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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模块的Vrefbuf和Vrefint采样功能，通过采样Vrefint的值，计算得出
Vrefbuf的值，并通过串口打印出来。

Function descriptions:
This example demonstrates the Vrefbuf and Vrefint sampling functions of the ADC
module. By sampling the value of Vrefint, the value of Vrefbuf is calculated and
printed through the serial port.
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测试环境：
测试用板：PY32F072C_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: PY32F072C_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. 编译下载程序到MCU，并运行；
2. 串口每隔1s打印Vrefbuf的电压值。

Example execution steps:
1. Compile and download the program and run it;
2. The serial port prints the voltage value of Vrefbuf every 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
PA02(TX)  -->  RX
PA03(RX)  -->  TX
GND       -->  GND

Notes:
Connect the PC to the STK board through the USB to TTL module, the connection
between the STK board and the USB to TTL module is as follows:
STK board      USB to TTL module
PA02(TX)  -->  RX
PA03(RX)  -->  TX
GND        --> GND
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