An Arduino project of HC-SR04+ demo

HCSR04P.ino

//HC-SR04+

const int trigpin = D4;  
const int echopin = D3;  
long duration;  
int distance;  
void setup(){  
  pinMode(trigpin,OUTPUT);  
  pinMode(echopin,INPUT);  
  Serial.begin(115200);
}  

void loop(){  
  digitalWrite(trigpin,HIGH);
  delayMicroseconds(10);
  digitalWrite(trigpin,LOW);
  duration=pulseIn(echopin,HIGH);  
  distance = duration*0.034/2;  
  Serial.println(distance);
  delay(100);
}