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ESP32 with Ultrasonic Sensor (HC-SR04)

14-06-2025

🧠 What is an Ultrasonic Sensor?

An ultrasonic sensor is a device that uses sound waves to detect how far something is.

🧩 HC-SR04 Ultrasonic Sensor: Pinout and Function

The HC-SR04 sensor has 4 pins:

Pin	Name	Function
1	VCC	Power supply (+5V)
2	Trig	Trigger pin – sends sound
3	Echo	Echo pin – receives sound
4	GND	Ground (0V)

🔌 Pin Details and Use:

VCC: Connect to +5V from your microcontroller or Arduino.
GND: Connect to ground (GND).
Trig (Trigger):
- You send a short pulse (about 10 microseconds) to this pin.
- This starts the sound wave.
Echo:
- This pin goes HIGH (on) when the echo is being received.
- You measure how long it's HIGH to calculate distance.

📏 Connection Example with ESP32:

HC-SR04 Pin	Arduino Pin
VCC	5V
GND	GND
Trig	D5 (example)
Echo	D18 (example)

🧪 Basic Working Flow:

Set Trig HIGH for 10 microseconds.
Then wait for the Echo pin to go HIGH and back to LOW.
Measure the time it stays HIGH.
Calculate the distance using the formula:

$Distance =(Speed of Sound \times Time)$

(Speed of sound in air ≈ 343 meters/second)

💡 Where It's Used:

Robots (to avoid hitting things)
Cars (reverse parking sensors)
Water tanks (to check water level)
Automatic doors

BASIC CODE WITH ESP32

#include <LiquidCrystal_I2C.h>

// ---------------------------------------------------------------------------

// Example NewPing library sketch that does a ping about 20 times per second.

// ---------------------------------------------------------------------------

#include <NewPing.h>

#define TRIGGER_PIN 5 // Arduino pin tied to trigger pin on the ultrasonic sensor.

#define ECHO_PIN 18 // Arduino pin tied to echo pin on the ultrasonic sensor.

#define MAX_DISTANCE 200 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

void setup() {

Serial.begin(115200); // Open serial monitor at 115200 baud to see ping results

}

void loop() {

delay(500); // Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.

Serial.print("Ping: ");

int d=sonar.ping_cm();

Serial.print(d); // Send ping, get distance in cm and print result (0 = outside set distance range)

Serial.println("cm");

}

HOW TO OPERATE USING BLYNK

#define BLYNK_TEMPLATE_ID

#define BLYNK_TEMPLATE_NAME

#define BLYNK_AUTH_TOKEN

#include <WiFi.h>

#include <WiFiClient.h>

#include <BlynkSimpleEsp32.h>

char ssid[] = "Airtel_ramn_7888"; //wifi name

char pass[] = "air45914"; //wifi password

BlynkTimer timer; // Creating a timer object

// ---------------------------------------------------------------------------

// Example NewPing library sketch that does a ping about 20 times per second.

// ---------------------------------------------------------------------------

#include <NewPing.h>

#define TRIGGER_PIN 5 // Arduino pin tied to trigger pin on the ultrasonic sensor.

#define ECHO_PIN 18 // Arduino pin tied to echo pin on the ultrasonic sensor.

#define MAX_DISTANCE 200 // Maximum distance we want to ping for (in centimeters). Maximum sensor distance is rated at 400-500cm.

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE); // NewPing setup of pins and maximum distance.

void setup() {

Serial.begin(115200); // Open serial monitor at 115200 baud to see ping results.

Serial.println("Device Started");

timer.setInterval(1000L, myData); //Staring a timer

Blynk.begin(BLYNK_AUTH_TOKEN,ssid,pass);

}

void loop() {

Blynk.run();

timer.run();

}

void myData() // This loop defines what happens when timer is triggered

{

// Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.

Serial.print("Ping: ");

int d=sonar.ping_cm();

Serial.println(d);

Blynk.virtualWrite(V0,d);

delay(2000);

}

ESP32 with Ultrasonic Sensor (HC-SR04)

🧠 What is an Ultrasonic Sensor?

🧩 HC-SR04 Ultrasonic Sensor: Pinout and Function

🔌 Pin Details and Use:

📏 Connection Example with ESP32:

🧪 Basic Working Flow:

💡 Where It's Used:

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Blog Details

ESP32 with Ultrasonic Sensor (HC-SR04)

🧠 What is an Ultrasonic Sensor?

🧩 HC-SR04 Ultrasonic Sensor: Pinout and Function

🔌 Pin Details and Use:

📏 Connection Example with ESP32:

🧪 Basic Working Flow:

💡 Where It's Used:

Related Post