LISA-C2 series and FW75-C200 - System Integration Manual
UBX-13000620 - R21
Early Production Information
System description
Page 30 of 103
u-blox
(DCE)
LISA (1.8v logic)
FW75 (3.0v logic)
TxD
Application Processor
(DTE)
RxD
RTS
CTS
DTR
DSR
RI
DCD
GND
TXD
RXD
RTS
CTS
RI
GND
0
Ω
0
Ω
TP
TP
0
Ω
0
Ω
TP
TP
Figure 14: UART interface application circuit with partial V.24 link (5-wire) in the DTE/DCE serial communication
If a 3.0 V Application Processor is used, appropriate unidirectional voltage translators must be provided using the
module
V_INT
output as 1.8 V supply, as described in Figure 15.
V_INT
TxD
Application Processor
(3.0V DTE)
RxD
RTS
CTS
DTR
DSR
RI
DCD
GND
LISA-C200 series
(1.8V DCE)
TXD
DTR
RXD
RTS
CTS
DSR
RI
DCD
GND
0
Ω
0
Ω
TP
TP
0
Ω
0
Ω
TP
TP
1V8
B1
A1
GND
U1
B3
A3
VCCB
VCCA
Unidirectional
Voltage Translator
C1
C2
3V0
DIR3
DIR2
OE
DIR1
VCC
B2
A2
B4
A4
DIR4
1V8
B1
A1
GND
U2
B3
A3
VCCB
VCCA
Unidirectional
Voltage Translator
C3
C4
3V0
DIR1
DIR3
OE
B2
A2
B4
A4
DIR4
DIR2
Figure 15: UART interface application circuit with complete V.24 link in DTE/DCE serial communication (3.0 V DTE)
Reference
Description
Part Number - Manufacturer
C1, C2, C3, C4
100 nF Capacitor Ceramic X7R 0402 10% 16 V
GRM155R61A104KA01 - Murata
U1, U2
Unidirectional Voltage Translator
SN74AVC4T774 - Texas Instruments
Table 14: Component for UART application circuit with complete V.24 link in DTE/DCE serial communication (3.0 V DTE)
Additional considerations
If the module USB interface is connected to the application processor, testpoints can be added on the lines to
accommodate the access. Each line must have a 0
Ω
series resistor mounted on it to detach the module pin from
any other connected device. Otherwise, if the USB interface is not connected to the application processor, it is
highly recommended to provide direct access to
VUSB_DET
,
USB_D+
,
USB_D-
lines for execution of firmware
upgrade over USB and for debugging purposes. In either case, also provide access to the
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.