Digi XBee Product Manual

Modes of operation for the XBee/XBee-PRO RF Modules
XBee / XBee-PRO RF Modules 802.15.4 Product Manual 32
The SM command is central to setting Sleep Mode configurations. By default, Sleep Modes are
disabled (SM = 0) and the module remains in Idle/Receive Mode. When in this state, the module is
constantly ready to respond to serial or RF activity.
Pin/Host-controlled sleep modes
The transient current when waking from pin sleep (SM = 1 or 2) does not exceed the idle current of
the module. The current ramps up exponentially to its idle current.
Pin Hibernate (SM = 1)
• Pin/Host-controlled
• Typical power-down current: < 10 μA (@3.0 VCC)
• Typical wake-up time: 10.2 msec
Pin Hibernate Mode minimizes quiescent power (power consumed when in a state of rest or
inactivity). This mode is voltage level-activated; when Sleep_RQ (pin 9) is asserted, the module will
finish any transmit, receive or association activities, enter Idle Mode, and then enter a state of sleep.
The module will not respond to either serial or RF activity while in pin sleep.
To wake a sleeping module operating in Pin Hibernate Mode, de-assert Sleep_RQ (pin 9). The module
will wake when Sleep_RQ is de-asserted and is ready to transmit or receive when the CTS line is low.
When waking the module, the pin must be de-asserted at least two 'byte times' after CTS goes low.
This assures that there is time for the data to enter the DI buffer.
Pin Doze (SM = 2)
• Pin/Host-controlled
• Typical power-down current: < 50 μA
• Typical wake-up time: 2.6 msec
Pin Doze Mode functions as does Pin Hibernate Mode; however, Pin Doze features faster wake-up
time and higher power consumption.
To wake a sleeping module operating in Pin Doze Mode, de-assert Sleep_RQ (pin 9). The module will
wake when Sleep_RQ is de-asserted and is ready to transmit or receive when the CTS line is low.
When waking the module, the pin must be de-asserted at least two 'byte times' after CTS goes low.
This assures that there is time for the data to enter the DI buffer.
Cyclic sleep modes
Cyclic Sleep Remote (SM = 4)
• Typical Power-down Current: < 50 μA (when asleep)
• Typical wake-up time: 2.6 msec
The Cyclic Sleep Modes allow modules to periodically check for RF data. When the SM parameter is
set to ‘4’, the module is configured to sleep, then wakes once a cycle to check for data from a module
configured as a Cyclic Sleep Coordinator (SM = 0, CE = 1). The Cyclic Sleep Remote sends a poll
request to the coordinator at a specific interval set by the SP (Cyclic Sleep Period) parameter. The
coordinator will transmit any queued data addressed to that specific remote upon receiving the poll
request.
If no data is queued for the remote, the coordinator will not transmit and the remote will return to
sleep for another cycle. If queued data is transmitted back to the remote, it will stay awake to allow
for back and forth communication until the ST (Time before Sleep) timer expires.

Digi XBee Specifications

General

Operating Frequency	2.4 GHz
RF Data Rate	250 kbps
Model	XBee S2C
Category	Control Unit
Operating Voltage	2.1 to 3.6V DC
Operating Temperature	-40 to +85 °C
Interface	UART
Dimensions	24.38 x 27.61 x 9.14 mm