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XBee Series 2 ZigBee OEM RF Modules v1.x2x [2007.07.019]
4.3. Sleep Mode Operation
4.3.1. End Device Operation
4.3.2. Parent Operation
4.4. I/O Line Configuration
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XBee Series 2 modules support sleep mode operation in the Router / End Device firmware. Sleep
modes allow a ZigBee end device to enter a low power mode when idle and wake as needed to
transmit or receive data. See Chapter 2 "RF Module Operation" for more information about
different sleep modes.
ZigBee end devices rely on a parent (router or coordinator) to remain awake and receive any data
packets destined for the end device. When the end device wakes from sleep, it sends a
transmission (poll request) to its parent asking if the parent has received any RF data destined for
the end device. The parent, upon receipt of the poll request, will send an RF response and the
buffered data (if present).
If the end device is awake with the ST timer running (SM=4), or if Sleep_RQ is de-asserted
(SM=1), the end device will send poll requests every 100ms to ensure it receives any new RF data
from its parent.
When an end device joins a ZigBee PAN, it becomes a child of the (coordinator or router) device it
joined to, and the device that allowed the join becomes the end device's parent. Thereafter, the
parent will manage RF data packets for the end device. If the parent receives an RF packet
destined for the end device, it will store the data packet until one of the following occurs:
• The parent runs out of storage space and cannot store a new packet.
• A packet has been stored for a period of time.
• The destination end device child sends a poll request transmission to request the data packet.
When the parent stores a packet destined for an end device child, it stores the packet for a
maximum time set by SP. The actual storage time is computed as (SP * 2.5), not exceeding 30
seconds. If end devices implement cyclic sleep, SP should be set the same on a parent as it is on
their sleeping end device children. In the case of pin sleep, where RF data could be received, the
end device should wake within SP time to ensure data is not lost.
The XBee Series 2 modules support both analog input and digital IO line modes on several
configurable pins.
Configuring A/D and Digital Lines
The following table lists the pin functions supported on the modules
.
Table 4‐08.
Module Pin Names Module Pin Numbers Configuration Command
CD/DIO12
4
PWM0/RSSI/DIO10
6
PWM/DIO11
7
SLEEP_RQ/DIO8
9
DIO4
11
CTS/DIO7
12
ON_SLEEP/DIO9
13
ASSOC/DIO5
15
© 2007 Digi International, Inc.
Chapter 4 ‐ RF Module Configuration
P2
P0
P1
IO Configuration not supported
D4
D7
IO Configuration not supported
D5
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