STM32 掉电检测程序

当VDD下降到PVD阀值以下或当VDD上升到PVD阀值之上时，根据外部中断第16线的上升/下降边沿触发设置，就会产生PVD中断

void  PVD_IRQHandler(void)
{
   led_ctrl(LED1, ON);

   if(PWR_GetFlagStatus(PWR_FLAG_PVDO))
   {
      MSD0_WriteSingleBlock(1, buf);
   }

   EXTI_ClearITPendingBit(EXTI_Line16);
}

void PVD_Init(void)
{
   EXTI_InitTypeDef EXTI_InitStructure;
   NVIC_InitTypeDef NVIC_InitStructure;

   NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
   NVIC_InitStructure.NVIC_IRQChannel = PVD_IRQn;
   NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
   NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
   NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
   NVIC_Init(&NVIC_InitStructure);

   RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);

   PWR_PVDLevelConfig(PWR_PVDLevel_2V9);	//可设置范围：2.2-2.9V
   PWR_PVDCmd(ENABLE);

   EXTI_DeInit();
   EXTI_StructInit(&EXTI_InitStructure);
   EXTI_InitStructure.EXTI_Line = EXTI_Line16;	//PVD连接到外部中断16
   EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
   EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising;
   EXTI_InitStructure.EXTI_LineCmd = ENABLE;
   EXTI_Init(&EXTI_InitStructure);
}

当检测到掉电以后，led会亮一下，然后进行掉电保存操作。

注意：

1. 掉电时间有限，如果耗时较长的操作，可能会操作失败；
2. 时钟频率设置也会有影响。（SysTick_Config）