SARA-G450 - System integration manual
UBX-18046432 - R08
System description
Page 40 of 143
C1-Public
1.9.2
Secondary auxiliary serial interface (AUX UART)
☞
Secondary auxiliary UART interface is not supported by the “00” product version. This interface
should be left unconnected and should not be driven by external devices.
The secondary auxiliary UART interface (AUX UART) is a 3-wire unbalanced asynchronous serial
interface available over RXD_AUX (data output pin) and TXD_AUX (data input pin), supporting:
AT command mode
11
Data mode and online command mode
GNSS tunneling
SARA-G450 modules’ auxiliary UART interface is configured by default for AT commands.
The serial interface configuration can be changed by means of the +USIO AT command to select
different alternative serial interface configuration variants, summarized in
, available in a
mutually exclusive way (for more details, see the u-blox AT commands manual
, +USIO AT
command).
AT+USIO UART
AUX UART
FT UART
Remarks
0
AT, data and MUX
AT, data
Diagnostic
1
AT, data and MUX
AT, data
Diagnostic
Default configuration
2
AT, data and MUX
AT, data
Diagnostic
3
AT, data and MUX
GNSS tunneling
Diagnostic
4
AT, data and MUX
GNSS tunneling
Diagnostic
Table 10: Alternative serial interface configuration variants supported by SARA-G4 modules product versions “01” onwards
☞
The serial interface configuration cannot be changed on the “00” product version of the
SARA-G450 modules: the +USIO AT command is not supported.
SARA-G450 modules’ auxiliary UART interface can be configured in AT command mode by means of
the AT+USIO command (for more details, see
) so that:
the cellular module waits for AT command instructions and interprets all the characters received
over the auxiliary UART interface as commands to be executed
the auxiliary UART interface provides RS-232 functionality conforming to ITU-T V.24
recommendation
with CMOS compatible signal levels: 0 V for low data bit or ON state and
1.8 V / 3 V for high data bit or OFF state (for detailed electrical characteristics, see the SARA-G450
data sheet
the cellular module is designed to operate as a modem, which represents the Data
Circuit-terminating Equipment (DCE) according to ITU-T V.24 recommendation
: the
application processor connected to the module through the auxiliary UART interface represents
the Data Terminal Equipment (DTE)
Flow control is not supported
2400, 4800, 9600, 19200, 38400, 57600 and 115200 bit/s baud rates can be set (see the u-blox AT
commands manual
, +IPR)
8N1, 8E1, 8O1 or 8N2 frame format can be set (see the u-blox AT commands manual
, +ICF)
11
See the u-blox AT commands manual
for the definition of the command mode, data mode, and online command mode.
