请帮我写一下stm32f405的串口1通信程序，波特率9600

好的，下面是一个简单的基于STM32F405的串口1通信程序，波特率为9600：

#include "stm32f4xx.h"

void USART1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStruct;
    USART_InitTypeDef USART_InitStruct;
    NVIC_InitTypeDef NVIC_InitStruct;

    // Enable GPIOA clock
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    // Enable USART1 clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);

    // Configure PA9 (USART1 TX) and PA10 (USART1 RX) as alternate function push-pull
    GPIO_StructInit(&GPIO_InitStruct);
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStruct);

    // Connect PA9 to USART1_TX and PA10 to USART1_RX
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource9, GPIO_AF_USART1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1);

    // Configure USART1
    USART_StructInit(&USART_InitStruct);
    USART_InitStruct.USART_BaudRate = 9600;
    USART_InitStruct.USART_WordLength = USART_WordLength_8b;
    USART_InitStruct.USART_StopBits = USART_StopBits_1;
    USART_InitStruct.USART_Parity = USART_Parity_No;
    USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_Init(USART1, &USART_InitStruct);

    // Enable USART1 interrupt
    NVIC_InitStruct.NVIC_IRQChannel = USART1_IRQn;
    NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStruct);

    // Enable USART1
    USART_Cmd(USART1, ENABLE);

    // Enable USART1 RX interrupt
    USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
}

void USART1_IRQHandler(void)
{
    if (USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
    {
        // USART1 received data
        uint8_t data = USART_ReceiveData(USART1);
        // Do something with received data...
        // Clear interrupt flag
        USART_ClearITPendingBit(USART1, USART_IT_RXNE);
    }
}

int main(void)
{
    USART1_Init();
    while(1)
    {
        // Do something else...
    }
}

这个程序中，我们使用USART1与计算机或其他设备进行串口通信。在初始化函数`USART1_Init()`中，我们首先启用了GPIOA和USART1的时钟，并将PA9和PA10配置为USART1的TX和RX引脚。然后我们初始化USART1的设置，包括波特率、数据位、停止位、校验位和流控制等。我们还启用了USART1和USART1 RX中断，以便在接收到数据时执行相应的操作。在中断处理函数`USART1_IRQHandler()`中，我们读取接收到的数据，并执行相应的操作。