/**
  @page PWR_EnterStandbyMode PWR standby example
  
  @verbatim
  ******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
  * @file    Examples_LL/PWR/PWR_EnterStandbyMode/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the PWR STANDBY mode 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 enter the system in STANDBY mode and wake-up from this
mode using external RESET or wake-up interrupt.

In the associated software, the system clock is set to 48 MHz, an EXTI line
is connected to the user button thru PC.13 and configured to generate an 
interrupt on falling edge upon key press.
LED2 is toggled each 200 ms in order to indicate that MCU is in RUN mode.

When a falling edge is detected on the EXTI line, an interrupt is generated. 
In the EXTI handler routine, the wake-up pin LL_PWR_WAKEUP_PIN1 is enabled and the 
corresponding wake-up flag cleared. Then, the system enters STANDBY mode causing 
LED2 to stop toggling. 

Next, a rising edge on PA.00 (connected to LL_PWR_WAKEUP_PIN1) will 
wake-up the system from STANDBY.
Alternatively, an external RESET of the board will lead to a system wake-up as well.

After wake-up from STANDBY mode, program execution restarts in the same way as 
after a RESET and LED2 restarts toggling.

LED2 is used to monitor the system state as follows:
 - LED2 fast toggling: system in RUN mode
 - LED2 slow toggling: system in RUN mode after exiting from standby mode
 - LED2 off : system in STANDBY mode

These steps are repeated in an infinite loop.

@note To measure the current consumption in STANDBY mode, remove JP6 jumper 
      and connect an ampere meter to JP6 to measure IDD current.     

@note This example can not be used in DEBUG mode due to the fact 
      that the Cortex-M0 core is no longer clocked during low power mode 
      so debugging features are disabled.

@par Directory contents 

  - PWR/PWR_EnterStandbyMode/Inc/stm32f0xx_it.h          Interrupt handlers header file
  - PWR/PWR_EnterStandbyMode/Inc/main.h                  Header for main.c module
  - PWR/PWR_EnterStandbyMode/Inc/stm32_assert.h          Template file to include assert_failed function
  - PWR/PWR_EnterStandbyMode/Src/stm32f0xx_it.c          Interrupt handlers
  - PWR/PWR_EnterStandbyMode/Src/main.c                  Main program
  - PWR/PWR_EnterStandbyMode/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 STMicroelectronics STM32F072RB-Nucleo RevC
    board and can be easily tailored to any other supported device
    and development board.

  - STM32F072RB-Nucleo RevC Set-up
    - LED2 connected to PA.05 pin
    - Put a wire between PA.00 (connected to pin 28 on CN7 connector) and 
    3.3V pin (pin 5 on CN7) to generate a rising edge on LL_PWR_WAKEUP_PIN1.
    - WakeUp Pin LL_PWR_WAKEUP_PIN1 connected to PA.00

@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>
 */
