STM32串口DMA超时接收方法，可大大节约CPU时间

//超时时间定义
#define UART1_TimeoutComp 2  //20ms
#define UART2_TimeoutComp 10  //100ms
#define UART3_TimeoutComp 10  //100ms

u8 UART1_Timeout,UART2_Timeout,UART3_Timeout;
u16 UART1_FlagTemp,UART2_FlagTemp,UART3_FlagTemp;
u8 uart1_data_temp[200],uart2_data_temp[500],uart3_data_temp[500];

//定时器初始化
void TimerInit(void)
{
//定时器初始化数据结构定义
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
//初始化定时器，用于超时接收，20ms

TIM_TimeBaseStructure.TIM_Period          = 100; //计数上限，100*100us = 10000us = 10ms
TIM_TimeBaseStructure.TIM_Prescaler       = 4799; //预分频4800,48MHz主频，分频后时钟周期100us
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;  //不分频
TIM_TimeBaseStructure.TIM_CounterMode    = TIM_CounterMode_Up;  //向上计数
TIM_TimeBaseStructure.TIM_RepetitionCounter=0;
//初始化
TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);

DMA_DeInit(DMA1_Channel5); //将DMA的通道1寄存器重设为缺省值
  DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)SRC_USART1_DR; //源头BUF既是 (&(USART1->DR))
  DMA_InitStructure.DMA_MemoryBaseAddr = (u32)uart1_data_temp; //目标BUF 既是要写在哪个个数组之中
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC; //外设作源头//外设是作为数据传输的目的地还是来源
  DMA_InitStructure.DMA_BufferSize = 200; //DMA缓存的大小单位在下边设定
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; //外设地址寄存器不递增
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; //内存地址递增
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte; //外设字节为单位
  DMA_InitStructure.DMA_MemoryDataSize = DMA_PeripheralDataSize_Byte; //内存字节为单位
  DMA_InitStructure.DMA_Mode = DMA_Mode_Circular; //工作在循环缓存模式
  DMA_InitStructure.DMA_Priority = DMA_Priority_High; //4优先级之一的(高优先)VeryHigh/High/Medium/Low
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; //非内存到内存
  DMA_Init(DMA1_Channel5, &DMA_InitStructure); //根据DMA_InitStruct中指定的参数初始化DMA的通道1寄存器
  DMA_ITConfig(DMA1_Channel5, DMA_IT_TC, ENABLE); //DMA5传输完成中断
  USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE); //使能USART1的接收DMA请求

//串口初始化，只列出一个通道，其他两个通道相同
void USART1_Configuration(void)
{
//串口初始化数据结构定义
USART_InitTypeDef USART_InitStructure;

//定时器中断服务程序
void TIM2_IRQHandler(void)
{
  u16 i;
  //清定时器中断
  TIM_ClearITPendingBit(TIM2, TIM_FLAG_Update);

if(i!=uart1_Flag_last)  //未完成传输
  {
    UART1_Timeout=0;
uart1_Flag_last=i;
  }
  else
  {
if(UART1_Timeout>UART1_TimeoutComp)  //产生超时
{
   if(i<200) //有数据接收到
   {
      UART1_FlagTemp=200-i;    //得到接收到的字节数

for(i=0;i<UART1_FlagTemp;i++)  //将数据拷贝到缓冲区
   uart1_data[i]=uart1_data_temp[i];
UART1_Flag=UART1_FlagTemp;

DMA_ClearFlag(DMA1_FLAG_TC5);
DMA_Cmd(DMA1_Channel5, DISABLE); //正式允许DMA
DMA5_Init();
   }
   UART1_Timeout=0;
}
  }
  //------------------------------------------------------------------
  i=DMA_GetCurrDataCounter(DMA1_Channel6);
  DMA_ClearITPendingBit(DMA1_IT_GL6); //清除全部中断标志

for(i=0;i<UART2_FlagTemp;i++)  //将数据拷贝到缓冲区
   uart2_data[i]=uart2_data_temp[i];
UART2_Flag=UART2_FlagTemp;

DMA_ClearFlag(DMA1_FLAG_TC6);
DMA_Cmd(DMA1_Channel6, DISABLE); //正式允许DMA
DMA6_Init();

   }
   UART2_Timeout=0;
}
  }
  //------------------------------------------------------------------
  i=DMA_GetCurrDataCounter(DMA1_Channel3);
  DMA_ClearITPendingBit(DMA1_IT_GL3); //清除全部中断标志

for(i=0;i<UART3_FlagTemp;i++)  //将数据拷贝到缓冲区
   uart3_data[i]=uart3_data_temp[i];
UART3_Flag=UART3_FlagTemp;

DMA_ClearFlag(DMA1_FLAG_TC3);
DMA_Cmd(DMA1_Channel3, DISABLE); //正式允许DMA
DMA3_Init();

   }
   UART3_Timeout=0;
}
  }
}

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STM32串口DMA超时接收方法，可大大节约CPU时间

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