Android ADK，PC 作为带有 libusb 的 USB 主机，批量传输错误

Question

我正在尝试使我的 PC 成为 Android 2.3.4 设备的 USB 主机，以便能够在不需要实际“配件”的情况下开发 API。为此，我需要将 PC 设置为 USB 主机和“设备”（在我的例子中是运行 2.3.4 的 Nexus One）。

我从 http://android.serverbox.ch/ 中的 libusb 代码开始，作为 PC 端以及 DemoKit 代码和 Android 的基础Android 端的文档。

两者似乎很好地协商了连接，并且接口被“声明”，但在批量传输的实际尝试中终止。在 OSX 上，错误为 -5 (LIBUSB_ERROR_NOT_FOUND)，在 Ubuntu Linux（作为 root）上，错误为 -1 (LIBUSB_ERROR_IO)。 （每个最新版本均包含最新的 libusb 1.0.8）。

这是代码。欢迎对问题提出其他评论，尽管这主要是一个概念验证，所以我真的只是在寻找批量传输不起作用的原因：

#include <stdio.h>
#include <libusb.h>
#include <string.h>

#define ENDPOINT_BULK_IN 0x83
#define ENDPOINT_BULK_OUT 0x03 // Have tried 0x00, 0x01 and 0x02

#define VID 0x18D1
#define PID 0x4E11

#define ACCESSORY_PID 0x2D00
#define ACCESSORY_ADB_PID 0x2D01 // Can't get this to work, if ADB is active, can't get handle on device

/*
ON OSX
gcc adktest.c -I/usr/local/include -o adktest -lusb-1.0.0 -I/usr/local/include -I/usr/local/include/libusb-1.0
ON UBUNTU
gcc adktest.c -I/usr/include -o adktest -lusb-1.0 -I/usr/include -I/usr/include/libusb-1.0

Testing on Nexus One with Gingerbread 2.3.4
*/

static int transferTest();
static int init(void);
static int shutdown(void);
static void error(int code);
static void status(int code);
static int setupAccessory(
const char* manufacturer,
const char* modelName,
const char* description,
const char* version,
const char* uri,
const char* serialNumber);

//static
static struct libusb_device_handle* handle;

int main (int argc, char *argv[]){
if(init() < 0)
    return;

if(setupAccessory(
    "PCHost",
    "PCHost1",
    "Description",
    "1.0",
    "http://www.mycompany.com",
    "SerialNumber") < 0){
    fprintf(stdout, "Error setting up accessory\n");
    shutdown();
    return -1;
};
if(transferTest() < 0){
    fprintf(stdout, "Error in transferTest\n");
    shutdown();
    return -1;
}   
shutdown();
fprintf(stdout, "Finished\n");
return 0;
}

static int transferTest(){
  // TEST BULK IN/OUT
  const static int PACKET_BULK_LEN=64;
  const static int TIMEOUT=5000;
  int r,i;
  int transferred;
  char answer[PACKET_BULK_LEN];
  char question[PACKET_BULK_LEN];
  for (i=0;i<PACKET_BULK_LEN; i++) question[i]=i;

    // ***FAILS HERE***
    r = libusb_bulk_transfer(handle, ENDPOINT_BULK_OUT, question, PACKET_BULK_LEN,
                             &transferred,TIMEOUT);
    if (r < 0) {
        fprintf(stderr, "Bulk write error %d\n", r);
        error(r);
        return r;
    }
    fprintf(stdout, "Wrote %d bytes", r);

    r = libusb_bulk_transfer(handle, ENDPOINT_BULK_IN, answer,PACKET_BULK_LEN,
                             &transferred, TIMEOUT);
    if (r < 0) {
        fprintf(stderr, "Bulk read error %d\n", r);
        error(r);
        return r;
    }
    fprintf(stdout, "Read %d bytes", r);

    if (transferred < PACKET_BULK_LEN) {
        fprintf(stderr, "Bulk transfer short read (%d)\n", r);
        error(r);
        return -1;
    }
    printf("Bulk Transfer Loop Test Result:\n");
    //     for (i=0;i< PACKET_BULK_LEN;i++) printf("%i, %i,\n ",question[i],answer[i]);
    for(i = 0;i < PACKET_BULK_LEN; i++) {
        if(i%8 == 0)
            printf("\n");
        printf("%02x, %02x; ",question[i],answer[i]);
    }
    printf("\n\n");

    return 0;

}


static int init(){
libusb_init(NULL);
if((handle = libusb_open_device_with_vid_pid(NULL, VID, PID)) == NULL){
    fprintf(stdout, "Problem acquiring handle\n");
    return -1;
}
libusb_claim_interface(handle, 0);  

return 0;
}

static int shutdown(){
if(handle != NULL)
    libusb_release_interface (handle, 0);
libusb_exit(NULL);
return 0;
}

static int setupAccessory(
const char* manufacturer,
const char* modelName,
const char* description,
const char* version,
const char* uri,
const char* serialNumber){

unsigned char ioBuffer[2];
int devVersion;
int response;

response = libusb_control_transfer(
    handle, //handle
    0xC0, //bmRequestType
    51, //bRequest
    0, //wValue
    0, //wIndex
    ioBuffer, //data
    2, //wLength
    0 //timeout
);

if(response < 0){error(response);return-1;}

devVersion = ioBuffer[1] << 8 | ioBuffer[0];
fprintf(stdout,"Version Code Device: %d\n", devVersion);

usleep(1000);//sometimes hangs on the next transfer :(

response = libusb_control_transfer(handle,0x40,52,0,0,(char*)manufacturer,strlen(manufacturer),0);
if(response < 0){error(response);return -1;}
response = libusb_control_transfer(handle,0x40,52,0,1,(char*)modelName,strlen(modelName)+1,0);
if(response < 0){error(response);return -1;}
response = libusb_control_transfer(handle,0x40,52,0,2,(char*)description,strlen(description)+1,0);
if(response < 0){error(response);return -1;}
response = libusb_control_transfer(handle,0x40,52,0,3,(char*)version,strlen(version)+1,0);
if(response < 0){error(response);return -1;}
response = libusb_control_transfer(handle,0x40,52,0,4,(char*)uri,strlen(uri)+1,0);
if(response < 0){error(response);return -1;}
response = libusb_control_transfer(handle,0x40,52,0,5,(char*)serialNumber,strlen(serialNumber)+1,0);
if(response < 0){error(response);return -1;}

fprintf(stdout,"Accessory Identification sent\n", devVersion);

response = libusb_control_transfer(handle,0x40,53,0,0,NULL,0,0);
if(response < 0){error(response);return -1;}

fprintf(stdout,"Attempted to put device into accessory mode\n", devVersion);

if(handle != NULL)
    libusb_release_interface (handle, 0);

int tries = 4;
for(;;){
    tries--;
    if((handle = libusb_open_device_with_vid_pid(NULL, VID, ACCESSORY_PID)) == NULL){
        if(tries < 0){
            return -1;
        }
    }else{
        break;
    }
    sleep(1);
}

libusb_claim_interface(handle, 0);
fprintf(stdout, "Interface claimed, ready to transfer data\n");
return 0;
}

// error reporting function left out for brevity

这是 Android 应用程序：

package com.cengen.android.pchost;

import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.os.ParcelFileDescriptor;
import com.android.future.usb.UsbAccessory;
import com.android.future.usb.UsbManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class MainActivity extends Activity implements Runnable
{
  private final Logger logger = LoggerFactory.getLogger("PCHost");

  private UsbManager usbManager;

  UsbAccessory accessory;
  ParcelFileDescriptor accessoryFileDescriptor;
  FileInputStream accessoryInput;
  FileOutputStream accessoryOutput;

  private final BroadcastReceiver usbBroadcastReceiver = new BroadcastReceiver()
  {
    public void onReceive(Context context, Intent intent)
    {
      String action = intent.getAction();
      if (UsbManager.ACTION_USB_ACCESSORY_ATTACHED.equals(action))
      {
        synchronized (this)
        {
          accessory = UsbManager.getAccessory(intent);
        }
      }
      else if (UsbManager.ACTION_USB_ACCESSORY_DETACHED.equals(action))
      {
        UsbAccessory accessory = UsbManager.getAccessory(intent);
        if (accessory != null)
        {
          // call your method that cleans up and closes communication with the accessory
        }
      }
    }
  };

  Handler messageHandler = new Handler()
  {
    @Override
    public void handleMessage(Message msg)
    {
      switch (msg.what)
      {
        case 1:
          logger.info("Got message type {}", msg.what);
//              SendFileMessage m = (SendFileMessage) msg.obj;
//              handleSendFile(m);
        break;
        case 2:
          logger.info("Got message type {}", msg.what);
//              SendFileMessage m = (SendFileMessage) msg.obj;
//              handleSendFile(m);
        break;
        case 3:
          logger.info("Got message type {}", msg.what);
//              SendFileMessage m = (SendFileMessage) msg.obj;
//              handleSendFile(m);
        break;
      }
    }
  };

  /**
   * Main USB reading loop, processing incoming data from accessory and parsing
   * it into messages via the defined format.
   */
  public void run()
  {
    int ret = 0;
    byte[] buffer = new byte[16384];
    int i;

    while (ret >= 0)
    {
      try
      {
        ret = accessoryInput.read(buffer);
        logger.debug("Read {} bytes.", ret);
      }
      catch (IOException e)
      {
        logger.debug("Exception in USB accessory input reading", e);
        break;
      }

      i = 0;
      while (i < ret)
      {
        int len = ret - i;

        switch (buffer[i])
        {
          case 0x1:
            if (len >= 3)
            {
              Message m = Message.obtain(messageHandler, 1);
//                      m.obj = new MessageTypeOne(buffer[i + 1], buffer[i + 2]);
              messageHandler.sendMessage(m);
            }
            i += 3;
            break;

          case 0x4:
            if (len >= 3)
            {
              Message m = Message.obtain(messageHandler, 1);
//                      m.obj = new MessageTypeTwo(buffer[i + 1], buffer[i + 2]);
              messageHandler.sendMessage(m);
            }
            i += 3;
            break;

          default:
            logger.debug("unknown msg: " + buffer[i]);
            i = len;
            break;
        }
      }

    }
  }

  @Override
  public void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);

    usbManager = UsbManager.getInstance(this);

    IntentFilter filter = new IntentFilter(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
    filter.addAction(UsbManager.ACTION_USB_ACCESSORY_DETACHED);
    registerReceiver(usbBroadcastReceiver, filter);

    if (getLastNonConfigurationInstance() != null)
    {
      accessory = (UsbAccessory) getLastNonConfigurationInstance();
      openAccessory(accessory);
    }
    setContentView(R.layout.main);
  }

  @Override
  public Object onRetainNonConfigurationInstance()
  {
    return accessory != null ? accessory : super.onRetainNonConfigurationInstance();
  }

 @Override
 public void onResume()
 {
   super.onResume();

   Intent intent = getIntent();
   if (accessoryInput != null && accessoryOutput != null)
     return;

   // TODO: verify, docs don't do this simple thing, not sure why?
   UsbAccessory accessory = UsbManager.getAccessory(intent);
   if (accessory != null)
     openAccessory(accessory);
   else
     logger.error("Failed to resume accessory.");
 }

  @Override
  public void onPause()
  {
    super.onPause();
    closeAccessory();
  }

  @Override
  public void onDestroy()
  {
    unregisterReceiver(usbBroadcastReceiver);
    super.onDestroy();
  }

  private void openAccessory(UsbAccessory accessory)
  {
    accessoryFileDescriptor = usbManager.openAccessory(accessory);
    if (accessoryFileDescriptor != null)
    {
      this.accessory = accessory;
      FileDescriptor fd = accessoryFileDescriptor.getFileDescriptor();
      accessoryInput = new FileInputStream(fd);
      accessoryOutput = new FileOutputStream(fd);
      Thread thread = new Thread(null, this, "AndroidPCHost");
      thread.start();
      logger.debug("accessory opened");
      // TODO: enable USB operations in the app
    }
    else
    {
      logger.debug("accessory open fail");
    }
  }

  private void closeAccessory()
  {
    // TODO: disable USB operations in the app
    try
    {
      if (accessoryFileDescriptor != null)
        accessoryFileDescriptor.close();
    }
    catch (IOException e)
    {}
    finally
    {
      accessoryFileDescriptor = null;
      accessory = null;
    }
  }
}

以及清单（包括意图过滤）因此，根据文档，它会自动关联并自动权限设备）：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.mycompany.android.pchost"
      android:versionCode="1"
      android:versionName="1.0">
  <uses-feature android:name="android.hardware.usb.accessory" />
  <uses-sdk android:minSdkVersion="10" />
  <application android:label="@string/app_name" android:icon="@drawable/icon">
    <uses-library android:name="com.android.future.usb.accessory" />
        <activity android:name="MainActivity"
                  android:label="@string/app_name"
                  android:launchMode="singleInstance">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
          <intent-filter>
              <action android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED" />
          </intent-filter>

          <meta-data android:name="android.hardware.usb.action.USB_ACCESSORY_ATTACHED"
              android:resource="@xml/accessory_filter" />

        </activity>
    </application>
</manifest> 

Answer 1

最初的问题是，为了告诉设备进入附件模式而与设备的原始连接永远不会关闭。如果您在原始设备仍保持打开状态时重新打开并声明接口，USB 子系统和/或 libusb 不会抛出错误。当您实际尝试写入端点或从端点写入时，您只会收到 IO 或 NOT FOUND 错误。

通过添加：

libusb_close(handle);

在 if 语句中从初始连接释放初始接口，libusb 方面的问题得到解决。

阻止数据在这个特定的软件组合中传递的下一个问题是，Android 端在接受读取之前正在等待更大的字节段，这会导致超时（尚未解决由于哪一端而导致的）因此，如果您将缓冲区设置为与 libusb 端 (64) 匹配，您将获得从 PC 写入 Android 设备的一组初始字节。此后软件仍然会崩溃，因为 PC/libusb 端随后尝试读取数据，但 Android 端没有写入任何数据，但这只是未完成的软件，不在问题的范围内。

Answer 2

该代码示例非常有用，只需进行一些修改即可使用 libusb 在 Windows 上运行并通过 安装 WinUSB 驱动程序 href="http://zadig.akeo.ie/" rel="nofollow noreferrer">Zadig。

#include <stdio.h>
#include <libusb.h>
#include <string.h>
#ifdef _WIN32
#include <Windows.h>
#define sleep Sleep
#else
#include <unistd.h>
#endif

#define ENDPOINT_BULK_IN 0x83
#define ENDPOINT_BULK_OUT 0x03 // Have tried 0x00, 0x01 and 0x02

#define VID 0x18D1
#define PID 0x4E11

#define ACCESSORY_PID 0x2D00
#define ACCESSORY_ADB_PID 0x2D01 // Can't get this to work, if ADB is active, can't get handle on device

#define PACKET_BULK_LEN 64
#define TIMEOUT 5000

static int transferTest(void);
static int setupAccessory(
    const char* manufacturer,
    const char* modelName,
    const char* description,
    const char* version,
    const char* uri,
    const char* serialNumber);

//static
static struct libusb_device_handle* handle;

int main (int argc, char *argv[])
{
    int r, tries;

    libusb_init(NULL);
    if((handle = libusb_open_device_with_vid_pid(NULL, VID, PID)) != NULL)
    {
        libusb_claim_interface(handle, 0);  

        r = setupAccessory("PCHost",
                           "PCHost1",
                           "Description",
                           "1.0",
                           "http://www.mycompany.com",
                           "SerialNumber");

        libusb_release_interface (handle, 0);
        libusb_close(handle);

        if (r < 0)
        {
            libusb_exit(NULL);
            fprintf(stdout, "Error setting up accessory\n");
            return -1;
        }
    }

    tries = 4;
    for(;;)
    {
        tries--;
        if((handle = libusb_open_device_with_vid_pid(NULL, VID, ACCESSORY_PID)) == NULL)
        {
            if(tries < 0)
            {
                libusb_exit(NULL);
                fprintf(stdout, "Problem acquiring handle\n");
                return -1;
            }
        }
        else
        {
            break;
        }
        sleep(1);
    }

    libusb_claim_interface(handle, 0);
    fprintf(stdout, "Interface claimed, ready to transfer data\n");

    r = transferTest();

    libusb_release_interface (handle, 0);
    libusb_close(handle);

    libusb_exit(NULL);

    if (r < 0)
    {
        fprintf(stdout, "Error in transferTest\n");
        return -1;
    }   
    fprintf(stdout, "Finished\n");
    return 0;
}

static int transferTest(void)
{
    // TEST BULK IN/OUT
    int r,i;
    int transferred;
    unsigned char answer[PACKET_BULK_LEN];
    unsigned char question[PACKET_BULK_LEN];
    struct libusb_device* device;
    struct libusb_config_descriptor* config;
    struct libusb_interface_descriptor const* interfaceDesc;
    unsigned char epInAddr = ENDPOINT_BULK_IN;
    unsigned char epOutAddr = ENDPOINT_BULK_OUT;
    unsigned char idx;

    for (i=0;i<PACKET_BULK_LEN; i++) 
        question[i]=(unsigned char)i;

    device = libusb_get_device(handle);
    r = libusb_get_active_config_descriptor(device, &config);
    if (r < 0) 
    {
        fprintf(stderr, "No active descriptor error %d\n", r);
        return r;
    }

    interfaceDesc = config->interface[0].altsetting;

    for(idx = 0; idx < interfaceDesc->bNumEndpoints; idx++)
    {
        if ((interfaceDesc->endpoint[idx].bmAttributes & LIBUSB_TRANSFER_TYPE_MASK) == LIBUSB_TRANSFER_TYPE_BULK)
        {
            if ((interfaceDesc->endpoint[idx].bEndpointAddress & LIBUSB_ENDPOINT_IN) == LIBUSB_ENDPOINT_IN)
            {
                epInAddr = interfaceDesc->endpoint[idx].bEndpointAddress;
            }
            else
            {
                epOutAddr = interfaceDesc->endpoint[idx].bEndpointAddress;
            }
        }
    }

    r = libusb_bulk_transfer(handle, epOutAddr, question, PACKET_BULK_LEN,
                             &transferred,TIMEOUT);
    if (r < 0) 
    {
        fprintf(stderr, "Bulk write error %d\n", r);
        return r;
    }
    fprintf(stdout, "Wrote %d bytes", r);

    r = libusb_bulk_transfer(handle, epInAddr, answer,PACKET_BULK_LEN,
        &transferred, TIMEOUT);
    if (r < 0) 
    {
        fprintf(stderr, "Bulk read error %d\n", r);
        return r;
    }
    fprintf(stdout, "Read %d bytes", r);

    if (transferred < PACKET_BULK_LEN) 
    {
        fprintf(stderr, "Bulk transfer short read (%d)\n", r);
        return -1;
    }
    printf("Bulk Transfer Loop Test Result:\n");
    for(i = 0; i < PACKET_BULK_LEN; i++) 
    {
        if(i%8 == 0)
            printf("\n");
        printf("%02x, %02x; ",question[i],answer[i]);
    }
    printf("\n\n");

    return 0;

}

static int setupAccessory(
    const char* manufacturer,
    const char* modelName,
    const char* description,
    const char* version,
    const char* uri,
    const char* serialNumber)
{
    unsigned char ioBuffer[2];
    int devVersion;
    int r;

    r = libusb_control_transfer(
        handle, //handle
        0xC0, //bmRequestType
        51, //bRequest
        0, //wValue
        0, //wIndex
        ioBuffer, //data
        2, //wLength
        0 //timeout
        );

    if(r < 0)
    {
        return-1;
    }

    devVersion = ioBuffer[1] << 8 | ioBuffer[0];
    fprintf(stdout,"Version Code Device: %d\n", devVersion);

    sleep(1); //sometimes hangs on the next transfer :(

    if ((libusb_control_transfer(handle,0x40,52,0,0,(unsigned char*)manufacturer,strlen(manufacturer)+1,0) < 0) ||
        (libusb_control_transfer(handle,0x40,52,0,1,(unsigned char*)modelName,strlen(modelName)+1,0) < 0) ||
        (libusb_control_transfer(handle,0x40,52,0,2,(unsigned char*)description,strlen(description)+1,0) < 0) ||
        (libusb_control_transfer(handle,0x40,52,0,3,(unsigned char*)version,strlen(version)+1,0) < 0) ||
        (libusb_control_transfer(handle,0x40,52,0,4,(unsigned char*)uri,strlen(uri)+1,0) < 0) ||
        (libusb_control_transfer(handle,0x40,52,0,5,(unsigned char*)serialNumber,strlen(serialNumber)+1,0) < 0))
    {
        return -1;
    }

    fprintf(stdout,"Accessory Identification sent\n", devVersion);

    r = libusb_control_transfer(handle,0x40,53,0,0,NULL,0,0);
    if(r < 0)
    {
        return -1;
    }

    fprintf(stdout,"Attempted to put device into accessory mode\n", devVersion);
    return 0;
}

除了 @ColinM 的答案中提到的一些重构和添加必要的 libusb_close(handle) 调用之外，这主要是添加：

1. 可用端点的枚举
2. 如果初始 PID/VID 不是，则假设设备已处于附件模式成立