Visual Studio(C#) 中的 OBD II 应用程序与 Xamarin

Question

我正在开发一个从 OBD II 蓝牙适配器接收数据的 Android 应用程序。设置应用程序和适配器之间的连接是可行的，但是当我向适配器发送命令时，我不会得到正确的结果。它要么返回：

+连接

或者我刚刚发送给适配器的命令。

应用在 Visual Studio 中编码，使用 Xamarin 为 Android 开发。 该代码仅显示应用程序的简化版本，并仅发送 01 -1f 之间支持的 PID 的代码。

BluetoothAdapter myAdapter;
BluetoothSocket socket = null; 
string rawData;
public BluetoothConnect()
    {

        myAdapter = BluetoothAdapter.DefaultAdapter;
        if (myAdapter == null)
        {
            //Device has no Bluetooth
        }
        if (!myAdapter.IsEnabled)
        {
            myAdapter.Enable();
        }
        BluetoothDevice d = myAdapter.GetRemoteDevice("AA:BB:CC:11:22:33");
        socket = d.CreateRfcommSocketToServiceRecord(UUID.FromString("00001101-0000-1000-8000-00805F9B34FB"));
        socket.Connect();

        byte[] cmd = Encoding.ASCII.GetBytes("AT D");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        ReadAnswer();
        socket.OutputStream.Flush();

        cmd = Encoding.ASCII.GetBytes("AT Z");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        socket.OutputStream.Flush();

        cmd = Encoding.ASCII.GetBytes("AT E0");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        ReadAnswer();
        socket.OutputStream.Flush();

        cmd = Encoding.ASCII.GetBytes("AT L0");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        ReadAnswer();
        socket.OutputStream.Flush();

        cmd = Encoding.ASCII.GetBytes("AT S0");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        ReadAnswer();
        socket.OutputStream.Flush();

        cmd = Encoding.ASCII.GetBytes("AT H0");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        ReadAnswer();
        socket.OutputStream.Flush();

        cmd = Encoding.ASCII.GetBytes("AT SP 0");
        socket.OutputStream.Write(cmd, 0, cmd.Length);
        ReadAnswer();
        socket.OutputStream.Flush();




        cmd = Encoding.ASCII.GetBytes("0100");
        socket.OutputStream.Write(cmd, 0, cmd.Length);

        ReadAnswer();


    }

    private void ReadAnswer() {
        try {
            rawData = "";
            int a = 0;

            System.Text.StringBuilder b = new   System.Text.StringBuilder();
            char c;
            while (((a = (byte)socket.InputStream.ReadByte()) > -1)) 
            {

                c = (char)a;
                if (c == '>')
                {
                    break;
                }
                b.Append(c);
            }

            rawData = b.ToString();
            Log.Info("-----------------------------------", "RawData: " + rawData);
            socket.InputStream.Flush();
        }
        catch(System.Exception e)
        {
            Log.Info("", "" + e.Message);
        }



    } 

我已经尝试过不同的初始化命令组合。

我可以想象问题与我读取输入流的方法或发送命令有关，但我不知道该怎么做，因为我是 Visual Studio、Xamarin 和 Android 开发的新手。

希望大家能给我一些建议！

Answer 1

现在太旧了，但也许有人需要。下面的代码是用 Xamarin 开发的 ELM327 测试的。

 public void SendCommand( string command , Action<string> onDataRecevied )
    {
        if ( BthSocket.IsConnected )
        {
            byte[] cmd = Encoding.ASCII.GetBytes( command + " \r" );
            BthSocket.OutputStream.Write( cmd , 0 , cmd.Length );
            BthSocket.OutputStream.Flush();


            ReadData( out string d );
            if ( d != "" )
            {
                onDataRecevied( d );
            }



        }
    }

读取数据

public void ReadData( out string data )
    {
        StringBuilder res = new StringBuilder();

        try
        {
            byte b = 0;


            // read until '>' arrives OR end of stream reached
            char c;
            // -1 if the end of the stream is reached
            while ( ( b = ( ( byte )BthSocket.InputStream.ReadByte() ) ) > -1 )
            {
                c = ( char )b;
                if ( c == '>' ) // read until '>' arrives
                {
                    break;
                }
                res.Append( c );
            }

        }
        catch ( Exception e )
        {
            System.Console.WriteLine( e.ToString() );
        }

      data = res.ToString().Replace( "SEARCHING" , "" );

        /*
         * Data may have echo or informative text like "INIT BUS..." or similar.
         * The response ends with two carriage return characters. So we need to take
         * everything from the last carriage return before those two (trimmed above).
         */

        data = data.Replace( "\\s" , "" );

    }

下面是初始化设备的命令

 obd2.SendCommand( "AT Z" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT E0" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT E0" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT L0" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT S0" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "ATD" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT SP 6" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT H0" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT 1" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "ATST 96" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT H1" , ( obj ) => { LogMessage( txtData , obj ); } );
             obd2.SendCommand( "AT H0" , ( obj ) => { LogMessage( txtData , obj ); } );

这一行 data = res.ToString().Replace( "SEARCHING" , "" );想象一下下面的响应 41 0c 00 0d。 ELM 发送字符串！！因此，ELM 在每个“字节”之间放置了空格。并注意我已将单词字节放在引号中，因为 41 实际上是套接字中的两个字节（两个字符）。所以，我们必须做更多的处理。

希望这会有所帮助。