HC-SR04 always showing the value 0

Projects General Guidance
1

Hi ,

So I'm working on this bot which does waste segregation. Part of the project depends upon the distance between a wall placed in front and the bot itself to locate the right bins. So, for testing the sensor , I uploaded a code from online and connected the pins as following.

HC-SR04 ----- ARDUINO
VCC 5v
GND GND
TRIG 2
ECHO 4

The code is the following.

const int trigPin = 2;

const int echoPin = 4;


void setup() {

Serial.begin(9600);}

void loop()

{

long duration, inches, cm;

pinMode(trigPin, OUTPUT);

digitalWrite(trigPin, LOW);

delayMicroseconds(2);

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

digitalWrite(trigPin, LOW);

pinMode(echoPin, INPUT);

duration = pulseIn(echoPin, HIGH);

inches = microsecondsToInches(duration);

cm = microsecondsToCentimeters(duration);

Serial.print(inches);

Serial.print("in, ");

Serial.print(cm);

Serial.print("cm");

Serial.println();

delay(100);

}

long microsecondsToInches(long microseconds)

{return microseconds / 74 / 2;

}

long microsecondsToCentimeters(long microseconds)

{return microseconds / 29 / 2;}

I've tested out 2 of these sensors on 2 different arduino UNO boards. Though one of these boards was connected to an L293DNE IC , the other one wasn't and I doubt that the IC would make any difference in the operation of the sensor. I first suspected an issue in the jumpers and replaced them with 4 new ones but that didn't resolve the issue. Then , I spotted out the 'pinMode' to be inside the void loop and did some more changes to the code hoping it would resolve my issue but didn't.

const int trigPin = 2;

const int echoPin = 4;


void setup() {
  pinMode(trigPin, OUTPUT);
  
pinMode(echoPin, INPUT);

Serial.begin(9600);}

void loop()

{

long duration, inches, cm;



digitalWrite(trigPin, LOW);

delayMicroseconds(2);

digitalWrite(trigPin, HIGH);







duration = pulseIn(echoPin, HIGH);
digitalWrite(trigPin, LOW);

inches = microsecondsToInches(duration);

cm = microsecondsToCentimeters(duration);

Serial.print(inches);

Serial.print("in, ");

Serial.print(cm);

Serial.print("cm");

Serial.println();

delay(100);

}

long microsecondsToInches(long microseconds)

{return microseconds / 74 / 2;

}

long microsecondsToCentimeters(long microseconds)

{return microseconds / 29 / 2;}

Beside that , there seemed to be no complaints in the comments section of the tutorial I referred to for the code and assumed it to be flawless and its highly unlikely that both my ultrasonic sensors don't work since one of them was a recent purchase.I've also used these before and I never came across such an issue. I also tried connecting the VCC pin to 3V3 rather than 5V but that didn't seem to help either. Now , I'm really confused on how to proceed further and hope to seek some guidance into resolving this incomprehensible issue. I hope this much details is enough.

Thank you :slight_smile:

2

I don't see anything obviously wrong. Those sensors won't work well, if at all, on 3.3V.

Try changing the pins in the code and wiring, to match. Disconnect everything else from the Uno.

It is possible that you received a bad batch of sensors. Try buying from a different source.

3

Finally got it to work. Turns out to be the jumpers that were the issue. Mounted the sensors on the breadboard and they work like a charm. With jumpers , I needed to bend it at the end for it to work , dont know why though.
Thank you for replying anyways :slight_smile: