Uart Interfaces - Quectel SC20-WL Hardware Design

3.10. UART Interfaces

The module provides two UART interfaces:

UART1: 4-wire UART interface which supports hardware flow control
Table 8: Pin Description of UART Interfaces
Pin Name Pin No
UART1_TXD 34
UART1_RXD 35
UART1_CTS 36
UART1_RTS 37
UART2_RXD 93
UART2_TXD 94
UART1 provides 1.8V logic level. A level translator should be used if customers' application is equipped
with a 3.3V UART interface. A level translator TXS0104EPWR provided by Texas Instruments is
recommended. The following figure shows the reference design.
LDO5_1V8
UART1_CTS
UART1_RTS
UART1_TXD
UART1_RXD
Figure 15: Reference Circuit with Level Translator Chip (for UART1)
SC20-WL_Hardware_Design

UART2: 2-wire UART interfaces and is used for debugging
I/O Description
DO UART1 transmit data
DI UART1 receive data
DI UART1 clear to send
DO UART1 request to send
UART2 receive data.
DI
Debug port by default.
UART2 transmit data.
DO
Debug port by default.
VCCA
C1
100pF
OE
A1
A2
TXS0104EPWR
A3
A4
VCCB
U1
GND
B1
B2
B3
B4
Smart Wi-Fi Module Series
SC20-WL Hardware Design
Comment
1.8V power domain.
If it is unused, keep it open.
1.8V power domain.
If it is unused, keep it open.
1.8V power domain.
If it is unused, keep it open.
1.8V power domain.
If it is unused, keep it open.
1.8V power domain.
If it is unused, keep it open.
1.8V power domain.
If it is unused, keep it open.
VDD_3.3V
C2
100pF
CTS_3.3V
RTS_3.3V
TXD_3.3V
RXD_3.3V
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