Smart Module Series
SC690A_Series_Hardware_Design 48 / 105
UART5 is a 4-wire UART interface with 1.8 V power domain. A level translator chip should be used if
your application is equipped with a 3.3 V UART interface. A level translator chip is recommended. The
following figure shows a reference design.
VCCA
VCCB
OE
A1
A2
A3
A4
GND
B1
B2
B3
B4
LDO9_1V8
UART 5_ RTS
UART5_ RXD
UART 5_ CTS
UART5_ TXD
RXD_3.3V
CTS_3.3V
TXD_3.3V
VDD_3.3V
U1
RTS_3.3V
C1
C2
Figure 13: Reference Circuit with Level Translator Chip (for UART5)
The following figure is an example of connection between the module and PC. A voltage level translator
and an RS-232 level translator chip are recommended to be added between the module and PC, as
shown below:
RXD_3.3V
CTS_3.3V
VCCA
Module
GND
GND
1.8 V
VCCB
3.3 V
DIN 1
ROUT 3
ROUT 2
ROUT 1
DIN 4
DIN 3
DIN 2
DIN 5
FORCEON
3.3V
DOUT1
DOUT2
DOUT3
DOUT4
DOUT5
RIN3
RIN2
RIN1
VCC
GND
OE
DB-9
RTS
TXD
CTS
RXD
GND
RTS_3.3V
UART5_TXD
UART5_RTS
UART5_RXD
UART5_CTS
TXD_1.8V
RTS_1.8V
RXD_1.8V
CTS_1.8V
/FORCEOFF
/INVALID
R1OUTB
TXD_3.3V
U1
U2
Figure 14: RS-232 Level Match Circuit (for UART5)
The reference circuit of debug UART and UART1 is similar to that of UART5.
UART1_RXD
61
DI
UART1 receive
GPIO_4
58
DI
General-purpose
input/output
Can be multiplexed into
UART1_CTS.
GPIO_5
59
DO
General-purpose
input/output
Can be multiplexed into
UART1_RTS.
NOTE
