写一个stm32f401的USART通信初始化函数

STM32F401 USART 通信初始化代码示例：

void USART2_Init(uint32_t baudrate)
{
  USART_InitTypeDef USART_InitStructure;
  GPIO_InitTypeDef GPIO_InitStructure;
  NVIC_InitTypeDef NVIC_InitStructure;
  
  /* Enable GPIOA clock */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
  
  /* Enable USART2 clock */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
  
  /* Connect PA2 to USART2_TX */
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);
  
  /* Connect PA3 to USART2_RX */
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);
  
  /* Configure USART2 Tx (PA.2) 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);
  
  /* Configure USART2 Rx (PA.3) as input floating */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
  
  /* USART2 configuration */
  USART_InitStructure.USART_BaudRate = baudrate;
  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_Init(USART2, &USART_InitStructure);
  
  /* Enable USART2 */
  USART_Cmd(USART2, ENABLE);
  
  /* Enable the USART2 Interrupt */
  NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0