# Zigbee : Which hardware to choose to create big mesh networks ?

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#### Jerepain

##### New Member
Hello,

It's my first post !

I bought 4 Microchip's Picdem Z, but I can create only a tree network with the Miwi stack provided. If I use the Zigbee 2006 Stack I have to spend 3500$O_O So is there a constructor that provide a stack which works with big mesh topology ? Sorry for the language, I'm french. Thank you. #### Sceadwian ##### Banned It's not hardware that you need to worry about it's software, thought about writing your own stack? How many device are you going to need to connect? #### Jerepain ##### New Member First thank you for your reply. I can't develop my own stack, it represents too much work. That's why I'd want to know if a constructor proposes a free stack which support big mesh networks design. I don't have a nodes limitation, so I'm opened to any suggestion. #### 3v0 ##### Coop Build Coordinator Forum Supporter The zigbee 2006 stack can be downloaded for free from the microchip web site. ZigBee for PIC18, PIC24 With it you can create a very large mesh network. You need to read the stack documentation prior to using it. It seems to have a problem with lost nodes rejoing the network automaticaly. #### Jerepain ##### New Member If we want to sell a Zigbee 2006 based product we have to join the Zigbee alliance... It is the problem. Thank you for your help anyway I'm still looking for a constructor who releases a free Zigbee stack for big networks. And support beacon, too ! Last edited: #### Sceadwian ##### Banned Price out the cost and time of developing your own stack. 3500 might seem cheap after. #### ronsimpson ##### Well-Known Member Most Helpful Member If we want to sell a Zigbee 2006 based product we have to join the Zigbee alliance... It is the problem. Why? What cost? #### 3v0 ##### Coop Build Coordinator Forum Supporter The Zigbee stack is a major software undertaking. If you intent to sell the product$3500 for the software is a bargain. You could not hire one decent software developer for a month for that and there are months if not years of work here.

There is an open source Zigbee stack effort at
open-ZB.net - OpenSource Toolset for IEEE 802.15.4 and ZigBee but they seem to be in research mode. I do not know if they have a working stack.

I can understand why people want and think all software should be free. Open source software can only happen when there are enough interested and talented people to make it happen. (or some company willing to underwrite the developent cost)

##### Banned
Not that it will ever really come up but it is illegal and worse morally reprehensible to use an opensource code project like that for a commercial product without observing the terms of the GPL it's likely placed under.
I think it was Cisco, or maybe some Linksys routers that a lawsuit was going on about because it used busybox but violated the GPL licenses doing it.

#### Jerepain

##### New Member
Is there a stack which supports beacon ?

Currently the Microchip stacks only supports non-beacon... And I want to put my routers in sleep mode.

#### 3v0

##### Coop Build Coordinator
Forum Supporter
ZigBee Beacon and Mesh ?

It looks like you will not easily (if at all) find a Beacon Mesh network. If you do it may not be free.

Freaklabs - Open Source Zigbee Blog - Reata TX in beacon enabled Router device. - FreakLabs Forum
The problem with using Zigbee in beacon mode is that you're limited to tree routing only. However tree routing is inherently unreliable because if you lose a router, you also lose all of the devices on the branches underneath the router.
On the other hand, if you use mesh routing, if one router goes down, you can do a route discovery and find an alternate path. This is (in marketing terms) called "self healing".
But it looks like Beacon Scheduling was a subject for research in 2008. Where there is research there is some hope.

Slotted Beacon Scheduling Using ZigBee Cskip Mechanism
In fact, the current IEEE 802.15.4 and ZigBee specifications restrict the synchronization in the beacon-enabled mode to star-based networks, while it supports multi-hop networking using the peer-to-peer mesh topology, but with no synchronization.
Elsewhere others have suggested TIMAC IEEE802.15.4 Medium Access control (MAC) software stack - TIMAC - TI Tool Folder

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