你是一名程序员，现在要用stm32f103ze给超声波模块GY_US42改IIC地址，并能够在串口调试助手查看模块的IIC地址，要求使用标准库写一份完整的代码，，完整代码包含IIC发送和接收函数，更改地址函数，mian函数，串口相关函数

好的，以下是我写的完整代码：

#include "stm32f10x.h"
#include "stdio.h"

#define GY_US42_ADDR 0xE0   // GY-US42默认IIC地址
#define NEW_ADDR 0xE2      // 要改为的新IIC地址

void I2C_GPIO_Config(void);
void I2C_Config(void);
void I2C_SendByte(uint8_t addr, uint8_t data);
uint8_t I2C_ReadByte(uint8_t addr);
void GY_US42_SetAddr(uint8_t newAddr);
void USART1_Config(void);
void USART1_SendChar(char c);
void USART1_SendString(char* str);
void delay_ms(uint32_t ms);

int main(void)
{
    SystemInit();
    I2C_GPIO_Config();
    I2C_Config();
    USART1_Config();

    GY_US42_SetAddr(NEW_ADDR);  // 改变GY-US42的IIC地址为NEW_ADDR

    while (1)
    {
        uint8_t addr = I2C_ReadByte(GY_US42_ADDR);  // 读取GY-US42的IIC地址
        char buf[20];
        sprintf(buf, "IIC Addr: 0x%x\r\n", addr);
        USART1_SendString(buf);
        delay_ms(1000);
    }
}

void I2C_GPIO_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_OD;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
}

void I2C_Config(void)
{
    I2C_InitTypeDef I2C_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);

    I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
    I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
    I2C_InitStructure.I2C_OwnAddress1 = 0x00;
    I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
    I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
    I2C_InitStructure.I2C_ClockSpeed = 100000;
    I2C_Init(I2C1, &I2C_InitStructure);

    I2C_Cmd(I2C1, ENABLE);
}

void I2C_SendByte(uint8_t addr, uint8_t data)
{
    while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY));
    I2C_GenerateSTART(I2C1, ENABLE);
    while (!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
    I2C_Send7bitAddress(I2C1, addr, I2C_Direction_Transmitter);
    while (!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));
    I2C_SendData(I2C1, data);
    while (!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
    I2C_GenerateSTOP(I2C1, ENABLE);
}

uint8_t I2C_ReadByte(uint8_t addr)
{
    uint8_t data;

    while (I2C_GetFlagStatus(I2C1, I2C_FLAG_BUSY));
    I2C_GenerateSTART(I2C1, ENABLE);
    while (!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
    I2C_Send7bitAddress(I2C1, addr, I2C_Direction_Receiver);
    while (!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));
    while (!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED));
    data = I2C_ReceiveData(I2C1);
    I2C_AcknowledgeConfig(I2C1, DISABLE);
    I2C_GenerateSTOP(I2C1, ENABLE);

    return data;
}

void GY_US42_SetAddr(uint8_t newAddr)
{
    I2C_SendByte(GY_US42_ADDR, 0xA0);
    I2C_SendByte(GY_US42_ADDR, 0xAA);
    I2C_SendByte(GY_US42_ADDR, 0xA5);
    I2C_SendByte(GY_US42_ADDR, newAddr);
}

void USART1_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    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_Mode_Rx;
    USART_Init(USART1, &USART_InitStructure);

    USART_Cmd(USART1, ENABLE);
}

void USART1_SendChar(char c)
{
    while (USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);
    USART_SendData(USART1, c);
}

void USART1_SendString(char* str)
{
    while (*str)
    {
        USART1_SendChar(*str++);
    }
}

void delay_ms(uint32_t ms)
{
    SysTick->LOAD = 72000 - 1;
    SysTick->CTRL = 0x05;
    for (uint32_t i = 0; i < ms; i++)
    {
        while (!(SysTick->CTRL & 0x10000));
    }
    SysTick->CTRL = 0x00;
}

其中，`I2C_GPIO_Config`和`I2C_Config`函数负责配置IIC总线，`I2C_SendByte`和`I2C_ReadByte`函数分别用于发送和接收IIC数据，`GY_US42_SetAddr`函数用于更改GY-US42的IIC地址，`USART1_Config`函数用于配置串口，`USART1_SendChar`和`USART1_SendString`函数分别用于发送单个字符和字符串，`delay_ms`函数用于延时。

在`main`函数中，首先进行各种配置，然后调用`GY_US42_SetAddr`函数将GY-US42的IIC地址更改为`NEW_ADDR`，然后进入一个死循环，每隔一秒读取一次GY-US42的IIC地址并通过串口输出。