Atmel AVR2070 Manuel D’Utilisation

 

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. 

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: 

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: