Sleep support Sleep conditions
Digi XBee3® 802.15.4 RF Module User Guide
78
Pinname Description
DTR/SLEEP_
RQ
For SM = 1, high puts the device to sleep and low wakes it up. For SM = 5, a high to
low transition wakes the device until the pin transitions back to a high state.
SPI_SSEL Alternative SLEEP_RQ line for devices operating in SPI. See Low power operation for
further information.
CTS If D7 = 1, high indicates that the device is asleep and low indicates that it is awake
and ready to receive serial data.
ON_SLEEP Low indicates that the device is asleep and high indicates that it is awake.
Sleep conditions
Since instructions stop executing while the device is sleeping, it is important to avoid sleeping when
the device has work to do. For example, the device will not sleep if any of the following are true:
1. The device is operating in Command mode, or in the process of getting into Command mode
with the +++ sequence.
2. The device is processing AT commands from API mode
3. The device is processing remote AT commands
4. Something is queued to the serial port and that data is not blocked by RTS flow control
If each of the above conditions are false, then sleep may still be blocked in these cases:
1. Enough time has not expired since the device has awakened.
a. If the device is operating in pin sleep, the amount of time needed for one character
to be received on the UART is enough time.
b. If the device is operating in cyclic sleep, enough time is defined by a timer. The
duration of that timer is:
i. defined by ST if in SM 5 mode and it is awakened by a pin
ii. 30 ms to allow enough time for a poll and a poll response
iii. 750 ms to allow enough time for association, in case that needs to
happen
c. In addition, the wake time is extended by an additional ST time when newOTA data
or serial data is received.
2. Sleep Request pin is not asserted when operating in pin sleep mode
3. Data is waiting to be sent OTA.
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