STM32的串口采用DMA方式接收数据测试

本文博客链接:,作者:jdh,转载请注明.

参考链接:http://www.amobbs.com/forum.php?mod=viewthread&tid=5511863&highlight=dma%E6%8E%A5%E6%94%B6

环境：

主机:WINXP

开发环境:MDK4.23

MCU:STM32F103CBT6

说明:

串口可以配置成用DMA的方式接收数据,不过DMA需要定长才能产生接收中断,如何接收可变长度的数据呢?

方法有以下3种:

1.将RX脚与一路时钟外部引脚相连,当串口一帧发完,即可利用此定时器产生超时中断.这个实时性较高,可以做到1个字节实时监测.

2.不改变硬件,开启一个定时器监控DMA接收,如果超时则产生中断.这个实时性不高,因为超时时间必须要大于需要接收帧的时间,精度不好控制.

3.STM32单片机有的串口可以监测总线是否处于空闲,如果空闲则产生中断.可以用它来监测DMA接收是否完毕.这种方式实时性很高.

本文采用第3种方式.在波特率576000下大数据包冲击证明可行.

源代码:

//串口接收DMA缓存#define UART_RX_LEN  128extern uint8_t Uart_Rx[UART_RX_LEN];

//串口接收DMA缓存uint8_t Uart_Rx[UART_RX_LEN] = {
   0};

//---------------------串口功能配置--------------------- //打开串口对应的外设时钟      RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 , ENABLE);  //串口发DMA配置   //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); //串口收DMA配置   //启动DMA时钟    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //DMA1通道5配置 DMA_DeInit(DMA1_Channel5); //外设地址 DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)(&USART1->DR); //内存地址 DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)Uart_Rx; //dma传输方向单向 DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC; //设置DMA在传输时缓冲区的长度 DMA_InitStructure.DMA_BufferSize = UART_RX_LEN; //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_MemoryDataSize_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_VeryHigh; //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_Channel5,&DMA_InitStructure); //使能通道5 DMA_Cmd(DMA1_Channel5,ENABLE);        //初始化参数      //USART_InitStructure.USART_BaudRate = DEFAULT_BAUD;      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 = DEFAULT_BAUD;  //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);  //中断配置 USART_ITConfig(USART1,USART_IT_TC,DISABLE); USART_ITConfig(USART1,USART_IT_RXNE,DISABLE); USART_ITConfig(USART1,USART_IT_IDLE,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);            //采用DMA方式发送 USART_DMACmd(USART1,USART_DMAReq_Tx,ENABLE); //采用DMA方式接收 USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE);    //启动串口      USART_Cmd(USART1, ENABLE);

//串口1接收中断   void USART1_IRQHandler(void)                               {    uint32_t temp = 0; uint16_t i = 0;  if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)    {     //USART_ClearFlag(USART1,USART_IT_IDLE);     temp = USART1->SR;     temp = USART1->DR; //清USART_IT_IDLE标志     DMA_Cmd(DMA1_Channel5,DISABLE);  temp = UART_RX_LEN - DMA_GetCurrDataCounter(DMA1_Channel5);  for (i = 0;i < temp;i++)  {   Data_Receive_Usart = Uart_Rx[i];     //启动串口状态机   usart_state_run();   }  //设置传输数据长度  DMA_SetCurrDataCounter(DMA1_Channel5,UART_RX_LEN);     //打开DMA  DMA_Cmd(DMA1_Channel5,ENABLE);    }   __nop(); }

测试结果:

条件:单片机运行于72M,与PC通信速率为460800.PC每隔100ms发送一个9个字节的包:c5 5c 6 0 6F 10 5 4e f7.

测试:单片机每次收到此包,一个IO作电平跳转,然后处理返回一包.

示波器显示:

放大显示: