Manage End Devices
End Device configuration
XBee/XBee-PRO® S2C ZigBee® RF Module
135
Note
SP
controls the packet buffer time on routers and coordinators. Set
SP
on all router and
coordinator devices to match the longest end device
SP
time. For more information, see
Router/Coordinator configuration
Extended cyclic sleep
In extended cyclic sleep operation, an end device can sleep for a multiple of
SP
time which can extend
the sleep time up to several days. Configure the sleep period using the
SP
and
SN
commands. The
total sleep period is equal to (
SP
*
SN
) where
SP
is measured in 10ms units. The
SO
command must be
set correctly to enable extended sleep.
Since routers and coordinators can only buffer incoming RF data for their end device children for up to
30 seconds, if an end device sleeps longer than 30 seconds, devices in the network need some
indication when an end device is awake before they can send data to it. End devices that use extended
cyclic sleep should send a transmission (such as an
I/O
sample) when they wake to inform other
devices that they are awake and can receive data. We recommended that extended sleep end devices
set
SO
to wake for the full
ST
time to provide other devices with enough time to send messages to the
end device.
Similar to short cyclic sleep, end devices running in this mode return to sleep when the sleep timer
expires, or when they receive the
SI
command.
Deep sleep
The following are preconditions for maintaining low current draw during sleep:
n
You must maintain the supply voltage within a valid operating range (2.1 to 3.6 V for the XBee,
3.0 to 3.6 V for the XBee-PRO (S2), 2.7 to 3. V for the XBee-PRO S2B).
n
Each GPIO input line with a pullup resistor which is driven low draws about 100 uA current
through the internal pullup resistor.
n
If circuitry external to the XBee drives such input lines low, then the current draw rises above
expected deep sleep levels.