如何通过Java向连接LCD的Arduino UNO发送串口文本？

Hey there! I totally get sticking with a language you’re comfortable with—Java is a great pick for this. Let’s break down the most reliable ways to get your Java app sending serial text to your Arduino UNO, so your LCD can display whatever you want.

• jSerialComm: This is my go-to for simplicity—it’s a no-fuss, pure Java library that doesn’t require messy native library setup (unlike some older options). It works cross-platform (Windows, macOS, Linux) and has a straightforward, easy-to-learn API.
• RXTX: A classic option, but it does need OS-specific native binaries to work. It’s a bit more involved to set up, but still widely used if you need legacy support or specific advanced features.

First, add the library to your project:

• If you’re using Maven, drop this into your pom.xml:

<dependency>
    <groupId>com.fazecast</groupId>
    <artifactId>jSerialComm</artifactId>
    <version>2.9.2</version>
</dependency>

• For Gradle, add this line to your build.gradle dependencies:

implementation 'com.fazecast:jSerialComm:2.9.2'

Then, here’s a complete Java example to send text to your Arduino:

import com.fazecast.jSerialComm.SerialPort;

public class ArduinoSerialSender {
    public static void main(String[] args) {
        // Step 1: Locate your Arduino's serial port
        SerialPort[] availablePorts = SerialPort.getCommPorts();
        SerialPort arduinoPort = null;
        
        // Auto-detect the Arduino (you can also hardcode the port name if you know it, like "COM3" or "/dev/ttyACM0")
        for (SerialPort port : availablePorts) {
            if (port.getDescriptivePortName().contains("Arduino") 
                || port.getSystemPortName().startsWith("/dev/ttyACM") 
                || port.getSystemPortName().startsWith("COM")) {
                arduinoPort = port;
                break;
            }
        }
        
        if (arduinoPort == null) {
            System.out.println("Oops—couldn't find your Arduino's serial port!");
            return;
        }
        
        // Step 2: Configure and open the port (match baud rate with your Arduino code!)
        arduinoPort.setBaudRate(9600);
        if (arduinoPort.openPort()) {
            System.out.println("Serial port opened successfully!");
        } else {
            System.out.println("Failed to open the serial port—check permissions or if it's in use.");
            return;
        }
        
        // Step 3: Send your desired text to the Arduino
        String displayText = "Hello from Java!";
        arduinoPort.writeBytes(displayText.getBytes(), displayText.length());
        
        // Pro tip: Add a small delay to ensure all data is sent before closing the port
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        
        // Step 4: Clean up and close the port
        arduinoPort.closePort();
        System.out.println("Serial port closed.");
    }
}

Make sure your Arduino code is set up to listen for serial input and display it on the LCD. Here’s a quick example (adjust pins to match your LCD wiring):

#include <LiquidCrystal.h>

// Initialize LCD (adjust these pins to match your setup)
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
  Serial.begin(9600); // Must match the baud rate in your Java code!
  lcd.begin(16, 2);   // For a 16x2 LCD screen
  lcd.print("Waiting...");
}

void loop() {
  if (Serial.available() > 0) {
    String inputText = Serial.readStringUntil('\n'); // Read input until newline
    lcd.clear();
    lcd.print(inputText);
  }
}

• Serial Port Permissions: On Linux/macOS, you might get a "permission denied" error. Fix this by adding your user to the appropriate group:

  # Linux
  sudo usermod -aG dialout your_username
  
  # macOS
  sudo dscl . append /Groups/uucp GroupMembership your_username
  

• Baud Rate Mismatch: Double-check that both your Java code and Arduino code use the exact same baud rate (9600 is standard, but adjust if needed).
• Port Already In Use: Make sure the Arduino IDE’s Serial Monitor isn’t open when you run your Java app—only one program can use the serial port at a time.
• Java Version Compatibility: If you’re on an older Java version (pre-Java 11), stick to jSerialComm v2.9.2 or earlier—newer versions require Java 11+.

内容的提问来源于stack exchange，提问作者KeionBeats