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STM32的串口采用DMA方式接收数据测试
本文博客链接:http://blog.csdn.net/jdh99,作者:jdh,转载请注明.
参考链接:http://www.amobbs.com/forum.php? ... a%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: [cpp] view plaincopy
- //串口接收DMA缓存
- #define UART_RX_LEN 128
- extern uint8_t Uart_Rx[UART_RX_LEN];
[cpp] view plaincopy
- //串口接收DMA缓存
- uint8_t Uart_Rx[UART_RX_LEN] = {0};
[cpp] view plaincopy
- //---------------------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);
[cpp] view plaincopy
- //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;
- //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:
本文博客链接:http://blog.csdn.net/jdh99,作者:jdh,转载请注明
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