The LuckFox Pico has three serial ports: UART2, UART3, and UART4. Among them, UART2 is the debug port.

The LuckFox Pico Plus has four serial ports: UART2, UART3, UART4, and UART5. Among them, UART2 is the debug port.

】Performing serial port testing using the GPIO sysfs interface：

(The following operations need to be performed in the terminal of the Pico development board.)

1] View serial port：

root@linaro-alip:/home/linaro# ls /dev/ttyS*

/dev/ttyS3 /dev/ttyS4

##The serial port devices here are UART3 and UART4

2] Use the “stty” tool to query the serial port communication parameters：

linaro@linaro-alip:~$ stty -F /dev/ttyS3

speed 9600 baud; line = 0;

-brkint -imaxbel

##The default baud rate is 9600

3] Modify the baud rate, where ispeed is the input rate and ospeed is the output rate：

stty -F /dev/ttyS3 ispeed 115200 ospeed 115200

4] Disable echo：

stty -F /dev/ttyS3 -echo

## Disabling echo refers to the situation where the characters entered in the terminal or serial communication are no longer displayed on the terminal.

5] Operation process screenshot:

】Communicating with a Windows host：

Connect one end of the serial port module to the computer, and the other end to the physical pins 18 (GND), 19 (UART7_TX), and 20 (UART7_RX) of the LuckFox Pico.

Download and open PuTTY (or any other serial port software), select the serial port, and set the baud rate (default is 9600, please adjust it according to your actual modified value).

Execute the following command on the terminal of the development board to write the strings “Hello” and “world!” to the terminal device file using the echo command:

echo Hello > /dev/ttyS3

echo "world !" > /dev/ttyS3

The serial port debugging assistant on Windows will receive the content:

】Test the built-in sample program of the official SDK：

1] Download SDK&Compiling test example code or download Compiled example code.:

SDK GitHub Download

2] Transfer the test example code file to the development board.

(The following operations need to be performed in the terminal of the Pico development board)

3] Run the test sample program:

chmod 777 ./luckfox_uart_test

## Grant executable permissions to the file

./luckfox_uart_test 3

##The parameter 3 in the example represents UART3.

4] Open the serial communication device to receive data:

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