Problems with sensor reading! Please help

Projects General Guidance
1

I'm using the HC-SR04 Ultrasonic Sensor, with the 'NewPing' library.

#include <NewPing.h>

#define TRIGGER_PIN  7
#define ECHO_PIN     6
#define MAX_DISTANCE 500
 
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE);

void setup()
{
Serial.begin(9600);
}

void loop()
{
  int uS = sonar.ping();
  int distance = uS / US_ROUNDTRIP_CM;
  
  Serial.println(distance);
  if(distance > 20)
  {
   ACTION
   }
}

When i open Serial Monitor, i see that most of the readings are fair incorrect, for instance, when i get closer to the sensor it shows 196 cm, and when i go away it shows 21cm.

But when i have ONLY the sensor on the code, without the "action", it works normally.

What is going on? Can my "action" (which is a led to turn on), be affecting the readings of my sensor?

2 
if(distance > 20)
  {
   ACTION
   }

That's going to cause problems with compilation.

3

The "ACTION" is to turn on a led...

4

But that macro is missing from your original post.
(There doesn't seem to be a way of turning the LED off)

5

Because that's not the part i'm having problems, the readings of the sensor are wrong...

6

Well, perhaps if you posted your actual code and some of the results . . .
Maybe your power supply isn't up to the job.
Who can tell?