【发布时间】：2016-08-29 10:37:39
【问题描述】：
我尝试从 Etrex 10 Garmin GPS 读取其 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）的 PVT（位置、速度、时间）记录。首先我使用一个模拟这种通信的 Windows 应用程序，我监控了 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，开始会话数据包）00 00 00 00 05 00 00 00 00 00 00 00
（GPS到PC，确认开始会话）00 00 00 00 06 00 00 00 04 00 00 00 0b ba aa e7
这是本文档第 6 节的一部分，展示了主机和设备 (GPS) 如何进行通信： …………
6-示例通信会话
本部分提供 USB 主机和 Garmin USB GPS 之间的示例通信会话。以下消息按时间顺序显示。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 应用程序中编写此通信。在 Android 代码中，当连接到平板电脑时，我可以识别 GPS 设备。有 3 个端点。一个 Bulk_Out，另一个 Bulk-in，第三个 Interrupt-in。当我发送开始会话 通过批量输出端点的数据包，我没有通过中断（甚至 Bulk_in）端点收到确认数据包。这是 Xamarin Studio 中使用 MONO 库的代码：
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
}
}
这是广播接收器类
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，我收到一些内容为 00 的数据包，然后我点击命令按钮和应用程序 发送 start-session-packet，BulkTransfer 函数返回 12 表示成功发送了 12 个字节但之后在广播类中没有收到任何字节。应用程序开始时收到的零字节表明广播类以正确的方式工作，但我找不到为什么不承认 来自 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 没有关于此的任何文档。你能告诉我出了什么问题使用此代码或程序？ 任何帮助或指导线都非常感谢
这是 android 应用程序的快照，正如我在 2016/9/4 的评论中所述
这是我在这一步中实现的代码：
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;
}
【问题讨论】：
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