Digi XTend User Manual page 21

Pin Sleep (SM = 1)
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Pin/Host-controlled
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Typical power-down current: < 147 A 147 µA
This mode is voltage level activated. When the SLEEP pin is asserted, the module will finish any transmitting or
receiving activity; enter Idle Mode; then enter a state of sleep. When in Pin Sleep Mode, the module will not respond to
serial or RF activity.
After enabling Pin Sleep, the SLEEP pin controls whether the module is active or sleeping. When SLEEP is de-asserted,
the module is fully operational. When SLEEP is asserted, the module transitions to Sleep Mode and remains in its
lowest power-consuming state until the pin is de-asserted. This pin is only active if the module is setup to operate in
this mode; otherwise the pin is ignored.
Once in Pin Sleep, CTS (GPO1) is de-asserted (high), indicating that data should not be sent to the module. The PWR
pin is also de-asserted (low) when the module is in Pin Sleep Mode.
Note: The module will complete a transmission or reception before activating Pin Sleep.
Serial Port Sleep (SM = 2)
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Wake on serial port activity
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Typical power-down current: < 10 mA
Serial Port Sleep is a Sleep Mode in which the module runs in a low power state until serial data is detected on the DI
pin.
The period of time the module sleeps is determined by ST (Time before Sleep) Command. Once a character is
received through the DI pin, the module returns to Idle Mode and is fully operational.
Cyclic Sleep (SM = 4-8)
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Typical Power-down Current: < 1.6 mA (when asleep)
Cyclic Sleep Modes allow modules to periodically wake and check for RF data. The module wakes according to the
times designated by the Cyclic sleep settings. If the module detects a wake-up initializer during the time it is awake,
the module synchronizes with the transmitting module and receives data after the wake-up initializer runs its
duration. Otherwise, the module returns to Sleep Mode and continues to cycle in and out of activity until a wake-up
initializer is detected.
While the module is in Cyclic Sleep Mode, CTS (GPO1) is de-asserted (high) to indicate that data should not be sent to
the module. When the module awakens to listen for data, GPO1 is asserted and any data received on the DI Pin is
transmitted. The PWR pin is also de-asserted (low) when the module is in Cyclic Sleep Mode.
The module remains in Sleep Mode for a user-defined period of time ranging from 0.5 seconds to 16 seconds (SM
parameters 4 through 8). After this interval of time, the module returns to Idle Mode and listens for a valid data
packet. The listen time will depend on the [BR] (RF Data Rate) parameter setting.The default [BR] setting of 1 will
require at least a 35ms wake time, while the [BR] setting of 0 will require a wake time of up to 225ms. If the module
does not detect valid data (on any frequency), the module returns to Sleep Mode. If valid data is detected, the module
transitions into Receive Mode and receives the incoming RF packets. The module then returns to Sleep Mode after a
period of inactivity determined by the ST (Time before Sleep) parameter.
The module can also be configured to wake from cyclic sleep when the SLEEP pin is de-asserted. To configure a
module to operate in this manner, PW (Pin Wake-up) Command must be issued. Once the SLEEP pin is de-asserted,
the module is forced into Idle Mode and can begin transmitting or receiving data. It remains active until data is no
longer detected for the period of time specified by the ST Command, at which point it resumes its low-power cyclic
state.
XTend RF Module User Guide
Modes of operation
21