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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ADC的多通道切换转换。

Function descriptions:
This example demonstrates the channel switching for an ADC.
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测试环境：
测试用板：PY32C642_STK
MDK版本： 5.28

Test environment:
Test board: PY32C642_STK
MDK Version: 5.28
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使用步骤：
1. 编译并下载程序；
2. 串口先打印一次通道3(PA6)的转换值
3. 之后切换到通道4(PA7)转换并打印其转换值.
4. 1s后又切换回通道3

Example execution steps:
1. Compile and download the program;
2. The serial port prints the conversion value of channel 3(PA6) first.
3. Then switch to channel 4(PA7) to convert and print its conversion value.
4. Switch back to channel 3 after 1 second
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注意事项：
通过USB转TTL模块连接PC与STK板,STK板与USB转TTL模块的连线方式如下；
STK板        USB转TTL模块
PB4(TX)  -->  RX
PB5(RX)  -->  TX
GND      -->  GND

Notes:
Connect the PC to the STK board through the USB to TTL module, and the connection
method between the STK board and the USB to TTL module is as follows:

STK board USB to TTL module
PB4 (TX) -->RX
PB5 (RX) -->TX
GND -->GND
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