There have been several MCU announcements recently regarding ZigBee-enabled MCUs. What caught my attention about them is how specific these products are. They do more than provide ZigBee connectivity, they address specific application profile standards that the ZigBee organization has been developing.
Here are the recent product announcements (in order of release) that caught my attention:
NXP indicated that it had achieved product certification for a ZigBee Light Link color scene remote control and an extended color light.
Other, similar, products are undoubtedly available and more are likely to come. What struck me about them, however, is that they target specific application profiles.
The ZigBee 2007 specification describes how the building blocks of a self-organizing mesh network built atop the IEEE 802.15.4 wireless standard should operate. The specification calls for two implementation options, or Feature Sets: ZigBee and ZigBee Pro. The two implementations interoperate, differing mostly in the network size they support. A second ZigBee specification, RF4CE, describes the implementation of a simpler, point-to-point network consisting of paired controllers and targets.
The ZigBee 2007 specification, however, only describes how devices communicate. What they communicate was originally left to the developer. That leaves plenty of room for innovation, but makes interoperability difficult. Just because two devices are ZigBee compliant doesn't mean they speak the same language. Thus, people wanting to create a system using ZigBee had to build everything themselves.
The ZigBee Standards seek to change that situation by providing an application-driven set of commands and responses that a device in that application might want to use. By creating a common language for an application, the standards can help the industry to create interoperable products so that end users can mix and match devices from different vendors when building a network.
A number of such standards (also called profiles) are now defined, with some on their second version. The ZigBee standards include:
The presence of all these standards, and the release of designs specifically targeting them, mean that developers today need to look beyond the ZigBee label when evaluating MCU design options. Support for the specific profile desired will need to be an essential part of the evaluation, as well.
What's your opinion of all these profiles? Do they help simplify design, or fragment the vendor's ZigBee offerings into overly-specific devices?
Didier_Juges 6/8/2012 7:57:54 AM User Rank Blogger
Re: Zigbee vs WiFi
Just because WiFi supports large data transfers does not make it inadequate for small command and control packets.
One issue with using WiFi for sensor networks is the generally higher power consumption of WiFi modules compared to other wireless topologies like ZigBee. However, this is being addressed. For instance, the Roving Network RN-131 WiFi module is able to wake up, connect to the network, send a data paquet and go back to sleep in 100mS.
northstar 6/7/2012 4:41:14 PM User Rank Program Manager
Re: Zigbee vs WiFi
I recall a ZigBee design that involves TV sets and remote controls (smart). I think that one benefit of ZigBee is that the emitter and receiver do not need too much power for their jobs.
I agree that WiFi supersedes ZigBee, but maybe sometimes is a too big hat for small applications.
halherta 6/7/2012 2:27:33 PM User Rank Program Manager
Re: Zigbee vs WiFi
While I agree that Zigbee has a niche that it specifically carves for itself (Mesh Networking, sensor networks, low power, low bandwidth, e.t.c) and it does it really well, WiFi can still do much of the work that Zigbee purports to be able to do...WiFi also has Adhoc mode where the network has to do some level of meshing if not as elaborate as that in the Zigbee standard.
- So if I for example have a sensor/node network with a one or a few nodes and especially if I also need these nodes to be connected to the internet, I think that WiFi would be great for that use.
- If however I have ten's or even hundreds of sensors/nodes and I need them to talk to each other, zigbee is ideal.
I think that most wireless products/solutions will fall into the first category where WiFi is the better solution. There will always be projects that can reap all the benefits of Zigbee but they will be less in numbers and will likely still use some form of WiFi connectivity along with Zigbee to allow remote access to the Zigbee network.
northstar 6/7/2012 3:42:11 AM User Rank Program Manager
Re: Zigbee vs WiFi
I think that ZigBee and WiFi is targeting a different type of applications. ZigBee is not data flow oriented, but control flow oriented. This means that it is not design to support large data traffic, but it means to distribute "commands" and "status" in the network. The WiFi is design to support large data flowing and less "control" flowing. From this perspective, I think those 2 protocols have different applications to target.
Also, I believe the power consumption and stand-by modes are more carefully designed in ZigBee than in WiFI.
halherta, while power may be one factor, I am of the impression that it is the mesh capabilities of ZigBee that make it interesting. You can add a zigbee unit to an existing network and it will find its own home, whereas you need to do some kind of setup to get something in a WiFi network. Also, WiFi presents challenges when you want to do peer-to-peer communications across the network to random nodes. ZigBee is designed to allow that. Then there is the attribute of Zigbee that you only need ot be in radio range of one other node to have full network access, allowing a widely separated network. WiFi needs a centrally-located server.
The security issue is the first thing that jumped into my mind when reading this article. Without standards, it's much more difficult for widespread attacks to take hold. But, without standards, adoption will be more difficult.
I had been interested in ZigBee but some of these issues held me back. Now, I'm thinking that WiFi is probably the way to go. Modules are getting much smaller and less expensive and more MCUs have support. My guess is that these improvements in ZigBee standards may be too little too late and the prototypical may end up largely relegated to specialize applications.
Didier_Juges 6/6/2012 1:34:50 PM User Rank Blogger
Re: Zigbee vs WiFi
Rich, I am afraid Zigbee is taking the road opened by Bluetooth. I have commented before on the problems I see (and that I have experienced) with Bluetooth. Namely, all these profiles require different, specific drivers, and if the specific profile you are interested in is not supported by your Zigbee device, it might as well be a door stop.
In the Bluetooth world, there are few protocols that are universally supported, resulting in wide incompatibilities.
Another aspect of Zigbee that concerns me is security. The protocol is not very widely deployed yet, but as its popularity grows, I am sure we will hear about it soon enough. Like everything else, as soon as the installed base becomes large enough, hackers will jump in.
I agree with Halerta that WiFi today appears to be a much better choice, even though it is missing some of the more intriguing aspects of the Zigbee radios, like mesh networking. The cost appears to be quite comparable, and so it should be since the hardware is very similar. WiFi has the advantage of being able to directly interface with a PC.
Of course, Wifi modules also have their own protocol compatibility issues, but I found that the core set of protocols that appears to be universally supported (telnet, FTP and HTTP clients, email) are sufficient in most cases.
halherta 6/6/2012 11:53:35 AM User Rank Program Manager
Zigbee vs WiFi
I realize that zigbee targets low power markets ( and modest bandwidth rrequirements) when compared to WiFi. Having said that the power consumption on some of the newer WIFI radio modules is approximately the same as that of Zigbee modules...especially the older ones. This renders zigbee somewhat redundant, especially that WIFI can offer so much more functionality. I think it would be wiser for MCU companies to invest more in low power WIFI solutions than in Zigbee.
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