SARA-G3 series - Data Sheet
UBX-13000993 - R19 Interfaces
Page 14 of 47
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 mode14
MUX functionality, including dedicated GNSS tunneling virtual channel15
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].
14 See the u-blox AT Commands Manual [1] for the definition of the interface data mode and online command mode.
15 GNSS tunneling is not supported by SARA-G300 and SARA-G310 modules.