1、功能说明

    1、此例程展示 USB CDC 设备

2、使用环境

    /* 硬件环境：工程对应的开发硬件平台 */
    开发板：N32L43XM-STB N32L40XM-STB V1.1

3、使用说明

    /* 描述相关模块配置方法；例如:时钟，I/O等 */
    SystemClock：96MHz
    USB Clock：48MHz
    GPIO:   LED:D1--PA8、D2--PB4
    日志：  USART1: TX--PA9  RX--PA10    波特率：115200


    /* 描述Demo的测试步骤和现象 */
    1.编译后下载程序复位运行
    2.通过 USB 线连接 J3 USB 口，USB 挂载完成后，在电脑设备管理中可以看到新增的串口，打开 USB 虚拟串口，可以看到串口一直接收到数据，虚拟串口也可以发送数据，发送的数据可以通过日志串口进行打印输出

4、注意事项
    无

1. Function description
    This routine shows a USB CDC device

2. Use environment
    Hardware environment: development hardware platform corresponding to the project 
    Development board:      N32L43XM-STB N32L40XM-STB V1.1

3. Instructions for use
    Describe the configuration method of related modules; for example: clock, I/O, etc. 
        1. SystemClock: 96MHz
    	2. USB Clock：48MHz
    	3. GPIO:   LED:D1--PA8、D2--PB4
        LOG: USART1: TX--PA9 RX--PA10 Baud rate: 115200

    Describe the test steps and phenomena of Demo 
        1. After compiling, download the program to reset and run;
        2. Connect the USB cable to the J3 USB port. After the USB is mounted, you can see the new serial port in computer device management. 
           Open the USB virtual serial port, you can see that the serial port is directly received, the virtual serial port can also send data, and the transmitted data can be printed through the log serial port.

4. Attention
    None.