Zigbee technology

www.1000projects.com

www.fullinterview.com

www.chetanasprojects.com
ZIGBEE TECHNOLOGY

The ZigBee Alliance, the standards body
ABSTRACT:
which defines ZigBee,[1] also publishes
ZigBee is the name of a specification for a
application profiles that allow multiple
suite of high level communication protocols
OEM vendors to create interoperable
using small, low-power digital radios based
products. The current list of application
on the IEEE 802.15.4-2006 standard for
profiles either published or in the works are:
wireless personal area networks (WPANs),
• Home Automation
such as wireless headphones connecting
• ZigBee Smart Energy
with cell phones via short-range radio. The
• Telecommunication Applications
technology is intended to be simpler and less
• Personal Home
expensive than other WPANs, such as
Bluetooth. ZigBee is targeted at radio-
INTRODUCTION:
frequency (RF) applications that require a
ZigBee is the name of a specification for a suite
low data rate, long battery life, and secure
of high level communication protocols using
networking.
small, low-power digital radios base on the IEEE
ZigBee is a low-cost, low-power, wireless
802.15.4-2006 standard for wireless personal
mesh networking standard. The low cost
area networks (WPANs), such as wireless
allows the technology to be widely deployed
headphones connecting with cell phones via
in wireless control and monitoring
short-range radio. The technology is intended
applications, the low power-usage allows
to be simpler and less expensive than other
longer life with smaller batteries, and the
WPANs, such as Bluetooth. ZigBee is targeted at
mesh networking provides high reliability
radio-frequency (RF) applications that require a
and larger range.

1






low data rate, long battery life, and secure ZigBee 2007 network, the same as ZigBee
networking. 2006 or ZigBee 2007 devices must become
ZEDs on a ZigBee Pro network.
OVERVIEW:
The relationship between IEEE 802.15.4 and
DEVICE TYPES AND HISTORY
ZigBee is similar to that between IEEE
There are three different types of ZigBee
802.11 and the Wi-Fi Alliance. The ZigBee
devices:
1.0 specification was ratified on 14
• ZigBee coordinator (ZC): The most
December 2004 and is available to members
capable device, the coordinator
of the ZigBee Alliance. The first ZigBee
forms the root of the network tree
Application Profile, Home Automation, was
and might bridge to other networks.
announced 2 November 2007.
There is exactly one ZigBee
The first stack release is now called Zigbee
coordinator in each network since it
2004. The second stack release is called
is the device that started the network
Zigbee 2006, and mainly replaces the
originally. It is able to store
MSG/KVP structure used in 2004 with a
information about the network,
"cluster library".
including acting as the Trust Centre
Zigbee 2007, now the current stack release,
& repository for security keys.
contains 2 stack profiles, stack profile 1
• ZigBee Router (ZR): As well as
(simply called ZigBee), for home and light
commercial use, and stack profile 2 (called running an application function a

ZigBee Pro). ZigBee 2007 is fully backward router can act as an intermediate

compatible with ZigBee 2006 devices. Due router, passing data from other

to differences in routing options, ZigBee Pro devices

devices must become non-routing ZigBee • ZigBee End Device (ZED): Contains

End-Devices (ZEDs) on a ZigBee 2006 or just enough functionality to talk to
the parent node (either the
2






coordinator or a router); it cannot the other hand, an uncertified physical layer
relay data from other devices. This that malfunctions could cripple the battery
relationship allows the node to be lifespan of other devices on a ZigBee
asleep a significant amount of the network. Where other protocols can mask
time thereby giving long battery life. poor sensitivity or other esoteric problems in
A ZED requires the least amount of a fade compensation response, ZigBee
memory, and therefore can be less radios have very tight engineering
expensive to manufacture than a ZR constraints: they are both power and
or ZC. bandwidth constrained. Thus, radios are
tested to the ISO 17025 standard with
Software and hardware: guidance given by Clause 6 of the 802.15.4-
The software is designed to be easy to 2006 Standard. Most vendors plan to
develop on small, inexpensive integrate the radio and microcontroller onto
microprocessors. The radio design used by a single chip.
ZigBee has been carefully optimized for low
cost in large scale production. It has few History:
analog stages and uses digital circuits
• ZigBee-style networks began to be
wherever possible.
conceived about 1998, when many
Even though the radios themselves are
installers realized that both WiFi and
inexpensive, the ZigBee Qualification
Bluetooth were going to be
Process involves a full validation of the
unsuitable for many applications.
requirements of the physical layer. This
• The IEEE 802.15.4 standard was
amount of concern about the Physical Layer
completed in May 2003.
has multiple benefits, since all radios
• The ZigBee specifications were
derived from that semiconductor mask set
ratified on 14 December 2004.
would enjoy the same RF characteristics. On

3






• The ZigBee Alliance announces A ZigBee network can adopt one of the
public availability of Specification three topologies: Star, Tree, Mesh. These
1.0 on 13 June 2005, known as are illustrated on the left and briefly
ZigBee 2004 Specification. described below.
Star Topology :
A Star network has a central node, which is
linked to all other nodes in the network. All
messages travel via the central node.
Tree Topology :
Origin of the term ZigBee: A Tree network has a top node with a
An urban myth perpetuated by the Zigbee branch/leaf structure below. To reach its
Alliance is that the term “ZigBee” originates destination, a message travels up the tree (as
from the silent, but powerful method of far as necessary) and then down the tree.
communication used by honeybees to report Mesh Topology:
information about food sources. The myth A Mesh network has a tree-like structure in
says that the communication system is which some leaves are directly linked.
[8]
known as the “ZigBee Principle" . By Messages can travel across the tree, when a
"dancing" around in a zig-zag waggle dance, suitable route is available.
a bee is able to share critical information,
such as the location, distance, and direction
Node Types
of a newly discovered food source to its
This section describes the types of node that
fellow hive members.
are used in a ZigBee network. Reference
will be made to the toplogies introduced on
ZigBee Topologies the previous page (Star, Tree, Mesh), but
Topology Overview : these topologies will be described in more
detail later in this module.
4






The ZigBee standard has the capacity to tasks of the Co-ordinator at the network
address up to 65535 nodes in a single layer are:
network. However, there are only three • Selects the frequency channel to be
general types of node: used by the network (usually the one
• Co-ordinator with the least detected activity)
• End Device • Starts the network
• Router • Allows other devices to connect to it
These node types are described below. (that is, to join the network)
Co-ordinator The Co-ordinator can also provide message
All ZigBee networks must have one (and routing (for example, in a Star network),
only one) Co-ordinator, irrespective of the security management and other services.
network topology. End Device
• In the Star topology, the Co- End Devices are always located at the
ordinator is the central node in the extremeties of a network:
network. • In the Star topology, they are
• In the Tree and Mesh topologies, the perimeter nodes
Co-ordinator is the top (root) node in • In the Tree and Mesh toplogies, they
the network. are leaf nodes
This is illustrated below, where the End
Devices are colour-coded in light blue.

At the network level, the Co-ordinator is
mainly needed at system initialisation. The

5






The specification goes on to complete the The Application Framework (AF) contains
standard by adding four main components: the application objects and facilitates
• network layer interaction between the applications and the

• application layer APS layer. An application object interacts
with the APS layer through an interface
• ZigBee device objects (ZDO's)
known as a Service Access Point (SAP).
(keeping of device roles,
Service Access Points
management of requests to join a
A Service Access Point (SAP) implements a
network, device discovery and
set of operations to pass information and
security)
commands between layers. There are usually
• manufacturer-defined application
four types of operation implemented by a
objects which allow for
SAP:
customization and favor total
Request: Typically, a layer using the
integration.
services of another layer generates a Request
On completing this section, you will be able
to the lower layer.
to describe:
Confirm: In general, the lower layer
• the three basic levels of the ZigBee
responds with a Confirm, which indicates
software stack
whether it has accepted or rejected the
• application endpoints that reside in a
request. A rejection could occur if the
ZigBee node
Request is invalid or the layer does not
• the components of the basic stack
implement the operation concerned (the
levels SAPs that allow an application
operation could be defined as optional).
to communicate with lower software
Response: Normally, Requests result in
layers and remote applications
some sort of Response from the lower layer.
This may be a simple status message
Application Framework and SAPs
indicating that the Request has been
Application Framework
7






The main tasks of an End Device at the • In a Mesh topology, a Router can be
network level are sending and receiving located anywhere that a message
messages. Note that End Devices cannot passing node is required.
relay messages and cannot allow other nodes However, in all topologies (Star, Tree and
to connect to the network through them. Mesh), Router devices can be located at the
An End Device can often be battery- extremeties of the network, if they run
powered and, when not transmitting or applications that are needed in these
receiving, can sleep in order to conserve locations - in this case, the Router will not
power. perform its message relay function, unless in
Router a Mesh network (see above).
Networks with Tree or Mesh topologies The possible positions of Routers in the
need at least one Router. The main tasks of a different network topologies are illustrated
Router are: below, where the Routers are colour-coded
• Relays messages from one node to in red:
another
• Allows child nodes to connect to it
In a Star topology, these functions are
handled by the Co-ordinator and, therefore,
a Star network does not need Routers.
In Tree and Mesh topologies, Routers are Note that a Router cannot sleep.
located as follows:
• In a Tree topology, Routers are
ZigBee Software Architecture:
normally located in network
ZigBee builds upon the physical layer and
positions that allow messages to be
medium access control defined in IEEE
passed up and down the tree.
standard 802.15.4 (2003 version) for low-
rate WPAN's.
6




Zigbee technology

Recomendados

Recomendados

Más contenido relacionado

La actualidad más candente

La actualidad más candente (20)

Similar a Zigbee technology

Similar a Zigbee technology (20)

Último

Último (20)

Zigbee technology