/**
  ******************************************************************************
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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  * Copyright (C) 2021 Shanghai Eastsoft Microelectronics Co., Ltd. ALL rights reserved.
  *******************************************************************************
  */

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Version history:
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2021-3-16	V1.0.0	AE TEAM

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Demo introduction:
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本示例功能：USART硬件流控制，CTS引脚电平为高时TX被禁止，等到电平为低时，数据发出。

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测试环境:
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测试用板；
ES-PDS-ES32H040xLQ-V1.0

辅助工具：
多功能接口转换工具ES-DAPLink(ES-Bridge)

辅助软件：
ES-Bridge上位机软件

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测试步骤：
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1) 编译工程，编译通过后将程序下载到目标芯片；
2) 将程序配置的目标芯片TX/RX对应的引脚分别连接ES-DAPLink(ES-Bridge)的RX/TX，目标芯片CTS引脚接高电平；
3) ES-DAPLink(ES-Bridge)通过USB线缆连接PC，打开上位机软件，“设备操作”选项里选择“打开”；
4) 上位机切换到UART标签页，按照程序同步配置波特率等参数（波特率9600-1位停止位-8位数据位-偶校验-正常模式），打开串口；
5) 复位芯片，或在线调试，运行程序，USART无数据发出；
6) 将CTS引脚切换到低电平，USART发送数据，并在上位机接收框打印。

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注意：
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1) 上位机UART模式选择“流控制模式”；
2) CTS为高电平时，TX虽被禁止，但TX端数据等待发送，CTS切换到低电平时，等待的数据立即发出；
3) 本示例CTS默认高电平；
4) 在线调试时，测试板上的TX/RX和PD02/PC12之间的短接帽需断开；
5) 测试板与ES-DAPLink(ES-Bridge)需共GND。

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System clock:
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Default internal HRC 24MHz

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Pin connection: 
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USART1_TX ---- PA2
USART1_RX ---- PA3
USART1_CTS --- PA0
