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STM32学习笔记三 竹天笑
前言：开始学USART+DMA的时候看到帖子《STM32 UART DMA实现未知数据长度接收》，觉得方法妙极了。此下出自此帖子——（整体的思路是这样的，一开始设置好DMA接收，可以把缓冲区长度设置为帧最大长度，我们可以把RX连接到定时器的管脚输入端，并且一开始设置输入并且使能引脚下降沿中断，当帧的第一个字节发送时，因为起始位为低电平，空闲时UART为高电平，满足条件，进入中断，禁止中断，并且在中断中开启定时器，该定时器工作在复位模式，上升沿复位，并且设置好定时器输出比较值为超时时间，比如20ms，这样，在传输后面字节时，肯定会有高低电平出现，即便是传输的是0x00，0xFF，虽然UART数据区不变，但是都为1，或都为0，但是因为起始位为低电平，停止位是高电平，所以肯定会有上升沿，定时器会一直复位，输出定时器的计数器一直到达不了输出比较值，当一帧传输结束后，定时在最后一个字节复位后，由于没有数据继续到达，无法复位，则计数器就能计到输出比较值，这时发出中断，在定时器中断中可以计算出接收数据的长度，并且通知外部数据已经接收完毕。）
今天我在工作中调通了另一种USART+DMA接收未知数据长度的接收，使用的是USRAT空闲总线中断接收，这种方法也在网站上比较多见，以前没试过，今天才知道如此的爽，另外我使用DMA发送USART数据替代了以前的查询法发送，发现更加爽了。其速度快了很多，尤其是在大量数据传输与发送的时候其优势更加明显。
我举个例子：1、后台数据->USART1-> USART2->其它设备，其它设备数据->USART2-> USART1->后台，这两个数据过程也可能同时进行。
2、由于硬件的限制，USART1和USART2的传输波特率不一样，比如USART1使用GPRS通信，USART2使用短距离无线通信；或者USART1使用以太网通信，USART2使用485总线通信。
由于在寝室只有笔记本电脑，只有一个串口转USB，没办法实现两个串口之间的数据转发了，只好实现串口各自的数据转发。
现在我把我实现的过程简单描述一下：
1、 初始化设置：USART1_RX+DMA1_ Channel5，USART2_RX+DMA1_ Channel6，USART1_TX+DMA1_ Channel4，USART2_TX+DMA1_ Channel7（具体设置请看程序包）。
2、 当数据发送给USART1接收完毕时候会引起USART1的串口总线中断，计算DMA1_ Channel5内存数组剩余容量，得到接收的字符长度。将接收的字符复制给DMA1_ Channel4内存数组，启动DMA1_ Channel4通道传输数据，（传输完成需要关闭。）下一次数据接收可以在启动DMA1_ Channel4时候就开始，不需要等待DMA1_ Channel4数据传输完成。但是上一次DMA1_ Channel4完成之前，不可以将数据复制给DMA1_ Channel4内存数组，会冲掉以前数据。
3、 USART2类同USART1。
呵呵，下面贴程序：- IO口定义：
- void GPIO_Configuration(void)
- {
- GPIO_InitTypeDef GPIO_InitStructure;
- /* 第1步：打开GPIO和USART部件的时钟 */
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
- /* 第2步：将USART Tx的GPIO配置为推挽复用模式 */
- 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);
- /* 第3步：将USART Rx的GPIO配置为浮空输入模式
- 由于CPU复位后，GPIO缺省都是浮空输入模式，因此下面这个步骤不是必须的
- 但是，我还是建议加上便于阅读，并且防止其它地方修改了这个口线的设置参数
- */
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
- GPIO_Init(GPIOA, &GPIO_InitStructure);
- /* 第1步：打开GPIO和USART2部件的时钟 */
- //RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
- /* 第2步：将USART2 Tx的GPIO配置为推挽复用模式 */
- 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);
- /* 第3步：将USART2 Rx的GPIO配置为浮空输入模式
- 由于CPU复位后，GPIO缺省都是浮空输入模式，因此下面这个步骤不是必须的
- 但是，我还是建议加上便于阅读，并且防止其它地方修改了这个口线的设置参数
- */
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
- GPIO_Init(GPIOA, &GPIO_InitStructure);
- /* 第3步已经做了，因此这步可以不做
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- */
- GPIO_Init(GPIOA, &GPIO_InitStructure);
- }
- 串口初始化：
- void USART_Configuration(void)
- {
- USART_InitTypeDef USART_InitStructure;
- /* 第4步：配置USART参数
- - BaudRate = 115200 baud
- - Word Length = 8 Bits
- - One Stop Bit
- - No parity
- - Hardware flow control disabled (RTS and CTS signals)
- - Receive and transmit enabled
- */
- USART_InitStructure.USART_BaudRate = 19200;
- 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);
- //空闲中断
- USART_ITConfig(USART1, USART_IT_IDLE , ENABLE);
- /* 第5步：使能 USART， 配置完毕 */
- USART_Cmd(USART1, ENABLE);
- /* CPU的小缺陷：串口配置好，如果直接Send，则第1个字节发送不出去
- 如下语句解决第1个字节无法正确发送出去的问题 */
- USART_ClearFlag(USART1, USART_FLAG_TC); /* 清发送外城标志，Transmission Complete flag */
- USART_InitStructure.USART_BaudRate = 9600;
- 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);
- USART_ITConfig(USART2, USART_IT_IDLE , ENABLE);//开启空闲,帧错,噪声,校验错中断
- USART_Cmd(USART2, ENABLE);
- /* CPU的小缺陷：串口配置好，如果直接Send，则第1个字节发送不出去
- 如下语句解决第1个字节无法正确发送出去的问题 */
- USART_ClearFlag(USART2, USART_FLAG_TC); /* 清发送外城标志，Transmission Complete flag */
- }
- DMA配置：
- 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 = 512;
- 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 Channel5 (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 = 512;
- 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 = 512;
- 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 = 512;
- 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);
- }
- 中断优先级配置：
- void NVIC_Configuration(void)
- {
- NVIC_InitTypeDef NVIC_InitStructure;
- /* Configure one bit for preemption priority */
- NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
- /* Enable the USART1 Interrupt */
- 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 */
- 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
- 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
- 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);
- /*Enable DMA Channel5 Interrupt */
- NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel5_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
- NVIC_Init(&NVIC_InitStructure);
- /*Enable DMA Channel6 Interrupt */
- NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel6_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
- NVIC_Init(&NVIC_InitStructure);
- }
- 数组定义，含义如题名：
- u8 USART1_SEND_DATA[512];
- u8 USART2_SEND_DATA[512];
- u8 USART1_RECEIVE_DATA[512];
- u8 USART2_RECEIVE_DATA[512];
- u8 USART1_TX_Finish=1;// USART1发送完成标志量
- u8 USART2_TX_Finish=1; // USART2发送完成标志量
- USART1中断服务函数
- void USART1_IRQHandler(void)
- {
- u16 DATA_LEN;
- u16 i;
- if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)//如果为空闲总线中断
- {
- DMA_Cmd(DMA1_Channel5, DISABLE);//关闭DMA,防止处理其间有数据
- //USART_RX_STA = USART1->SR;//先读SR，然后读DR才能清除
- //USART_RX_STA = USART1->DR;
- DATA_LEN=512-DMA_GetCurrDataCounter(DMA1_Channel5);
- if(DATA_LEN > 0)
- {
- while(USART1_TX_Finish==0)//等待数据传输完成才下一次
- {
- ;
- }
- //将数据送DMA存储地址
- for(i=0;i<DATA_LEN;i++)
- {
- USART1_SEND_DATA[i]=USART1_RECEIVE_DATA[i];
- }
- //USART用DMA传输替代查询方式发送，克服被高优先级中断而产生丢帧现象。
- DMA_Cmd(DMA1_Channel4, DISABLE); //改变datasize前先要禁止通道工作
- DMA1_Channel4->CNDTR=DATA_LEN; //DMA1,传输数据量
- USART1_TX_Finish=0;//DMA传输开始标志量
- DMA_Cmd(DMA1_Channel4, ENABLE);
- }
- //DMA_Cmd(DMA1_Channel5, DISABLE);//关闭DMA,防止处理其间有数据
- DMA_ClearFlag(DMA1_FLAG_GL5 | DMA1_FLAG_TC5 | DMA1_FLAG_TE5 | DMA1_FLAG_HT5);//清标志
- DMA1_Channel5->CNDTR = 512;//重装填
- DMA_Cmd(DMA1_Channel5, ENABLE);//处理完,重开DMA
- //读SR后读DR清除Idle
- i = USART1->SR;
- i = USART1->DR;
- }
- if(USART_GetITStatus(USART1, USART_IT_PE | USART_IT_FE | USART_IT_NE) != RESET)//出错
- {
- USART_ClearITPendingBit(USART1, USART_IT_PE | USART_IT_FE | USART_IT_NE);
- }
- USART_ClearITPendingBit(USART1, USART_IT_TC);
- USART_ClearITPendingBit(USART1, USART_IT_IDLE);
- }
- USART2中断服务函数
- void USART2_IRQHandler(void)
- {
- u16 DATA_LEN;
- u16 i;
- if(USART_GetITStatus(USART2, USART_IT_IDLE) != RESET) //如果为空闲总线中断
- {
- DMA_Cmd(DMA1_Channel6, DISABLE);//关闭DMA,防止处理其间有数据
- //USART_RX_STA = USART1->SR;//先读SR，然后读DR才能清除
- //USART_RX_STA = USART1->DR;
- DATA_LEN=512-DMA_GetCurrDataCounter(DMA1_Channel6);
- if(DATA_LEN > 0)
- {
- while(USART2_TX_Finish==0)//等待数据完成才下一次
- {
- ;
- }
- //将数据送DMA存储地址
- for(i=0;i<DATA_LEN;i++)
- {
- USART2_SEND_DATA[i]=USART2_RECEIVE_DATA[i];
- }
- //USART用DMA传输替代查询方式发送，克服被高优先级中断而产生丢帧现象。
- DMA_Cmd(DMA1_Channel7, DISABLE); //改变datasize前先要禁止通道工作
- DMA1_Channel7->CNDTR=DATA_LEN; //DMA1,传输数据量
- USART2_TX_Finish=0;//DMA传输开始标志量
- DMA_Cmd(DMA1_Channel7, ENABLE);
- }
- //DMA_Cmd(DMA1_Channel5, DISABLE);//关闭DMA,防止处理其间有数据
- DMA_ClearFlag(DMA1_FLAG_GL6 | DMA1_FLAG_TC6 | DMA1_FLAG_TE6 | DMA1_FLAG_HT6);//清标志
- DMA1_Channel6->CNDTR = 512;//重装填
- DMA_Cmd(DMA1_Channel6, ENABLE);//处理完,重开DMA
- //读SR后读DR清除Idle
- i = USART2->SR;
- i = USART2->DR;
- }
- if(USART_GetITStatus(USART2, USART_IT_PE | USART_IT_FE | USART_IT_NE) != RESET)//出错
- {
- USART_ClearITPendingBit(USART2, USART_IT_PE | USART_IT_FE | USART_IT_NE);
- }
- USART_ClearITPendingBit(USART2, USART_IT_TC);
- USART_ClearITPendingBit(USART2, USART_IT_IDLE);
- }
- DMA1_Channel5中断服务函数
- void DMA1_Channel5_IRQHandler(void)
- {
- DMA_ClearITPendingBit(DMA1_IT_TC5);
- DMA_ClearITPendingBit(DMA1_IT_TE5);
- DMA_Cmd(DMA1_Channel5, DISABLE);//关闭DMA,防止处理其间有数据
- DMA1_Channel5->CNDTR = 580;//重装填
- DMA_Cmd(DMA1_Channel5, ENABLE);//处理完,重开DMA
- }
- DMA1_Channel6中断服务函数
- void DMA1_Channel6_IRQHandler(void)
- {
- DMA_ClearITPendingBit(DMA1_IT_TC6);
- DMA_ClearITPendingBit(DMA1_IT_TE6);
- DMA_Cmd(DMA1_Channel6, DISABLE);//关闭DMA,防止处理其间有数据
- DMA1_Channel6->CNDTR = 580;//重装填
- DMA_Cmd(DMA1_Channel6, ENABLE);//处理完,重开DMA
- }
- DMA1_Channel4中断服务函数
- //USART1使用DMA发数据中断服务程序
- void DMA1_Channel4_IRQHandler(void)
- {
- DMA_ClearITPendingBit(DMA1_IT_TC4);
- DMA_ClearITPendingBit(DMA1_IT_TE4);
- DMA_Cmd(DMA1_Channel4, DISABLE);//关闭DMA
- USART1_TX_Finish=1;//置DMA传输完成
- }
- DMA1_Channel7中断服务函数
- //USART2使用DMA发数据中断服务程序
- void DMA1_Channel7_IRQHandler(void)
- {
- DMA_ClearITPendingBit(DMA1_IT_TC7);
- DMA_ClearITPendingBit(DMA1_IT_TE7);
- DMA_Cmd(DMA1_Channel7, DISABLE);//关闭DMA
- USART2_TX_Finish=1;//置DMA传输完成
- }
工程下载地址：http://115.com/file/dpj82l3j#
USART_DMA_Interrupt.rar
说明文档下载地址：http://115.com/file/dpj8i8ov#
STM32实现USART+DMA接收未知长度的数据和发送.doc
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发表于 2012-7-14 23:22:52
楼主
