我要设计一个基于单片机的非接触式人体红外测温系统，系统包括STC89C52单片机，MLX90614红外测温模块，LCD1602显示模块等装置，请写一段代码，实现测量人体温度并将温度值显示在LCD1602上的功能

好的，以下是代码实现：

#include <reg52.h>

#define SDA P0_1
#define SCL P0_0
#define ADDR 0x5A   // MLX90614的I2C地址

sbit RS = P2^0;
sbit RW = P2^1;
sbit EN = P2^2;

void delay(unsigned int count)
{
    unsigned int i,j;
    for(i=0;i<count;i++)
        for(j=0;j<1275;j++);
}

void I2C_start()
{
    SDA = 1;
    SCL = 1;
    delay(5);
    SDA = 0;
    delay(5);
    SCL = 0;
}

void I2C_stop()
{
    SDA = 0;
    SCL = 1;
    delay(5);
    SDA = 1;
    delay(5);
}

void I2C_write(unsigned char dat)
{
    unsigned char i;
    for(i=0;i<8;i++)
    {
        SDA = dat&0x80;
        SCL = 1;
        delay(5);
        SCL = 0;
        dat <<= 1;
    }
}

unsigned char I2C_read_ack()
{
    unsigned char i, dat = 0;
    SDA = 1;
    for(i=0;i<8;i++)
    {
        SCL = 1;
        delay(5);
        dat <<= 1;
        dat |= SDA;
        SCL = 0;
    }
    SDA = 0;
    return dat;
}

unsigned char I2C_read_nack()
{
    unsigned char i, dat = 0;
    SDA = 1;
    for(i=0;i<8;i++)
    {
        SCL = 1;
        delay(5);
        dat <<= 1;
        dat |= SDA;
        SCL = 0;
    }
    SDA = 0;
    return dat;
}

void LCD_send_cmd(unsigned char cmd)
{
    RS = 0;
    RW = 0;
    EN = 1;
    P0 = cmd;
    delay(5);
    EN = 0;
}

void LCD_send_data(unsigned char dat)
{
    RS = 1;
    RW = 0;
    EN = 1;
    P0 = dat;
    delay(5);
    EN = 0;
}

void LCD_init()
{
    LCD_send_cmd(0x38);
    LCD_send_cmd(0x0c);
    LCD_send_cmd(0x06);
    LCD_send_cmd(0x01);
}

void LCD_display_temp(float temp)
{
    unsigned char buf[16];
    sprintf(buf, "Temp: %.1fC  ", temp);
    LCD_send_cmd(0x80);
    for(unsigned char i=0; i<16; i++)
    {
        if(buf[i] == '\0')
            break;
        LCD_send_data(buf[i]);
    }
}

float MLX90614_read_temp()
{
    float temp;
    unsigned char i;
    I2C_start();
    I2C_write(ADDR<<1);
    I2C_write(0x07);
    I2C_start();
    I2C_write((ADDR<<1) | 1);
    i = I2C_read_ack();
    temp = I2C_read_ack();
    temp += (float)I2C_read_nack()/16.0;
    I2C_stop();
    return temp;
}

void main()
{
    float temp;
    LCD_init();
    while(1)
    {
        temp = MLX90614_read_temp();
        LCD_display_temp(temp);
        delay(1000);
    }
}

这段代码实现了通过I2C协议从MLX90614红外测温模块中读取温度值，并将温度值通过LCD1602显示出来。在主函数中，通过一个循环不断地读取温度值，并显示在LCD上。