Android 应用程序与 Arduino 串行通信不同步 [英] Android app not synchronized with Arduino Serial communication

问题描述

我有一个简单的声纳 arduino 项目，以便它每秒打印一次距离.我已经使用 UsbSerial 实现了一个 android 应用程序来与我的 arduino 通信.到目前为止一切顺利，我能够接收数据并且我收到的数据是正确的，但问题是有时无法正确发送值.这是我收到的示例输出:

I have a simple sonar arduino project so that it prints the distance every second. I have implemented an android app using UsbSerial to communicate with my arduino. So far so good, I am able to receive data and the data I receive is correct, but the problem is that the values are sometimes not properly sent. Here is the sample output I receive:

data: 7
data: 1    
data: 
data: 71

这里是生成输出的代码:

and here is the code that generates output:

private UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {

        @Override
        public void onReceivedData(byte[] arg0)
        {
            try {
                String data = new String(arg0, "UTF-8");
                System.out.println("data: " + data);
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
    };

所以我认为这里有两个问题:

So in my opinion there is 2 problems here:

• 第 1 行和第 1 行2 必须是 71
值的一行
• 第 3 行不应该存在，因为我的应用程序正在侦听 onReceivedData 并且 arduino 总是发送一些东西.

• Lines 1 & 2 must be just one line with the value of 71
• Line 3 should not exists as my application is listening onReceivedData and arduino always send something.

任何帮助将不胜感激.

推荐答案

我已经找到了该问题的解决方案.通过阅读此链接，我注意到我需要对收到的数据进行一些操作在 onReceivedData 方法中.所以我改变了 mCallBack 如下:

I have found a solution for the issue. by reading this link I noticed that I need to do some manipulation on the data I receive in the onReceivedData method. So I changed the mCallBack as follow:

private UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {

        @Override
        public void onReceivedData(byte[] arg0)
        {
            if(arg0!= null && arg0.length > 0){
                if (isStartByte(arg0[0])) {
                    printData();
                    clearBytes();
                }
                appendBytes(arg0);
            }
        }
    };

这是我添加的其他方法:

and here is the other methods I added:

    private void clearBytes(){
        buffer=new byte[8];
        bufferSize = 0;
    }

    private void appendBytes(byte[] buf){
        System.arraycopy(buf, 0, buffer, bufferSize, buf.length);
        bufferSize += buf.length;
    }

    private void printData() {
        if (bufferSize == 0) {
            return;
        }
        byte[] buf = new byte[bufferSize];
        System.arraycopy(buffer, 0, buf, 0, bufferSize);

        String data = null;
        try {
            data = new String(buf, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        }
        if (null != data && !data.isEmpty()) {
            System.out.println("data: " + data);
        }
    }

    public boolean isStartByte(byte firstChar){
        return firstChar=='A';
    }

我还修改了 Arduino 代码并在串行输出的开头添加了字符 A.这解决了问题，但是我认为这不是最佳实践.我认为 UsbSerial 库应该提供更好的输出处理(或者我可能错了，这就是使用串行通信的本质).

And also I modified the Arduino code and added character A to the beginning of the serial output. This solves the issue, however I think this is not the best practice. I think the UsbSerial library should provide better output handling( or maybe I am wrong and this is the nature of working with serial communication ).

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