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Introduction to Zigbee

PostPosted: Wed Dec 16, 2009 9:32 pm
by Digit
Because i'll be doing some posts in the near future about my ZigBee experiences, i thought it would be handy to first summarize some things about Zigbee, so we know what we're talking about.

ZigBee is a high level communication protocol for small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). ZigBee is specifically useful for applications that require a low data rate, long battery life, and secure networking.

A wireless personal area network (WPAN) is meant to cover a small area like for instance a home, where communication is needed over relatively short distances. One of the key aspects of WPANs is ad-hoc networking, which means that devices can be part of a network on a temporary basis. ZigBee is known as a sleepy, battery powered WPAN that would be a perfect fit for wireless sensor networks for applications in agricultural, building and industrial automation and home control.

Some ZigBee characteristics:
Frequency: 2.4 GHz
Physical Standard: IEEE 802.15.4
Range: 30-100m
Current: 3 uA asleep, 30-60 mA while transmitting
Datarate : max 250 kbps
Network join time: 30 ms
Nodes per network: 64000

The ZigBee specification adds support to the IEEE 802.15.4 standard for the mesh and cluster tree network topologies. After a device has joined a ZigBee network, it can send commands to all the other devices on the same network.

Zigbee device types
All ZigBee devices can be divided into 3 types.

ZigBee Coordinator (ZC)
- This is the only device required for creating a ZigBee network.
- It initiates network formation.
- There's always only 1 coordinator in a ZigBee network.

ZigBee Router (ZR)
- This is an optional component.
- It may associate with the ZC or a ZR.
- Takes care of it's ZEDs regarding routing data.

ZigBee End Device (ZED)
- No routing capability;
- Low power operation
- Used as sensor/actuator

Advantages of ZigBee
- Based on open standards and detailed documentation is freely available;
- Vendor independence, no proprietary solution
- Its network is reliable and self healing;
- It's easy to use (all the hard work has been done for you 'inside' the firmware);
- It's secure (encryption);
- It supports a large number of nodes;
- It enables long battery life;
- It's low cost.

Want to experiment with ZigBee? Then you'll probably have to read 'some more' and in that case go see where you can find a huge amount of information on their Zigbee products.

Below a picture of some 802.15.4- and Zigbee-modules i've experimented with:
DSC_2042_resize.JPG (86.83 KiB) Viewed 15353 times

Re: Introduction to Zigbee

PostPosted: Thu Aug 19, 2010 11:38 pm
by Fuego
How can one say that Zigbee is based on open standards when it is a requirement of the Zigbee Alliance (wherein the intellectual property of Zigbee is vested) to join (become a member of) the alliance if you develop and sell any Zigbee product, or any product which itself contains a Zigbee product, given that the minimum membership fee is 3,500 USD per annum?

The answers in the above FAQ would almost certainly conflict with a GPL license.

Re: Introduction to Zigbee

PostPosted: Sun Sep 05, 2010 11:11 am
by Digit
I don't get it.
What closed standards are involved? None AFAIK.
And as long as you don't sell any ZigBee based products for commercial gain, you can develop with and use ZigBee products for free.
So ZigBee is totally cool for creating your own Domotica sensors and all other stuff you can think of.

But maybe i am missing something here?

Re: Introduction to Zigbee

PostPosted: Mon Sep 06, 2010 11:18 am
by Fuego
It's true that "open" and "standard" are often both quantitive and qualicative. Note that your definition of what an open standard is includes the qualifier "as long as you don't sell any Zb based products". I think you are confusing "open source" with "open standard". An "open standard" (in my book) is anything which is 100% completely free to use for whichever purpose one may wish.