这个示例实现了一个复合设备的CDC（IAD）及HID CDC接口“USB CDC F32X和 F34x”在这两种接口实现的代码的基础上，该设备环回的OUT传输至IN。-This example implements a composite device of CDC (with IAD) and HID The CDC interface is based on the code of "USB CDC implementation for F32x and F34x" In ei