confused about zigbee

[hityou123]

I am trying to decide between 3 zigbee development kits - TI Z-accel, Microchip and of course freescale.
The TI kit is a bit cheap, but the zigbee chip itself is 10$. Too much I think.
But both microchip and freescale chips are very reasonable. Both Kits are around 250$.
Price wise freescale makes more sense, RF chip and uC for 5$.

If I go with freescale then I have to learn HCS08. But I already know PIC uC.
How big is the learning curve?
I don't understand the zigbee stack licencing by freescale. Its only for 90 days. what after that? Do I have to buy it?
Whats a stack anyway. protocol?
Microchip doesn't mention anything about licensing their stack. I think its free.
Can the kit network with 16 other zigbee devices or is it limited?
Please help me decide.
Thanks.

[Witztronics]

I'm not a zigbee expert , but for starters, you need to make sure you are comparing apples to apples and understand what "zigbee" really is.

First zigbee (there are multiple versions of zigbee) is not hardware, it is a software standard, that rides on top of the 802.15.4 standard protocol stack and compliant hardware.

Most "zigbee" vendors offer multiple "layers" of products to get customers involved in "zigbee" hardware development.

1) some proprietary point to point or point to multi-point communication stack.  Sometimes this uses hardware that may be called zigbee, but is really a 2.4Ghz or 900Mhz rf link.  This is the one that is usually free (even for the source code).

2) 802.15.4 - this is where a product starts to become "zigbee" but not quite.  It is a hardware physical interface and software protocol standard, but not "zigbee" compliant.  This is where you start hearing the term "mesh network".  Usuallly, you will only get the binary code and not the source (unless you pay big bucks).

3) zigbee - a true zigbee device is everything that 802.15.4 is and more.  It is zigbee compliant, meaning that any zigbee device is interoperable with any other zigbee device (in a given catagory).  Note that there are now several "zigbee" standards; like Zigbee, Zigbee pro, Zigbee 2007 and now there are all kinds of subsets for electric power devices, media interfaces, ect...  I would be shocked if anyone gives this code away.

A few other things to think about...
If you do not need to be interoperable with other companies zigbee products, then you most likely do not need true zigbee.  Usually, 802.15.4 will do.  If you do want to be true zibee, you will have to join the zigbee association and pay the fees or you can not call you product a zigbee product.
Freescale has some great zigbee parts (especially the new ARM based devices), but since you mentioned some of the others, don't forget to look at Atmel, Renesas, ST, NXP and Silicon Labs.

[hityou123]

Thanks for the info.
My application would require RF connection between 2 zigbee chips from same manufacturer.
Its just a wireless application implemented in zigbee to save power and improve battery life.
I think I will go with either freescale or microchip.
If I go with others then the learning process will take a long time. Both offer 802.15.4
I think this will work for my application. I don't need true zigbee.
But I would like to connect to more than one wireless zigbee device.
Do I still have to pay for the stack?
 

[Witztronics]

Check out the free SMAC from Freescale:

http://www.freescale.com/webapp/sps/site/overview.jsp?code=PROTOCOL_SMAC

I think that is all you will need.