#define SCB_SysCtrl              ((uint32_t)0xE000ED10)
#define SysCtrl_SLEEPDEEP_Set    ((uint32_t)0x00000004)

RCC->APB1ENR |= (1UL<<28);
PWR->CR |= (1UL<<0);
PWR->CR &=~(1UL<<1);

*(__IO uint32_t *) SCB_SysCtrl |= SysCtrl_SLEEPDEEP_Set;
__wfi();

PWR_EnterSTOPMode(PWR_Regulator_LowPower, PWR_STOPEntry_WFI);
    SYSCLKConfig_STOP();



void SYSCLKConfig_STOP(void)
{ErrorStatus HSEStartUpStatus;
/* Enable HSE */
RCC_HSEConfig(RCC_HSE_ON);

/* Wait till HSE is ready */
HSEStartUpStatus = RCC_WaitForHSEStartUp();

if(HSEStartUpStatus == SUCCESS)
{

  /* Enable PLL */
  RCC_PLLCmd(ENABLE);

  /* Wait till PLL is ready */
  while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);

  /* Select PLL as system clock source */
  RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

  /* Wait till PLL is used as system clock source */
  while(RCC_GetSYSCLKSource() != 0x08);
}
}