#include "wdg.h"
/*****************************************************************************
 * Function      : Iwdg_Init
 * Description   : none
 * Input         : u8 timeout  为以秒为单位的看门狗超时时间，不得低于1s,看门狗定时器的数据不能超过u16的大小65536
 * Output        : None
 * Return        : 
 * Others        : 
 * Record
 * 1.Date        : 20170412
 *   Author      : barry
 *   Modification: Created function

*****************************************************************************/
void Iwdg_Init(u8 timeout)
{  
  #define WDG_PRE         256
  #define WDG_PER_COUNT   (40000/WDG_PRE)
  #define IWDG_Prescaler  IWDG_Prescaler_256


  u8 max_timeout = 0xFFF / WDG_PER_COUNT;
  
  u16 reloadCount = 0;
  
  timeout = (timeout == 0)? 1:timeout;
  timeout = (timeout >= max_timeout)? max_timeout: timeout;
  
  reloadCount = timeout* WDG_PER_COUNT;

  /* Check if the system has resumed from IWDG reset */
  if (RCC_GetFlagStatus(RCC_FLAG_IWDGRST) != RESET)
  {
    RCC_ClearFlag();
  }

  /* IWDG timeout equal to 280 ms (the timeout may varies due to LSI frequency
  dispersion) */
  /* Enable write access to IWDG_PR and IWDG_RLR registers */
  IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable);

  /* IWDG counter clock: 40KHz(LSI) / 32 = 1.25 KHz */
  IWDG_SetPrescaler(IWDG_Prescaler);
  
  /* Set counter reload value to 1250, 1s timeout */
  IWDG_SetReload(reloadCount);

  /* Reload IWDG counter */
  IWDG_ReloadCounter();

  /* Enable IWDG (the LSI oscillator will be enabled by hardware) */
  IWDG_Enable();  
}