STM32F401用配置串口2的dma，并用串口dma发送数据给上位机，请只用c语言详细编写相关库函数代码

以下是STM32F401串口2 DMA发送数据的相关库函数代码，仅供参考：

1. 配置串口2：

void UART2_Config(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
  USART_InitTypeDef USART_InitStructure;
  
  // Enable the GPIOA clock
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
  
  // Enable the USART2 clock
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
  
  // Connect PA2 to USART2_Tx
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
  
  // Configure USART Tx as alternate function push-pull
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  
  // USART configuration
  USART_InitStructure.USART_BaudRate = 115200;
  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_Tx;
  USART_Init(USART2, &USART_InitStructure);
  USART_Cmd(USART2, ENABLE);
}

2. 配置DMA：

void DMA_Config(void)
{
  DMA_InitTypeDef DMA_InitStructure;
  
  // Enable the DMA1 clock
  RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
  
  // DMA configuration
  DMA_DeInit(DMA1_Stream6);
  DMA_InitStructure.DMA_Channel = DMA_Channel_4;
  DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART2->DR;
  DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)TxBuffer;
  DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
  DMA_InitStructure.DMA_BufferSize = TxBufferSize;
  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;
  DMA_InitStructure.DMA_Priority = DMA_Priority_High;
  DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
  DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
  DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
  DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
  DMA_Init(DMA1_Stream6, &DMA_InitStructure);
  
  // Enable the USART2 DMA requests
  USART_DMACmd(USART2, USART_DMAReq_Tx, ENABLE);
  
  // Enable the DMA1 Stream6
  DMA_Cmd(DMA1_Stream6, ENABLE);
}

3. 发送数据：

void UART2_DMA_SendData(uint8_t* data, uint16_t length)
{
  // Wait for the DMA1 Stream6 to be ready
  while (DMA_GetFlagStatus(DMA1_Stream6, DMA_FLAG_TCIF6) == RESET);
  
  // Clear the DMA1 Stream6 transfer complete flag
  DMA_ClearFlag(DMA1_Stream6, DMA_FLAG_TCIF6);
  
  // Copy the data to the TxBuffer
  for (int i = 0; i < length; i++) {
    TxBuffer[i] = data[i];
  }
  
  // Set the DMA1 Stream6 transfer length
  DMA_SetCurrDataCounter(DMA1_Stream6, length);
  
  // Enable the DMA1 Stream6
  DMA_Cmd(DMA1_Stream6, ENABLE);
}

在上述代码中，我们使用DMA1的Stream6配置串口2发送数据。首先，我们需要调用UART2_Config()函数来配置串口2，然后调用DMA_Config()函数来配置DMA。在发送数据时，我们需要将数据复制到TxBuffer中，并调用UART2_DMA_SendData()函数来启动DMA传输。DMA传输完成后，我们需要等待DMA传输完成，并清除DMA传输完成标志。