Integration Manual

SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 Design-in Page 81 of 119
u-blox GNSS
3.0 V receiver
24
GPIO3
1V8
B1 A1
GND
U3
B2A2
VCCBVCCA
Unidirect ional
Volt age Translat or
C4
C5
3V0
TxD1
R1
INOUT
LDO Regulat or
SHDN n
R2
VM AIN3V0
U1
23
GPIO2
26
SDA
27
SCL
1V8
SDA_A SDA _B
GND
U2
SCL_ASCL_B
VCCAVCCB
I2C-bus Bidirect ional
Volt age Translat or
4
V_INT
C1
C2 C3
R3
SDA2
SCL2
VCC
DIR1
DIR2 OEn
OE
GNSS dat a ready
GNSS supply enabled
GND
SARA-R4/N4
(except ‘00 ’,’01’ versions)
Figure 52: Application circuit for connecting SARA-R4/N4 series modules to u-blox 3.0 V GNSS receivers
Reference Description Part Number - Manufacturer
R1, R2 4.7 kΩ Resistor 0402 5% 0.1 W RC0402JR-074K7L - Yageo Phycomp
R3 47 kΩ Resistor 0402 5% 0.1 W RC0402JR-0747KL - Yageo Phycomp
C2, C3, C4, C5 100 nF Capacitor Ceramic X5R 0402 10% 10V GRM155R71C104KA01 - Murata
U1, C1 Voltage Regulator for GNSS receiver and related output
bypass capacitor
See GNSS receiver Hardware Integration Manual
U2 I2C-bus Bidirectional Voltage Translator TCA9406DCUR - Texas Instruments
U3 Generic Unidirectional Voltage Translator SN74AVC2T245 - Texas Instruments
Table 35: Components for connecting SARA-R4/N4 series modules to u-blox 3.0 V GNSS receivers
For additional guidelines regarding the design of applications with u-blox 3.0 V GNSS receivers see the Hardware
Integration Manual of the u-blox GNSS receivers.
2.6.5.2 Guidelines for DDC (I
2
C) layout design
The DDC (I
2
C) serial interface requires the same consideration regarding electro-magnetic interference as any other digital
interface. Keep the traces short and avoid coupling with RF line or sensitive analog inputs, since the signals can cause the
radiation of some harmonics of the digital data frequency.
2.7 Audio
2.7.1 Guidelines for Audio circuit design
☞
☞☞
☞ Audio is not supported by “00”, “01”, “02” and “52” product versions: the I
2
S interface pins should not be driven by
any external device.
2.8 General Purpose Input/Output
2.8.1 Guidelines for GPIO circuit design
A typical usage of SARA-R4/N4 series modules’ GPIOs can be the following:
• Network indication provided over GPIO1 pin (see Figure 53 / Table 36 below)
• GNSS supply enable function provided by the GPIO2 pin (see section 2.6.5)
• GNSS Tx data ready function provided by the GPIO3 pin (see section 2.6.5)