#include <LiquidCrystal.h> 
LiquidCrystal lcd(2, 11, 10, A1, A0, A2);
const int Trig = 6;                                           
const int Echo = 3; 
double distance,time ; 
void setup() 
{   
        Serial.begin(9600);                                    
        pinMode(Trig, OUTPUT); 
  
        pinMode(Echo, INPUT);                                  
    Serial.println("The distance is :");
    lcd.begin(16, 2); 
 lcd.clear(); // 清屏
} 
void loop() 
{ 
    
        digitalWrite(Trig, LOW);                                 
        delayMicroseconds(2);                                   
        digitalWrite(Trig, HIGH);                               
        delayMicroseconds(10);                                  //产生一个10us的高脉冲去触发SR04
        digitalWrite(Trig, LOW);                                
        
        distance = pulseIn(Echo, HIGH)* 0.0343 / 2;                             // 检测脉冲宽度，注意返回值是微秒u                                 
 
        Serial.print(distance);   
        lcd.print(distance);   
        lcd.print("cm");                          
        Serial.println("cm"); 
        delay(1000); 
        lcd.clear(); // 清屏
}