AeroComm ZB2430 6 4 - b i t M A C a d d r e s s, T a b l e 3 D e v i c e T a b l e E x a m p l e

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T HE O R Y OF O P E R A TI O N

E N G I N E E R ’ S T I P

16-bit Network Addresses.

In a ZigBee network, nodes are assigned a 16-bit NWK address according to how the network formed. By design, the Coordinator will always have a NWK address of 0x0000. The first Router to that associates with the Coordinator is assigned a NWK address of 0x0001. The second Router that associates with the Coordinator is assigned an address of 0x143E.

The 16-bit address is persistent through power loss and only resets when an NV Reset command is issued performed or NV Restore is disabled in EEPROM (EEPROM address 0x45, bit-3).

6 4 - b i t M A C a d d r e s s

The 64-bit MAC address consists of a 40-bit Organizationally Unique Identifier (OUI) and a 24-bit address programmed by the manufacturer. All ZB2430 transceivers have the same OUI of 0x00 0x00 0x00 0x50 0x67 which can be used to distinguish Aerocomm devices on a network but cannot be used to route packets throughout the network.

When a packet needs to be sent to a specific device through the network, the 16-bit network address must be used. In order to send data to a specific device in the network, the OEM can compile a table which lists the 64-bit MAC and the corresponding 16-bit Network address (see Table 3 below). The ZB2430’s built-in Discover IEEE Address and Discover Network Address commands allow the OEM to query the network and discover all available devices that respond within a fixed period.

T a b l e 3 : D e v i c e T a b l e E x a m p l e

Index	MAC Address (64-bit)	NWK Address (16-bit)
0	0x00 0x00 0x00 0x50 0x67 0x12 0x34 0x56	0x0000
1	0x00 0x00 0x00 0x50 0x67 0x16 0x45 0x34	0x0001
2	0x00 0x00 0x00 0x50 0x67 0x34 0x21 0x78	0x143E

M e s h R o u t i n g ( A O D V )

The ZigBee protocol uses the Ad-Hoc On-Demand Distance Vector (AODV) routing algorithm. AODV allows nodes to pass messages through their neighbors to devices which they cannot communicate directly. This is done by discovering the routes along which messages can be passed using the shortest route possible.

Figure 4 below shows a typical ZigBee network. The circles surrounding the 4 nodes represent the Personal Operating Space (POS) of each node. Because of the limited range, each node can only communicate with the neighboring node(s) next to it. When a node needs to send a message to a node which is not a neighbor, it broadcasts a Route Request (RREQ) message containing the Source Destination Address, the Network Address of the Destination radio and a path cost metric.

In the example below, Node 0 needs to send a message to Node 3; however the two are not within communication range of each other. Node 0’s neighbors are Node 1 and Node 2. Since Node 0 cannot directly communicate with Node 3, it sends out a RREQ which is heard by Nodes 1 and 2 (see Figure 5: "ZigBee Route Request" on page 17).