AT commands MAC diagnostics commands
Digi XBee3® 802.15.4 RF Module User Guide
93
You can set CA to 0 to disable CCA; this can improve latency but may cause interference with other
2.4GHz devices when transmitting. You can disable and enable CCA at runtime, which does not require
a power cycle.
Parameter range
0 (disabled), 0x28 - 0x64 (-dBm)
Default
0x41
RN command
Defines the minimum value of the back-off exponent in the CSMA-CA algorithm. The Carrier Sense
Multiple Access - Collision Avoidance (CSMA-CA) algorithm was engineered for collision avoidance
(random delays are inserted to prevent data loss caused by data collisions.
If RN = 0, there is no delay between a request to transmit and the first iteration of CSMA-CA.
Unlike CSMA-CD, which reacts to network transmissions after collisions have been detected, CSMA-CA
acts to prevent data collisions before they occur. As soon as a device receives a packet that is to be
transmitted, it checks if the channel is clear (no other device is transmitting). If the channel is clear,
the packet is sent over-the-air. If the channel is not clear, the device 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.
Parameter range
0 - 5 (exponent)
Default
0
DB command
Reports the RSSI in -dBm of the last received RF data packet. DB returns a hexadecimal value for the
-dBm measurement.
For example, if DB returns 0x60, then the RSSI of the last packet received was -96 dBm.
If the XBee3 802.15.4 RF Module has been reset and has not yet received a packet, DB reports 0.
This value is volatile (the value does not persist in the device's memory after a power-up sequence).
Parameter range
0 - 0xFF [read-only]
Default
N/A
MAC diagnostics commands
The following AT commands are MAC/PHY commands.
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