TOBY-L2 and MPCI-L2 series - System Integration Manual
UBX-13004618 - R07
Advance Information
System description
Page 54 of 158
1.9.3
DDC (I
2
C) interface
The I
2
C bus compatible Display Data Channel interface is not available on the MPCI-L2 series modules, as
AssistNow embedded GNSS positioning aiding, CellLocate
®
positioning through cellular information and
custom functions over GPIOs for the integration with u-blox positioning chips / modules.
The I
2
C bus compatible Display Data Channel interface is not supported by the TOBY-L2 series modules
“00”, “01” and “50” product versions, as the AssistNow embedded GNSS positioning aiding, CellLocate
®
positioning through cellular information and custom functions over GPIOs for the integration with u-blox
positioning chips / modules.
The
SDA
and
SCL
pins of TOBY-L2 series modules represent an I
2
C bus compatible Display Data Channel (DDC)
interface for the communication with u-blox GNSS receivers and with other external I
2
C devices as audio codecs:
an I
2
C master can communicate with more I
2
C slaves in accordance to the
I
2
C bus specifications
The DDC (I
2
C) interface is the only one interface dedicated for communication between u-blox cellular module
and u-blox positioning receivers. The AT commands interface is not available on the DDC (I
2
C) interface.
The DDC (I
2
C) interface pads of the module, serial data (
SDA
) and serial clock (
SCL
), are open drain output and
external pull up resistors must be used conforming to the
I
2
C bus specifications
u-blox has implemented special features in the cellular modules to ease the design effort for the integration of a
u-blox cellular module with a u-blox GNSS receiver (details in
GNSS Implementation Application Note
Combining a u-blox cellular module with a u-blox GNSS receiver allows designers to full access the GNSS receiver
directly via the cellular module: it relays control messages to the GNSS receiver via a dedicated DDC (I
2
C)
interface. A 2
nd
interface connected to the GNSS receiver is not necessary: AT commands via the AT interfaces of
the cellular module (UART, USB) allows a full control of the GNSS receiver from any host processor.
u-blox cellular modules feature embedded GNSS aiding that is a set of specific features developed by u-blox to
enhance GNSS performance, decreasing Time To First Fix (TTFF), thus allowing to calculate the position in a
shorter time with higher accuracy.
Additional custom functions over GPIO pins are designed to improve the integration with u-blox GNSS receivers:
GNSS receiver power-on/off: “GNSS supply enable” function over the
GPIO2
pin improves the positioning
receiver power consumption. When the GNSS functionality is not required, the positioning receiver can be
completely switched off by the cellular module controlled by the application processor over AT commands
The wake up from idle-mode when the GNSS receiver is ready to send data: “GNSS data ready” function
over the
GPIO3
pin improves the cellular module power consumption. When power saving is enabled in the
cellular module by the AT+UPSV command and the GNSS receiver does not send data by the DDC (I
2
C)
interface, the module automatically enters idle-mode whenever possible. With the “GNSS data ready”
function the GNSS receiver can indicate to the cellular module that it is ready to send data: the positioning
receiver can wake up the cellular module to avoid data loss even if power saving is enabled.
The RTC synchronization signal to the GNSS receiver: “GNSS RTC sharing” function over the
GPIO4
pin
improves GNSS receiver performance, decreasing the Time To First Fix (TTFF), and thus allowing to calculate
the position in a shorter time with higher accuracy. When GNSS local aiding is enabled, the cellular module
automatically uploads data such as position, time, ephemeris, almanac, health and ionospheric parameter
from the positioning receiver into its local memory, and restores this to the GNSS receiver at the next power
up of the positioning receiver
