ETRX357 Development Kit
©2016 Silicon Labs
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ETRX357DVK Product Manual (Rev 1.12)
case of the two MCBs provided with the previous ETRX2-based DVKA) you will just need to wait for
them to join the network automatically. By default, once every minute all nodes (except coordinators)
are set up to check whether there are any neighbours on the same PAN nearby, or if they have been
orphaned. If no neighbours are found after 5 consecutive tries, the unit will leave the (deserted) PAN
and then try to join a new one once every minute.
This initial network set-up can take a few minutes, especially with no serial access to remote nodes,
but once the network is set up it will remain set even after power cycles. New nodes joining will
cause a prompt ‘
NEWNODE:
’ on the remote side and display the
JPAN
message locally as
described above.
The ETRX357 stores its network parameters in non-volatile memory, so if you reset or power-cycle
a module there is no need to re-establish or join the PAN again.
If devices do not join the desired PAN automatically, check that they are not already in a network of
their own. The command
AT+PANSCAN
will reveal the presence of other networks in the vicinity.
To learn more about setting up and maintaining a PAN please refer to the user guide and the AT
Command Dictionary.
Mesh networking
A typical ZigBee network is a mesh, where every device can send a message to any other device.
If the two devices are in radio range of each other the message passes directly, but if they are too
far apart the message is relayed via an intermediate device. The routing is taken care of by the
firmware and the user is generally not even aware that it is happening. You can easily discover the
basic principles of mesh networking: simply move a Development Board out of range (if you do not
have enough space simply turn the transmit power down or put it behind a metal screen) and then
add another Development Board between the local node and the remote one. You will find that the
network has healed the broken link and all three nodes are accessible again.
Node types
A ZigBee node is one of several types:
Router. If you have started a network as described so far in this manual, all the devices are
routers and can communicate directly with each other
Coordinator. This is merely the device which first established the network. It is also the trust
centre which grants permission for other devices to join, so do not disassociate it from your
network
Sleepy End Device. SEDs do not play any part in the routing so they can be put into a sleep
state while they do not need to send or receive messages. To turn a device into an SED
disassociate it from your network, set bit E of register S0A with the command
ATS0AE=1;password
then let it join the network. An SED is adopted by a parent router which
buffers any messages sent to the SED until it sends a Data Request (or poll) to its parent to
indicate it is ready to receive. The power mode is defined in register S39, so refer to the AT
command manual for more details
Mobile End Device. MEDs are like SEDs but they react more quickly when they move of range
of their parent and need to find a new one. Set bits E and F of register S0A to create an MED
ZigBee End Device. ZEDs cannot be put into a sleep state to save power nor do they take part
in the routing, so they are of very limited use
