SARA-G3 and SARA-U2 series - System Integration Manual
UBX-13000995 - R08
Objective Specification
System description
Page 53 of 188
1.9.1.5
Multiplexer protocol (3GPP 27.010)
SARA-G3 and SARA-U2 series modules have a software layer with MUX functionality, the
3GPP TS 27.010
Multiplexer Protocol
[13], available on the UART physical link. The auxiliary UART, the USB and the DDC (I
2
C)
serial interfaces do not support the multiplexer protocol.
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 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:
Channel 0: control channel
Channel 1: AT and Data
Channel 2: AT and Data
Channel 3: AT and Data (not available on SARA-G300 / SARA-G310 modules)
Channel 4: AT and Data (not available on SARA-G300 / SARA-G310 modules)
Channel 5: AT and Data (not available on SARA-G300 / SARA-G310 modules)
Channel 6: GNSS tunneling (not available on SARA-G300 / SARA-G310 modules)
Channel 7: SIM Access Profile (not available on SARA-G3 series modules)
For more details, refer to
Mux implementation Application Note
1.9.2
Auxiliary asynchronous serial interface (UART AUX)
The auxiliary UART interface is not available on SARA-U2 series modules.
SARA-G3 modules provide the auxiliary UART interface: it 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 module FW
upgrade by means of the u-blox EasyFlash tool and for diagnostic purpose.
The AT commands interface is not available on the auxiliary UART interface.
1.9.3
USB interface
The USB interface is not available on SARA-G3 series modules.
1.9.3.1
USB features
SARA-U2 modules include a High-Speed USB 2.0 compliant interface with maximum data rate of 480 Mb/s
between the module and a host processor.
The module itself acts as a USB device and can be connected to any USB host such as a Personal Computer or an
embedded application microprocessor for AT commands, data communication, FW upgrade by means of the
FOAT feature, FW upgrade by means of the u-blox EasyFlash tool and for diagnostic purpose.
The
USB_D+
/
USB_D-
pins carry USB serial data and signaling while the
VUSB_DET
input pin senses the VBUS
USB supply presence (nom5 V at the source) to detect the host connection and enable the interface.
The USB interface of the module is enabled only if a valid voltage is detected by the
VUSB_DET
input (see the
SARA-U2 series Data Sheet
[2]). Neither the USB interface, nor the whole module is supplied by the
VUSB_DET
input: the
VUSB_DET
senses the USB supply voltage and absorbs few microamperes.
