/******************** (C) COPYRIGHT 2008 STMicroelectronics ********************
* File Name          : readme.txt
* Author             : MCD Application Team
* Version            : V2.0.3
* Date               : 09/22/2008
* Description        : Description of the IWDG Example.
********************************************************************************
* THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE TIME.
* AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY DIRECT,
* INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING FROM THE
* CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE CODING
* INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
*******************************************************************************/

Example description
===================
This example shows how to reload at regulate period the IWDG counter using the
SysTick interrupt. The IWDG timeout is set to 280 ms (the timeout may varies due
to LSI frequency dispersion).

SysTick is configured to generate an interrupt every 250 ms. In the SysTick interrupt
service routine (ISR), the IWDG counter is reloaded to prevent an IWDG reset, and
a specific GPIO pin is toggled.
An EXTI is connected to a specific GPIO pin and configured to generate an interrupt
on its falling edge.
In the NVIC, this EXTI line corresspondant interrupt vector is enabled with a 
priority equal to 0, and the SysTick interrupt vector priority is set to 1 
(EXTI IT > SysTick IT).

The EXTI Line is used to simulate a software failure: when the EXTI Line event is
triggered (by pressing the Key push-button on the board), the corresponding interrupt
is served. In the ISR, the GPIO pin turns off and the EXTI line pending bit is 
not cleared. So the CPU executes the EXTI line ISR indefinitely and the SysTick 
ISR is never entered (IWDG counter not reloaded).
As a result, when the IWDG counter reaches 00h, the IWDG generates a reset.
If the IWDG reset is generated, an other specific GPIO pin is turned on after 
the system resumes operation.

If the EXTI Line event does not occur, the IWDG counter is indefinitely reloaded in
the SysTick ISR, which prevents any IWDG reset.

In this example the system is clocked by the high-speed external (HSE) clock (8 MHz).


Directory contents
==================
platform_config.h    Evaluation board specific configuration file
stm32f10x_conf.h     Library Configuration file
stm32f10x_it.c       Interrupt handlers
stm32f10x_it.h       Header for stm32f10x_it.c
main.c               Main program


Hardware environment
====================
This example runs on STMicroelectronics STM3210B-EVAL and STM3210E-EVAL evaluation
boards and can be easily tailored to any other hardware.
To select the STMicroelectronics evaluation board used to run the example, uncomment
the corresponding line in platform_config.h file.

 + STM3210B-EVAL 
    - Use LD1 and LD2 leds connected respectively to PC.06 and PC.07 pins, and the
      KEY push button connected to PB.09 pin.
 
 + STM3210E-EVAL
    - Use LD1 and LD2 leds connected respectively to PF.06 and PF.07 pins, and the
      KEY push button connected to PG.08 pin.

    
How to use it
=============
In order to make the program work, you must do the following:
- Create a project and setup all your toolchain's start-up files
- Compile the directory content files and required Library files:
  + stm32f10x_lib.c
  + stm32f10x_gpio.c
  + stm32f10x_rcc.c
  + stm32f10x_nvic.c
  + stm32f10x_iwdg.c
  + stm32f10x_flash.c
  + stm32f10x_exti.c  
  + stm32f10x_systick.c  

- Link all compiled files and load your image into target memory
- Run the example in standalone mode (without debugger connection)

******************* (C) COPYRIGHT 2008 STMicroelectronics *****END OF FILE******
