Ublox SARA-R5 Series System Integration Manual

SARA-R5 series - System integration manual
UBX-19041356 - R04 Design-in Page 84 of 118
C1-Public
Providing 2 UARTs with the TXD, RXD, RTS and CTS lines only
☞ Compatible with USIO variants 2/3/4; not compatible with USIO variants 0/1 (see section 1.9.1.1).
If RS-232 compatible signal levels are needed, two Maxim MAX13234E voltage level translators can be
used. These chip translates voltage levels from 1.8 V (module side) to the RS-232 standard.
If a 1.8 V application processor is used, the circuit should be implemented as described in Figure 60.
TxD
Application Processor
(1.8V DTE)
RxD
RTS
CTS
TxD
RxD
RTS
CTS
GND
SARA-R5 series
(1.8V DCE)
12
TXD (TxD1)
9
DTR (TxD2)
13
RXD (RxD1)
10
RTS (RTS1)
11
CTS (CTS1)
8
DCD (RxD2)
6
DSR (RTS2)
7
RI (CTS2)
GND
0Ω
TP
0Ω
TP
UART1
UART2
0Ω
TP
0Ω
TP
Figure 60: 2 UART interfaces application circuit with 5-wire links in DTE/DCE serial communications (1.8 V DTE)
If a 3.0 V application processor (DTE) is used, then it is recommended to connect the 1.8 V UART
interfaces of the module (DCE) by means of appropriate unidirectional voltage translators using the
module V_INT output as 1.8 V supply for the voltage translators on the module side, as in Figure 61.
4
V_INT
TxD
Application Processor
(3.0V DTE)
RxD
RTS
CTS
TxD
RxD
RTS
CTS
GND
SARA-R5 series
(1.8V DCE)
12
TXD (TxD1)
9
DTR (TxD2)
13
RXD (RxD1)
10
RTS (RTS1)
11
CTS (CTS1)
8
DCD (RxD2)
6
DSR (RTS2)
7
RI (CTS2)
GND
1V8
B1 A1
GND
U1
B3A3
VCCBVCCA
Unidirectional
voltage translator
C1
C2
3V0
DIR3
DIR2 OE
DIR1
VCC
B2 A2
B4A4
DIR4
1V8
B1 A1
GND
U2
B3A3
VCCBVCCA
Unidirectional
voltage translator
C3
C4
3V0
DIR3
DIR1
OE
B2 A2
B4A4
DIR4
DIR2
0Ω
TP
0Ω
TP
TP
UART1
UART2
0Ω
TP
0Ω
TP
Figure 61: 2 UART interfaces application circuit with 5-wire links in DTE/DCE serial communications (3.0 V DTE)
Reference
Description
Part number - Manufacturer
C1, C2, C3, C4
100 nF capacitor ceramic X7R 0402 10% 16 V
GCM155R71C104KA55 - Murata
U1, U2
Unidirectional voltage translator
SN74AVC4T774
9
- Texas Instruments
Table 39: Components for 2 UARTs application circuit with 5-wire links in DTE/DCE serial communications (3.0 V DTE)
☞ Provide accessible test points directly connected to TXD and RXD pins for FW update purpose and
to DCD and DTR pins for diagnostic purpose.
9
Voltage translator providing partial power down feature, so the 3 V supply can be also ramped up before V_INT 1.8 V supply

Ublox SARA-R5 Series Specifications

General

Brand	Ublox
Model	SARA-R5 Series
Category	Control Unit
Language	English