Modes
Command mode
Digi XBee® 3 802.15.4 RF Module User Guide
76
Command mode is available on the UART interface for all operating modes. You cannot use the SPI
interface to enter Command mode.
Enter Command mode
To get a device to switch into Command mode, you must issue the following sequence:
+++
within one
second. There must be at least one second preceding and following the
+++
sequence. Both the
command character (
CC
) and the silence before and after the sequence (
GT
) are configurable. When
the entrance criteria are met the device responds with
OK\r
on UART signifying that it has entered
Command mode successfully and is ready to start processing AT commands.
If configured to operate in
, when entering Command mode the XBee 3
802.15.4 RF Module knows to stop sending data and start accepting commands locally.
Note
Do not press
Return
or
Enter
after typing
+++
because it interrupts the guard time silence and
prevents you from entering Command mode.
When the device is in Command mode, it listens for user input and is able to receive AT commands on
the UART. If
CT
time (default is 10 seconds) passes without any user input, the device drops out of
Command mode and returns to the previous operating mode. You can force the device to leave
Command mode by sending
.
You can customize the command character, the guard times and the timeout in the device’s
configuration settings. For more information, see
,
and
Troubleshooting
Failure to enter Command mode is often due to baud rate mismatch. Ensure that the baud rate of the
connection matches the baud rate of the device. By default,
=
3
(9600 b/s).
There are two alternative ways to enter Command mode:
n
A serial break for six seconds enters Command mode. You can issue the "break" command
from a serial console, it is often a button or menu item.
n
Asserting DIN (serial break) upon power up or reset enters Command mode. XCTU guides you
through a reset and automatically issues the break when needed.
Note
You must assert RTS for both of these methods, otherwise the device enters the bootloader.
Both of these methods temporarily set the device's baud rate to 9600 and return an
OK
on the UART
to indicate that Command mode is active. When Command mode exits, the device returns to normal
operation at the baud rate that
BD
is set to.
Send AT commands
Once the device enters Command mode, use the syntax in the following figure to send AT commands.
Every AT command starts with the letters
AT
, which stands for "attention." The AT is followed by two
characters that indicate which command is being issued, then by some optional configuration values.
To read a parameter value stored in the device’s register, omit the parameter field.
