User Manual

XBee®/XBee‐PRO®RFModules‐802.15.4‐v1.xEx[2011.06.1]
©2011DigiInternatonal,Inc. 41
NOTE: Refer the scan table in the SD description to determine scan times. If using API Mode, no
<CR>’s are returned in the response. Refer to the API Mode Operation section.
BD (Interface Data Rate) Command
<Serial Interfacing> The BD command is used to
set and read the serial interface data rate used
between the RF module and host. This parameter
determines the rate at which serial data is sent to
the module from the host. Modified interface data
rates do not take effect until the CN (Exit AT Com-
mand Mode) command is issued and the system
returns the 'OK' response.
When parameters 0-7 are sent to the module, the
respective interface data rates are used (as
shown in the table on the right).
The RF data rate is not affected by the BD param-
eter. If the interface data rate is set higher than
the RF data rate, a flow control configuration may
need to be implemented.
Non-standard Interface Data Rates: 
Any value above 0x07 will be interpreted as an actual baud rate. When a value above 0x07 is sent,
the closest interface data rate represented by the number is stored in the BD register. For exam-
ple, a rate of 19200 bps can be set by sending the following command line "ATBD4B00". NOTE:
When using Digi’s X-CTU Software, non-standard interface data rates can only be set and read
using the X-CTU ‘Terminal’ tab. Non-standard rates are not accessible through the ‘Modem Config-
uration’ tab.
When the BD command is sent with a non-standard interface data rate, the UART will adjust to
accommodate the requested interface rate. In most cases, the clock resolution will cause the
stored BD parameter to vary from the parameter that was sent (refer to the table below). Reading
the BD command (send "ATBD" command without an associated parameter value) will return the
value actually stored in the module’s BD register.
* The 115,200 baud rate setting is actually at 111,111 baud (-3.5% target UART speed).
CA (CCA Threshold) Command
<RF Interfacing> CA command is used to set and
read CCA (Clear Channel Assessment) thresholds.
Prior to transmitting a packet, a CCA is performed
to detect energy on the transmit channel. If the
detected energy is above the CCA Threshold, the
RF module will not transmit the packet.
ParametersSentVer sus ParametersStored
BD Parameter Sent (HEX) Interface Data Rate (bps) BD Parameter Stored (HEX)
0 1200 0
4 19,200 4
7 115,200* 7
12C 300 12B
1C200 115,200 1B207
AT Command: ATBD
Parameter Range:0 - 7 (standard rates)
0x80-0x3D090 (non-standard rates up to
250 Kbps)
Parameter Configuration (bps)
01200
12400
24800
39600
4 19200
5 38400
6 57600
7 115200
Default Parameter Value:3
AT Command: ATCA
Parameter Range: 0 - 0x50 [-dBm]
Default Parameter Value: 0x2C 
(-44 decimal dBm)
Minimum Firmware Version Required: v1.x80