int count = 0;
int TrigPin = A0; 
int EchoPin = A1;
  
long duration;
// PULSE WIDTH

void setup() {
    // set Serial communication
    Serial.begin(115200);
    // set pin mode
    pinMode(TrigPin, OUTPUT);
    pinMode(EchoPin, INPUT);
    // init pin
    digitalWrite(TrigPin, LOW);
    delay(1);
}

void loop() {
    Serial.println(count++);
    Serial.println(getDistance());
    Serial.println("");
    Serial.println("");
    delay(1000);
}

long getDistance() {
    // trig
    digitalWrite(TrigPin, LOW);
    delayMicroseconds(2);
    digitalWrite(TrigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(TrigPin, LOW);
    // echo
    duration = pulseIn(EchoPin, HIGH);     // unit: us
    return duration * 0.34029 / 2;         // unit: mm
}