/**
  @page WWDG_Example WWDG example
  
  @verbatim
  ******************** (C) COPYRIGHT 2012 STMicroelectronics *******************
  * @file    WWDG/WWDG_Example/readme.txt 
  * @author  MCD Application Team
  * @version V1.1.1
  * @date    13-April-2012
  * @brief   Description of the WWDG example.
  ******************************************************************************
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
   @endverbatim

@par Example Description 

This example shows how to update at regular period the WWDG counter and how to
simulate a software fault generating an MCU WWDG reset on expiry of a programmed 
time period.

The WWDG timeout is set to 65.53ms and the refresh window is set to 80. 
The WWDG counter is refreshed each 50ms in the main program infinite loop to 
prevent a WWDG reset.
LED2 is also toggled each 50ms indicating that the program is running.

An EXTI Line is connected to a GPIO pin, and configured to generate an interrupt
on the rising edge of the signal.

The EXTI Line is used to simulate a software failure: once the EXTI Line event 
occurs, by pressing the Key push-button, the corresponding interrupt is served.
In the ISR, a write to invalid address generates a Hardfault exception containing
an infinite loop and preventing to return to main program (the WWDG counter is 
not refreshed).
As a result, when the WWDG counter falls to 63, the WWDG reset occurs.
If the WWDG reset is generated, after the system resumes from reset, LED1 turns on.

If the EXTI Line event does not occur, the WWDG counter is indefinitely refreshed
in the main program infinite loop, and there is no WWDG reset.

In this example the system clock is set to 32 MHz on Ultra Low Power Medium-Density
Devices.

@par Directory contents 

  - WWDG/WWDG_Example/stm32l1xx_conf.h    Library Configuration file
  - WWDG/WWDG_Example/stm32l1xx_it.c      Interrupt handlers
  - WWDG/WWDG_Example/stm32l1xx_it.h      Interrupt handlers header file
  - WWDG/WWDG_Example/main.c              Main program
  - WWDG/WWDG_Example/system_stm32l1xx.c  STM32L1xx system source file
  
@note The "system_stm32l1xx.c" is generated by an automatic clock configuration 
      system and can be easily customized to your own configuration. 
      To select different clock setup, use the "STM32L1xx_Clock_Configuration_V1.1.0.xls" 
      provided with the AN3309 package available on <a href="http://www.st.com/internet/mcu/family/141.jsp">  ST Microcontrollers </a>
         
@par Hardware and Software environment

  - This example runs on STM32L1xx Ultra Low Power High-, Medium-Density and Medium-Density Plus Devices.
  
  - This example has been tested with STMicroelectronics STM32L152D-EVAL (STM32L1xx 
    Ultra Low Power High-Density) and STM32L152-EVAL (STM32L1xx Ultra Low 
    Power Medium-Density) evaluation board and can be easily tailored to any 
    other supported device and development board.

  - STM32L152-EVAL Set-up
    - Use LD1 and LD2 leds connected respectively to PD.00 and PD.01 pins
    - Use the KEY push button connected to PA.00 pin (EXTI Line0).


  - STM32L152-EVAL Set-up
    - Use LD1 and LD2 leds connected respectively to PD.03 and PD.07 pins
    - Use the KEY push button connected to PA.00 pin (EXTI Line0).
      

@par How to use it ? 

In order to make the program work, you must do the following :
 - Copy all source files from this example folder to the template folder under
   Project\STM32L1xx_StdPeriph_Templates
 - Open your preferred toolchain 
 - Rebuild all files and load your image into target memory
 - Run the example

@note
- Ultra Low Power Medium-density devices are STM32L151xx and STM32L152xx 
  microcontrollers where the Flash memory density ranges between 64 and 128 Kbytes.
- Ultra Low Power Medium-density Plus devices are STM32L151xx, STM32L152xx and 
  STM32L162xx microcontrollers where the Flash memory density is 256 Kbytes.
- Ultra Low Power High-density devices are STM32L151xx, STM32L152xx and STM32L162xx 
  microcontrollers where the Flash memory density is 384 Kbytes.
    
 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */


