Question

我尝试从Etrex 10 Garmin GPS读取PVT（位置，速度，时间）记录，其USB端口连接到Android平板电脑（三星Galaxy Tab S，型号SM-T705支持USB主机功能）。首先我用过一个用于模拟此通信的Windows应用程序，我监控USB发送/接收的数据包。根据Garmin文档（Garmin GPS接口规范，USB附录），这些数据包已成功发送和接收（所有数字均为十六进制）：

（PC到GPS，开始会话包）00 00 00 00 05 00 00 00 00 00 00 00

（GPS到PC，确认启动会话）00 00 00 00 06 00 00 00 04 00   00 00 0b ba aa e7

这是本文档第6部分的一部分，它显示了主机和设备（GPS）如何进行通信： ..........................

6样本通信会话

本节提供USB主机和Garmin USB GPS之间的示例通信会话。以下信息按时间顺序列出。所有数据均以HEX格式显示。批量输出（USB传输层 - 开始会话）主机首先将其发送到Garmin USB设备，告诉它准备传输。 00 00 00 00 05 00 00 00 00 00 00 00 中断输入（USB传输层 - 会话已启动）设备响应主机，让主机知道设备已准备好进行对话。 00 00 00 00 06 00 00 00 04 00 00 00 37 C4 E4 AB

..............................

我尝试在Android应用程序中对此通信进行编码。在Android代码中，我可以在连接到平板电脑时识别GPS设备。有3个端点。一个Bulk_Out，另一个Bulk-in和第三个Interrupt-in.When我发送开始会话在Bulk-out端点上的数据包，我不会通过中断（甚至是Bulk_in）端点接收Acknowledge数据包.Xamarin Studio中的代码使用MONO库：

public class MainActivity : Activity
{
private UsbManager m_USBManager = null;
private UsbDevice m_GPS = null;
private UsbInterface m_USBInterface = null;
private UsbEndpoint m_BulkOut = null;
private UsbEndpoint m_BulkIn = null;
private UsbEndpoint m_InterruptIn = null;
private UsbDeviceConnection m_USBConnection = null;

public static string ACTION_USB_PERMISSION = "GarminEtrex10.USB_PERMISSION";

private TextView m_TxMsg;
private ListView m_LvTxRxRows;

private USBReceiver m_USBRx;
PendingIntent m_PermissionIntent;

public List<TxRxRow> m_TxRxRows = new List<TxRxRow> ();

protected override void OnCreate (Bundle bundle)
{
    base.OnCreate (bundle);

    SetContentView (Resource.Layout.Main);

    this.m_PermissionIntent = PendingIntent.GetBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), 0);

    Button button = FindViewById<Button> (Resource.Id.myButton);
    this.m_TxMsg = FindViewById<TextView> (Resource.Id.TxMsg);
    this.m_LvTxRxRows = FindViewById<ListView> (Resource.Id.LvTxRx);

    this.m_USBManager = (UsbManager) this.GetSystemService (Context.UsbService);
    this.m_USBRx = new USBReceiver (this, this.m_USBManager);
    IntentFilter filter = new IntentFilter (ACTION_USB_PERMISSION);
    RegisterReceiver (this.m_USBRx, filter);

    button.Click += new EventHandler (this.ButtonClicked);
}

protected override void OnResume ()
{
    base.OnResume ();

    bool bHasPermission = false;

    if (this.m_USBManager != null)
    {
        foreach (string strKey in this.m_USBManager.DeviceList.Keys)
        {
            UsbDevice usbd = this.m_USBManager.DeviceList [strKey];
            if (usbd.VendorId == 2334)//Garmin product Id
            {
                this.m_GPS = usbd;
                break;
            }
        }
    }
    else
        this.m_TxMsg.Text = "USB Manager is null";
    if (this.m_GPS != null) 
    {
        this.m_USBManager.RequestPermission (this.m_GPS, this.m_PermissionIntent);
        bHasPermission = this.m_USBManager.HasPermission (this.m_GPS);
        this.m_TxMsg.Text = "Garmin GPS found.";
        if (bHasPermission)
            this.m_TxMsg.Text += " and have permission to use it.";
        else
            this.m_TxMsg.Text += " but not have permission to use it.";
    }
    else
        this.m_TxMsg.Text = "No GPS found.";
    if (bHasPermission) 
    {
        this.m_USBInterface = this.m_GPS.GetInterface (0);
        if (this.m_USBInterface != null) 
        {

            for (int i = 0; i < this.m_USBInterface.EndpointCount; i++)
            {
                UsbEndpoint ep = this.m_USBInterface.GetEndpoint (i);
                if (ep.Type == UsbAddressing.XferBulk && ep.Direction == UsbAddressing.Out && this.m_BulkOut == null)
                    this.m_BulkOut = ep;
                if (ep.Type == UsbAddressing.XferBulk && ep.Direction == UsbAddressing.In && this.m_BulkIn == null)
                    this.m_BulkIn = ep;
                if (ep.Type == UsbAddressing.XferInterrupt && ep.Direction == UsbAddressing.DirMask && this.m_InterruptIn == null) 
                    this.m_InterruptIn = ep;
            }
        }
    }
}

public void PopulateListView(byte[] bytes, byte port)
{
    TxRxRow row = new TxRxRow (port, bytes);
    this.m_TxRxRows.Add (row);
    TxRxAdapter adp = new TxRxAdapter (this, this.m_TxRxRows);
    this.m_LvTxRxRows.Adapter = adp;
}

public void SetStatus(string strMsg)
{
    this.m_TxMsg.Text = strMsg;
}

public void SetDevice(UsbDevice gps, UsbInterface gpsInterface, UsbDeviceConnection gpsConnection, UsbEndpoint gpsBulkout,UsbEndpoint gpsBultIn,UsbEndpoint gpsInterruptIn)
{
    if (this.m_BulkIn != null)
        return;
    this.m_GPS = gps;
    this.m_USBConnection = gpsConnection;
    this.m_USBInterface = gpsInterface;
    this.m_InterruptIn = gpsInterruptIn;
    this.m_BulkIn = gpsBultIn;
    this.m_BulkOut = gpsBulkout;
}
private void ButtonClicked(object sender, EventArgs e)
{
    if (this.m_BulkOut == null || (this.m_BulkIn == null && this.m_InterruptIn == null)) 
    {
        Toast.MakeText (this, "Could not find right endpoints", ToastLength.Long).Show ();
        return;
    }
    if(this.m_USBConnection ==null)
        this.m_USBConnection = this.m_USBManager.OpenDevice (this.m_GPS);
    if (this.m_USBConnection == null) 
    {
        Toast.MakeText (this, "Can not open USB device", ToastLength.Long).Show ();
        return;
    }

    if (!this.m_USBConnection.ClaimInterface (this.m_USBInterface, true)) 
    {
        Toast.MakeText (this, "Can not claim interface", ToastLength.Long).Show ();
        return;
    }

    int sentBytesCount = 0;

    #region Send Start_Session Packet
    byte[] obuffer = new byte[12];
    for(int i = 0; i < 12; i++)
        obuffer[i] = 0;
    obuffer[4]=5;

    this.m_TxMsg.Text = "Sending Start session packet....";
    sentBytesCount += this.m_USBConnection.BulkTransfer (this.m_BulkOut, obuffer, 12, 100);

    if (sentBytesCount >= 0) 
    {
        this.m_TxMsg.Text = "Sent bytes = "+sentBytesCount.ToString();
        this.PopulateListView(obuffer,1);
        this.m_USBRx.ReceiveFlag = true;
        this.m_USBConnection.RequestWaitAsync();
    }
    else
    {
        Toast.MakeText (this, "Sent bytes for start session packet = 0.operation failed", ToastLength.Long).Show ();
    }
    #endregion
}
}

这是braodcast接收器类

public class USBReceiver : BroadcastReceiver
{
private UsbManager m_USBMngr = null;
private Context m_Activity = null;
private UsbEndpoint m_BulkIN = null;
private UsbEndpoint m_InterruptIN = null;
private UsbDeviceConnection m_USBConnection=null;

public bool ReceiveFlag = false;

public USBReceiver(Context activity, UsbManager mngr) 
{
    this.m_Activity = activity;
    this.m_USBMngr = mngr;
}
public override void OnReceive (Context context, Intent intent)
{
    String action = intent.Action;
    (this.m_Activity as MainActivity).SetStatus ("Receiving activity=" + intent.Action + "...");
    if (action.Equals (MainActivity.ACTION_USB_PERMISSION)) 
    {
        lock (this) 
        {
            UsbDevice device = (UsbDevice)intent.GetParcelableExtra (UsbManager.ExtraDevice);
            bool bHasPermission = intent.GetBooleanExtra (UsbManager.ExtraPermissionGranted, false);
            //For the first time initialize MainActivity local parameters
            if (this.m_USBConnection == null) 
            {
                if (device != null && bHasPermission) 
                {
                    if (device.VendorId != 2334)
                        return;
                    this.m_USBConnection = this.m_USBMngr.OpenDevice (device);
                    UsbInterface ui = device.GetInterface (0);
                    UsbEndpoint epBulkOut = null;
                    for (int i = 0; i < ui.EndpointCount; i++) 
                    {
                        UsbEndpoint ep = ui.GetEndpoint (i);
                        if (ep.Type == UsbAddressing.XferInterrupt && ep.Direction == UsbAddressing.In)
                            this.m_InterruptIN = ep;
                        if (ep.Type == UsbAddressing.XferBulk && ep.Direction == UsbAddressing.In)
                            this.m_BulkIN = ep;
                        if (ep.Type == UsbAddressing.XferBulk && ep.Direction == UsbAddressing.Out)
                            epBulkOut = ep;
                    }
                    (this.m_Activity as MainActivity).SetDevice (device, ui, this.m_USBConnection, epBulkOut, this.m_BulkIN, this.m_InterruptIN);
                }
            }
            if (this.m_BulkIN != null) 
            {
                int maxPacketSize = this.m_BulkIN.MaxPacketSize;
                byte[] buff = new byte[maxPacketSize];
                int bytesRead = this.m_USBConnection.BulkTransfer (this.m_BulkIN, buff, maxPacketSize, 4000);
                if (bytesRead > 0) 
                {
                    (this.m_Activity as MainActivity).PopulateListView (buff, 2);
                    ReceiveFlag = false;
                }
            }
            if (this.m_InterruptIN != null) 
            {
                UsbRequest req = new UsbRequest ();
                if (req.Initialize (this.m_USBConnection, this.m_InterruptIN)) 
                {

                    int maxsize = this.m_InterruptIN.MaxPacketSize;
                    Java.Nio.ByteBuffer buff = Java.Nio.ByteBuffer.Allocate (maxsize);
                    if (req.Queue (buff, maxsize)) 
                    {
                        if (this.m_USBConnection.RequestWait () == req)
                        {
                            byte[] bb = new byte[maxsize];
                            buff.Get (bb, 0, buff.Remaining ());
                            if (bb.Length > 0) 
                            {
                                (this.m_Activity as MainActivity).PopulateListView (bb, 3);
                            }
                        }
                    }
                }
            }
        }
    }
}
}

当我将GPS连接到平板电脑并运行应用程序时，我会收到一些包含00内容的数据包，然后点击命令按钮和应用程序发送start-session-packet，BulkTransfer函数返回12意味着它成功发送了12个字节但之后没有广播类中的任何接收字节。应用程序启动时收到的零字节显示广播calss以一种严谨的方式工作，但我找不到为什么不承认从GPS。似乎GPS没有收到命令字节，即使函数返回一个大于零的数字。我应该通过控制端点向GPS发送任何命令吗？Garmin没有任何关于此的文件。你能告诉我吗？这段代码或程序有什么问题？任何帮助或指南都非常受欢迎

这是android app的快照，正如我在2016/9/4的评论中所述

这是我实现此步骤的代码：

        private void ButtonClicked(object sender, EventArgs e)
    {
        if (this.m_BulkOut == null || (this.m_BulkIn == null && this.m_InterruptIn == null)) 
        {
            Toast.MakeText (this, "Could not find right endpoints", ToastLength.Long).Show ();
            return;
        }

        if (this.m_USBConnection == null) {
            try {
                this.m_USBConnection = this.m_USBManager.OpenDevice (this.m_GPS);
            } catch {
            }
        }

        if (this.m_USBConnection == null) 
        {
            Toast.MakeText (this, "Can not open USB device", ToastLength.Long).Show ();
            return;
        }

        if (!this.m_USBConnection.ClaimInterface (this.m_USBInterface, true)) 
        {
            Toast.MakeText (this, "Can not claim interface", ToastLength.Long).Show ();
            return;
        } 
        else
            this.PopulateListView (null, (byte)USBOpCode.ClaimInterface);

        int sentBytesCount = 0;

        #region Send Start_Session Packet
        byte[] obuffer = new byte[12];
        byte[] ibuffer = new byte[12];
        for(int i = 0; i < 12; i++)
        {
            obuffer[i] = 0;
            ibuffer[i] = 0;
        }
        obuffer[4]=5;

        UsbRequest req=new UsbRequest();
        if(req.Initialize(this.m_USBConnection,this.m_InterruptIn))
        {
            this.PopulateListView(null,(byte)USBOpCode.InitializeRequest);
            ByteBuffer buff=ByteBuffer.Wrap(ibuffer,0,12);
                //.Allocate(12);
            if(req.Queue(buff, 12))
            {
                this.PopulateListView(null,(byte)USBOpCode.QueueRequest);

                sentBytesCount += this.m_USBConnection.BulkTransfer (this.m_BulkOut, obuffer, obuffer.Length, 100);
                if(sentBytesCount>0)
                    this.PopulateListView(obuffer,(byte)USBOpCode.BultTransferOut);
                sentBytesCount=0;
                sentBytesCount += this.m_USBConnection.BulkTransfer (this.m_BulkOut, obuffer, obuffer.Length, 100);
                if(sentBytesCount>0)
                    this.PopulateListView(obuffer,(byte)USBOpCode.BultTransferOut);
                sentBytesCount=0;
                sentBytesCount += this.m_USBConnection.BulkTransfer (this.m_BulkOut, obuffer, obuffer.Length, 100);
                if(sentBytesCount>0)
                    this.PopulateListView(obuffer,(byte)USBOpCode.BultTransferOut);

                if(this.m_USBConnection.RequestWait() == req)
                    this.PopulateListView(null,(byte)USBOpCode.RequestWait);
                if(true)//buff.Position() > 0)
                {

                    //buff.Get(ibuffer,0,12);
                    this.PopulateListView(ibuffer,(byte)USBOpCode.InterruptIn_Received);
                }
            }
            req.Close();
        }
        this.m_USBConnection.ReleaseInterface(this.m_USBInterface);
        this.PopulateListView(null,(byte)USBOpCode.ReleaseInterface);
        return;

}

Answer 1

Garmin设备在linux上有点棘手，肯定在android上。这是（美国）商业战略的另一个案例（闭源，丑陋的文档......）

请参阅：http://wiki.openstreetmap.org/wiki/USB_Garmin_on_GNU/Linux

在linux上你需要一个名为'garmin'的内核驱动程序lsmod | grep garmin http://northwestspatial.com/wp/?p=162

这是一个针对类似问题的应用，也许您可以联系作者https://play.google.com/store/apps/details?id=com.carlopescio.sportablet

从＆＃34; USB GPS＆＃34;获取PVT数据包在Android应用中

6样本通信会话

1 个答案: