SARA-G3 series - System Integration Manual
UBX-13000995 - R06
Objective Specification
Design-in
Page 137 of 218
“GNSS data ready” and “GNSS RTC sharing” functions are not supported by all u-blox GNSS
receivers HW or ROM/FW versions. Refer to the
GNSS Implementation Application Note [21] or to
the
Hardware Integration Manual of the u-blox GNSS receivers for the supported features.
illustrates an application circuit for SARA-G350 connection to a u-blox 1.8 V GNSS
receiver:
The
SDA
and
SCL
pins of the SARA-G350 module are directly connected to the related pins of the
u-blox 1.8 V GNSS receiver, with appropriate pull-up resistors.
The
GPIO3
and
GPIO4
pins are directly connected respectively to
TXD1
and
EXTINT0
pins of the u-
blox 1.8 V GNSS receiver providing “GNSS data ready” and “GNSS RTC sharing” functions.
The
GPIO2
pin is connected to the active-high enable pin of the voltage regulator that supplies the
u-blox 1.8 V GNSS receiver providing the “GNSS supply enable” function. A pull-down resistor is
provided to avoid a switch on of the positioning receiver when the SARA-G350 module is switched off
or in the reset state.
The
V_BCKP
supply output of the SARA-G350 wireless module is connected to the
V_BCKP
backup
supply input pin of the GNSS receiver to provide the supply for the GNSS real time clock and backup
RAM when the
VCC
supply of the wireless module is within its operating range and the
VCC
supply
of the GNSS receiver is disabled. This enables the u-blox GNSS receiver to recover from a power
breakdown with either a Hot-start or a Warm-start (depending on the actual duration of the GNSS
VCC
outage) and to maintain the configuration settings saved in the backup RAM.
SARA-G350
R1
IN
OUT
GND
GNSS LDO
Regulator
SHDN
u-blox GNSS
1.8 V receiver
SDA2
SCL2
R2
1V8
1V8
VMAIN
1V8
U1
23
GPIO2
SDA
SCL
C1
TxD1
EXTINT0
GPIO3
GPIO4
26
27
24
25
VCC
R3
V_BCKP
V_BCKP
2
Figure 55: DDC (I
2
C) application circuit for u-blox 1.8 V GNSS receiver
Reference
Description
Part Number - Manufacturer
R1, R2
4.7 k
Ω
Resistor 0402 5% 0.1 W
RC0402JR-074K7L - Yageo Phycomp
R3
47 k
Ω
Resistor 0402 5% 0.1 W
RC0402JR-0747KL - Yageo Phycomp
U1
Voltage Regulator for GNSS receiver
See GNSS receiver Hardware Integration Manual
Table 31: Components for DDC (I
2
C) application circuit for u-blox 1.8 V GNSS receiver
