写一个dht11显示在lcd屏上，并用HCsr04测距的程序，C51，并距离＜10的时候报警

以下是基于C51单片机的DHT11和HC-SR04测距的程序，将温湿度数据显示在16x2 LCD上，并在距离小于10cm时触发蜂鸣器报警。

#include <reg51.h>
#include <intrins.h>

#define LCD_RS P1_0
#define LCD_RW P1_1
#define LCD_EN P1_2
#define LCD_DATA P2

sbit TRIG = P3^5;
sbit ECHO = P3^4;
sbit BUZZER = P3^7;

unsigned char code lcd_init[] = {0x38,0x08,0x01,0x06,0x0c};
unsigned char humi_data = 0, temp_data = 0;
unsigned int distance = 0;

void delay(unsigned int t) {
    while(t--);
}

void lcd_write_cmd(unsigned char cmd) {
    LCD_RS = 0;
    LCD_RW = 0;
    LCD_DATA = cmd;
    LCD_EN = 1;
    _nop_();
    _nop_();
    LCD_EN = 0;
    delay(5);
}

void lcd_write_data(unsigned char dat) {
    LCD_RS = 1;
    LCD_RW = 0;
    LCD_DATA = dat;
    LCD_EN = 1;
    _nop_();
    _nop_();
    LCD_EN = 0;
    delay(5);
}

void lcd_init_seq() {
    unsigned char i;
    for (i = 0; i < 5; i++) {
        lcd_write_cmd(lcd_init[i]);
        delay(5);
    }
}

void lcd_display(unsigned char row, unsigned char col, unsigned char *str) {
    unsigned char addr;
    if (row == 0) addr = 0x80 + col;
    else addr = 0xc0 + col;
    lcd_write_cmd(addr);
    while (*str) {
        lcd_write_data(*str++);
    }
}

void dht11_start() {
    P3_3 = 0;
    delay(20);
    P3_3 = 1;
    delay(30);
    P3_3 = 0;
}

unsigned char dht11_read_byte() {
    unsigned char i, dat = 0;
    for (i = 0; i < 8; i++) {
        while(!P3_3);
        delay(30);
        if (P3_3) dat |= (1 << (7 - i));
        while(P3_3);
    }
    return dat;
}

void dht11_read() {
    unsigned char rh_integral, rh_decimal, temp_integral, temp_decimal, check_sum;
    dht11_start();
    if (!P3_3) {
        while(!P3_3);
        while(P3_3);
        rh_integral = dht11_read_byte();
        rh_decimal = dht11_read_byte();
        temp_integral = dht11_read_byte();
        temp_decimal = dht11_read_byte();
        check_sum = dht11_read_byte();
        if (check_sum == rh_integral + rh_decimal + temp_integral + temp_decimal) {
            humi_data = rh_integral;
            temp_data = temp_integral;
        }
    }
}

void hcsr04_measure() {
    unsigned long t;
    TRIG = 0;
    delay(10);
    TRIG = 1;
    delay(10);
    TRIG = 0;
    while(!ECHO);
    t = 0;
    while(ECHO) {
        t++;
        delay(1);
    }
    distance = t / 58;
}

void main() {
    unsigned char str[16];
    lcd_init_seq();
    while(1) {
        dht11_read();
        hcsr04_measure();
        if (distance < 10) {
            BUZZER = 1;
        } else {
            BUZZER = 0;
        }
        sprintf(str, "H:%d.%d%% T:%d.%dC", humi_data, temp_data, temp_data, humi_data);
        lcd_display(0, 0, str);
        sprintf(str, "Distance:%dcm", distance);
        lcd_display(1, 0, str);
        delay(500);
    }
}

注意，该程序中使用的是P3.3作为DHT11的数据引脚，P3.5作为HC-SR04的TRIG引脚，P3.4作为HC-SR04的ECHO引脚，P3.7作为蜂鸣器引脚。

另外，需要在程序中添加LCD相关的头文件和函数，这里就不再贴出。