SARA-G3 series - Data Sheet
UBX-13000993 - R21 Interfaces Page 15 of 49
2.5.1 Asynchronous serial interface (UART)
The UART interface is a 9-wire unbalanced 1.8 V asynchronous serial interface provided on all
SARA-G3 modules for communication with an application processor, supporting:
AT command mode
Data mode and Online command mode
MUX functionality, including dedicated GNSS tunneling virtual channel
FW upgrades by means of the FOAT feature
UART characteristics are:
Complete serial port with RS-232 functionality conforming to the ITU-T V.24
Recommendation [8], with CMOS compatible signal levels (0 V for low data bit or ON state
and 1.8 V for high data bit or OFF state)
Data lines (RXD as output, TXD as input), hardware flow control lines (CTS as output, RTS as
input), modem status and control lines (DTR as input, DSR as output, DCD as output, RI as
output) are provided
Hardware flow control (default value), software flow control, or none flow control are
supported
Power saving indication available on the hardware flow control output (CTS line): the line is
driven to the OFF state when the module is not ready to accept data signals
2400, 4800, 9600, 19200, 38400, 57600, 115200 b/s baud rates are supported
Auto baud rate detection (autobauding) is the default configuration
Frame format can be: 8N1 (8 data bits, no parity, 1 stop bit), or 8N2 (8 data bits, no parity,
2 stop bits), or 8E1 (8 data bits, even parity, 1 stop bit), or 8O1 (8 data bits, odd parity, 1 stop
bit), or 7E1 (7 data bits, even parity, 1 stop bit), or 7O1 (7 data bits, odd parity, 1 stop bit)
Automatic frame recognition is supported: this feature is the default configuration and it is
enabled in conjunction with the auto baud rate detection only
Default frame configuration with fixed baud is 8N1 (8 data bits, no parity, 1 stop bit),
2.5.1.1 Multiplexer protocol
SARA-G3 module has a software layer with MUX functionality, 3GPP TS 27.010 [11], available on the
UART physical link.
This is a data link protocol (layer 2 of OSI model) which uses HDLC-like framing and operates
between the module (DCE) and the application processor (DTE), and allows a number of
simultaneous sessions over the physical link (UART): the user can concurrently use AT command
interface on one MUX channel and data communication on another MUX channel.
SARA-G340 and SARA-G350 modules define the following virtual channels:
Channel 0: control channel
Channel 1 – 5: AT commands / data connection
Channel 6: GNSS tunneling
SARA-G300 and SARA-G310 modules define the following virtual channels:
Channel 0: control channel
Channel 1 – 2: AT commands / data connection
For more details, see the Mux Implementation Application Note [4].
See the u-blox AT Commands Manual [1] for the definition of the interface data mode and online command mode.
GNSS tunneling is not supported by SARA-G300 and SARA-G310 modules.