stm32 串口+DMA+环形FIFO缓存收发数据_单片机 环形fifo

μcos环境例程
freertos环境例程
重要几点
1.配置DMA，串口及环形buff之间的关系；
2.USART_IT_IDLE空闲中断接收完一帧数据，处理环形buff入口指针,通知用户程序接收完一次数据；
3.发送数据无需利用环形buff，直接将待传数据作为DMA的源地址，再使能相应DMA通道，根据串口TC中断判断发送完成；
4.用户程序中读取FIF0；

环形FIFO buff

FIFO实现为一个维护入口下标和出口下标的数组，循环覆写，与DMA的循环模式类似

typedef struct {
	uint8_t* buffer;	//FIFO数据
	uint16_t in;			//入口下标
	uint16_t out;			//出口下标
	uint16_t size;		//FIFO大小
}FIFO_Type;

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几个FIFO功能函数

void Fifo_Init(FIFO_Type* fifo, uint8_t* buffer, uint16_t size)
{
	fifo->buffer = buffer;
	fifo->in = 0;
	fifo->out = 0;
	fifo->size = size;
}

uint16_t Fifo_Get(FIFO_Type* fifo, uint8_t* buffer, uint16_t len)
{
	uint16_t lenght;
	uint16_t in = fifo->in;	
	uint16_t i;
	lenght = (in + fifo->size - fifo->out)%fifo->size;
	if(lenght > len)
		lenght = len;
	for(i = 0; i < lenght; i++)
	{
		buffer[i] = fifo->buffer[(fifo->out + i)%fifo->size];
	}
	fifo->out = (fifo->out + lenght)%fifo->size;
	return lenght;
}

uint16_t Fifo_Status(FIFO_Type* fifo)
{
	uint16_t lenght;
	lenght = (fifo->in + fifo->size - fifo->out)%fifo->size;
	return lenght;
}
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USART初始化

注意使能串口TC中断，IDLE中断及串口DMA收发，分别标志传输完成和接受完成，其他配置为常规配置，根据自己需求配置即可，串口1为例

  //GPIO端口设置
  GPIO_InitTypeDef GPIO_InitStructure;
	USART_InitTypeDef USART_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
	 
	RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1|RCC_APB2Periph_GPIOA, ENABLE);	//使能USART1，GPIOA时钟
  
	//USART1_TX   GPIOA.9
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //PA.9
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;	//复用推挽输出
  GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIOA.9
   
  //USART1_RX	  GPIOA.10初始化
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;//PA10
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空输入
  GPIO_Init(GPIOA, &GPIO_InitStructure);//初始化GPIOA.10  

  //Usart1 NVIC 配置
 	 NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;//抢占优先级3
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3;		//子优先级3
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;			//IRQ通道使能
	NVIC_Init(&NVIC_InitStructure);	//根据指定的参数初始化VIC寄存器
  
   //USART 初始化设置

	USART_InitStructure.USART_BaudRate = 115200;//串口波特率
	USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
	USART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
	USART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位
	USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
	USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;	//收发模式

  USART_Init(USART1, &USART_InitStructure); //初始化串口1
 USART_ITConfig(USART1, USART_IT_IDLE , ENABLE);//空闲中断
 USART_ITConfig(USART1, USART_IT_TC , ENABLE);//传输完成中断
 USART_DMACmd(USART1, USART_DMAReq_Tx|USART_DMAReq_Rx, ENABLE);//使能串口DMA收发
  USART_Cmd(USART1, ENABLE);                    //使能串口1 

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DMA初始化

使能相应的DMA通道，通道表如下

如上表得知，串口1的DMA收发通道为DMA1的通道4通道5，初始化如下

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);		

	DMA_DeInit(DMA1_Channel5);
	DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(&USART1->DR);
	DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)Uart1_Rx_Buffer;  //FIFO的buffer指针指向
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
	DMA_InitStructure.DMA_BufferSize = BSP_UART1_RX_SIZE;  //FIF0的buffer大小
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
	DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;  //DMA循环覆盖写入
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;
	DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
	DMA_Init(DMA1_Channel5, &DMA_InitStructure);
	/* Enable USART1 DMA TX request */

	DMA_Cmd (DMA1_Channel5,ENABLE); 

	DMA_DeInit(DMA1_Channel4);
	DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)(&USART1->DR);
	DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)0;  //传输再修改地址，并使能该通道
	DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
	DMA_InitStructure.DMA_BufferSize = 1;
	DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
	DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
	DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
	DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
	DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
	DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;
	DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
	DMA_Init(DMA1_Channel4, &DMA_InitStructure);

	//接收FIFO初始化
	Fifo_Init(&Uart1_Rx_Fifo,Uart1_Rx_Buffer,BSP_UART1_RX_SIZE);


	//同步量，RTOS相关
	OSMutexCreate (&Uart1TxSem, "uart1 tx mutex", &err); 
	OSSemCreate (&Uart1TxWaitSem, "uart1 tx wait sem", 0,&err); 
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串口中断服务函数

处理串口TC中断，IDLE中断

void Bsp_IntHandler(CPU_FNCT_VOID isr)//  RTOS相关
{
    CPU_SR_ALLOC();

    CPU_CRITICAL_ENTER();                                       /* Tell the OS that we are starting an ISR            */

    OSIntEnter();

    CPU_CRITICAL_EXIT();

    if (isr != (CPU_FNCT_VOID)0) {
        isr();
    }
    OSIntExit();  	
}
void USART1_IRQHandler(void)  //中断
{
	Bsp_IntHandler(USART1_IntHandler);
}
void USART1_IntHandler(void)   //   中断服务函数
{
	uint32_t temp = 0;
	OS_ERR err;	
	if(USART_GetITStatus(USART1,USART_IT_IDLE)!= RESET)//空闲中断
	{
		Uart1_Rx_Fifo.in = BSP_UART1_RX_SIZE - DMA_GetCurrDataCounter(DMA1_Channel5);
		OSTaskSemPost(&MyTask_TCB, OS_OPT_POST_NONE, &err);//通知用户任务接收到一次数据帧
		temp = USART1->SR; //软件序列清除IDLE位
		temp = USART1->DR; //先读USART_SR,然后读USART_DR
		USART_ClearITPendingBit(USART1,USART_IT_IDLE);
	}
	else if(USART_GetITStatus(USART1,USART_IT_TC)!= RESET)//发送完成中断
	{
		USART_ClearITPendingBit(USART1,USART_IT_TC);
		DMA_Cmd(DMA1_Channel4, DISABLE);
		OSSemPost (&Uart1TxWaitSem, OS_OPT_POST_NONE, &err);
 		if(err != OS_ERR_NONE)
		{
			temp = err;
		}			
	}	
}

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发送函数接收函数

发送，串口资源互斥访问，信号量通知串口发送成功

void Uart_Send(const uint8_t* buf, uint16_t len)
{
	OS_ERR err;
	if(len > BSP_UART1_TX_SIZE || len == 0)
	{
		return;
	}

	OSMutexPend(&Uart1TxSem, 500, OS_OPT_PEND_BLOCKING, (CPU_TS *) 0, &err);
	OSSemSet(&Uart1TxWaitSem, 0, &err);
	if(err != OS_ERR_NONE)
	{
		return err;
	}
	DMA_Cmd(DMA1_Channel4, DISABLE);
	DMA1_Channel4->CNDTR = len;//发送数据大小
	DMA1_Channel4->CMAR = (uint32_t)buf;//发送数据地址
	/* Enable USART1 DMA TX request */
	DMA_Cmd (DMA1_Channel4,ENABLE);
	OSSemPend(&Uart1TxWaitSem, 500, OS_OPT_PEND_BLOCKING, (CPU_TS *) 0, &err);
	 OSMutexPost (&Uart1TxSem, OS_OPT_POST_NONE, &err);
}


uint16_t Uart_1_Get(uint8_t *buffer, uint16_t len)
{
	return Fifo_Get(&Uart1_Rx_Fifo,buffer, len);  //读出长度len的fifo中的数据存在buffer参数中，fifo数据不足则有多少回多少
}
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