Smart Wi-Fi Module Series
SC20-WL Hardware Design
SC20-WL_Hardware_Design
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The following figure is an example of connection between SC20-WL and PC. A voltage level translator
and a RS-232 level translator chip are also recommended to be added between the module and PC, as
these two UART interfaces do not support the RS-232 level, while support the 1.8V CMOS level only.
TXS0104EPWR
RTS_3.3V
RXD_3.3V
CTS_3.3V
TXD_3.3V
UART1_RTS
UART1_RXD
UART1_CTS
UART1_TXD
RTS_1.8V
RXD_1.8V
CTS_1.8V
TXD_1.8V
VCCA
Module
GND
GND
1.8V
VCCB
3.3V
DIN1
ROUT3
ROUT2
ROUT1
DIN4
DIN3
DIN2
DIN5
ROUT1B
FORCEON
/FORCEOFF
/INVALID
3.3V
DOUT1
DOUT2
DOUT3
DOUT4
DOUT5
RIN3
RIN2
RIN1
VCC
GND
OE
SN65C3238
DB-9
RTS
TXD
CTS
RXD
GND
Figure 16: RS232 Level Match Circuit (for UART1)
UART2 is similar to UART1. Please refer to UART1 reference circuit designs for UART2’s.
3.11. SD Card Interface
SC20-WL module supports SD cards with 4-bit data interfaces or SDIO devices. The pin definition of the
SD card interface is shown below.
Table 9: Pin Definition of SD Card Interface
Pin Name
Pin No.
I/O Description
Comment
SD_LDO11
38
PO
Power supply for SD card
Vnorm=2.95V
I
O
max=600mA
SD_LDO12
32
PO
1.8V/2.95V output power
supply
Support 1.8V or 2.95V power supply.
The maximum drive current is 50mA.
SD_CLK
39
DO
High speed digital clock
signal of SD card
Control characteristic impedance as
50
Ω.
NOTE