My project is to be able to toggle an LED using a GUI written in java over bluetooth, by using a HC-05 module. I am using pin 2 to control the LED. I have wired a voltage divider between the Arduino and the HC-05 as the HC-05 cannot take the full 5V.
However, the LED doesn't go on when I click the button.
I was able to do this without the bluetooth module by just using the USB.
This is my Arduino code for the project
#include <SoftwareSerial.h>
// Connecting Arduino Pin 10 (RX) to HC-05 TXD
// Connecting Arduino Pin 11 (TX) to HC-05 RXD
SoftwareSerial bluetoothSerial(10, 11); // RX, TX
const int ledPin = 2; // Digital pin for the LED
void setup() {
Serial.begin(9600); //Arduino baud rate
Serial.println("Listening for commands from HC-05...");
bluetoothSerial.begin(9600); //HC-05 baud rate
Serial.println("SoftwareSerial initialized at 9600 baud.");
pinMode(ledPin, OUTPUT);
digitalWrite(ledPin, LOW); //LED is off initially
Serial.println("LED initialized on Pin 2 (OFF).");
}
void loop() {
//Checking if 3 bytes are available from HC-05
if (bluetoothSerial.available() >= 3) {
byte byte1 = bluetoothSerial.read();
byte byte2 = bluetoothSerial.read();
byte byte3 = bluetoothSerial.read();
//Prints bytes to the Serial Monitor via USB
Serial.print("Received BT: 0x");
if (byte1 < 0x10) Serial.print("0"); Serial.print(byte1, HEX);
Serial.print(" 0x");
if (byte2 < 0x10) Serial.print("0"); Serial.print(byte2, HEX);
Serial.print(" 0x");
if (byte3 < 0x10) Serial.print("0"); Serial.print(byte3, HEX);
Serial.print(" -> ");
if (byte2 == (byte)ledPin) { // Checking if the command is for the LED pin (Pin 2)
if (byte1 == (byte)0xF4) { // Command 0xF4: Initial setup
if (byte3 == (byte)1) { // 1 for ON
digitalWrite(ledPin, HIGH);
Serial.println("INIT command: LED ON");
} else if (byte3 == (byte)0) { // 0 for OFF
digitalWrite(ledPin, LOW);
Serial.println("INIT command: LED OFF");
} else {
Serial.println("INIT command: Unknown state for LED.");
}
} else if (byte1 == (byte)0xF5) { // 0xF5 toggles LED
if (byte3 == (byte)0) { // 0 for OFF
digitalWrite(ledPin, LOW);
Serial.println("TOGGLE command: LED OFF");
} else if (byte3 == (byte)1) { // 1 for ON
digitalWrite(ledPin, HIGH);
Serial.println("TOGGLE command: LED ON");
} else {
Serial.println("TOGGLE command: Unknown state for LED.");
}
} else {
Serial.println("Unknown command type for Pin 2.");
}
} else {
Serial.println("Command not for LED pin (byte2 did not match ledPin).");
}
}
delay(5);
}
This is my java code written in the IntelliJ IDE.
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import com.fazecast.jSerialComm.SerialPort;
public class GUI {
private JFrame frame;
public SerialPort arduino_port = null;
private static final String TARGET_PORT_NAME = "cu.HC-05"; //This is my port name for the HC-05
public boolean LED_IS_ON = false;
private JButton button = new JButton(" ");
private JLabel statusLabel; // For displaying connection status
public static final int BAUD_RATE = 9600;
public GUI() {
makeFrame();
frame.setVisible(true);
ports();
}
private void makeFrame() {
frame = new JFrame("BLUETOOTH LED CONTROL");
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
statusLabel = new JLabel("Status: Initializing...");
frame.add(statusLabel, BorderLayout.NORTH);
JLabel instructionLabel = new JLabel("Click the button to switch the LED on/off");
button.setEnabled(false);
button.setText("OFF");
button.setBackground(Color.RED);
button.setOpaque(true);
button.setBorderPainted(true);
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (arduino_port != null && arduino_port.isOpen()) {
System.out.println("Button clicked. Current internal LED state: " + (LED_IS_ON ? "ON" : "OFF"));
LED_IS_ON = !LED_IS_ON; // Toggles the LED's state
byte[] command = new byte[3];
command[0] = (byte) 0xF5; // 0xF5 (Toggles LED on Arduino)
command[1] = (byte) 0x02; // Pin 2 (Arduino's ledPin)
if (LED_IS_ON) {
command[2] = (byte) 0x01; //LED on
button.setText("OFF");
button.setBackground(Color.GREEN);
System.out.println("Sending command: 0xF5 0x02 0x01 (Turn LED ON)");
} else {
command[2] = (byte) 0x00; // LED off
button.setText("ON");
button.setBackground(Color.RED);
System.out.println("Sending command: 0xF5 0x02 0x00 (Turn LED OFF)");
}
arduino_port.writeBytes(command, command.length);
} else {
statusLabel.setText("Status: Not connected!");
System.err.println("Button clicked but port is not open.");
}
}
});
JPanel controlPanel = new JPanel(new FlowLayout());
controlPanel.add(instructionLabel);
controlPanel.add(button);
frame.add(controlPanel, BorderLayout.CENTER);
frame.pack();
frame.setLocationRelativeTo(null);
}
private void ports() {
statusLabel.setText("Status: Attempting to connect to " + TARGET_PORT_NAME + "...");
button.setEnabled(false); // Disables button when truing to connect
if (arduino_port != null && arduino_port.isOpen()) {
arduino_port.closePort();
System.out.println("Closed the previously open port.");
}
//This lists all the available ports
SerialPort[] ports = SerialPort.getCommPorts();
System.out.println("Available Serial Ports: ");
boolean targetPortFound = false;
for (SerialPort port : ports) {
String currentPortName = port.getSystemPortName();
System.out.println(currentPortName); // Print all ports found
if (currentPortName.equals(TARGET_PORT_NAME)) {
arduino_port = port;
targetPortFound = true;
System.out.println("Target port '" + TARGET_PORT_NAME + "' found.");
try {
Thread.sleep(100);
} catch (InterruptedException e) {
System.err.println("Thread interrupted before port open: " + e.getMessage());
Thread.currentThread().interrupt();
statusLabel.setText("Status: Connection interrupted.");
return;
}
if (arduino_port.openPort()) {
System.out.println("Port " + TARGET_PORT_NAME + " opened successfully.");
statusLabel.setText("Status: Connected to " + TARGET_PORT_NAME);
button.setEnabled(true);
arduino_port.setBaudRate(BAUD_RATE);
arduino_port.setComPortTimeouts(SerialPort.TIMEOUT_READ_BLOCKING, 0, 0);
try {
Thread.sleep(100);
byte[] initialCommand = new byte[3];
initialCommand[0] = (byte) 0xF4; // Command 0xF4 (Init LED on Arduino)
initialCommand[1] = (byte) 0x02; // Pin 2 (Arduino's ledPin)
initialCommand[2] = (byte) 0x01; // Send 1 (LED ON)
arduino_port.writeBytes(initialCommand, initialCommand.length);
System.out.println("Initial command sent: " + String.format("0x%02X 0x%02X 0x%02X", initialCommand[0], initialCommand[1], initialCommand[2]));
LED_IS_ON = true; // Sync GUI state with initial command (LED should be ON)
button.setText("OFF"); // Button says "OFF" for next click (to turn it OFF)
button.setBackground(Color.GREEN); // LED is ON, so button implies next action is OFF
} catch (InterruptedException e) {
System.err.println("Thread interrupted during initial command send: " + e.getMessage());
Thread.currentThread().interrupt();
statusLabel.setText("Status: Initial command interrupted.");
arduino_port.closePort();
} catch (Exception e) {
System.err.println("Error sending initial command: " + e.getMessage());
statusLabel.setText("Status: Initial command failed.");
arduino_port.closePort();
}
break;
} else {
System.err.println("Failed to open port: " + TARGET_PORT_NAME + ". It might be in use or permissions issue.");
statusLabel.setText("Status: Failed to open " + TARGET_PORT_NAME);
button.setEnabled(false);
}
}
}
System.out.println("End of Port Scan");
if (!targetPortFound || !arduino_port.isOpen()) {
System.err.println("Error: Target port '" + TARGET_PORT_NAME + "' not found or could not be opened. " +
"Please verify the name, Bluetooth pairing, and ensure it's not already in use.");
statusLabel.setText("Status: " + TARGET_PORT_NAME + " not found or accessible.");
button.setEnabled(false);
}
}
This is my wiring. I am not too sure but I suspect the problem lies here.
I am hoping someone could alert me to where I have gone wrong.