/**
  ******************************************************************************
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  * Copyright (C) 2023 Shanghai Eastsoft Microelectronics Co., Ltd. ALL rights reserved.
  *******************************************************************************
  */

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Version history:
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2023-04-26	V1.0.0	AE TEAM

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Demo introduction:
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本示例功能：电池和市电同时供电的系统，市电供电时系统全速运行。LVD监测到市电掉电后
立即切换到电池供电，MCU也进入休眠状态，STOP与SLEEP的唤醒端口为PD2（开发板上的按键）。
LVD监测到市电恢复系统立即进入全速运行状态。

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测试环境:
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测试用板；
ES-PDS-ES32VF2264LT

辅助工具：
多功能接口转换工具ES-Bridge

辅助软件：
ESBridge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) 将测试用板对应的VDD和GND引脚分别连接到ES-Bridge的VCC和GND；
3) 将测试用板与ESLINK2的连接断开，由ES-Bridge供电；
4) 按下测试用板的RESET键；
5) 上位机切换到功耗检测标签页，选择“开始”进行功耗监测；
6) LVD检测电源电压高于3.6V：MCU全速运行。PA15持续电平翻转；
7) LVD检测电源电压低于3.6V: MCU进入低功耗状态，PD2（按键）产生上升沿，MCU唤醒，对PA15进行
一次电平翻转后MCU继续进入低功耗状态。

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注意：
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1) 测试板与ES-Bridge需共GND。

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System clock:
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PLL 72MHz

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Pin connection: 
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PMU_EXTI     ---- PD2[GPIO_FUNC_1]
LED          ---- PA15[GPIO_FUNC_1]
