慢Arduino串行传输

Question

我正在测试我的Arduino UNO的串行传输速度.根据我的要求,我必须从主机PC向Arduino传输3KB/s.我编写了一个非常简单的程序,它回复了结果,Serial.available()然后在Arduino IDE的串行监视器中进行了测试.我已经开始发送字符,直到达到63字节的最大值.我对此感到非常惊讶,因为我在某处看到Arduino有一个128byte的串行缓冲区.

无论如何,我已经编写了一个非常简单的协议,它以48字节的数据包传输数据(实际上是49个字节,因为标题字符).主机发送一个d字符,然后发送48个字节的数据.为了测试传输的有效性,我发送一个从0到47的简单字节序列,在Arduino端进行验证.如果验证失败,UNO开始闪烁PIN13上的板载LED.一旦发送了字节,主机就会等待一个简单k字符的确认.一旦完成处理实际数据包,Arduino就会发送它.

主机程序测量传输的数据包的数量,并在1秒后显示它.波特率为9600时,PC成功传输~16包/秒(~800字节/秒),这是相当不错的.我试图通过将双方的波特率提高到57600来改善这一点; 但是,发送的数据包数量只会增加一点.我不知道问题是什么.也许我已经达到USB串口转换器的某种限制？

---

这是我的代码.

PC(Java,我使用jSSC进行串口通信)

  package hu.inagy.tapduino.server;

  import jssc.SerialPort;
  import jssc.SerialPortException;

  /**
   * Test Arduino communication.
   */
  public class App
  {

    private static void testComm(SerialPort port) throws SerialPortException {
      long runningSeconds = 0;
      long time = System.currentTimeMillis();
      long numberOfPackets = 0;
      boolean packetSent = false;
      while (runningSeconds < 10) {
        long currentTime = System.currentTimeMillis();
        if (currentTime - time > 1000) {
          runningSeconds++;
          time = currentTime;
          System.out.println(numberOfPackets + " packets/s");
          numberOfPackets = 0;
        }

        if (!packetSent) {
          packetSent = true;
          port.writeByte((byte) 'd');
          for (int i = 0; i < 48; i++) {
            port.writeByte((byte) i);
          }
        } else {
          byte[] received = port.readBytes();
          if (received != null) {
            if (received.length > 1) {
              throw new IllegalStateException("One byte expected, instead got: " + received.length);
            }

            char cmd = (char) received[0];
            if ('k' != cmd) {
              throw new IllegalStateException("Expected response 'k', instead got: " + cmd);
            }
            packetSent = false;
            numberOfPackets++;
          }
        }

      }
    }

    public static void main(String[] args)
    {
      SerialPort port = new SerialPort("COM7");

      try {
        if (!port.openPort()) {
          throw new IllegalStateException("Failed to open port.");
        }
        port.setParams(57600, 8, 1, 0);
      } catch (SerialPortException e) {
        throw new IllegalStateException("Exception while setting up port.", e);
      }

      try {
        // Wait 1.5sec for Arduino to boot successfully.
        Thread.sleep(1500);
      } catch (InterruptedException e) {
        throw new IllegalStateException("Interrupt while waiting?", e);
      }

      try {
        testComm(port);
      } catch (SerialPortException exc) {
        throw new IllegalStateException("Failure while testing communication.", exc);
      } finally {
        try {
          if (!port.closePort()) {
            throw new IllegalStateException("Failed to close port.");
          }
        } catch (SerialPortException e) {
          throw new IllegalStateException("Exception while closing port.", e);
        }
      }
    }
  }

Arduino的

void setup() {
   pinMode(13, OUTPUT);
   Serial.begin(57600);
}

boolean error = false;

void loop() {
  if (error) {
      digitalWrite(13, HIGH);
      delay(1000);
      digitalWrite(13, LOW);
      delay(1000);
  } else {
    while (Serial.available()<49);
    char cmd = Serial.read();
    if ('d'!=cmd) {
       error=true;
       return;
    }

    for (int i=0; i<48; i++) {
       int r = Serial.read();
       if (r!=i) {
         error=true;
         return;
       } 
    }

    Serial.write('k');
  }

}

Answer 1

NagyI,jSSC方法writeByte(字节b)是相同的writeBytes(new byte [] {b}).例如:

serialPort.writeByte((byte)0xFF);
serialPort.writeBytes(new byte[]{(byte)0xFF});

这些字符串是等价的.writeByte()方法为要发送的每个字节创建一个新的字节数组.在Java中创建一个对象是一项昂贵的操作,这就是为什么,如果你需要高速数据传输,请使用像你的答案中那样准备好的字节数组.问候,阿列克谢.