To interface ultrasonic proximity sensor with Node MCU ESP8266 and write a program to calculate the distance of an object.

 Objective : To interface ultrasonic proximity sensor with Node MCU ESP8266 and write a program to calculate the distance of an object.

Code:

const int trigPin = 18;

const int echoPin = 17;

//define sound speed in cm/uS

#define SOUND_SPEED 0.034

#define CM_TO_INCH 0.393701

long duration;

float distanceCm;

float distanceInch;

void setup()

    {

        Serial.begin(115200); // Starts the serial communication

        pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output

        pinMode(echoPin, INPUT); // Sets the echoPin as an Input

    }

void loop()

{

// Clears the trigPin

   digitalWrite(trigPin, LOW);

    delayMicroseconds(2);

   // Sets the trigPin on HIGH state for 10 micro seconds

    digitalWrite(trigPin, HIGH);

    delayMicroseconds(10);

    digitalWrite(trigPin, LOW);

// Reads the echoPin, returns the sound wave travel time in microseconds

    duration = pulseIn(echoPin, HIGH);

// Calculate the distance

    distanceCm = duration * SOUND_SPEED/2

// Convert to inches

    distanceInch = distanceCm * CM_TO_INCH;

// Prints the distance in the Serial Monitor

    Serial.print("Distance (cm): ");

    Serial.println(distanceCm);

    Serial.print("Distance (inch): ");

    Serial.println(distanceInch);

    delay(1000);

}

Output: