Ultrasonic distance sensor HC-SR04 giving a fix false value.

Other Hardware Sensors
1

Hi there,
I have the very well known HC-SR04 and I am trying to use it with an Arduino Uno.
I used the basic example code :

    /*
HC-SR04 Ping distance sensor
VCC to Arduino 5V
GND to Arduino GND
Echo to Arduino pin 13
Trig to Arduino pin 12
More info at: http://goo.gl/kJ8Gl
Original code improvements to the Ping sketch sourced from Trollmaker.com
Some code and wiring inspired by http://en.wikiversity.org/wiki/User:Dstaub/robotcar
Modified by Tolson Winters (Aug 27, 2014) for simplified serial monitor reading.
*/

#define trigPin 12
#define echoPin 13

void setup() {
  Serial.begin (9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  long duration, distance;
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  duration = pulseIn(echoPin, HIGH);
  distance = (duration/2) / 29.1;

  if (distance >= 50000 ) {
    Serial.println("Out of range");
  }
  else {
    Serial.print(distance);
    Serial.println(" cm");
  }
  delay(500);
}

As a result I have a value that oscillate around 2273 cm (waaaaay beyond the sensor range).

The only similar issue that I found in the internet is on this article

I added a 10k ohm resistor as suggested but it made no change.

Any clue ?

2

Probably either a sensor fault or wiring issue.

3

Thanks wvmarle
Is there an easy fix for those kind of problems ? if not I think I'll buy others of those sensors.

4

Quite simple indeed.
If it's a sensor fault: replace sensor.
If it's a wiring fault: fix wiring.
Start with the latter. Make sure the wires are connected correctly and actually make good electric contact (use your multimeter to check).