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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EPWM1_SOCA外部触发源触发ADC1对参考电压进行采样的功能，
每次触发、采样和转换完成后，串口每秒打印4次VCC电压值。

Function descriptions:
This example demonstrates the function of the EPWM1_SOCA external trigger source 
triggering ADC1 to sample the reference voltage. After each trigger, sampling and 
conversion are completed, the serial port prints the VCC voltage value 4 times per second.
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测试环境：
测试用板：PY32F420_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: PY32F420_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. 串口每秒打印4次VCC电压值。

Example execution steps:
1.Compile and download the program.
2.The serial port prints the VCC voltage value 4 times per 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；
@PrintfConfigStart
STK板        USB转TTL模块
PA2(TX)  -->  RX
PA3(RX)  -->  TX
GND       -->  GND
UART配置为波特率115200，数据位8，停止位1，校验位None
@PrintfConfigEnd

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:
@PrintfConfigStart
STK board USB to TTL module
PA2(TX)  -->  RX
PA3(RX)  -->  TX
GND       -->  GND
UART is configured as BaudRate 115200, data bit 8, stop bit 1, and parity None.
@PrintfConfigEnd
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