Zigbee Tutorial

IEEE802.15.4 defines the Physical and MAC layers, and ZigBee defines the network and application layers. Zigbee layers build on top of IEEE802.15.4.

Zigbee provides the features of low power consumption, low cost, small footprint, and mesh networking capabilities.

Two version: Zigbee 2006, Zigbee Pro (2007)
Zigbee Pro can scale up to thousands of devices.

Zigbee Architecture:

Application Profile is defined by Zigbee specification.
Eg. Home Automation (HA) and Smart Energy (SE).

Devices within an application profile communicate with each other by means of clusters, which may
be inputs to or outputs from the device.

Eg. In HA profile, cluster 0x0006 is the on/off cluster. Cluster 0x0702 is the zigbee power consumption report cluster. In HA profile, to use Zigbee on/off switch to control Zigbee power switch, we can bind the endpoint number of Zigbee on/off switch, with endpoint number Zigbee power switch, on the cluster 0x0006.

An endpoint defines a communication entity within a device. Zigbee Device Object (ZDO) is always endpoint zero. In all, 240 endpoints are available for use within ZigBee device, with endpoint zero dedicated to the ZigBee Device Object (ZDO), which provides control and management commands.

Joining a Zigbee network:

A ZigBee router or coordinator that wishes to allow other devices to join must issue a NLME-PERMIT-JOINING.request.  The joining device must issue a NLME-JOIN.request with the rejoin flag set to FALSE.

ZigBee Security:

It is based on the 128-bit AES algorithm.

Zigbee coordinator also functions as the trust center when security is enabled on the network.

• Master key - used as an initial shared secret to generate Link key
• Trust center master key - used to establish the Link key
• Link Key - at the Application layer, two types: Trust center link key; application layer link key. Link key is used to encrypt the network key
• Network Key - at the Network layer

Zigbee Concepts:

Three type of devices:
Zigbee end device, Zigbee router, Zigbee coordinator.

PAN ID - Personal Area Network Identifier. The Zigbee coordinator assigns a PAN ID to the network.

Binding - connecting endpoints
Device discovery - finding out other Zigbee devices, requires

• IEEE address
• NWK address

Service discovery - finding out services available on endpoints at the receiving device

IEEE802.15.4 Concepts:

IEE802.15.4 operating frequency is at 2.4GHz and 915MHz.

2.4GHz: channel 11-26

915MHz: channel 1-10

IEEE802.15.4 defines 4 types of MAC frame:

• beacon frame
• data frame
• Ack frame
• MAC command frame

IEEE802.15.4 data frame in action:

Zigbee Home Automation profile:

The Zigbee HA profile defines various device types that have various roles in the HA network. Device types such as Power Outlet(0x0009), On/Off Switch(0x0000), Combined Interface(0x0007), Pump(0x0303), Temperature sensor(0x0302), IAS devices; are frequently used.

Intruder Alarm Systems - IAS

• IAS Zone(0x0402) - door sensor, smoke sensor
• IAS Warning Device(0x0403) - siren
• IAS ACE(0x0401) - remote control
• IAS CIE(0x0400) - usually it is the Zigbee coordinator

To control zigbee devices. Firstly, zigbee devices must join the zigbee network. Then, Zigbee coordinator can send a data frame to the zigbee devices, to perform desired action. Zigbee devices can also report its status periodically to the zigbee coordinator.

On/Off switch can bind to power outlet, to control the power outlet directly. It is useful when the zigbee coordinator is down.

Zigbee Certification:

We can do testing in four modes:

Zigbee continuous TX
Zigbee continuous RX
Zigbee packet TX
Zigbee packet RX

For TX test, we can set TX channel, TX power, use range extender (an IC) to obtain higher TX power, send modulated or unmodulated signals.

To perform a Zigbee RX test, we need to setup a Zigbee end device and a Zigbee coordinator. The Zigbee end device can join the Zigbee coordinator, provided with the right key and PAN ID.