在 java 中使用连续触发事件使用 arduino 控制直流电机

Question

I'm trying to control a small DC motor through Arduino Uno with pc java. This java application is server app and connect with android app using socket. And it works on single command from java. But doesn't work continuously pressed. I want rotating motor when I continuously press down the button and stop press up. Please help me.

Here is android code. /continuously press/

   class RepetitiveUpdater implements Runnable {

        @Override
        public void run() {
            if (autoIncrement) {
                increment();
                try {
                    Thread.sleep(100);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                repeatUpdateHandler.postDelayed(new RepetitiveUpdater(), REPEAT_DELAY);
            } else if (autoDecrement) {
                decrement();
                repeatUpdateHandler.postDelayed(new RepetitiveUpdater(), REPEAT_DELAY);
            }
        }

    }

    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            increment();
        }
    });

    btn.setOnLongClickListener(new View.OnLongClickListener() {

        @Override
        public boolean onLongClick(View v) {
            autoIncrement = true;
            repeatUpdateHandler.post(new RepetitiveUpdater());
            return false;
        }
    });

    btn1.setOnLongClickListener(new View.OnLongClickListener() {

        @Override
        public boolean onLongClick(View v) {
            autoDecrement = true;
            repeatUpdateHandler.post(new RepetitiveUpdater());
            return false;
        }
    });

And here is java server.

private void sendMsgToPort(int k) {
    try {
        String s = String.valueOf(k);
        char buf2[] = s.toCharArray();
        serialPort.writeByte((byte) buf2[0]);
    } catch (SerialPortException ex) {
        System.out.println(ex);
    }
}

// ........
        while (true) {
            try {

                clientSocket = serverSocket.accept(); // accept the client connection
                inputStreamReader = new InputStreamReader(clientSocket.getInputStream());
                bufferedReader = new BufferedReader(inputStreamReader); // get the client message
                message = bufferedReader.read();
                sendMsgToPort(message);
                System.out.println("m=:" + message);
               // System.out.println("Serial : "+serialPort.readString());
                //inputStreamReader.close();
               // clientSocket.close();
                //System.out.println(serialPort.readBytes());
                //Thread.sleep(100);

            } catch (IOException ex) {
                // status.setText("Error: " + ex);
                System.out.println("Problem in message reading");
            } 
        } 

And here is ardiuno example code:

int val = 0;
int led = 8;

void setup()
{
   Serial.begin(9600);
   pinMode(led, OUTPUT);
}

void loop()
{
   delay(100);
}

void serialEvent() // To check if there is any data on the Serial line
{
   if (Serial.available())
   {
       val = Serial.parseInt();
       if(val == 1)   //Switch on the LED, if the received value is 1.
       {
          digitalWrite(led, HIGH);
       }
   }

}

`

Answer 1

One problem is in your Java server program:

clientSocket = serverSocket.accept();

You accept a new connection, read/process one message, and then? That client socket just goes out of scope. The connection is just left open and your code waits for a new connection again.

Search for "Java multithreaded server" examples, it's really easy. Have each connection fully handled in a dedicated thread after accepting, so that you can do both wait for another connection and handle a longer dialog on an established connection at the same time.