《ZigBee Wireless Networking》这本书对ZigBee技能阐释地比较全面，强烈推荐各位同仁阅览！
ZigBee does not exactly fit the OSI 7-layer networking model, but it does have some of
the same elements, including the PHY (physical), MAC (link layer), and NWK (network)
layers. Layers 4–7 (transport, session, presentation, and application) are wrapped up in
the APS and ZDO layers in the ZigBee model.
Between the layers are Service Access Points (SAPs). SAPs provide an API that isolates
the inner workings of that layer from the layers above and below. Like the IEEE 802.15.4
specification, ZigBee uses a two-SAP approach per layer, one for data and one for
management. For e美女壁纸xample, all data co珠宝品牌mmunications to and from the network layer go
through the Network Layer Data Entity Service Access Point (NLDE-SAP). Why the data
SAP for the MAC layer is called MAC Common Part Service SAP (MCPS-SAP) instead
of the MLDE-SAP is confusing to me, but it is. You’ll see commands in 脾the ZigBee
specification that look like APSDE-DATA.request. Now you know that is a request to
send data out the radio, but initiated just above APS layer.
The two lowest layers, the MAC and PHY, are defined by the IEEE 802.15.4
spec粮票ification. The PHY layer simply translates packets into over-the-air bits and back
again. The MAC layer provides the concept of a network, including a PAN ID, and
networking discovery through beacon requests龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道 and responses. It also provides per-hop
acknowledgments and some of the commands for joining and forminled显示屏g a network. The
MAC does not multi-hop or mesh.
The NWK layer is responsible for mesh networking, which includes broadcasting packets
across the network, determining routes for unicasting packets, and generally making sure
packets are 龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道sent reliably潮汐广东气候预报 from one node to another. The network layer also has a set of
commands poifor security purposes, including secure joining and rejoining. ZigBee networks
are all secured at the NWK layer, and the entire papmcyload of the龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道 NWK frame is encrypted.
The APS layer is responsible for application meaning. It acts as a filter for th威海荣成气候e
applications running above it on endpoints to simplify the logic in those applications.
It understands what clusters and endpoints mean, and checks to see if the endpoint is a
member of the Application Profile and (if present) group before sending the message on
up. The APS layer also filters out duplicate messages that may have been sent up by the
NWK layer. The APS layer keeps a local 完毕的英文binding table, a table which indicates the nodes
or 龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道groups in the network that this node wishes to speak to.
The ZDO layer (which includes the ZigBee Device Profile, ZDP), is responsible for local
and over-the-air management of the network. It provides services to discover other nodes
and services in the network, and is directly responsible for the current state of this node
on the network.
The Application Framework contains the ZigBee Cluster Library and provides a
framework withi马化腾关于坑钱回应n wh龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道ich application龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道s run. Endpoints are the mechanis我国新声代m used to
distinguish one application from another.
The security services are used by a variety of layers, and can be used by ZDO, AP靠近大众六走进S, or
the NWK layer, hence it’s off to the side.
All layers have what is called an information base. At the MAC layer, 欧派this is called a PAN
Information Base (or PIB)茶叶分类. At the network layer it’s called a Network Information Base
(or NIB), and of course there is an AIB for the APS layer. All “ information base ” means
is the current settings of that layer. How many retries are required? What is the current
PAN ID or network address of a particular node? The fields in 王瑞子the information base
are generally either set by higher layers or through the use of management commands
through the management SAPs.
Notice there is nothing in here about interaction with any hardware within a given ZigBee
device other than the radio. There is nothing that talks to LEDs, the LCD, speaker, GPIO
ports, non-volatile or flash memory. ZigBee is exclusively concerned with the network龙胆泻肝丸,“ZigBee无线网络”学习笔记“2”-火竞猜下载-火竞猜下载-火竞猜电子竞技赛事渠道ing
protocol and over-the-air behavior. The ZigBee test suites reflect this fact. Since all
the over-the-air messages can be interpreted correctly by any other ZigBee node, this
approach allows vendors to innovate while still providing complete compatibility between
6，PAN ID用来差异不同的ZigBee网络，PAN ID狐仙是0x0000~0x3fff之间的16bits的数字。