Zigbee(802.15.4)
*.It is a technological standard created for control & sensor
network.
*.Zigbee is a wireless technology standard that defines a set of communication protocols for short range communications.
*.Zigbee is built on top of the IEEE 802.15.4 physical layer and designed
To meet the needs of low cost battery operated device
*.ZigBee is a standard networking protocol aimed at the wireless control
market.The ZigBee protocol fits on 8-bit microcontrollers, with 16- and
32-bit solutions available.
*.ZigBee is great at wireless control, where anywhere from two
to thousands of nodes are all connected together, in multi-hop mesh network.
*.802.15.4(task group 4, zigbee,WPAN, low rate)
*.designed for wireless controls & sensors.
*.WPAN, operates in PAN’s & device-to-device network
*.controls of lights,switches,thermostats,appiance etc.
q).what is zigbee ?
ans).
*.Zigbee is a standard that addresses the need of very low-cost implementation of low power devices with low data rate for short range wireless communications.
*.opensource standard developed by zigbee-alliance
*.low-power consumption:
Devices can typically operate for several years on a single
battery.
*.low-date rate:
Zigbee: 20kbps - 250kbps (low-data rate)
Wifi: Mbps-3Gbps
Bluetooth : 1-3Mbps
*.short-range:
Indoor 70-100 mtr
Outdoor upto 300 mtr (line of speed)
*.network join-time
Zigbee ~30msec
Wifi 3sec
Bluetooth 10sec
*.support small and large networks:
65000 devices can connect theoretically/240 in practical
*.low cost of products and cheap implementation, becoz of simple
Implementation, opensource.
*.Security:
Zigbee network use AES Encryption algorithum
*.types of devices:
Coordinator
Router
End device
Coordinator:
*.Most capable device.
*.root of the network
*.one coordinator in each network.
Coordinator Tasks:
*.channel selection. Good channel
*.assign an ID for network.
*.allocates unique address to each network
*.initiates and transfer messages in the network.
Routers:
*.they act as intermediate nodes between the coordinator and the end
device.
*.route traffic between different nodes.
*.receives and store messages intended for their children
End-Device:
*.contains just enough information to talk to the parent node.
*.they may sleep(a standby), which makes end-devices a suitable choice
For battery operated devices.
*.all traffic to an end device is first routed to its parent.
*.the end-device is responsible for requesting any pending messages
From its parent.
Zigbee operating mode:
Src: https://www.youtube.com/watch?v=2wICHFIM6j4
1.application transparent mode - default mode
2.application programming interface mode.
3.command mode
q).Why another short-range communication standars?
ans).
*.wifi and bluetooth ?
*.Zigbee standard is specially build for control and sensor networks.
*.wifi uses high data rate(over kill).
Eg: zigbee device connects to patient
*.bluetooth device connects limited to 7 devices.
*.so for controlling devices and sensors wifi and bluetooth and suitable
For requirement of Zigbee.
Home network
—------------
->PAN (personal Area Network)
->Bluetooth
->Zigbee
Zigbee topologies:
1.star
*.no routers, end-devices can’t communicate with each other.
2.mesh
*.every node is connected with neighbouring node, except for
the
other devices, if one node fails, data can be re-routed
using another
Path.
*.all the devices in this topology, except end-devices can
communicate
each other.
3.tree
*.routers are not interconnected.
*.it is not very different from a mesh configuration.
3.b. Cluster tree network:
*.expand network range.
*.
Channel Access:
Application profile:
*.The ZigBee Alliance, which is the alliance of companies who developed and support ZigBee as a standard, has also defined what are called Application Profiles. These profiles describe how ZigBee devices interact, specifically between products of certain types and within certain markets. For example, the Home Automation profile describes how switches can control lights, how a temperature sensor sends its data to a thermostat
and how that thermostat controls a heating or cooling unit (heater or air conditioner). A well-defined standard saves effort and money when developing products that need to interoperate with other vendors.
*.In addition to stack-level compatibility, ZigBee also defines application level compatibility through Application Profiles. Application Profiles describe how various application objects connect and work together, such as lights and switches, remotes and televisions. The Application Profiles also specify a test suite for verifying compatibility
among applications from various vendors.
*.Applications interoperate through what is called an Application Profile. With each Application Profile, test suites are defined and used by test houses to ensure that products interoperate with each other if they are within the same application domain, or that they at least do no harm to other ZigBee networks if they are proprietary applications.
*.
q).what is profile?
ans).
*.Zigbee application is called as a profile.
q).what is an endpoint ?
ans)
*.a profile(application) is addressed by an endpoint - similar to port number.
q).what is ZDO?
ans).
*.ZDO is a management application required by Zigbee on every device.
q).what is ZCL?
ans).
*.ZCL - defines set of clusters that can be supported on multiple applications(Home automation etc).
ZDO
—---
*.ZDO is simply the application running on endpoint 0 in every ZigBee device. This application, ZDO, keeps track of the state of the ZigBee device on and off the network, and provides an interface to the ZDP, a specialized application profile for discovering, configuring, and maintaining ZigBee devices and services on the network.