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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复合设备功能
USB复合设备主要是借助 USB CDC和audio 类实现，将其模拟成一个双通道麦克风和CDC串口

Function descriptions:
This sample demonstrates the functionality of a USB composite device
The USB composite device is mainly implemented by means of the USB CDC and audio
classes, simulating it as a dual-channel microphone and a CDC serial port
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测试环境：
测试用板：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: 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. 下载并运行程序；
2. 在PC电脑上打开一个设备管理器,可以看到端口栏中新增一个USB串行设备，音频输入和
输出新增一个麦克风(PUYA COMPOSITE DEMO)设备。
3. 使用此麦克风进行语音，对面会听到1000hz的正弦波声音
4. PC打开串口设备，选择此设备，会收到0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 
0x08, 0x09, 0x0A 起始的128字节数据

1. Download and run the program;
2. Open a device manager on a PC, and you can see that a new USB serial device has
been added to the port bar, and a microphone (PUYA COMPOSITE DEMO) device has 
been added to the audio input and output
3. Use this microphone to make a voice call, and the other side will hear a 
1000hz sinusoidal sound. 
4. Open the PC serial port device, select this device,You will receive 128-byte 
data starting from 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, and 0x0A
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注意事项：
如果需要使用按键:
StartKit版本为V2.0以下,需将StartKit.h中的StartKitVersion 2 注释掉，并打开
StartKitVersion 1
StartKit版本为V2.0及以上版本,则无需操作

Notes:
If you need to use buttons:
StartKit version is below V2.0, you need to comment StartKitVersion 2 in
StartKit.h, and open StartKitVersion 1 
StartKit version is V2.0 and above, no operation is required

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