1、功能说明
    双USB, USB1和USB2 CDC 设备回环测试

2、使用环境

    软件开发环境：KEIL MDK-ARM V5.34
                  IAR EWARM 8.50.1 
    芯片支持：
        N32H760
        N32H762
        N32H765
        N32H765EC
        N32H785
        N32H785EC
        N32H787
    开发板支持：
        N32H787_EVB:     USBHS1支持主机/设备  USBHS2支持主机/设备
        N32H787_HMI:     USBHS1支持设备       USBHS2支持主机/设备
        N32H787_EVB_PRO: USBHS1支持设备       USBHS2支持主机/设备

3、使用说明
    描述相关模块配置方法；例如:时钟，I/O等 
         1. SystemClock：HSE_PLL 600MHz
         2. USBHS Clock: HSE 25MHz
         3. GPIO: KEY--PA0

    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 USB1和USB2 口，
            设备:电脑识别出虚拟串口设备, 打开 USB 虚拟串口，USB 虚拟串口发送数据，串口工具会马上收到刚刚发送的数据
            主机:连接OTG转接线，再接上鼠标或键盘，等待枚举完成,枚举完成后，按下KEY按键，开始鼠标或键盘数据通信
         


4、注意事项
    1. 可通过修改宏定义 USE_USB_HS_IN_FS 或 USE_USB_HS_IN_HS 切换设备为全速模式或者高速模式；
       另外需要使用10MHz、12MHz、19.2MHz、24MHz、25MHz、27MHz、30MHz、或40MHz外部晶体。
    2. 使用H78x工程时需保证CM4有代码运行，建议跑LED点灯Demo(examples_m4\GPIO\LedBlink)。

1. Function description
    Dual USB, USB1 and USB2 CDC device loopback test

2. Development environment
    Software development environment: KEIL MDK-ARM V5.34
                                      IAR EWARM 8.50.1 
    MCU support:
        N32H760
        N32H762
        N32H765
        N32H765EC
        N32H785
        N32H785EC
        N32H787
    Development board support：
        N32H787_EVB:     USBHS1 supports host/device, USBHS2 supports host/device
        N32H787_HMI:     USBHS1 supports device,      USBHS2 supports host/device
        N32H787_EVB_PRO: USBHS1 supports device,      USBHS2 supports host/device

3. How to use
    Describe the configuration method of related modules; for example: clock, I/O, etc. 
        1. SystemClock: HSE_PLL 600MHz
        2. USBHS Clock: HSE 25MHz
        3. GPIO: KEY--PA0

    Describe the testing steps and phenomena of the Demo
    1. After compiling, the downloaded program is reset and run;
    2. Connect the USB1 and USB2 ports via a USB cable, 
       Device: the computer will recognize virtual serial port devices, open the USB virtual serial port separately on the PC. 
               When data is sent through the USB virtual serial port, the serial port tool will immediately receive the data that was just sent.
       Host: Connect the OTG adapter, followed by the mouse or keyboard, and wait for enumeration to complete. 
             After enumeration is complete, press the KEY button to start mouse or keyboard data communication
      
        
4. Attention
    1. The device can be switched to Full-Speed mode or High-Speed mode by modify the macro definition USE_USB_HS_IN_FS or USE_USB_HS_IN_HS;
       In addition, external crystal of 10MHz, 12MHz, 19.2MHz, 24MHz, 25MHz, 27MHz, 30MHz or 40MHz is required.
    2. When using the H78x project, it is necessary to ensure that the CM4 has code to run, and it is recommended to run the LED lighting demo(examples_m4\GPIO\LedBlink). 