LENA-R8 series - System integration manual
UBX-22015376 - R02
Design-in
Page 90 of 116
C1-Public
2.11
GNSS serial communication interface
☞
LENA-R8001 modules do not include a GNSS receiver: GNSS UART interface is not available.
2.11.1
GNSS UART interface
The GNSS UART of LENA-R8001M10 modules, consisting of the
RXD_GNSS
data input line and the
TXD_GNSS
data output line of the internal u-blox M10 GNSS chipset as is illustrated in
, can
be used as serial interface for direct communication between the internal u-blox M10 GNSS chipset
and an external host.
In case 1.8 V external host application processor use, the GNSS UART can be directly connected as
illustrated in
LENA-R8001M10
48
RXD_GNSS
47
TXD_GNSS
TxD
RXD
GND
GND
Application
Processor
VCC
1V8
Test-Point
Test-Point
Figure 69: Application circuit for LENA-R8001M10 GNSS UART with 1.8 V external host application processor
In case 3 V external host application processor use, the GNSS UART has to be connected using proper
voltage translator as illustrated in
LENA-R8001M10
48
RXD_GNSS
47
TXD_GNSS
TxD
RXD
GND
GND
Application
Processor
VCC
Test-Point
Test-Point
1V8
B1
A1
GND
U1
B2
A2
VCCB
VCCA
C1
C2
3V0
DIR1
DIR2
OEn
99
VCC_GNSS
Unidirectional
Voltage Translator
Figure 70: Application circuit for LENA-R8001M10 GNSS UART with 3 V external host application processor
Reference
Description
Part number - manufacturer
C1, C2
100 nF Capacitor Ceramic
Various Manufacturers
U1
Unidirectional Voltage Translator
SN74AVC2T245
- Texas Instruments
Table 49: Components for LENA-R8001M10 GNSS UART with 3 V external host application processor
☞
It is recommended to provide access to the
RXD_GNSS
and
TXD_GNSS
pins of LENA-R8001M10
modules for diagnostic purpose, by means of test points directly connected to the pins.
☞
As long as
VCC_GNSS
is not supplied, the GNSS UART pins cannot be driven by an external host
processor. If driving the GNSS UART pins cannot be avoided, buffers are required for isolating the
GNSS UART pins.
☞
For more information and examples about GNSS UART external circuit guidelines, see the u-blox
M10 standard precision GNSS chip data sheet
2.12
GNSS Peripheral Input/Output
☞
LENA-R8001 modules do not include a GNSS receiver: GNSS PIOs are not available.
The GNSS peripheral input/output pins of LENA-R8001M10 modules, consisting of the
TIMEPULSE
output pin and the
EXTINT
external interrupt input pin as is illustrated in
, can be connected
