Measuring Distance with Arduino: A Guide to the HC-SR04 Ultrasonic Sensor

HC-SR04 Ultrasonic Sensor

The HC-SR04 sensor uses ultrasonic sound to determine the distance to an object. It can measure distances from 2 cm to 400 cm. Its operation is not affected by sunlight or black surfaces, but temperature and humidity can affect the accuracy of its readings. It also has difficulty detecting soft materials, such as cloth. The HC-SR04 sensor has an ultrasonic receiver and transmitter.

Here, my goal is to help you understand how this sensor works and how to program it with Arduino.

HC-SR04 Ultrasonic sensor Technical Specification

HC-SR04

power supply                  :- 5DC
Quiescent Current           :- 2mA
Working Current               :-15mA
Effect Angle                    :<15 degrees
Distance                           :- 2cm to 400cm
Resolution                        :-0.3cm
Trigger input pulse width :-10us
Ultrasonic Frequency       :-40KHz

Pins

VCC  :- arduino 5v pin
TRIG  :- arduino Digital pin
ECHO :- arduino Digital pin
GND  :- arduino GND pin

The TRIG pin is used to send ultrasonic sound, and the ECHO pin is used to listen.


Example

int triggerPin= 8;
int echoPin= 7;
long pulsDuration =0;
long distanceCM =0;
long distanceINC =0;
void setup() {
  // put your setup code here, to run once:
  pinMode(triggerPin,OUTPUT);
  pinMode(echoPin,INPUT);

  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
   digitalWrite(triggerPin,LOW);
   delayMicroseconds(5);
   digitalWrite(triggerPin,HIGH);
   delayMicroseconds(10);
   digitalWrite(triggerPin,LOW);

  pulsDuration =pulseIn(echoPin,HIGH);

  distanceCM = (pulsDuration/2) / 29.1;
  distanceINC = (pulsDuration/2) / 74; 

   Serial.println("CM");
  Serial.println(distanceCM);

   Serial.println("INCH");
  Serial.println(distanceINC);

  delay(1000);

   Serial.println("**********************************************");
}