int trigPin = D7;
int echoPin = D8;
int pingTravelTime;

void setup(){
pinMode(trigPin,OUTPUT);
pinMode(echoPin,INPUT);
Serial.begin(9600);
}
void loop()
{
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
pingTravelTime=pulseIn(echoPin, HIGH);
delay(25);
digitalWrite(trigPin, LOW);
Serial.println(pingTravelTime);
}