LISA-U2 series - System integration manual
UBX-13001118 - R27
System description
Page 74 of 183
C1-Public
1.9.3
USB interface
LISA-U2 modules provide a high-speed USB interface at 480 Mbit/s compliant with the Universal
Serial Bus Revision 2.0 specification
. It acts as a USB device and can be connected to any USB host
such as a PC or other application processor.
The USB-device shall look for all upper SW layers like any other serial device. This means that the
LISA-U2 modules emulate all serial control logical lines.
Name
Description
Remarks
VUSB_DET
USB detect input
Apply 5 V typical to enable USB
USB_D+
USB Data Line D+
90
Ω
nominal differential characteristic impedance (Z
0
)
30
Ω
nominal common mode characteristic impedance (Z
CM
)
Pull-up or pull-down resistors and external series resistors as
required by the USB 2.0 high-speed specification
the USB pad driver and need not be provided externally.
USB_D-
USB Data Line D-
90
Ω
nominal differential characteristic impedance (Z
0
)
30
Ω
nominal common mode characteristic impedance (Z
CM
)
Pull-up or pull-down resistors and external series resistors as
required by the USB 2.0 high-speed specification
are part of
the USB pad driver and need not be provided externally.
Table 33: USB pins
☞
The USB interface pins ESD sensitivity rating is 1 kV (Human Body Model according to
JESD22-A114F). Higher protection levels could be required if the lines are externally accessible on
the application board. Higher protection levels can be achieved by mounting a very low capacitance
(i.e. less or equal to 1 pF) ESD protection (e.g. Tyco Electronics PESD0402-140 ESD protection
device) on the lines connected to these pins, close to the accessible points.
1.9.3.1
USB features
LISA-U2 modules include a High-Speed USB 2.0 compliant interface with a maximum data rate of
480 Mbit/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 purposes.
The
USB_D+
/
USB_D-
lines carry the USB serial bus 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 LISA
–
U2 series data sheet
). 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 only a few
microamperes.
LISA-U2 series modules can provide the following functions over the USB interface:
•
CDC-ACM for AT commands and data communication
•
CDC-ACM for GNSS tunneling
•
CDC-ACM for diagnostic
•
CDC-ACM for SAP (SIM Access Profile)
•
CDC-ECM for Ethernet-over-USB