XBP24-PKI-001-RA Digi International/Maxstream, XBP24-PKI-001-RA Datasheet - Page 46

• Manufacturer Part Number: XBP24-PKI-001-RA
• Description: MODULE 802.15.4 RS-232 ANT
• Manufacturer: Digi International/Maxstream
• Series: XBEE-PRO™r

Specifications of XBP24-PKI-001-RA

• Frequency: 2.4GHz
• Data Rate - Maximum: 250kbps
• Modulation Or Protocol: 802.15.4
• Applications: Home/Building Automation, Industrial Control, ZigBee™
• Power - Output: 0dBm
• Sensitivity: -92dBm
• Voltage - Supply: 2.8 V ~ 3.4 V
• Current - Receiving: 55mA
• Data Interface: Connector, Female DB-9
• Antenna Connector: RP-SMA
• Operating Temperature: -40°C ~ 85°C
• Package / Case: Module
• Memory Size: -
• Current - Transmitting: -
• Other names: Q3255595

© 2008 Digi International, Inc.
XBee‐PRO PKG‐R® RS‐232 RF Modem – 802.15.4 ‐ Product Manual v1.xAx
RN (Random Delay Slots) Command
RO (Packetization Timeout) Command
RP (RSSI PWM Timer) Command
<Networking & Security> The RN command is
used to set and read the minimum value of the
back-off exponent in the CSMA-CA algorithm. The
CSMA-CA algorithm was engineered for collision
avoidance (random delays are inserted to prevent
data loss caused by data collisions).
If RN = 0, collision avoidance is disabled during the first iteration of the algorithm (802.15.4 -
macMinBE).
CSMA-CA stands for "Carrier Sense Multiple Access - Collision Avoidance". Unlike CSMA-CD (reacts
to network transmissions after collisions have been detected), CSMA-CA acts to prevent data
collisions before they occur. As soon as a modem receives a packet that is to be transmitted, it
checks if the channel is clear (no other modem is transmitting). If the channel is clear, the packet
is sent over-the-air. If the channel is not clear, the modem waits for a randomly selected period of
time, then checks again to see if the channel is clear. After a time, the process ends and the data
is lost.
<Serial Interfacing> RO command is used to set
and read the number of character times of inter-
character delay required before transmission.
RF transmission commences when data is
detected in the DI (data in from host) buffer and
RO character times of silence are detected on the
UART receive lines (after receiving at least 1 byte).
RF transmission will also commence after 100 Bytes (maximum packet size) are received in the DI
buffer.
Set the RO parameter to '0' to transmit characters as they arrive instead of buffering them into
one RF packet.
<I/O Settings {I/O Line Passing}> The RP
command is used to enable PWM (Pulse Width
Modulation) output on the RF modem. The output
is calibrated to show the level a received RF signal
is above the sensitivity level of the modem. The
PWM pulses vary from 24 to 100%. Zero percent
means PWM output is inactive. One to 24% percent means the received RF signal is at or below
the published sensitivity level of the modem. The following table shows levels above sensitivity
and PWM values.
The total period of the PWM output is 64 µs. Because there are 445 steps in the PWM output, the
minimum step size is 144 ns.
PWM Percentages
A non-zero value defines the time that the PWM output will be active with the RSSI value of the
last received RF packet. After the set time when no RF packets are received, the PWM output will
be set low (0 percent PWM) until another RF packet is received. The PWM output will also be set
low at power-up until the first RF packet is received. A parameter value of 0xFF permanently
enables the PWM output and it will always reflect the value of the last received RF packet.
dB above Sensitivity
10
20
30
(high period / total period)
PWM percentage
41%
58%
75%
AT Command: ATRO
Parameter Range:0 - 0xFF
Default Parameter Value: 3
AT Command: ATRN
Parameter Range: 0 - 3 [exponent]
Default Parameter Value: 0
AT Command: ATRP
Parameter Range:0 - 0xFF
Default Parameter Value: 0x28 (40 decimal)
[x character times]
[x 100 msec]
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