Atmel AVR2070 - Manual (Page 35)

AVR2070
35
8240B-AVR-06/09
• If neither of the above conditions apply, then send the packet to the last
routed address used for sending (which was stored from a routing frame).
4. If an association response is received with the router's short address as
parent, then add the child node to a table of child nodes and short addresses,
and forward the association response to the new child node.
5. Listen for frames received from non-parent nodes – both end nodes and
other routers. Forward all frames to parent. This includes association
request frames. Note that a router can only receive frames that are explicitly
sent to its short address and PAN ID.
A.4.3 Coordinator node
The coordinator keeps track of every node in the PAN, including the route needed to
reach a given node. With each association request/response transaction, the
coordinator builds a table that contains information on each node in the network:
Table A-4-1. Coordinator network table
Short Address Type MAC address Parent Short Addr IPv6
Address
Last
Route
Sleeping
2-byte address
issued by
coordinator at
association End node or
router node The unique 8-
byte 802.15.4
address The short address of
the parent of the given
node. Node’s
IPV6
address Short addr
of last
node
routed Flag: is the
node
sleeping?
• The short address of a node is really the index into the table of the node, so
that the address is not explicitly stored.
• The node Type is either end (3) or router (2). The coordinator is Type (1).
• The “Last Route” entry in the table is only used for a node that is a router
directly connected to the coordinator. This entry contains the short address
of the last destination node routed to that router's tree. This is useful for
sending a data packet to a node in the tree without having to re-send a
routing packet. The coordinator figures out which router to use to send a
routing packet, and if the destination node is the same as “Last Route”, then
no routing packet is necessary.
When the coordinator starts, it performs the following actions:
1. Do a scan to find any existing networks, and scan for RF energy at the same
time. Pick a free and clear channel and randomly choose a PAN ID. Or,
alternatively, pick a pre-defined channel and PAN ID if PAN_CHANNEL
and/or PAN_ID compiler variables are set.
2. Listen for beacon request packets from other nodes. Same as step 2 of router
node.
3. For each association request, store the new node's information in the network
table shown in Table A-4. Then send an association response back to the
new node.
4. To send a packet to a child node, a routing packet may be required. Note
that a routing packet is only required under certain circumstances: