Sleep modes Asynchronous pin sleep mode
XBee®-PRO 900HP/XSC RF Modules
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When synchronized, a device in Normal mode relays sync messages that sleep-compatible nodes
generate, but does not generate sync messages itself.
Once a device in Normal mode synchronizes with a sleeping network, you can put it into a sleep-
compatible sleep mode at any time.
Asynchronous pin sleep mode
Set SM to 1 to enter asynchronous pin sleep mode.
Pin sleep allows the device to sleep and wake according to the state of the SLEEP_RQ pin (pin 9).
When you assert SLEEP_RQ (high), the device finishes any transmit or receive operations and enters a
low-power state.
When you de-assert SLEEP_RQ (low), the device wakes from pin sleep.
When you enable indirect messaging polling see CE (Node Messaging Options), when the device
wakes, it sends a poll to the parent node. For more information, see Indirect messaging and polling.
Asynchronous cyclic sleep mode
Set SM to 4 to enter asynchronous cyclic sleep mode.
Cyclic sleep allows the device to sleep for a specific time and wake for a short time to poll.
If the device receives serial or RF data while awake, it extends the time before it returns to sleep by
the specific amount the ST command provides. Otherwise, it enters sleep mode immediately.
The ON_SLEEP line (pin pin 13) is asserted (high) when the device wakes, and is de-asserted (low)
when the device sleeps.
If you use the D7 command to enable hardware flow control, the CTS pin asserts (low) when the
device wakes and can receive serial data, and de-asserts (high) when the device sleeps.
When you enable indirect messaging polling see CE (Node Messaging Options), when the device
wakes, it sends a poll to the parent node. For more information, see Indirect messaging and polling.
Asynchronous cyclic sleep with pin wake up mode
Set SM to 5 to enter asynchronous cyclic sleep with pin wake up mode.
(SM = 5) is similar to both the (SM = 1) and (SM = 4) modes. When the host asserts the SLEEP_
REQUEST pin, the device enters a cyclic sleep mode similar to (SM = 4). When the host de-asserts the
SLEEP_REQUEST pin, the device immediately wakes up. The device will not sleep when the SLEEP_
REQUEST pin is de-asserted.
When you enable indirect messaging polling see CE (Node Messaging Options), when the device
wakes, it sends a poll to the parent node. For more information, see Indirect messaging and polling.
Synchronous sleep support mode
Set SM to 7 to enter synchronous sleep support mode.
A device in synchronous sleep support mode synchronizes itself with a sleeping network, but does not
sleep itself. At any time, the node responds to new nodes that attempt to join the sleeping network
with a sync message. A sleep support node only transmits normal data when the other nodes in the
sleeping network are awake.
Sleep support nodes are especially useful:
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