Ultrasonic sensor HC-SR04

Hi, I got a few hc-sr04’s ultra sonic sensors and trying to get it to work with sodaq one.

This is the code I found online, but I just always get 0. It does not seem to be reading anything.


  • created by Rui Santos, https://randomnerdtutorials.com
  • Complete Guide for Ultrasonic Sensor HC-SR04
  • Ultrasonic sensor Pins:
    VCC: +5VDC
    Trig : Trigger (INPUT) - Pin11
    Echo: Echo (OUTPUT) - Pin 12
    GND: GND

int trigPin = 10; // Trigger
int echoPin = 11; // Echo
long duration, cm, inches;

void setup() {
//Serial Port begin
SerialUSB.begin (9600);
//Define inputs and outputs
pinMode(trigPin, OUTPUT);
pinMode(echoPin, INPUT);

void loop() {
// The sensor is triggered by a HIGH pulse of 10 or more microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
digitalWrite(trigPin, LOW);
digitalWrite(trigPin, HIGH);
digitalWrite(trigPin, LOW);

// Read the signal from the sensor: a HIGH pulse whose
// duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.
pinMode(echoPin, INPUT);
duration = pulseIn(echoPin, HIGH);

// Convert the time into a distance
cm = (duration/2) / 29.1; // Divide by 29.1 or multiply by 0.0343
inches = (duration/2) / 74; // Divide by 74 or multiply by 0.0135

SerialUSB.print("in, ");


I have it connected with VCC GRN and the to pins Echo and Trigger. Any idea why it wont work?