简述DMA
DMA优点
老板想要寄送一个快递到北京，只需要一个口令安排员工即可，具体填写快递单号、物流、派送等一系列工作老板不用关心。最后快递被对方收到，通知一声老板即可。
实例代码：DMA发送配置
/* COMM通信 */
/************************************************函数名称 ：USART_COMM_Configuration功 能 ：通信串口配置参 数 ：无返 回 值 ：无作 者 ：strongerHuang*************************************************/void USART_COMM_Configuration(void){GPIO_InitTypeDef GPIO_InitStructure;USART_InitTypeDef USART_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;/* 时钟配置 */RCC_AHB1PeriphClockCmd(COMM_COM_TX_GPIO_CLK | COMM_COM_RX_GPIO_CLK, ENABLE);if((USART1 == COMM_COM) || (USART6 == COMM_COM))RCC_APB2PeriphClockCmd(COMM_COM_CLK, ENABLE);elseRCC_APB1PeriphClockCmd(COMM_COM_CLK, ENABLE);/* 复用配置 */GPIO_PinAFConfig(COMM_COM_TX_GPIO_PORT, COMM_COM_TX_SOURCE, COMM_COM_TX_AF);GPIO_PinAFConfig(COMM_COM_RX_GPIO_PORT, COMM_COM_RX_SOURCE, COMM_COM_RX_AF);/* 引脚配置 */GPIO_InitStructure.GPIO_Pin = COMM_COM_TX_PIN; //USART TxGPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; //复用模式GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;GPIO_Init(COMM_COM_TX_GPIO_PORT, &GPIO_InitStructure);GPIO_InitStructure.GPIO_Pin = COMM_COM_RX_PIN; //USART RxGPIO_Init(COMM_COM_RX_GPIO_PORT, &GPIO_InitStructure);/* NVIC配置 */NVIC_InitStructure.NVIC_IRQChannel = COMM_COM_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = COMM_COM_Priority;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);/* USART配置 */USART_InitStructure.USART_BaudRate = COMM_COM_BaudRate; //波特率USART_InitStructure.USART_WordLength = USART_WordLength_8b; //传输位数USART_InitStructure.USART_StopBits = USART_StopBits_1; //停止位USART_InitStructure.USART_Parity = USART_Parity_No ; //校验位USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //收发功能USART_Init(COMM_COM, &USART_InitStructure);USART_ClearFlag(COMM_COM, USART_FLAG_RXNE | USART_FLAG_TC);USART_ITConfig(COMM_COM, USART_IT_RXNE, ENABLE); //接收中断USART_DMACmd(COMM_COM, USART_DMAReq_Tx, ENABLE); //使能DMAUSART_Cmd(COMM_COM, ENABLE); //使能USART}
/* COMM_DMA */
/************************************************函数名称 ：USART_COMM_DMA_Configuration功 能 ：通信串口的DMA配置参 数 ：无返 回 值 ：无作 者 ：strongerHuang*************************************************/void USART_COMM_DMA_Configuration(void){DMA_InitTypeDef DMA_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;/* 使能时钟 */RCC_AHB1PeriphClockCmd(COMM_DMA_CLK, ENABLE);/* NVIC配置 */NVIC_InitStructure.NVIC_IRQChannel = COMM_TX_DMA_IRQn;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = COMM_TX_DMA_Priority;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);/* DMA配置 */DMA_DeInit(COMM_TX_DMA_STREAM);DMA_InitStructure.DMA_Channel = COMM_TX_DMA_CHANNEL; //DMA通道DMA_InitStructure.DMA_PeripheralBaseAddr = COMM_DR_ADDRESS; //外设地址DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)0; //内存地址(待传入参数)DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral; //传输方向DMA_InitStructure.DMA_BufferSize = 0; //传输长度(待传入参数)DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; //外设递增DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; //内存递增DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; //数据宽度DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; //循环模式DMA_InitStructure.DMA_Priority = DMA_Priority_Medium; //优先级DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;DMA_Init(COMM_TX_DMA_STREAM, &DMA_InitStructure);DMA_ClearFlag(COMM_TX_DMA_STREAM, COMM_TX_DMA_FLAG_TCIF);DMA_ITConfig(COMM_TX_DMA_STREAM, DMA_IT_TC, ENABLE); //使能DMA传输完成中断DMA_Cmd(COMM_TX_DMA_STREAM, DISABLE); //初始化禁止}
3.DMA发送UART数据包
/************************************************函数名称 ：COMM_SendBufByDMA功 能 ：通信串口通过DMA发送数据参 数 ：Buf ------ 数据(地址)Length --- 数据长度(字节)返 回 值 ：无作 者 ：strongerHuang*************************************************/void COMM_SendBufByDMA(uint8_t *Buf, uint16_t Length){DMA_Cmd(COMM_TX_DMA_STREAM, DISABLE); //关闭DMA//内存地址DMA_MemoryTargetConfig(COMM_TX_DMA_STREAM, (uint32_t)Buf, DMA_Memory_0);DMA_SetCurrDataCounter(COMM_TX_DMA_STREAM, Length); //设置DMA传输长度DMA_Cmd(COMM_TX_DMA_STREAM, ENABLE); //使能DMA}
