User Manual

XBee®/XBee‐PRO®RFModules‐802.15.4‐v1.xEx[2011.06.1]
©2011DigiInternatonal,Inc. 25
Sleep Mode
Sleep Modes enable the RF module to enter states of low-power consumption when not in use. In
order to enter Sleep Mode, one of the following conditions must be met (in addition to the module
having a non-zero SM parameter value):
• Sleep_RQ (pin 9) is asserted and the module is in a pin sleep mode (SM = 1, 2, or 5)
• The module is idle (no data transmission or reception) for the amount of time defined by the
ST (Time before Sleep) parameter. [NOTE: ST is only active when SM = 4-5.]
The SM command is central to setting Sleep Mode configurations. By default, Sleep Modes are dis-
abled (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 inac-
tivity). 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
Table 2‐04. SleepModeConfigurations
Sleep Mode
Setting
Transition into
Sleep Mode
Transition out of
Sleep Mode (wake)
Characteristics
Related
Commands
Power
Consumption
Pin Hibernate
(SM = 1)
Assert (high) Sleep_RQ
(pin 9)
De-assert (low) Sleep_RQ
Pin/Host-controlled /
NonBeacon systems
only / Lowest Power
(SM)
< 10 µA (@3.0
VCC)
Pin Doze
(SM = 2)
Assert (high) Sleep_RQ
(pin 9)
De-assert (low) Sleep_RQ
Pin/Host-controlled /
NonBeacon systems
only / Fastest wake-up
(SM) < 50 µA
Cyclic Sleep
(SM = 4)
Automatic transition to
Sleep Mode as defined by
the SM (Sleep Mode) and
ST (Time before Sleep)
parameters.
Transition occurs after the
cyclic sleep time interval
elapses. The time interval
is defined by the SP
(Cyclic Sleep Period)
parameter.
RF module wakes in
pre-determined time
intervals to detect if RF
data is present / When
SM = 5
(SM), SP, ST
< 50 µA
when sleeping
Cyclic Sleep
(SM = 5)
Automatic transition to
Sleep Mode as defined by
the SM (Sleep Mode) and
ST (Time before Sleep)
parameters or on a falling
edge transition of the
SLEEP_RQ pin.
Transition occurs after the
cyclic sleep time interval
elapses. The time interval
is defined by the SP
(Cyclic Sleep Period)
parameter.
RF module wakes in
pre-determined time
intervals to detect if RF
data is present. Module
also wakes on a falling
edge of SLEEP_RQ
(SM), SP, ST
< 50 µA
when sleeping