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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OPA的可编程增益放大器功能,OPA的输出端会输出正端2倍的电压值。

Function descriptions:
This example demonstrates the programmable gain amplifier function of OPA, where
the output terminal outputs a voltage value twice of the positive terminal.
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测试环境：
测试用板：PY32F005_STK
MDK版本： 5.41
IAR版本： 9.20
GCC 版本：GNU Arm Embedded Toolchain 10.3-2021.10

Test environment:
Test board: PY32F005_STK
MDK Version: 5.41
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. PA2输入0.5V/1V/1.5V,PA0能输出1V/2V/3V.

Example execution steps:
1.Compile and download the program.
2.PA2 inputs 0.5V/1V/1.5V, PA0 can output 1V/2V/3V.
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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
GND       -->  GND
UART配置为波特率9600

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
GND      -->  GND
UART is configured as BaudRate 9600
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