A24-HASM-450 Digi International/Maxstream, A24-HASM-450 Datasheet - Page 14

• Manufacturer Part Number: A24-HASM-450
• Description: ANT 2.4GHZ DIPOLE HALF-WAVE
• Manufacturer: Digi International/Maxstream
• Series: XPressr

Specifications of A24-HASM-450

• Antenna Type: Whip: 1/2 Wave, Swivel, Tilt (Right Angle)
• Number Of Bands: 1
• Frequency: 2.4GHz
• Vswr: 2
• Gain: 2.1dBi
• Termination: RP-SMA
• Mounting Type: Connector
• Height (max): 4.35" (110.5mm)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 70000340; Q2724499B

XBee/XBee‐PRO OEM RF Modules ‐ ZigBee ‐ v1.x1x [2007.06.01]
2.2.5. Sleep Mode
Data Management
End Device Sleep Modes
For an example of programming the RF module using AT Commands and descriptions of each
configurable parameter, refer to the "RF Module Configuration" chapter.
Sleep modes are supported on end devices only. Router and coordinator devices participate in
routing data packets and are intended to be mains powered. End devices must be joined to a
parent (router or coordinator) before they can participate on a ZigBee network. The parent device
does not track when an end device is awake or asleep. Instead, the end device must inform the
parent when it is able to receive data. The parent must be able to buffer incoming data packets
destined for the end device until the end device can awake and receive the data. When an end
device is able to receive data, it sends a poll command to the parent. When the parent router or
coordinator receives the poll command, it will transmit any buffered data packets for the end
device. Routers and coordinators are capable of buffering one broadcast transmission for sleeping
end device children.
The SM, ST, SP, and SN commands are used to configure sleep mode operation.
The SP command on the parent determines how long the parent will buffer a packet. It should be
set to match the maximum SP value on any end device that may join to it. SP can be set up to 28
seconds (0xAF0).
Pin Sleep
Setting SM=1 or SM=2 configures a device as a pin-sleep enabled end device. When operating in
this mode, an end device monitors the Sleep_Request pin for a high state. When Sleep_Request
goes high, the module enters sleep mode once any pending transmissions have finished. The
module remains in a low power state until the Sleep_Request pin goes low.
When the module wakes from pin sleep, it sends a poll request to the parent to see if any data is
pending for the end device. Since routers and coordinators can only buffer data up to 30 seconds,
end devices should not remain in pin sleep longer than about 28 seconds if incoming data packets
must be received. Using pin sleep for more than 28 seconds is recommended only if incoming data
packets are not expected.
When the module wakes from a pin sleep mode, the CTS line goes low, and On/Sleep goes high.
Cyclic Sleep
Cyclic sleep allows the end device to sleep for a specified period of time. The period of time is
specified by SP. Since routers and coordinators can only buffer data packets for up to 30 seconds,
SP on end devices can be set up to 28 seconds (0xAF0). The module will wake after SP time and
send a poll request to the parent to check for data. If any serial or RF data is received, the ST time
is restarted. Once ST time has expired with no serial or RF activity, the end device will resume
cyclic sleep operation.
When the module wakes, CTS goes low allowing the application to send serial data to the module
if necessary. The On/Sleep indicator will be set high to alert the application that the end device has
awakened. If serial or RF data is received, the ST timer will be reset, otherwise, the end device will
resume low power operation.
Off board peripherals may wish to sleep longer than the maximum SP time of the end device. The
SN command can be used to not wake off board peripherals for longer than SP time.
For example, if SP=28 seconds, and SN=5, the end device will wake up every 28 seconds and poll
the parent for data. If no data is pending, the end device will return to sleep. In this example, if
the parent has no data for the end device, On/Sleep will go high after 140 seconds, assuming the
parent never has data for the end device. If the parent has data for the end device, On/Sleep will
go high and the SN counter will reset.
© 2007 Digi International, Inc.
Chapter 2 ‐ RF Module Operation
14