STM32串口+DMA使用

STM32有5个串口资源（USART1，USART2，USART3及UART4，UART5）。其中3个USART（通用同步/异步收/发器universalsynchronous asynchronous receiver and transmitter）；2个UART（通用异步收/发器universalasynchronous receiver and transmitter）；至于USART与UART的区别，如果只是拿来做串口用，没什么区别，在车载项目里，我们拿来做串口用，USART与UART在编程上并没有区别。

其中USART1，USART2，USART3，UART4支持DMA方式，UART5不支持DMA。(详见数据手册stm32f105&107_datesheet_English的P18/2.3.17)。

DMA（Derect MemoryAcess直接存储器存取），STM32有2个DMA，DMA1有7个通道，DMA2有5和通道，每个通道对应不同的外设（详见数据手册P272/13.3.7）。

1.时钟RCC配置：串口时钟 + DMA时钟 + IO时钟static void RCC_Configuration(void){RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4,ENABLE);  //串口时钟       RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2,ENABLE);  //DMA2时钟 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC| RCC_APB2Periph_AFIO, ENABLE);//IO时钟} 2.GPIO配置：UART4的TX为PC10脚，发送端配置为复用推挽输出模式（GPIO_Mode_AF_PP）UART4的RX为PC11脚，接收端配置为浮空输入模式（GPIO_Mode_IN_FLOATING）
static void GPIO_Configuration(void){GPIO_InitTypeDef GPIO_InitStructure;GPIO_InitStructure.GPIO_Pin =GPIO_Pin_10;              GPIO_InitStructure.GPIO_Mode =GPIO_Mode_AF_PP;  //TX复用推挽输出模式GPIO_InitStructure.GPIO_Speed =GPIO_Speed_50MHz;GPIO_Init(GPIOC,&GPIO_InitStructure);               GPIO_InitStructure.GPIO_Pin =GPIO_Pin_11;             GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //RX浮空输入模式GPIO_InitStructure.GPIO_Speed =GPIO_Speed_50MHz;GPIO_Init(GPIOC,&GPIO_InitStructure);}3.中断NVIC配置：配置两个DMA通道中断：UART4的RX的DMA通道为DMA2的通道3；UART4的TX的DMA通道为DMA2的通道5；static void NVIC_Configuration(void){NVIC_InitTypeDef NVIC_InitStructure;NVIC_InitStructure.NVIC_IRQChannel =UART4_IRQn;//串口中断NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority= 0;NVIC_InitStructure.NVIC_IRQChannelCmd =ENABLE;NVIC_Init(&NVIC_InitStructure);NVIC_InitStructure.NVIC_IRQChannel = DMA2_Channel3_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;NVIC_InitStructure.NVIC_IRQChannelCmd =ENABLE;NVIC_Init(&NVIC_InitStructure);NVIC_InitStructure.NVIC_IRQChannel = DMA2_Channel5_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd= ENABLE; NVIC_Init(&NVIC_InitStructure);}4.串口配置：即填充串口配置结构体static void UART4_Configuration(void){USART_InitTypeDef USART_InitStructure;USART_InitStructure.USART_BaudRate =115200;USART_InitStructure.USART_WordLength =USART_WordLength_8b;//数据位8位USART_InitStructure.USART_StopBits =USART_StopBits_1;//停止位1位USART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位USART_InitStructure.USART_HardwareFlowControl= USART_HardwareFlowControl_None;//不采用硬件流控USART_InitStructure.USART_Mode =USART_Mode_Rx | USART_Mode_Tx;//TX、RX都开启USART_Init(UART4,&USART_InitStructure);USART_Cmd(UART4, ENABLE); //使能UART4外设}5.DMA配置：DMA可以把数据从外设转移到内存（如串口接收的时候），也可以从内存转移到外设（如串口发送的时候）；不同方向的数据转移要各做相应的配置串口接收：void UART4_Start_DMA_Recv(void * recvBuf, uint32_t bufLen){DMA_InitTypeDef DMA_InitStructure;UART4_Configuration();/* DMA1 Channel5 (triggered by USART1 Rxevent) Config */DMA_InitStructure.DMA_PeripheralBaseAddr =(u32)&(UART4->DR);//外设基地址，串口4数据寄存器DMA_InitStructure.DMA_MemoryBaseAddr =(u32)recvBuf;//内存基地址，数组UART4_DMA_HeadBufDMA_InitStructure.DMA_DIR =DMA_DIR_PeripheralSRC;//SRC外设到内存DMA_InitStructure.DMA_BufferSize =bufLen;//DMA数据传输长度DMA_InitStructure.DMA_PeripheralInc =DMA_PeripheralInc_Disable;//外设地址不自增DMA_InitStructure.DMA_MemoryInc =DMA_MemoryInc_Enable;//内存地址自增DMA_InitStructure.DMA_PeripheralDataSize =DMA_PeripheralDataSize_Byte;//外设数据单位为1字节DMA_InitStructure.DMA_MemoryDataSize =DMA_MemoryDataSize_Byte;//内存数据单位为1字节DMA_InitStructure.DMA_Mode =DMA_Mode_Normal;//DMA传输数据模式，正常模式，传一轮DMA_InitStructure.DMA_Priority =DMA_Priority_High;//DMA通道优先级DMA_InitStructure.DMA_M2M =DMA_M2M_Disable;//禁止DMA内存到内存传输DMA_DeInit(DMA2_Channel3);//UART4的RX为DMA2通道3DMA_Init(DMA2_Channel3,&DMA_InitStructure);DMA_ITConfig(DMA2_Channel3, DMA_IT_TC,ENABLE);//配置DMA2发送完成后产生中断USART_DMACmd(UART4, USART_DMAReq_Rx,ENABLE);//配置串口向DMA发出Tx请求，请求传输数据DMA_Cmd(DMA2_Channel3, ENABLE);//正式开启DMA}串口发送：void UART4_Start_DMA_Send(void * sendBuf, uint32_t bufLen){DMA_InitTypeDefDMA_InitStructure;if (bufLen == 0)return ;memcpy(UART4_DMA_SendBuf, sendBuf, bufLen);DMA_InitStructure.DMA_PeripheralBaseAddr =(u32)(&UART4->DR);//外设基地址，串口4数据寄存器DMA_InitStructure.DMA_MemoryBaseAddr =(uint32_t)UART4_DMA_SendBuf; DMA_InitStructure.DMA_DIR =DMA_DIR_PeripheralDST;//DST内存到外设 DMA_InitStructure.DMA_BufferSize =bufLen; 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_PeripheralDataSize_Byte; DMA_InitStructure.DMA_Mode =DMA_Mode_Normal; DMA_InitStructure.DMA_Priority =DMA_Priority_High; DMA_InitStructure.DMA_M2M =DMA_M2M_Disable;DMA_DeInit(DMA2_Channel5); //UART4的TX为DMA2通道5DMA_Init(DMA2_Channel5,&DMA_InitStructure);          DMA_ITConfig(DMA2_Channel5, DMA_IT_TC,ENABLE);//配置DMA2发送完成后产生中断USART_DMACmd(UART4,USART_DMAReq_Tx,ENABLE);//配置串口向DMA发出Tx请求，请求传输数据DMA_Cmd(DMA2_Channel5, ENABLE);//正式开启DMAgDMA2Channel5Running = true;}6.DMA中断函数：串口接收或发送的时候，DMA数据传输完成后会产生中断，在相应中断函数编写代码(注意中断函数名一定要与启动文件中断向量表一致)DMA串口接收完成中断：void DMA2_Channel3_IRQHandler(void)//接收完成中断{    OSIntEnter();//ucos进入中断服务函数if(DMA_GetITStatus(DMA2_IT_TC3)){//获取剩余长度，一般都为0，调试用DMA_ClearITPendingBit(DMA2_IT_GL3);   //清除全部中断标志  DMA_Cmd(DMA2_Channel3, DISABLE);if(0 == DMAReciveState){if(HOST_MSG_START_CODE_FIRST_BYTE== UART4_DMA_HeadBuf[0])//比较读取的第1个字节FF{DMAReciveState = 1;UART4_Start_DMA_Recv((void*)(UART4_DMA_HeadBuf + 1), 3);//再读取后3个字节FFFFFF}else{UART4_Start_DMA_Recv((void*)UART4_DMA_HeadBuf, 1);}}else if(1 == DMAReciveState){if(HOST_MSG_START_CODE ==*(uint32_t *)UART4_DMA_HeadBuf)//比较整个起始码FFFFFFFF{DMAReciveState = 2;UART4_Start_DMA_Recv((void*)(UART4_DMA_HeadBuf + 4), 8);//再读取后8个字节（cmdtype+bodylen）}else{DMAReciveState = 0;memset(UART4_DMA_HeadBuf, 0, sizeof(UART4_DMA_HeadBuf));UART4_Start_DMA_Recv((void*)UART4_DMA_HeadBuf, 1);}}else if(2 == DMAReciveState){HOST_MSG_HEADER_T *pMCUMsgHeader;DMAReciveState = 3;pMsgBuffer = (uint8_t*)GetPhoneRecvBuf();//申请一个PhoneRecvBuf接收内存块if(pMsgBuffer == NULL){DMAReciveState = 0;memset(UART4_DMA_HeadBuf, 0,sizeof(UART4_DMA_HeadBuf));UART4_Start_DMA_Recv((void*)UART4_DMA_HeadBuf, 1);OSIntExit();    //means get out of the inturrept!return;}memcpy(pMsgBuffer,UART4_DMA_HeadBuf, sizeof(HOST_MSG_HEADER_T));//把数组数据（startcode+cmdtype+bodylen）拷贝到内存块pMCUMsgHeader = (HOST_MSG_HEADER_T*)pMsgBuffer;//指针类型转换UART4_Start_DMA_Recv((void*)(pMsgBuffer +sizeof(HOST_MSG_HEADER_T)), pMCUMsgHeader->bodyLen + CRC_LEN);//再读取后面数据（data+crc）到内存块}else if(3 == DMAReciveState){DMAReciveState = 0;memset(UART4_DMA_HeadBuf, 0,sizeof(UART4_DMA_HeadBuf));UART4_Start_DMA_Recv((void*)UART4_DMA_HeadBuf, 1);//此处再读1个字节（起始码第1个字节FF），开始下一轮接收数据if (pMsgBuffer != NULL){PutMsg2PhoneRecvQueue(pMsgBuffer);//把PhoneRecvBuf接收内存块指针发送到PhoneRecvQ接收消息队列pMsgBuffer = NULL;}}}OSIntExit();//ucos退出中断服务函数}
DMA串口发送完成中断：void DMA2_Channel5_IRQHandler(void)//发送完成中断
{OSIntEnter();if(DMA_GetITStatus(DMA2_IT_TC5)==SET){DMA_ClearFlag(DMA2_IT_GL5);DMA_Cmd(DMA2_Channel5,DISABLE);gDMA2Channel5Running = false;}OSIntExit();}

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DMA常用库函数：