit would all need a common standard to enable intelligible communication. ZigBee is such a standard for embedded application software and has been ratified in late 2004 under IEEE 802.15.4 Wireless Networking Standards.
ZigBee is an established set of specifications for wireless personal area networking (WPAN), i.e., digital radio connections between computers and related devices. This kind of network eliminates use of physical data buses like USB and Ethernet cables. The devices could include telephones, hand-held digital assistants, sensors and controls located within a few meters of each other.
ZigBee is one of the global standards of communication protocol formulated by the relevant task force under the IEEE 802.15 working group. The fourth in the series, WPAN Low Rate/ZigBee is the newest and provides specifications for devices that have low data rates, consume very low power and are thus characterized by long battery life. Other standards like Bluetooth and IrDA address high data rate applications such as voice, video and LAN communications.
Device Types:
There are three different ZigBee device types that operate on these layers in any self-organizing application network.
These devices have 64-bit IEEE addresses, with option to enable shorter addresses to reduce packet size, and work in either of two addressing modes – star and peer-to-peer.
1. The ZigBee coordinator node : There is one, and only one, ZigBee coordinator in each network to act as the router to other networks, and can be likened to the root of a (network) tree. It is designed to store information about the network.
2. The full function device FFD : The FFD is an intermediary router transmitting data from other devices. It needs lesser memory than the ZigBee coordinator node, and entails lesser manufacturing costs. It can operate in all topologies and can act as a coordinator.
3. The reduced function device RFD : This device is just capable of talking in the network; it cannot relay data from other devices. Requiring even less memory, (no flash, very little ROM and RAM), an RFD will thus be cheaper than an FFD. This device talks only to a network coordinator and can be implemented very simply in star topology.
ZigBee Characteristics:
The focus of network applications under the IEEE 802.15.4 / ZigBee standard include the features of low power consumption, needed for only two major modes (Tx/Rx or Sleep), high density of nodes per network, low costs and simple implementation.
These features are enabled by the following characteristics. 2.4GHz and 868/915 MHz dual PHY modes. This represents three license-free bands: 2.4-2.4835 GHz, 868-870 MHz and 902-928 MHz. The number of channels allotted to each frequency band is fixed at sixteen (numbered 11-26), one (numbered 0) and ten (numbered 1-10) respectively. The higher frequency band is applicable worldwide, and the lower band in the areas of North America, Europe, Australia and New Zealand .
• Low power consumption, with battery life ranging from months to years. Considering the number of devices with remotes in use at present, it is easy to see that more numbers of batteries need to be provisioned every so often, entailing regular (as well as timely), recurring expenditure. In the ZigBee standard, longer battery life is achievable by either of two means: continuous network connection and slow but sure battery drain, or intermittent connection and even slower battery drain.
• Maximum data rates allowed for each of these frequency bands are fixed as 250 kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz.
• High throughput and low latency for low duty-cycle applications (<0.1%)
• Channel access using Carrier Sense Multiple Access with Collision Avoidance (CSMA - CA)
• Addressing space of up to 64 bit IEEE address devices, 65,535 networks
• 50m typical range
• Fully reliable “hand-shaked” data transfer protocol.
• Different topologies as illustrated below: star, peer-to-peer, mesh
Technology Comparisons:
The “Why ZigBee” question has always had an implied, but never quite worded follower phrase “…when there is Bluetooth”. A comparative study of the two can be found in The bandwidth of Bluetooth is 1 Mbps, ZigBee's is one-fourth of this value. The strength of Bluetooth lies in its ability to allow interoperability and replacement of cables, ZigBee's, of course, is low costs and long battery life.
In terms of protocol stack size, ZigBee's 32 KB is about one-third of the stack size necessary in other wireless technologies (for limited capability end devices, the stack size is as low as 4 KB).
Most important in any meaningful comparison are the diverse application areas of all the different wireless technologies. Bluetooth is meant for such target areas as wireless USB's, handsets and headsets, whereas ZigBee is meant to cater to the sensors and remote controls market and other battery operated products.
The IEEE 802.15.4–based ZigBee is designed for remote controls and sensors, which are very many in number, but need only small data packets and, mainly, extremely low power consumption for (long) life. Therefore they are naturally different in their approach to their respective application arenas.
ZigBee Applications:
The ZigBee Alliance targets applications "across consumer, commercial, industrial and government markets worldwide".
Unwired applications are highly sought after in many networks that are characterized by numerous nodes consuming minimum power and enjoying long battery lives.
ZigBee technology is designed to best suit these applications, for the reason that it enables reduced costs of development, very fast market adoption, and rapid ROI.
Airbee Wireless Inc has tied up with Radio crafts AS to deliver "out-of-the-box" ZigBee-ready solutions; the former supplying the software and the latter making the module platforms. With even light controls and thermostat producers joining the ZigBee Alliance, the list is growing healthily and includes big OEM names like HP, Philips, Motorola and Intel.
With ZigBee designed to enable two-way communications, not only will the consumer be able to monitor and keep track of domestic utilities usage, but also feed it to a computer system for data analysis.
A recent analyst report issued by West Technology Research Solutions estimates that by the year 2008, "annual shipments for ZigBee chipsets into the home automation segment alone will exceed 339 million units," and will show up in "light switches, fire and smoke detectors, thermostats, appliances in the kitchen, video and audio remote controls, landscaping, and security systems."
Futurists are sure to hold ZigBee up and say, "See, I told you so". The ZigBee Alliance is nearly 200 strong and growing, with more OEM's signing up. This means that more and more products and even later, all devices and their controls will be based on this standard.
1.2 SCOPE OF THE PROJECT
The application is aimed at providing up to channeled data from various sensors. Each module is a part of the proposed star/mesh network. The module for demonstration purpose digitizes …
1) Temperature
2) Fire
3) LDR
4) Logical switching
1.3 ORGANISATION OF MCU AND ZIGBEE MODULE
The XBee/XBee-PRO OEM RF Modules interface to a host device through a logic-level asynchronous serial port. Through its serial port, the module can communicate with any logic and voltage compatible UART; or through a level translator to any serial device (For example: Through a Max-Stream proprietary RS-232 or USB interface board).
2. Block Diagram
Zigbee tranceiver
Block diagram Explanation:
The microcontroller is interfaced with different sensor, devices and a ZigBee module. The sensors and devices will give status to the controller; this status information is fed to the main control unit through the ZigBee modules. In the MCU the devices are monitored, if needed it can control the operations through microcontroller via ZigBee module. The functionality of each module is given below.
