DMA+USART+stm32

Posted 2020-10-02

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众所周知，串口是按照字节传输的，每一次传输一个字节。要传一帧数据，需要按照协议，帧头，帧尾，长度等信息，从字节流里面去分离。或者按照超时去分离。

STM32里面提供了DMA传输方式，整个过程有硬件控制。不占用处理器时间，高效。

发包：采用DMA方式，DMA发包完成会生成一个DMA发包完成中断。

收包：采用DMA+串口空闲中断方式，DMA空闲中断在，收到串口数据，串口空闲1个字节，自动触发。

代码如下：

第一步：引脚和时钟初始化

void GPIO_Configuration(void)
{
        GPIO_InitTypeDef GPIO_InitStructure;
        /* 使能USART1 时钟和所在端口时钟 */
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
        /*初始化USART1_TX端口*/
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
        GPIO_Init(GPIOA, &GPIO_InitStructure);
        /*初始化USART1_RX端口  */
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
				GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
        GPIO_Init(GPIOA, &GPIO_InitStructure);
		
        /* 使能USART2时钟和USART2所占用引脚的时钟 */
        //RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
        /* 初始化USART2_Tx时钟 */
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
        GPIO_Init(GPIOA, &GPIO_InitStructure);
         /* 初始化USART2_Rx时钟 */
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
        GPIO_Init(GPIOA, &GPIO_InitStructure);    
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;        
        GPIO_Init(GPIOA, &GPIO_InitStructure);				
				/*初始化RS485引脚 */																			   
				GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;	
				GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;   
				GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; 
				GPIO_Init ( GPIOA, & GPIO_InitStructure );	
}

第二步：串口配置

void USART_Configuration(void)
{
        USART_InitTypeDef USART_InitStructure;
        /* USART1 115200 n  8  1 */
        USART_InitStructure.USART_BaudRate = 115200;
        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;
        USART_Init(USART1, &USART_InitStructure);
        //开串口空闲中断
        USART_ITConfig(USART1, USART_IT_IDLE , ENABLE);
		//使能USART1
        USART_Cmd(USART1, ENABLE);
        USART_ClearFlag(USART1, USART_FLAG_TC);
		
		/*usart2 115200 n 8 1*/
        USART_InitStructure.USART_BaudRate = 115200;
        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;
        USART_Init(USART2, &USART_InitStructure);
		//开串口空闲中断
        USART_ITConfig(USART2, USART_IT_IDLE , ENABLE);
	    //使能USART2
        USART_Cmd(USART2, ENABLE);
        USART_ClearFlag(USART2, USART_FLAG_TC); 
}

第三步：DMA设置

void DMA_Configuration(void)
{
		DMA_InitTypeDef DMA_InitStructure;
		/* DMA clock enable */
		RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);//DMA1
		/* DMA1 Channel4 (triggered by USART1 Tx event) Config */
		DMA_DeInit(DMA1_Channel4);
		DMA_InitStructure.DMA_PeripheralBaseAddr = 0x40013804;
		DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART1_SEND_DATA;
		DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
		DMA_InitStructure.DMA_BufferSize = 128;
		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_InitStructure.DMA_Priority = DMA_Priority_High;
		DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
		DMA_Init(DMA1_Channel4, &DMA_InitStructure);
	
		DMA_ITConfig(DMA1_Channel4, DMA_IT_TC, ENABLE);
		DMA_ITConfig(DMA1_Channel4, DMA_IT_TE, ENABLE);
		/* Enable USART1 DMA TX request */
		USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
		DMA_Cmd(DMA1_Channel4, DISABLE);
		/* DMA1 Channel7 (triggered by USART2 Tx event) Config */
		DMA_DeInit(DMA1_Channel7);
		DMA_InitStructure.DMA_PeripheralBaseAddr = 0x40004404;
		DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART2_SEND_DATA;
		DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
		DMA_InitStructure.DMA_BufferSize = 128;
		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_InitStructure.DMA_Priority = DMA_Priority_High;
		DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
		DMA_Init(DMA1_Channel7, &DMA_InitStructure);
		
		DMA_ITConfig(DMA1_Channel7, DMA_IT_TC, ENABLE);
		DMA_ITConfig(DMA1_Channel7, DMA_IT_TE, ENABLE);
		/* Enable USART1 DMA TX request */
		USART_DMACmd(USART2, USART_DMAReq_Tx, ENABLE);
		DMA_Cmd(DMA1_Channel7, DISABLE);
		/* DMA1 Channel5 (triggered by USART1 Rx event) Config */
		DMA_DeInit(DMA1_Channel5);
		DMA_InitStructure.DMA_PeripheralBaseAddr = 0x40013804;
		DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART1_RECEIVE_DATA;
		DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
		DMA_InitStructure.DMA_BufferSize = 128;
		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_InitStructure.DMA_Priority = DMA_Priority_High;
		DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
		DMA_Init(DMA1_Channel5, &DMA_InitStructure);
		DMA_ITConfig(DMA1_Channel5, DMA_IT_TC, ENABLE);
		DMA_ITConfig(DMA1_Channel5, DMA_IT_TE, ENABLE);
		/* Enable USART1 DMA RX request */
		USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
		DMA_Cmd(DMA1_Channel5, ENABLE);
		/* DMA1 Channel6 (triggered by USART1 Rx event) Config */
		DMA_DeInit(DMA1_Channel6);
		DMA_InitStructure.DMA_PeripheralBaseAddr = 0x40004404;
		DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART2_RECEIVE_DATA;
		DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
		DMA_InitStructure.DMA_BufferSize = 128;
		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_InitStructure.DMA_Priority = DMA_Priority_Medium;
		DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
		DMA_Init(DMA1_Channel6, &DMA_InitStructure);
		DMA_ITConfig(DMA1_Channel6, DMA_IT_TC, ENABLE);
		DMA_ITConfig(DMA1_Channel6, DMA_IT_TE, ENABLE);
		/* Enable USART2 DMA RX request */
		USART_DMACmd(USART2, USART_DMAReq_Rx, ENABLE);
		DMA_Cmd(DMA1_Channel6, ENABLE);
}

第四步：NVIC中断配置

void NVIC_Configuration(void)
{
		NVIC_InitTypeDef NVIC_InitStructure;
		/* Configure one bit for preemption priority */
		NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
		/* Enable the USART1 Interrupt串口空闲中断 */
		NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
		NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
		NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
		NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
		NVIC_Init(&NVIC_InitStructure);
		/* Enable the USART2 Interrupt 串口空闲中断 */
		NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
		NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
		NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
		NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
		NVIC_Init(&NVIC_InitStructure);
		//Enable DMA Channel4 Interrupt DMA 发包完成中断 
		NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn;
		NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
		NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
		NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
		NVIC_Init(&NVIC_InitStructure);
		//Enable DMA Channel7 Interrupt  DMA 发包完成中断
		NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel7_IRQn;
		NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
		NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
		NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
		NVIC_Init(&NVIC_InitStructure);
}

第五步：串口空闲中断配置

void USART1_IRQHandler(void)
{
        u16 DATA_LEN;
        if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)//收包完成，触发空闲中断
        {
                DMA_Cmd(DMA1_Channel5, DISABLE);//关掉DMA防干扰
                DATA_LEN=128-DMA_GetCurrDataCounter(DMA1_Channel5); //计算长度
                if(DATA_LEN > 0)
                {                        
                   //数据处理    
                                            
                }
                DMA_ClearFlag(DMA1_FLAG_GL5 | DMA1_FLAG_TC5 | DMA1_FLAG_TE5 | DMA1_FLAG_HT5);//清楚中断标志位，方便下一次接收
                DMA1_Channel5->CNDTR = 128;//
                USART1->SR;
                USART1->DR;
								
					   DMA_ClearITPendingBit(DMA1_IT_TC5);
					   DMA_ClearITPendingBit(DMA1_IT_TE5);
					   DMA_Cmd(DMA1_Channel5, DISABLE);//
					   DMA1_Channel5->CNDTR = 128;//?
					   DMA_Cmd(DMA1_Channel5, ENABLE);//
        }
        if(USART_GetITStatus(USART1, USART_IT_PE | USART_IT_FE | USART_IT_NE) != RESET)//
        {
                USART_ClearITPendingBit(USART1, USART_IT_PE | USART_IT_FE | USART_IT_NE);
        }
        USART_ClearITPendingBit(USART1, USART_IT_TC);
        USART_ClearITPendingBit(USART1, USART_IT_IDLE);
}
void USART2_IRQHandler(void)
{
        u16 DATA_LEN;
        if(USART_GetITStatus(USART2, USART_IT_IDLE) != RESET) //?????????
        {
                DMA_Cmd(DMA1_Channel6, DISABLE);
                DATA_LEN=512-DMA_GetCurrDataCounter(DMA1_Channel6); 
                if(DATA_LEN > 0)
                {                        
           
                }
                //DMA_Cmd(DMA1_Channel5, DISABLE);//??DMA,?????????
                DMA_ClearFlag(DMA1_FLAG_GL6 | DMA1_FLAG_TC6 | DMA1_FLAG_TE6 | DMA1_FLAG_HT6);//???
                DMA1_Channel6->CNDTR = 512;//???
                DMA_Cmd(DMA1_Channel6, ENABLE);//???,??DMA
                //?SR??DR??Idle
                USART2->SR;
                USART2->DR;	
				DMA_ClearITPendingBit(DMA1_IT_TC6);
				DMA_ClearITPendingBit(DMA1_IT_TE6);
				DMA_Cmd(DMA1_Channel6, DISABLE);//
				DMA1_Channel6->CNDTR = 128;//?
				DMA_Cmd(DMA1_Channel6, ENABLE);//
								
        }
        if(USART_GetITStatus(USART2, USART_IT_PE | USART_IT_FE | USART_IT_NE) != RESET)//??
        {
                USART_ClearITPendingBit(USART2, USART_IT_PE | USART_IT_FE | USART_IT_NE);
        }
        USART_ClearITPendingBit(USART2, USART_IT_TC);
        USART_ClearITPendingBit(USART2, USART_IT_IDLE);
}

第六步：DMA发包

void usart1_DMA_send_data(int DATA_LEN)
{
		DMA_Cmd(DMA1_Channel4, DISABLE); 
		DMA1_Channel4->CNDTR=DATA_LEN; //DMA1
		DMA_Cmd(DMA1_Channel4, ENABLE);   
}
void usart2_DMA_send_data(int DATA_LEN)
{
		DMA_Cmd(DMA1_Channel7, DISABLE); //
		DMA1_Channel7->CNDTR=DATA_LEN; //DMA1,?????
		DMA_Cmd(DMA1_Channel7, ENABLE);                  
}

第7步：配置发包完成中断

//DMA1_Channel4
void DMA1_Channel4_IRQHandler(void)
{
	DMA_ClearITPendingBit(DMA1_IT_TC4);
	DMA_ClearITPendingBit(DMA1_IT_TE4);
	DMA_Cmd(DMA1_Channel4, DISABLE);//
}
//DMA1_Channel7
void DMA1_Channel7_IRQHandler(void)
{
	DMA_ClearITPendingBit(DMA1_IT_TC7);
	DMA_ClearITPendingBit(DMA1_IT_TE7);
	DMA_Cmd(DMA1_Channel7, DISABLE);
}

第8步：RS485首发引脚配置

void set_RS485_TX_mode()
{
	int cnt = 72000;
	PAout(8) =1;
	while(cnt--);
}
void set_RS485_Rx_mode()
{
	int cnt = 72000;
	while(cnt--);
	PAout(8) =0;
}

第9步 DMA发包封装:

void rs485_DMA_send_data(uint8_t* data,uint8_t size)
{
	set_RS485_TX_mode();
	memcpy(USART1_SEND_DATA,data,size);
	usart1_DMA_send_data(size);	
	set_RS485_Rx_mode();
}
void USART_DMA_send_data(uint8_t* data,uint8_t size)
{
	memcpy(USART2_SEND_DATA,data,size);
	usart2_DMA_send_data(size);	
}

以上就是全部的API。经测试收发数据都正常。

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