Control HCSR04 Ultrasonic Sensor Using BlueBot App

Control HCSR04 Ultrasonic Sensor : If you’re working on a project involving an HC-SR04 ultrasonic sensor and want to send distance measurements to a smartphone via Bluetooth, this guide is for you. With this code, you can monitor real-time distance and calculate the fill percentage through a Bluetooth app like BlueBot. Below, you’ll find a step-by-step explanation of the code and how it works.

Full Code for HC-SR04 and Bluetooth Integration

#include <SoftwareSerial.h>

// Pin definitions for HC-SR04
const int trigPin = 5; // Trigger pin of the ultrasonic sensor
const int echoPin = 6; // Echo pin of the ultrasonic sensor

// HC-05 Bluetooth module
SoftwareSerial bluetooth(2, 3); // RX, TX pins for Bluetooth

// Variables for ultrasonic sensor
long duration;
int distance;
int maxDistance = 100; // Maximum measurable distance in cm

void setup() {
  // Initialize Serial Monitor
  Serial.begin(9600);

  // Initialize Bluetooth
  bluetooth.begin(9600);
  Serial.println("Bluetooth initialized");

  // Set pin modes for the ultrasonic sensor
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}

void loop() {
  // Measure distance using the ultrasonic sensor
  distance = getDistance();

  // Calculate fill percentage based on distance
  //int fillPercentage = map(distance, 0, maxDistance, 100, 0);
  //fillPercentage = constrain(fillPercentage, 0, 100);

  // Calculate fill percentage based on distance (increasing with distance)
  int fillPercentage = map(distance, 0, maxDistance, 0, 100);
  fillPercentage = constrain(fillPercentage, 0, 100);


  // Format and send the data via Bluetooth
  bluetooth.print(distance);
  bluetooth.print(";");
  bluetooth.print(fillPercentage);
  bluetooth.println(";");

  // Debugging: Print the values to Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.print(" cm, Fill Percentage: ");
  Serial.print(fillPercentage);
  Serial.println("%");

  // Add a delay for stability
  delay(1000);
}

// Function to measure distance using the HC-SR04 sensor
int getDistance() {
  // Send a 10-microsecond pulse to the trigger pin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read the duration of the echo pulse
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance in cm
  int distance = duration * 0.034 / 2;
  return distance;
}

Step-by-Step Explanation of the Code

1. Setting Up the HC-SR04 Sensor

• The HC-SR04 sensor has two main pins for interaction: trigPin and echoPin.
• The trigPin sends an ultrasonic pulse, and the echoPin receives the reflected signal.
• In the code, we defined:
  • trigPin as pin 5.
  • echoPin as pin 6.

2. Configuring the HC-05 Bluetooth Module

• The HC-05 module allows communication between the Arduino and the BlueBot app.
• The SoftwareSerial library is used to create a virtual serial connection on pins 2 (RX) and 3 (TX).

3. Distance Measurement Logic

• A short pulse of 10 microseconds is sent from the trigger pin.
• The duration of the returned pulse is measured using pulseIn(echoPin, HIGH).
• The formula distance = duration * 0.034 / 2 converts the duration into distance in centimeters.
  • 0.034: Speed of sound in cm/µs.
  • /2: Divides by 2 to account for the pulse traveling to and from the object.

4. Calculating the Fill Percentage

• The map() function translates the distance (0 to maxDistance) into a percentage value (0% to 100%).
• This value is constrained to ensure it stays within valid limits.

5. Sending Data Over Bluetooth

• Data is sent in the format distance;fillPercentage; for easy parsing.
• The app can extract these values to display real-time information.

6. Debugging Information

• The Serial.print statements help you verify the sensor’s output in the Serial Monitor.
• These logs are helpful for debugging or testing without Bluetooth.

How to Use the Code

Components Required

• HC-SR04 Ultrasonic Sensor.
• HC-05 Bluetooth Module.
• Arduino Uno (or similar board).
• Jumper wires.

Connection Diagram

Steps to Run

1. Upload the code to your Arduino board.
2. Pair your HC-05 module with your smartphone.
3. Open the BlueBot app and connect to the HC-05 module.
4. The app will display:
   • Real-time distance in centimeters.
   • Fill percentage (e.g., for tank or container levels).

Why This Project is Useful

• Real-Time Monitoring: Get distance and fill levels instantly on your phone.
• Custom Alerts: Use the app to trigger notifications or sound alarms.
• Versatile Applications: Perfect for monitoring tank levels, parking sensors, or obstacle detection.

Common Issues and Troubleshooting

1. Bluetooth Not Connecting
   • Ensure your smartphone is paired with the HC-05 module.
   • Double-check the RX and TX connections.
2. Incorrect Distance Values
   • Verify the ultrasonic sensor connections.
   • Ensure there are no obstructions near the sensor.
3. No Data Received
   • Check the baud rate in the BlueBot app matches 9600.

Control HCSR04 Ultrasonic Sensor : With this project, you’ll not only learn to interface an ultrasonic sensor and a Bluetooth module but also send and display data in a user-friendly format.