HC-SR04 Ultrasonic Distance Sensor

Ultrasonic distance sensor for measuring distances from 2cm to 400cm

HC-SR04 Ultrasonic Distance Sensor

Pin names

VCC · Power

Voltage supply (5V)

TRIG · Digital Input

Pulse to start the measurement

ECHO · Digital Output

Measure the high pulse length to get the distance

GND · Ground

Ground

Attributes

distance · string · default: "400"

Initial distance value, in centimeters

Operation

To start a new distance measurement set the TRIG pin to high for 10uS or more. Then wait until the ECHO pin goes high, and count the time it stays high (pulse length). The length of the ECHO high pulse is proportional to the distance. Use the following table to convert the ECHO pulse length in microseconds into centimeters / inches:

Unit	Distance
Centimeters	PulseMicros / 58
Inches	PulseMicros / 148

Setting the distance

To change the distance while the simulation is running, click on the HC-SR04 drawing in the diagram and use the slider to set the distance value. You can choose any value between 2cm and 400cm.

Arduino code example

#define PIN_TRIG 3
#define PIN_ECHO 2

void setup() {
  Serial.begin(115200);
  pinMode(PIN_TRIG, OUTPUT);
  pinMode(PIN_ECHO, INPUT);
}

void loop() {
  // Start a new measurement:
  digitalWrite(PIN_TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(PIN_TRIG, LOW);

  // Read the result:
  int duration = pulseIn(PIN_ECHO, HIGH);
  Serial.print("Distance in CM: ");
  Serial.println(duration / 58);
  Serial.print("Distance in inches: ");
  Serial.println(duration / 148);

  delay(1000);
}

Try this example on Wokwi

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