User Manual

XBee® Wi-Fi RF Modules

5. Sleep

The XBee Wi-Fi module supports two different sleep modes.

• Pin Sleep

• Cyclic Sleep

In addition the sleep mode current draw can be modified with the following sleep

options.

• AP Associated Sleep

• Deep Sleep

Pin sleep allows an external microcontroller to determine when the XBee should sleep

and when it should wake by using either the SleepRq pin (default) or the SPI_nSSEL pin.

In contrast, cyclic sleep allows the sleep period and wake times to be configured

through the use of AT commands. The module can stay associated to the access point

or can enter a deeper sleep and associate to the access point for each sleep/wake

occurrence. The sleep mode is configurable with the SM and SO commands.

Besides the four sleep modes mentioned above, each of them operate a little differently

based on the serial interface (UART or SPI).

Using Sleep Mode: UART

When the serial interface is UART, the On/nSleep pin is used to indicate that the module

is entering sleep mode, unless pin 13 is configured for a different usage. (See command

reference table) If D9 is configured for On/nSleep, then it is driven low when asleep and

high when awake, whether using pin sleep or cyclic sleep.

If CTS hardware flow control is enabled (D7 command), the CTS pin (pin 12) is de-

asserted (high) when entering sleep to indicate that serial data should not be sent to the

module. The module will not respond to serial or RF data when it is sleeping.

Applications that utilize the UART are encouraged to observe CTS flow control in any of

the sleep modes. When the XBee wakes from sleep with flow control enabled, the CTS

pin is asserted (low).

If using pin sleep, D8 (mapped to XBee pin 9) must be configured for SleepRq (See

command reference table) to put the module to sleep. Otherwise, there is no sleep at

all, meaning the module will always stay awake in full power mode. When D8 is

configured for SleepRq, the host should drive pin 9 high to put the module to sleep, and

the host should drive pin 9 low to wake up the module.

Using Sleep Mode: SPI

When the serial interface is SPI, pin 19 is used as an attention indicator to tell the SPI

master when it has data to send. Since SPI only operates in API mode, it will assert

SPI/nATTN and send out a modem status indicator after initialization. The host can use

this to know when the radio is ready to operate as a SPI slave. Since the function of pin