About Sleep Modes; Normal Mode; Pin Sleep Mode; Cyclic Sleep Mode - Digi XBee 3 Cellular LTE-M User Manual

Sleep modes

About sleep modes

A number of low-power modes exist to enable devices to operate for extended periods of time on
battery power. Use

Normal mode

Set SM to 0 to enter Normal mode.
Normal mode is the default sleep mode. If a device is in this mode, it does not sleep and is always
awake.
Devices in Normal mode are typically mains powered.

Pin sleep mode

Set SM to 1 to enter pin sleep mode.
Pin sleep allows the device to sleep and wake according to the state of the SLEEP_RQ pin (SLEEP_RQ).
When you assert SLEEP_RQ (high), the device finishes any transmit or receive operations, closes any
active connection, and enters a low-power state.
When you de-assert SLEEP_RQ (low), the device wakes from pin sleep.

Cyclic sleep mode

Set SM to 4 to enter Cyclic sleep mode.
Cyclic sleep allows the device to sleep for a specific time and wake for a short time to poll.
If you use the D7 command to enable hardware flow control, the CTS pin asserts (low) when the
device wakes and can receive serial data, and de-asserts (high) when the device sleeps.

Cyclic sleep with pin wake up mode

Set SM to 5 to enter Cyclic sleep with pin wake up mode.
This mode is a slight variation on Cyclic sleep mode (SM = 4) that allows you to wake a device
prematurely by de-asserting the SLEEP_RQ pin (SLEEP_RQ).
In this mode, you can wake the device after the sleep period expires, or if a high-to-low transition
occurs on the SLEEP_RQ pin.

SPI mode and sleep pin functionality

SLEEP_RQ/ DIO8 is configured as a peripheral by default and is used for pin sleep to wake the XBee
Smart Modem and put it to sleep. This applies regardless of if the serial interface is UART or SPI.
However, if SLEEP_RQ is not configured as a peripheral and SPI_SSEL is configured as a peripheral,
then pin sleep is controlled by SPI_SSEL rather than by SLEEP_RQ. Asserting SPI_SSEL by driving it low
wakes the XBee Smart Modem, or keeps it awake. De-asserting SPI_SSEL by driving it high puts the
device to sleep.
If neither pin is configured as a peripheral, then the device stays awake, being unable to sleep when
SM (Sleep Mode) is 1.
Digi XBee® 3 Cellular LTE-M/NB-IoT Global Smart Modem User Guide
SM (Sleep Mode) to enable these sleep modes.
About sleep modes
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