SARA-G3 series - System Integration Manual
UBX-13000995 - R06
Objective Specification
System description
Page 63 of 218
over the used physical link (UART or SPI): the user can concurrently use AT command interface on one
MUX channel and Packet-Switched / Circuit-Switched Data communication on another multiplexer channel.
Each session consists of a stream of bytes transferring various kinds of data such as SMS, CBS, PSD,
GNSS, AT commands in general. This permits, for example, SMS to be transferred to the DTE when a
data connection is in progress.
The following virtual channels are defined for SARA-G350 modules:
Channel 0: control channel
Channel 1 – 5: AT commands / data connection
Channel 6: GNSS tunneling
The following virtual channels are defined for SARA-G300 and SARA-G310 modules:
Channel 0: control channel
Channel 1 – 2: AT commands / data connection
For more details, refer to
Mux implementation Application Note [20].
1.9.2
Auxiliary asynchronous serial interface (UART AUX)
The auxiliary UART interface is a 3-wire unbalanced 1.8 V asynchronous serial interface (only the
RXD_AUX
data output and
TXD_AUX
data input are provided), available for SARA-G3 modules FW
upgrade by means of the u-blox EasyFlash tool and for Trace log capture (debug purpose). The AT
commands interface is not available on the auxiliary UART interface.
1.9.3
DDC (I
2
C) interface
SARA-G300 and SARA-G310 modules do not support DDC (I
2
C) interface.
An I
2
C bus compatible Display Data Channel (DDC) interface for communication with u-blox GNSS
receivers is available on
SDA
and
SCL
pins of SARA-G350 modules. Only this interface provides the
communication between the u-blox wireless module and u-blox positioning chips and modules. The AT
commands interface is not available on the DDC (I
2
C) interface.
DDC (I
2
C) slave-mode operation is not supported: the SARA-G350 wireless module can act as master
only, and the connected u-blox GNSS receiver automatically acts as slave in the DDC (I
2
C)
communication.
Two lines, serial data (
SDA
) and serial clock (
SCL
), carry information on the bus.
SCL
is used to
synchronize data transfers, and
SDA
is the data line. To be compliant to the I
2
C bus specifications, the
module bus interface pads are open drain output and pull up resistors must be used conforming to the
I
2
C bus specifications [13].
u-blox has implemented special features in SARA-G350 wireless modules to ease the design effort
required for the integration of a u-blox wireless module with a u blox GNSS receiver.
Combining a u-blox wireless module with a u-blox GNSS receiver allows designers to have full access to
the positioning receiver directly via the wireless module: it relays control messages to the GNSS receiver
