XBee‐PRO®900HP/XBee‐PRO®XSCRFModules
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Asynchronous Cyclic Sleep with Pin Wake Up Mode (SM=5)
(SM=5) is similar to both the (SM=1) and (SM=4) modes. When the SLEEP_REQUEST pin is asserted the
module will enter a cyclic sleep mode similar to (SM=4). When the SLEEP_REQUEST pin is de-asserted the
module will immediately wake up. The module will not sleep when the SLEEP_REQUEST pin is de-asserted.
When indirect messaging polling is enabled (see the CE command) upon waking a poll will be sent to the
module's parent node as described in the Indirect Messaging and Polling Section. Polls will also be regularly
sent to the parent while the module is held awake.
Synchronous Sleep Support Mode (SM=7)
A node in synchronous sleep support mode will synchronize itself with a sleeping network but will not itself
sleep. At any time, the node will respond to new nodes which are attempting to join the sleeping network with
a sync message. A sleep support node will only transmit normal data when the other nodes in the sleeping
network are awake. Sleep support nodes are especially useful when used as preferred sleep coordinator nodes
and as aids in adding new nodes to a sleeping network.
Note: Because sleep support nodes do not sleep, they should be mains powered.
Synchronous Cyclic Sleep Mode (SM=8)
A node in synchronous cyclic sleep mode sleeps for a programmed time, wakes in unison with other nodes,
exchanges data and sync messages, and then returns to sleep. While asleep, it cannot receive RF messages or
read commands from the UART port. Generally, sleep and wake times are specified by the SP and ST
respectively of the network’s sleep coordinator. These parameters are only used at start up until the node is
synchronized with the network. When a module has synchronized with the network, its sleep and wake times
can be queried with the OS and OW commands respectively. If D9 = 1 (ON_SLEEP
enabled) on a cyclic sleep
node, the ON_SLEEP
line will assert when the module is awake and de-assert when the module is asleep.
CTS is also de-asserted while asleep (D7 = 1). A newly-powered unsynchronized sleeping node will poll for a
synchronized message and then sleep for the period specified by SP, repeating this cycle until it becomes
synchronized by receiving a sync message. Once a sync message is received, the node will synchronize itself
with the network.
Note: All nodes in a synchronous sleep network should be configured to operate in either Synchronous
Sleep Support Mode or Synchronous Cyclic Sleep Mode. Asynchronous sleeping nodes are not com-
patible with synchronous sleep nodes.
Asynchronous Sleep Operation
Wake Timer
In cyclic sleep mode (SM=4 or SM=5), if serial or RF data is received, the module will start a sleep timer (time
until sleep). Any data received serially or by RF link will reset the timer. The timer duration can be set using
the ST command. The module returns to sleep when the sleep timer expires.
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