Arduino Basics: The ultrasonic sensor

The ultrasonic sensor allow us to measure distances by sending ultrasonic waves and receiving them back to calculate the time between the emision and reception. 

This have a lot of utilities but in this case I'm just focusing on measuring the distance from the sensor to common objects.

const int Trigger=2;

const int Echo=3;

int last=0;

 

void setup() {

  Serial.begin(9600);

  pinMode(Trigger,OUTPUT);

  pinMode(Echo,INPUT);

  digitalWrite(Trigger,LOW);

}

 

void loop(){

  long t;

  long d;

  digitalWrite(Trigger, HIGH);

  delayMicroseconds(10);

  digitalWrite(Trigger, LOW);

 

  t = pulseIn(Echo, HIGH);

  d = t/59;

  if(last!=d){

    Serial.print("-> Distance: ");

    Serial.print(d);

    Serial.println("cm");

    last=d;

  }

  delay(200);

}