STM32CubeMX 使用DMA 实现不定长数据收发
这里教程是选择的STM32F407。STM32F103也测试过。1.首先选择串口，选择异步通信。2.添加DMA
3.打开中断
4.生成代码，生成代码选择了每个外设单独使用.c/.h
5.我使用的是Keil5。打开工程，首先注释掉dma.c里的DMA接收中断，因为不需要DMA接收中断，DMA发送中断是需要的。(dma.c)
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[*]void MX_DMA_Init(void)
[*]{
[*]/* DMA controller clock enable */
[*]__HAL_RCC_DMA2_CLK_ENABLE();
[*]
[*]/* DMA interrupt init */
[*]/* DMA2_Stream0_IRQn interrupt configuration */
[*]HAL_NVIC_SetPriority(DMA2_Stream0_IRQn, 2, 0);
[*]HAL_NVIC_EnableIRQ(DMA2_Stream0_IRQn);
[*]/* DMA2_Stream2_IRQn interrupt configuration */
[*]//HAL_NVIC_SetPriority(DMA2_Stream2_IRQn, 0, 0);
[*]//HAL_NVIC_EnableIRQ(DMA2_Stream2_IRQn);
[*]/* DMA2_Stream7_IRQn interrupt configuration */
[*]HAL_NVIC_SetPriority(DMA2_Stream7_IRQn, 1, 0);
[*]HAL_NVIC_EnableIRQ(DMA2_Stream7_IRQn);
[*]
[*]}
6.在usart.h文件里定义串口接收数据类型我是如下定义的(usart.h)
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[*]/* USER CODE BEGIN Private defines */
[*]#define RECEIVELEN 1024
[*]#define USART_DMA_SENDING 1//发送未完成
[*]#define USART_DMA_SENDOVER 0//发送完成
[*]typedef struct
[*]{
[*]uint8_t receive_flag:1;//空闲接收标记
[*]uint8_t dmaSend_flag:1;//发送完成标记
[*]uint16_t rx_len;//接收长度
[*]uint8_t usartDMA_rxBuf;//DMA接收缓存
[*]}USART_RECEIVETYPE;
[*]
[*]extern USART_RECEIVETYPE UsartType1;
[*]
[*]
[*]/* USER CODE END Private defines */
7.然后在usart.c里需要添加空闲中断处理函数，以及DMA发送函数等。(usart.c)
首先定义串口数据类型：
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[*]/* USER CODE BEGIN 0 */
[*]
[*]USART_RECEIVETYPE UsartType1;
[*]
[*]/* USER CODE END 0 */
然后定义空闲中断处理函数和DMA发送函数
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[*]/* USER CODE BEGIN 1 */
[*]#ifdef __GNUC__
[*]
[*]/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf
[*] set to 'Yes') calls __io_putchar() */
[*]#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
[*]#else
[*]
[*]#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
[*]#endif /* __GNUC__ */
[*]
[*]PUTCHAR_PROTOTYPE
[*]{
[*] HAL_UART_Transmit(&huart1 , (uint8_t *)&ch, 1, 0xFFFF);
[*] return ch;
[*]}
[*]
[*]//DMA发送函数
[*]void Usart1SendData_DMA(uint8_t *pdata, uint16_t Length)
[*]{
[*] while(UsartType1.dmaSend_flag == USART_DMA_SENDING);
[*] UsartType1.dmaSend_flag = USART_DMA_SENDING;
[*] HAL_UART_Transmit_DMA(&huart1, pdata, Length);
[*]}
[*]
[*]//DMA发送完成中断回调函数
[*]void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
[*]{
[*] __HAL_DMA_DISABLE(huart->hdmatx);
[*] UsartType1.dmaSend_flag = USART_DMA_SENDOVER;
[*]}
[*]
[*]//串口接收空闲中断
[*]void UsartReceive_IDLE(UART_HandleTypeDef *huart)
[*]{
[*] uint32_t temp;
[*]
[*] if((__HAL_UART_GET_FLAG(huart,UART_FLAG_IDLE) != RESET))
[*] {
[*] __HAL_UART_CLEAR_IDLEFLAG(&huart1);
[*] HAL_UART_DMAStop(&huart1);
[*] temp = huart1.hdmarx->Instance->NDTR;
[*] UsartType1.rx_len =RECEIVELEN - temp;
[*] UsartType1.receive_flag=1;
[*] HAL_UART_Receive_DMA(&huart1,UsartType1.usartDMA_rxBuf,RECEIVELEN);
[*] }
[*]}
[*]
[*]/* USER CODE END 1 */
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[*]</pre><p></p><pre>
8.在中断文件里添加(当然，上面的空闲中断处理函数需要**)(stm32f4xxit.c) view plain copy
[*]void USART1_IRQHandler(void)
[*]{
[*]/* USER CODE BEGIN USART1_IRQn 0 */
[*] UsartReceive_IDLE(&huart1);
[*]/* USER CODE END USART1_IRQn 0 */
[*]HAL_UART_IRQHandler(&huart1);
[*]/* USER CODE BEGIN USART1_IRQn 1 */
[*]
[*]/* USER CODE END USART1_IRQn 1 */
[*]}
9.主函数里，打开空闲中断，初始化DMA接收
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[*]/* USER CODE BEGIN 2 */
[*] HAL_UART_Receive_DMA(&huart1, UsartType1.usartDMA_rxBuf, RECEIVELEN);
[*] __HAL_UART_ENABLE_IT(&huart1, UART_IT_IDLE);
[*]/* USER CODE END 2 */
10.然后就可以在while(1)里处理数据了
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[*]/* Infinite loop */
[*]/* USER CODE BEGIN WHILE */
[*]
[*]while (1)
[*]{
[*] if(UsartType1.receive_flag)//如果产生了空闲中断
[*] {
[*] UsartType1.receive_flag=0;//清零标记
[*] Usart1SendData_DMA(UsartType1.usartDMA_rxBuf,UsartType1.rx_len);//串口打印收到的数据。
[*] }
[*]/* USER CODE END WHILE */
[*]
[*]/* USER CODE BEGIN 3 */
[*]
[*]}
[*]/* USER CODE END 3 */
IoT软件平台 不定长数据收发和定长数据收发，两者有什么区别和特点
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