一、初始化部分代码
//串口接收DMA缓存 uint8_t Uart_Rx[UART_RX_LEN] = {0}; uint32_t Uart_Send_Buffer[100] = {1}; void USART1_DMA1_CHANNEL4_Config(void) { GPIO_InitTypeDef GPIO_InitStructure; USART_InitTypeDef USART_InitStructure; DMA_InitTypeDef DMA_InitStructure; NVIC_InitTypeDef NVIC_InitStructure; //---------------------串口功能配置--------------------- //打开串口对应的外设时钟 RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 , ENABLE); //启动DMA时钟 RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //DMA发送中断设置 NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel4_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); //DMA1通道4配置 DMA_DeInit(DMA1_Channel4); //外设地址 DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)(&USART1->DR); //内存地址 DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)Uart_Send_Buffer; //dma传输方向单向 DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; //设置DMA在传输时缓冲区的长度 DMA_InitStructure.DMA_BufferSize = 100; //设置DMA的外设递增模式，一个外设 DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; //设置DMA的内存递增模式 DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; //外设数据字长 DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte; //内存数据字长 DMA_InitStructure.DMA_MemoryDataSize = DMA_PeripheralDataSize_Byte; //设置DMA的传输模式 DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; //设置DMA的优先级别 DMA_InitStructure.DMA_Priority = DMA_Priority_High; //设置DMA的2个memory中的变量互相访问 DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel4,&DMA_InitStructure); DMA_ITConfig(DMA1_Channel4,DMA_IT_TC,ENABLE); //使能通道4 //DMA_Cmd(DMA1_Channel4, ENABLE); //设置IO口时钟 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE); //串口1的管脚初始化--------------------------------------------- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //管脚9 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz; //选择GPIO响应速度 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出 GPIO_Init(GPIOA, &GPIO_InitStructure); //TX初始化 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; //管脚10 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz; //选择GPIO响应速度 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //浮空输入 GPIO_Init(GPIOA, &GPIO_InitStructure); //RX初始化 //初始化参数---------------------------------------------------- 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_InitStructure.USART_BaudRate = 115200; //初始化串口 USART_Init(USART1,&USART_InitStructure); //TXE发送中断,TC传输完成中断,RXNE接收中断,PE奇偶错误中断,可以是多个 USART_ITConfig(USART1,USART_IT_RXNE,ENABLE); //配置UART1中断-------------------------------------------------- NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3); NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn; //通道设置为串口1中断 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //中断占先等级0 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; //中断响应优先级0 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //打开中断 NVIC_Init(&NVIC_InitStructure); //初始化 //采用DMA方式发送 USART_DMACmd(USART1,USART_DMAReq_Tx,ENABLE); //启动串口 USART_Cmd(USART1, ENABLE); }
串口初始化后要连上DMA通道。DMA的通道在参考手册里有对应的表格DMA1和DMA2。
DMA_Cmd(DMA1_Channel4, ENABLE);
运行一次，后如果是DMA_Mode_Normal就进中断。所以准备好数据后，就可以开启DMA命令，就会自动发送。
二、DMA中断函数
void DMA1_Channel4_IRQHandler(void) { if(DMA_GetFlagStatus(DMA1_FLAG_TC4)==SET) { DMA_Cmd (DMA1_Channel4,DISABLE);//关闭DMA通道 DMA_ClearFlag(DMA1_FLAG_TC4);//清中断标志，否则会一直中断 // DMA_SetCurrDataCounter(DMA1_Channel4, 2);//重置传输数目，当再次达到这个数目就会进中断 // DMA_Cmd(DMA1_Channel4,ENABLE);//开启DMA通道 } }
中断函数需要清除中断。
启动发送函数，size是char数据长度
void DMA1_Channel4_Send(uint32_t *buff, uint16_t size) { uint16_t i; for(i=0;i<size;i++) { Uart_Send_Buffer[i] = buff[i]; } DMA_SetCurrDataCounter(DMA1_Channel4, size); DMA_Cmd(DMA1_Channel4, ENABLE); }