Wi-Fi&Bluetooth Module Series
FCM561D-P_Hardware_Design
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Table 9: Pin Definition of UARTs
The UART1 can be used for command communication and data transmission. It is recommended to use
the CH340 serial port tool and set the communication rate to 2000000 bps during flash download or
firmware upgrading. The UART1 connection between the module and the MCU is illustrated below.
UART1_TXD
UART1_RXD
UART_RXD
UART_TXD
Module
GND
GND
MCU
3V3
VBAT
Figure 4: UART1 Connection
3.4.4. SDIO Interface
In the case of multiplexing the module provides 1 SDIO 2.0 interface It can be used as a host to read
external SD cards or as a slave communicating with an external host. It allows a maximum 40 MHz clock
speed and supports 1 bit (default) or 4 bits data bus mode.
Pin Name
Pin No.
Multiplexing Function I/O
Comment
UART1_RXD
37
-
DI
UART1 receive
UART1_TXD
38
-
DO
UART1 transmit
USB_DP
6
UART1_CTS
DI
Clear to send signal to the module
USB_DM
7
UART1_RTS
DO
Request to send signal from the module
GPIO0
40
UART2_TXD
DO
UART2 transmit
GPIO1
39
UART2_RXD
DI
UART2 receive
GPIO40
69
UART3_RXD
DI
UART3 receive
GPIO41
35
UART3_TXD
DO
UART3 transmit