u-blox LARA-R203 System Integration Manual page 40

1.9.1.2 UART AT interface configuration
The UART interface of LARA-R2 series modules is available as the AT command interface with the default
configuration described in Table 10 (for more details and information about further settings, see the u-blox AT
Commands Manual [2]).
Interface AT Settings
UART interface AT interface: enabled
AT+IPR=0
AT+ICF=3,1
AT&K3
AT&S1
AT&D1
AT&C1
MUX protocol: disabled
Table 10: Default UART AT interface configuration
1.9.1.3 UART signal behavior
At the module switch-on, before the UART interface initialization (as described in the power-on sequence reported
in Figure 14), each pin is first tri-stated and then is set to its related internal reset state
sequence, the UART interface is initialized, the module is by default in active mode, and the UART interface is
enabled as an AT commands interface.
The configuration and the behavior of the UART signals after the boot sequence are described below. See section
1.4 for the definition and description of the module operating modes referred to in this section.
RXD signal behavior
The module data output line (RXD) is set by default to the OFF state (high level) at UART initialization. The module
holds RXD in the OFF state until the module does not transmit any data.
TXD signal behavior
The module data input line (TXD) is set by default to the OFF state (high level) at UART initialization. The TXD line
is then held by the module in the OFF state if the line is not activated by the DTE: an active pull-up is enabled inside
the module on the TXD input.
9
See the u-blox AT Commands Manual [2] for the definition of the command mode, data mode, and online command mode
10
Not supported by LARA-R204-02B and LARA-R211-02B-00 product versions.
11 Refer to the pin description table in the LARA-R2 series Data Sheet [1].
UBX-16010573 - R12
Comments
AT command interface is enabled by default on the UART physical interface
One-shot autobauding enabled by default on the modules
8N1 frame format enabled by default
HW flow control enabled by default
DSR line (Circuit 107 in ITU-T V.24) set ON in data mode
Upon an ON-to-OFF transition of the DTR line (Circuit 108/2 in ITU-T V.24), the module
(DCE) enters online command mode
DCD line (Circuit 109 in ITU-T V.24) changes in accordance with the Carrier detect status;
ON if the Carrier is detected, OFF otherwise
Multiplexing mode is disabled by default and it can be enabled by the AT+CMUX
command. For more details, see the Mux Implementation Application Note [21].
The following virtual channels are defined:

Channel 0: control channel

Channel 1 – 5: AT commands / data connection

Channel 6: GNSS tunneling
LARA-R2 series - System Integration Manual
9 and set OFF in command mode
9
and issues an OK result code
10
11
. At the end of the boot
9
System description
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