Mux Protocol (3Gpp 27.010); Ddc (I C) Interface; Overview - u-blox LISA-C2 Series System Integration Manual

If the USB interface is not connected to the application processor, it is highly recommended to provide
direct access to the VUSB_DET, USB_D+, USB_D- lines for execution of firmware upgrade over USB and for
debugging purposes: testpoints can be added on the lines to accommodate the access. Provide access to
RESET_N pin, or to the PWR_ON pin, or enable the DC supply connected to the VCC pin to start the
module firmware upgrade
If the USB interface is not used, the USB_D+, USB_D- and VUSB_DET pins can be left unconnected, but it is
highly recommended to provide (test points) direct access to the lines for execution of firmware upgrade
and for debugging purposes.
1.9.4

MUX Protocol (3GPP 27.010)

LISA-C200 and FW75-C200 modules have a software layer with MUX functionality, 3GPP TS 27.010 Multiplexer
Protocol [8], available on the UART physical link. The USB interface doesn't 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 UART:
the user can concurrently use the AT command interface on one MUX channel and Packet-Switched Data
communication on another MUX channel. Each session consists of a stream of bytes transferring various kinds of
data such as SMS, PSD, 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 commands
•
Channel 2: data connection
2
1.10 DDC (I C) interface
2
DDC(I C) interface is supported only by LISA-C200-03S/23S and successive versions

1.10.1 Overview

2
An I C bus compatible Display Data Channel (DDC) interface for communication with u-blox GNSS receivers is
available on LISA-C modules. The communication between a u-blox cellular module and a u-blox GNSS receiver
is only provided by this DDC (I
Name Description
SCL 2
I C bus clock line
SDA I 2 C bus data line
Table 17: DDC pins
2
The DDC (I C) interface pins ESD sensitivity rating is 1 kV (HBM according to JESD22-A114F). Higher
protection level could be required if the lines are externally accessible on the application board. Higher
protection level can be achieved by mounting an ESD protection (e.g. EPCOS CA05P4S14THSG varistor
array) on the lines connected to these pins, close to accessible points.
u-blox has implemented special features in LISA-C200 and FW75-C200 cellular modules to ease the design effort
required for the integration of a u-blox cellular module with a u-blox GNSS receiver.
Combining a u-blox cellular module with a u-blox GNSS receiver allows designers to have full access to the GNSS
receiver directly via the cellular module: it relays control messages to the GNSS receiver via a dedicated DDC (I
UBX-13000620 - R21
LISA-C2 series and FW75-C200 - System Integration Manual
2
C) interface.
Early Production Information
Remarks
Open drain. External pull-up required.
Open drain. External pull-up required.
C)
2
System description
Page 34 of 103