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                                样例使用说明
                             Sample Description
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功能描述：
此样例演示了USB虚拟打印机功能。
主要通过USB printer类实现，将其模拟成一个打印机设备，当插在电脑上时，可以显示成
一个打印设备。

Function descriptions:
This example demonstrates the functionality of a USB virtual printer.
It is primarily implemented through the USB printer class, which simulates a 
printer device. When connected to a computer, it can be recognized and displayed
as a printing device.
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测试环境：
测试用板：PY32E407_STK
MDK版本： 5.28
IAR版本： 9.20
GCC版本：GNU Arm Embedded Toolchain 10.3-2021.10

Test environment:
Test board: PY32E407_STK
MDK Version: 5.28
IAR Version: 9.20
GCC Version: GNU Arm Embedded Toolchain 10.3-2021.10
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使用步骤：
1. 编译并下载程序；
2. 运行,电脑端出现一个打印机设备;

Example execution steps:
1.Compile and download the program.
2.Run, the computer side appears a printer device;
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注意事项：

Notes:  
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