LENA-R8 series - System integration manual
UBX-22015376 - R02
System description
Page 27 of 116
C1-Public
1.10.1.2
Cellular auxiliary UART interface
LENA-R8 series cellular system includes an auxiliary secondary UART serial interface (AUX UART) for
communication with a host processor, supporting:
•
AT / data communication
•
GNSS data tunneling
The auxiliary secondary UART interface is disabled by default, and it can be enabled by dedicated AT
command (see the AT commands manual
, +USIO AT command) as alternative function of the
DTR
,
DSR
,
DCD
and
RI
pins of the main primary UART interface, in mutually exclusive way.
The AUX UART interface provides RS-232 functionality conforming to ITU-T V.24
, 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 (for
detailed electrical characteristics, see the LENA-R8 series data sheet
), providing:
•
data lines (
DCD
as data output,
DTR
as data input),
•
hardware flow control lines (
RI
as flow control output,
DSR
as flow control input).
Similar to the main primary UART interface, one-shot autobauding is supported on the auxiliary
secondary UART interface and it is the default configuration, with other baud rates configurable by
+IPR AT command. The 8N1 frame format is supported and it is enabled by default, with other frame
formats configurable by +ICF AT command. For further details, see the AT commands manual
☞
The
DSR
and
DCD
pins toggle as output for ~600 ms during the boot of the module cellular system.
The
DSR
and
DCD
pins are also set as output during the firmware update over the USB interface.
Proper precaution must be taken for the
DSR
line if it is connected to an output of an external
device, or if it is grounded. Use for example an external 100 Ohm series resistor to detach the
output of the module from the output of the external device or the ground.
1.10.1.3
Multiplexer protocol
LENA-R8 series modules include multiplexer functionality on the main UART physical interface as per
3GPP TS 27.010
. The multiplexer functionality is not supported on the auxiliary UART interface.
The multiplexer functionality is a data link protocol which uses HDLC-like framing and operates
between the module (DCE) and the application processor (DTE), allowing several simultaneous
sessions over the physical link (main primary UART): the user can concurrently use AT interface on
one MUX channel and data communication on another MUX channel.
1.10.2
Cellular USB interface
LENA-R8 series modules include a High-Speed USB 2.0 interface with a 480 Mbit/s maximum data
rate, representing the main interface for transferring high speed data with a host application
processor, supporting:
•
AT / data communication
•
Ethernet-over-USB
•
GNSS data tunneling
•
FW upgrades by the FOAT feature
•
FW upgrades by dedicated tool running on host PC
•
Trace log capture for diagnostic purposes
The module acts as a USB device and can be connected to a USB host such as a Personal Computer
or an embedded application microprocessor equipped with compatible drivers.
The
USB_D+
/
USB_D-
lines carry USB serial bus data and signaling according to the Universal Serial
Bus Revision 2.0 specification
. The USB interface is enabled if an external valid USB VBUS voltage
applied on the
VUSB_DET
input pin of the module.
