XBee®/XBee‐PRO® ZB SMT RF Modules
IR = 0x258 (600 decimal). Set IR to a value greater than (2 seconds / 4) to get 4 samples in 2 seconds. The
end device sends an IO sample at the IR rate until the sleep timer has expired.
At least one analog or digital IO line must be enabled for IO sampling to work. To enable pin 32 (AD1/DIO1) as
a digital input line, the following must be set:
D1 = 3
All router and coordinator devices on the network should set SP to match SP on the end device. This ensures
that RF packet buffering times and transmission timeouts will be set correctly.
Example 3
Configure a device for extended sleep: to sleep for 4 minutes.
SP and SN must be set such that SP * SN = 4 minutes. Since SP is measured in 10ms units, the following
settings can be used to obtain 4 minute sleep.
SM = 4 (cyclic sleep) or 5 (cyclic sleep, pin wake)
SP = 0x7D0 (2000 decimal, or 20 seconds)
SN = 0x0B (12 decimal)
SO = 0x04 (enable extended sleep)
With these settings, the module will sleep for SP * SN time, or (20 seconds * 12) = 240 seconds = 4 minutes.
For best results, the end device should send a transmission when it wakes to inform the coordinator (or
network) when it wakes. It should also remain awake for a short time to allow devices to send data to it. The
following are recommended settings.
ST = 0x7D0 (2 second wake time)
SO = 0x06 (enable extended sleep and wake for ST time)
IR = 0x800 (send 1 IO sample after waking). At least one analog or digital IO sample should be enabled for IO
sampling.
With these settings, the end device will wake after 4 minutes and send 1 IO sample. It will then remain awake
for 2 seconds before returning to sleep.
SP and SN should be set to the same values on all routers and coordinators that could allow the end device to
join. This will ensure the parent does not timeout the end device from its child table too quickly.
The SI command can optionally be sent to the end device to cause it to sleep before the sleep timer expires.
© 2010 Digi International, Inc.
90
DCD [ DIGITAL CORE DESIGN ]
