STM32串口DMA超时接收方法,可大大节约CPU时间
当某一个串口的数据接收超时以后,定时器中断中将数据拷贝到缓冲区,在主程序中可以判断数据标志UART1_Flag,大于0的时候即代表有数据接收到,可以处理,处理完后将此变量清零即可。
两个数据包间隔较小时,可以将定时器的周期调短些。
//超时时间定义
#define UART1_TimeoutComp 2//20ms
#define UART2_TimeoutComp 10//100ms
#define UART3_TimeoutComp 10//100ms
#define SRC_USART1_DR (&(USART1->DR)) //串口接收寄存器作为源头
#define SRC_USART2_DR (&(USART2->DR)) //串口接收寄存器作为源头
#define SRC_USART3_DR (&(USART3->DR)) //串口接收寄存器作为源头
extern u16 UART1_Flag,UART2_Flag,UART3_Flag;
extern u8uart1_data[200],uart3_data[500],uart2_data[500];
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];
u16 uart1_Flag_last=0,uart2_Flag_last=0,uart3_Flag_last=0;
//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
//复位计数器
TIM_DeInit(TIM2);
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);
//清中断
TIM_ClearFlag(TIM2, TIM_FLAG_Update);
//使能定时器中断
TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE);
TIM_UpdateDisableConfig(TIM2,DISABLE);
//定时器清零
TIM_SetCounter(TIM2,0);
//定时器启动
TIM_Cmd(TIM2,ENABLE);
}
//DMA初始化,只列出一个通道,其他两个通道相同
void DMA5_Init(void)
{
DMA_InitTypeDef DMA_InitStructure;
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
DMA_Cmd(DMA1_Channel5, ENABLE); //正式允许DMA
}
//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;
//初始化串口为38400,n,8,1
USART_InitStructure.USART_BaudRate = 38400;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_Parity = USART_Parity_No ;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
//初始化
USART_Init(USART1, &USART_InitStructure);
//启动串口,不需要接收中断
USART_Cmd(USART1, ENABLE);
//默认设置为输入状态
DMA5_Init();
}
//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);
UART1_Timeout++;
UART2_Timeout++;
UART3_Timeout++;
//------------------------------------------------------------------
i=DMA_GetCurrDataCounter(DMA1_Channel5);
DMA_ClearITPendingBit(DMA1_IT_GL5); //清除全部中断标志
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_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
if(i!=uart2_Flag_last)//未完成传输
{
UART2_Timeout=0;
uart2_Flag_last=i;
}
else
{
if(UART2_Timeout>UART2_TimeoutComp)//产生超时
{
if(i<500) //有数据接收到
{
UART2_FlagTemp=500-i;//得到接收到的字节数
for(i=0;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
if(i!=uart3_Flag_last)//未完成传输
{
UART3_Timeout=0;
uart3_Flag_last=i;
}
else
{
if(UART3_Timeout>UART3_TimeoutComp)//产生超时
{
if(i<500) //有数据接收到
{
UART3_FlagTemp=500-i;//得到接收到的字节数
for(i=0;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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