此程序是STM32F1系列单片机使用非阻塞异步DMA+USART发送与接收的程序,适合单片机部分处理速度大于上位机的情形。程序使用DMA进行数据传输,串口空闲标志位查询方式接收,几乎不占用程序处理时间。
#include "stm32f10x.h #include <string.h> uint8_t USART1_TxBuf[256]; uint8_t USART1_RxBuf[256]; void USART1_Init(uint32_t baud) //初始化USART1 { GPIO_InitTypeDef GPIO_InitStructure; USART_InitTypeDef USART_InitStructure; DMA_InitTypeDef DMA_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_USART1, ENABLE); RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //GPIO初始化 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;//复用推挽输出 GPIO_Init(GPIOA, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;//输入上拉 GPIO_Init(GPIOA, &GPIO_InitStructure); //USART初始化 USART_DeInit(USART1); //复位USART1外设 USART_InitStructure.USART_BaudRate = baud; //串口波特率 USART_InitStructure.USART_WordLength = USART_WordLength_8b; //字长为8位数据格式 USART_InitStructure.USART_StopBits = USART_StopBits_1; //一个停止位 USART_InitStructure.USART_Parity = USART_Parity_No; //无奇偶校验位 USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; //无硬件数据流控制 USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx; //使能收发 USART_Init(USART1, &USART_InitStructure); //初始化串口 USART_ITConfig(USART1, USART_IT_IDLE, ENABLE); //开启串口空闲中断 不配置NVIC只使用中断标志位 USART_DMACmd(USART1, USART_DMAReq_Tx | USART_DMAReq_Rx, ENABLE); //开启串口DMA请求 //DMA初始化 DMA_DeInit(DMA1_Channel4); //USART1_Tx DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART1->DR); DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART1_TxBuf; DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; //内存到外设 DMA_InitStructure.DMA_BufferSize = sizeof(USART1_TxBuf); //仅占位作用 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_Normal;//单次模式 DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh; DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel4, &DMA_InitStructure); //USART1_Tx DMA_DeInit(DMA1_Channel5); //USART1_Rx DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(USART1->DR); DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART1_RxBuf; DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC; //外设到内存 DMA_InitStructure.DMA_BufferSize = sizeof(USART1_RxBuf);; 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_Normal;//单次模式 DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh; DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel5, &DMA_InitStructure); //USART1_Rx //开启DMA与串口 DMA_Cmd(DMA1_Channel5, ENABLE); //USART1_Rx USART_Cmd(USART1, ENABLE);//使能串口 } uint16_t USART1_Read(void *buf) { //读取串口接收缓冲区 uint16_t buf_size; if(USART_GetITStatus(USART1, USART_IT_IDLE) != ENABLE) { //没有接收到数据 return 0; } DMA_Cmd(DMA1_Channel5, DISABLE); //关闭USART1_Rx DMA以配置 USART_ReceiveData(USART1); //先读SR 再读DR 清除标志位 buf_size = sizeof(USART1_RxBuf) - DMA_GetCurrDataCounter(DMA1_Channel5); //获取数据大小 memcpy(buf, USART1_RxBuf, buf_size); //复制缓冲区 memset(USART1_RxBuf, 0, sizeof(USART1_RxBuf)); //清空数据区 DMA_ClearFlag(DMA1_FLAG_TC5); //清除传输完成标志位 防止溢出 DMA_SetCurrDataCounter(DMA1_Channel5, sizeof(USART1_RxBuf)); //重新设定数据大小 DMA_Cmd(DMA1_Channel5, ENABLE); //重新开启USART1_Rx DMA return buf_size; } void USART1_Write(void *buf, uint16_t size) { //串口发送 DMA_Cmd(DMA1_Channel4, DISABLE); //关闭USART1_Tx DMA以配置 DMA_SetCurrDataCounter(DMA1_Channel4, size); //设置发送数据大小 memcpy(USART1_TxBuf, buf, size); //复制缓冲区 DMA_ClearFlag(DMA1_FLAG_TC4); //清除传输完成标志位 DMA_Cmd(DMA1_Channel4, ENABLE); //重新开启USART1_Tx DMA 开始发送 }
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