stm32串口DMA问题

ID:929517 · 发表于 2024-7-14 16:36

最近在学习串口的DMA接收，发现一个问题，就是RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE); 这条时钟无论是否开启，都能正常接收，有没有高手能解释下这条语句。具体程序我压缩包上传，经过测试串口助手是可以发送并将收到的信息发回。请大师们指正，这个工程未完工，阶段测试可以。

void Serial_Init(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
  USART_InitTypeDef USART_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  DMA_InitTypeDef DMA_InitStructure;

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1,ENABLE);
//  RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);// ???

  USART_DeInit(USART1);  //复位串口1
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);

  //Usart1 NVIC 配置

  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3 ;//抢占优先级3
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //子优先级3
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能
NVIC_Init(&NVIC_InitStructure); //根据指定的参数初始化VIC寄存器

  //NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);

USART_InitStructure.USART_BaudRate = 9600;
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;
USART_InitStructure.USART_Parity = USART_Parity_No;
USART_InitStructure.USART_StopBits = USART_StopBits_1;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;

  USART_Init(USART1, &USART_InitStructure); //初始化串口
  USART_ITConfig(USART1, USART_IT_IDLE, ENABLE);//开启空闲中断
  USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE); //使能串口1 DMA接收
  USART_Cmd(USART1,ENABLE);                   //使能串口

  DMA_DeInit(DMA1_Channel5); //将DMA的通道5寄存器重设为缺省值  串口1对应的是DMA通道5
  DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&USART1->DR;  //DMA外设ADC基地址
  DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)DMA_RX_Buf;  //DMA内存基地址
  DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;  //数据传输方向，从外设读取发送到内存
  DMA_InitStructure.DMA_BufferSize = DMA_Max_Size;  //DMA通道的DMA缓存的大小
  DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;  //外设地址寄存器不变
  DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;  //内存地址寄存器递增
  DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;  //数据宽度为8位
  DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; //数据宽度为8位
  DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;  //工作在正常缓存模式
  DMA_InitStructure.DMA_Priority = DMA_Priority_Medium; //DMA通道 x拥有中优先级
  DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;  //DMA通道x没有设置为内存到内存传输
  DMA_Init(DMA1_Channel5, &DMA_InitStructure);  //根据DMA_InitStruct中指定的参数初始化DMA的通道

  USART_DMACmd(USART1, USART_DMAReq_Rx, ENABLE);
  DMA_Cmd(DMA1_Channel5, ENABLE);  //正式驱动DMA传输

}