End device association
End device association occurs if CE is 0 and A1 has bit 2 set. See the following table.
| Bit | Hex value | Meaning |
|---|---|---|
|
0 |
0x01 |
Allow PAN ID reassignment |
|
1 |
0x02 |
Allow channel reassignment |
|
2 |
0x04 |
Auto association |
|
3 |
0x08 |
Poll coordinator on pin wake |
By default, A1 is 0, which disables association and effectively causes an end device to operate in peer-to-peer mode. When bit 2 is set, the end device associates to a coordinator. This is done by sending out an active scan to detect beacons from nearby networks. The active scan selects one channel and transmits a Beacon Request command to the broadcast address and the broadcast PAN ID. It then listens on that channel for beacons from any coordinator operating on that channel. The listen time on each channel is determined by the SD parameter. Once that time expires, the active scan selects the next channel, repeating until all channels have been scanned.
If A1 is 0x04 (bit 0 clear, bit 1 clear, and bit 2 set), then the active scan will reject all beacons that do not match both the configured PAN ID and the configured channel. This is the best way to join a particular coordinator.
If A1 is 0x05 (bit 0 set, bit 1 clear, and bit 2 set), then the active scan will accept a beacon from any PAN ID, providing the channel matches. This is useful if the channel is known, but not the PAN ID.
If A1 is 0x06 (bit 0 clear, bit 1 set, and bit 2 set), then the active scan will accept a beacon from any channel, providing the PAN ID matches. This is useful if the PAN ID is known, but not the channel.
If A1 is 0x07 (bit 0 set, bit 1 set, and bit 2 set), then the active scan will accept a beacon from any PAN ID and from any channel. This is useful when the network does not matter, but the one with the best signal is desired.
Whenever multiple beacons are received that meet the criteria of the active scan, then the beacon with the best link quality is selected. This applies whether A1 is 0x04, 0x05, 0x06, or 0x07.
Before the End Device joins a network, the Associate LED will be on solid. After it joins a network, the Associate LED will blink twice per second.
In the event that association parameters are changed after the end device is associated, the end device will leave the network and re-join in accordance with the new configuration parameters.
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