/**
  @page USART_WakeUpFromStop USART example
  
  @verbatim
  ******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
  * @file    Examples_LL/USART/USART_WakeUpFromStop/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the USART_WakeUpFromStop USART example.
  ******************************************************************************
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * 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
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * 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.
  *
  ******************************************************************************
  @endverbatim

@par Example Description
  
This example shows how to configure GPIO and USART peripherals
for allowing characters received on USART RX pin, to wake Up MCU from low power mode,
using STM32F0xx USART LL API. Peripheral initialization done 
using LL unitary services functions for optimization purpose (performance and size).

USART Peripheral is configured in asynchronous mode (9600 bauds, 8 data bit, 1 start bit, 1 stop bit, no parity).
No HW flow control is used.
USART Clock is based on HSI.

Example execution:
After startup from reset and system configuration, LED2 is blinking quickly during 3 sec,
then MCU  enters Stop mode (LED2 off).
On first  character reception by the USART from PC Com port (ex: using HyperTerminal)
after Stop Mode period, MCU wakes up from Stop Mode.
Received character value is checked :
- On a specific value ('S' or 's'), LED2 is turned On and program ends.
- If different from 'S' or 's', program performs a quick LED2 blinks during 3 sec and 
  enters again Stop mode, waiting for next character to wake up.

In case of errors, LED2 is slowly blinking (1 sec period).

@par Directory contents 

  - USART/USART_WakeUpFromStop/Inc/stm32f0xx_it.h          Interrupt handlers header file
  - USART/USART_WakeUpFromStop/Inc/main.h                  Header for main.c module
  - USART/USART_WakeUpFromStop/Inc/stm32_assert.h          Template file to include assert_failed function
  - USART/USART_WakeUpFromStop/Src/stm32f0xx_it.c          Interrupt handlers
  - USART/USART_WakeUpFromStop/Src/main.c                  Main program
  - USART/USART_WakeUpFromStop/Src/system_stm32f0xx.c      STM32F0xx system source file

@par Hardware and Software environment

  - This example runs on STM32F072xB devices.

  - This example has been tested with STM32F072RB-Nucleo RevC board and can be
    easily tailored to any other supported device and development board.

  - STM32F072RB-Nucleo RevC Set-up
    - Connect STM32 MCU board USART1 TX pin (GPIO PA9 connected to pin 21 of CN10 connector)
      to PC COM port RX signal
    - Connect STM32 MCU board USART1 RX pin (GPIO PA10 connected to pin 33 of CN10 connector)
      to PC COM port TX signal
    - Connect STM32 MCU board GND to PC COM port GND signal

@par How to use it ? 

In order to make the program work, you must do the following :
 - Open your preferred toolchain
 - Rebuild all files and load your image into target memory
 - Run the example

 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */
