Zigbee and Xbee
ZigBee is a standard defined by the IEEE ( Institure of Electrical and Electronics Engineers) back in 1998. When a group of big guy say WiFi and Bluetooth might not be suitable enough for some applications, they started to define new protocol, new standard. ZigBee aim to have lower data rate compared to Bluetooth, at 250Kbps (Bluetooth is 1Mbps back then, now is higher with EDR-Enhanced Data Rate). More importantly, ZigBee aims for lower power applications which should offer years (2 to 3 years) of operation on non-rechargeable battery and it can connect to more nodes (2 ^ 16 = 16-bit address > 65,000); while Bluetooth only offers 8 devices connection in piconet. ZigBee designed for control and monitor while Bluetooth for cable replacement. ZigBee uses RF (Radio Frequency) to communicate. There are 3 frequencies available, 2.4GHz – which we are using in Malaysia (this is actually world wide frequency and it is sharing with Bluetooth and WiFi), 915MHz – For America, forbiden in Malaysia and the last frequency is 868MHz – For Europe, again forbiden in Malaysia too. So what the hack for me to know all these technical stuff? OK, you can forget about it, let’s talk about XBee.
XBee is a product name , not a standard. OK, so what is the different between standard and product? Standard is like WiFi, product is like modem from Aztech or linksys. So why is XBee being used widely and mistakenly as ZigBee? One of the reasons is XBee is low cost and easy to use, therefore it gains the popularity, further making it to have a equal sign between these 2 words. XBee = ZigBee. XBee is a product series (brand) name from Digi International. Currently (2013), there are XBee Series 1 (802.15.4), Series 2(ZigBee compliance) and XBee-Wifi. And this might surprise you, The XBee and XBee Pro that you are using today is not fully ZigBee standard compliance, if you are using Series 1. Again, what does that mean? It means XBee that you are using nowsaday cannot communicate with other ZigBee product Are you kidding me? I need to do a ZigBee wireless project, how can you tell me this is not ZigBee? Sorry, but that’s the true, XBee is not fully ZigBee….is partially ZigBee, at least this applied to Series 1 and XBee-WiFi. The popular XBee is actually XBee 802.15.4 (sometime called XBee series 1), it uses the same MAC (Medium Access Control) layer as the ZigBee, but XBee’s upper layer is proprietary by the manufacturer So what is that again? OK, not to worry too much about that. Let me put it this way, this is about communication. If I want to communicate with my friend, he have to know what I am talking about and of course the other way around, I need to understand what he is talking about – Same language. If I want to talk to him, I have a lot of method, writing email, sending mail, call, telegram, SMS, these are what we called lower layer, the method you send information. MAC is low layer of communication. ZigBee defines 802.15.4 MAC, XBee uses 802.15.4 MAC too, so why can’t XBee communicate with other ZigBee product? Because at higher layer they speak in different language. If I talk in English, my friend talk in Japanese, though I call his phone and he accept it, we still fail to communicate. OK, maybe is lousy example, I still hope you get the idea.
Back to the question, is XBee ZigBee? No, I have answered in the above discussion. Yes, because the manufacturer of XBee do have another series of XBee, they called it XBee ZB or it is more known as XBee series 2.0. OK, I think that is good enough for a brief introduction on XBee. I know we should talk about how to use it, not to worry, the time will come. Let’s move to XBee and XBee Pro that we are going to use. Commonly, we are using 2 types of XBee – XBee & XBee Pro. For your information, Cytron is carrying XBee and XBee PRO series 1, we do not carry other series of XBee, at least during the time I write this. We do carry XBee Series 1, 2 and Wifi.
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