Compile and link against libusb for android

Question

I consider trying to compile a certain C-programm which allows the control of Gembird SilverShield power outlets via USB for android. On my android HDMI TV-stick this would be very useful. There is an open project for this. It works under Linux and depends on libusb. The target platform is android ICS. I want to develop on Ubuntu Linux. What are the chances I get it working? What are the required steps. Setup android SDK, NDK, crosscompiler ...
There is an older question here, related to libusb on android but no information how.
Is it maybe easier to port the application to androids own usb library?

Here is a project called libusbdroid http://sourceforge.net/projects/libusbdroid/ . How would I link sispmctl against and install it? — highsciguy, Apr 19 '13 at 12:36

Goz · Accepted Answer · 2013-04-26T23:58:31.150

Libusb can work on a non-rooted android (provided the device supports USB host ... this is VERY important as not all devices do). You need to use the standard android USB stack. You can then get a device descriptor from the USBDevice and pass that over to libusb.

Unfortunately you also need to modify libusb. Fortunately other people have explained how you need to modify LibUSB.

LibUSB has been modified here.

Good luck!

Edit:

First you need to define a broadcast receiver:

private final BroadcastReceiver mUsbReceiver = new BroadcastReceiver() 
{
    public void onReceive(Context context, Intent intent)
    {
        String action = intent.getAction();
        if (ACTION_USB_PERMISSION.equals(action)) 
        {
            synchronized (this) 
            {
                UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);

                if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) 
                {
                    if(device != null)
                    {
                        UsbDeviceConnection deviceConnection    = mUsbManager.openDevice( device );
                        Log.d( "USB",  deviceConnection.getSerial() );
                    }
                } 
                else 
                {
                    Log.d( "USB", "permission denied for device " + device);
                }
            }
        }
    }
}

Now you need to create a USBManager and enumerate the devices:

    mUsbManager         = (UsbManager) getSystemService( Context.USB_SERVICE );
    HashMap< String, UsbDevice > stringDeviceMap    =       mUsbManager.getDeviceList();
    Collection< UsbDevice > usbDevices              = stringDeviceMap.values();

    mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent( ACTION_USB_PERMISSION ), 0 );
    IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
    registerReceiver( mUsbReceiver, filter );

    Iterator< UsbDevice > usbDeviceIter             = usbDevices.iterator();
    while( usbDeviceIter.hasNext() )
    {
        if ( USBDeviceValid( usbDevice ) )
        {
            // Request permission to access the device.
            mUsbManager.requestPermission( usbDevice, mPermissionIntent );

            // Open the device.
            UsbDeviceConnection connection = mUsbManager.openDevice( usbDevice );
            int fd = connection.getFileDescriptor();

            // Now pass the file descriptor to libusb through a native call.
        }
    }

Edit 2:

Getting libusb to build is just a matter of putting the files somewhere handy (I put them in jni/libusb) and then adding the following lines to your Android.mk:

include $(CLEAR_VARS)
LOCAL_MODULE    := libusb
LOCAL_SRC_FILES := libusb/core.c libusb/descriptor.c libusb/io.c libusb/sync.c libusb/os/linux_usbfs.c

LOCAL_LDLIBS    := -llog
include $(BUILD_SHARED_LIBRARY)

Can I somewhere find an example for the creation and passing of the device descriptor. — highsciguy, Apr 26 '13 at 10:31
Yes, it helps me. USB hosts should be supported (I successfully connected other USB devices). I shall need to figure out how to compile and link the libraries still. So far I only wrote Java Android apps. — highsciguy, Apr 26 '13 at 23:25
@highsciguy: I've edited my post with a bit of handy info on building libusb. If you like the answer feel free to click the little blue +50 box under the answered tick ;) — Goz, Apr 26 '13 at 23:58
... where the jni directory is in the android ndk path, or do you refer to /usr/lib/*-linux-gnu/jni? I thought you get the points once I click the check ... — highsciguy, Apr 27 '13 at 09:17
@highsciguy: The jni directory is usually off the base of your android application directory. — Goz, Apr 27 '13 at 10:20
Can you please add some code in the JNI on how to use the lib with file descriptior, as I'm having trouble claiming iterfaces and thus cannot transfer anything. Thank you very much. — Bojan Kseneman, Jun 19 '14 at 07:58
When I use the linked code for libusb and call `libusb_init`, it returns `-99` (i.e. `LIBUSB_ERROR_OTHER`). Do you have any idea why that would be and what I need to do about it? — JellicleCat, Oct 15 '16 at 18:39
I am facing this issue https://stackoverflow.com/questions/44946675/android-ndk-make-no-rule-to-make-target-stop do you have an idea what could be the problem ? — N Sharma, Jul 06 '17 at 11:17

score 4 · Answer 2 · answered Aug 28 '14 at 14:03

The solution I implemented is to open the USB device using the Java APIs and then using the file descriptor with libusb.I used libusb from openni project by primesense(https://github.com/OpenNI/OpenNI2)

Code bits:

Opening the device(Using swig):

int LibUsbAndroid::android_open(libusb_device *device, libusb_device_handle **devHandle)
{
    int fd = USBJNICallbacks::getCallback()->getDeviceFd(device->bus_number, device->device_address);

    __android_log_print(ANDROID_LOG_VERBOSE,"USB","Got  FD:%d",fd);
    if(fd==-1)
    {
        __android_log_print(ANDROID_LOG_ERROR,"USB","android_open, bad fd");
        return -1;
    }

    return libusb_open(device, devHandle, fd);
}

Opening the device in JAVA code(Not running on main thread!):

public int getDeviceFd(int busNumber, int deviceAddress) {
        UsbDevice device = findDevice(busNumber, deviceAddress);

        if(device!=null)
        {
            mReceivedPermission = false;
            PermissionRequester pr = new PermissionRequester(device);
            pr.run();

            if(!mUsbManager.hasPermission(device))
            {
                Log.v("USB", "Requesting permissiom to device");
                mPermissionIntent = PendingIntent.getBroadcast(mContext, 0, new Intent(ACTION_USB_PERMISSION), 0);
                IntentFilter filterPermission = new IntentFilter(ACTION_USB_PERMISSION);
                mContext.registerReceiver(mUsbPermissionReceiver, filterPermission);
                mUsbManager.requestPermission(device, mPermissionIntent);
            }
            else
            {
                Log.v("USB", "Already has permission");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

                mReceivedPermission = true;

                Log.v("USB", "Opening device");
                OpenDevice od = openDevice(device);
                Log.v("USB", "Adding to open devices");
                mOpenDevices.put(""+busNumber+"/"+deviceAddress, od);


            }

            Log.v("USB", "Waiting for permission");
            waitForPermissionResult();
            OpenDevice od = mOpenDevices.get(""+busNumber+"/"+deviceAddress);
            if(od!=null)
            {
                Log.v("USB", "Getting FD");
                int result = od.mConnection.getFileDescriptor();

                Log.i("USB","USB File desc:"+result);
                return result;
            }
            else
            {
                Log.v("USB", "Error getting FD");
                return -1;
            }
        }

        return -1;
    }

Permission handling code:

private BroadcastReceiver mUsbPermissionReceiver=new BroadcastReceiver(){

@Override
public void onReceive(Context context, Intent intent) {

    Log.v("USB", "Received permission result");
    String action = intent.getAction();
    if (ACTION_USB_PERMISSION.equals(action)) {
        synchronized (this) {
            UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
            if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                Log.v("USB", "Received permission result OK");
                if(device != null){
                    Log.v("USB", "Device OK");
                    mContext.unregisterReceiver(this);      
                    Log.v("USB", "Openning device");
                    OpenDevice od = openDevice(device);
                    Log.v("USB", "Adding to open device list");
                    mOpenDevices.put(""+od.mBus+"/"+od.mAddress,od);

                    Log.v("USB", "Received permission is true");
                    mReceivedPermission = true;
                } 
                else {
                    Log.d(TAG, "permission denied for device " + device);
                }
            }
        }
    }
}

};

Open function:

public OpenDevice openDevice(UsbDevice device) {
        UsbDeviceConnection connection = mUsbManager.openDevice(device);

        Log.i("USB","Device name="+device.getDeviceName());

        int bus = getBusNumber(device.getDeviceName());
        int address = getAddress(device.getDeviceName());

        return new OpenDevice(device, connection, bus, address);

    }

USB lib change(core.c):

int API_EXPORTED libusb_open(libusb_device *dev,
    libusb_device_handle **handle, int fd)
{
    struct libusb_context *ctx = DEVICE_CTX(dev);
    struct libusb_device_handle *_handle;
    size_t priv_size = usbi_backend->device_handle_priv_size;
    int r;
    usbi_dbg("open %d.%d", dev->bus_number, dev->device_address);

    _handle = malloc(sizeof(*_handle) + priv_size);
    if (!_handle)
        return LIBUSB_ERROR_NO_MEM;

    r = usbi_mutex_init(&_handle->lock, NULL);
    if (r) {
        free(_handle);
        return LIBUSB_ERROR_OTHER;
    }

    _handle->dev = libusb_ref_device(dev);
    _handle->claimed_interfaces = 0;
    memset(&_handle->os_priv, 0, priv_size);

    r = usbi_backend->open(_handle,fd);
    if (r < 0) {
        usbi_dbg("open %d.%d returns %d", dev->bus_number, dev->device_address, r);
        libusb_unref_device(dev);
        usbi_mutex_destroy(&_handle->lock);
        free(_handle);
        return r;
    }

    usbi_mutex_lock(&ctx->open_devs_lock);
    list_add(&_handle->list, &ctx->open_devs);
    usbi_mutex_unlock(&ctx->open_devs_lock);
    *handle = _handle;
    /* At this point, we want to interrupt any existing event handlers so
     * that they realise the addition of the new device's poll fd. One
     * example when this is desirable is if the user is running a separate
     * dedicated libusb events handling thread, which is running with a long
     * or infinite timeout. We want to interrupt that iteration of the loop,
     * so that it picks up the new fd, and then continues. */
    usbi_fd_notification(ctx);

    return 0;
}

op_open(libusb_fs.c) change:

static int op_open(struct libusb_device_handle *handle, int fd)
{
    struct linux_device_handle_priv *hpriv = _device_handle_priv(handle);
    char filename[PATH_MAX];

    _get_usbfs_path(handle->dev, filename);
    usbi_dbg("opening %s", filename);

    hpriv->fd = fd;

    if (hpriv->fd < 0) {
        if (errno == EACCES) {
            usbi_err(HANDLE_CTX(handle), "libusb couldn't open USB device %s: "
                "Permission denied.", filename);
            usbi_err(HANDLE_CTX(handle),
                "libusb requires write access to USB device nodes.");
            return LIBUSB_ERROR_ACCESS;
        } else if (errno == ENOENT) {
            usbi_err(HANDLE_CTX(handle), "libusb couldn't open USB device %s: "
                "No such file or directory.", filename);
            return LIBUSB_ERROR_NO_DEVICE;
        } else {
            usbi_err(HANDLE_CTX(handle),
                "open failed, code %d errno %d", hpriv->fd, errno);
            return LIBUSB_ERROR_IO;
        }
    }

    return usbi_add_pollfd(HANDLE_CTX(handle), hpriv->fd, POLLOUT);
}

Thanks, this is quite helpful. Can you also share how you create the libusb_device* that's required for the call to libusb_open()? — rsp1984, Oct 22 '16 at 15:45

score 1 · Answer 3 · answered Apr 25 '13 at 21:01

1

Even if you get it compiled, Android is probably not going to let you access the USB device through libusb unless your device is rooted. If it is feasible to port your app to Android's native USB stack, that would almost certainly be a more stable solution.

answered Apr 25 '13 at 21:01

mlc

1,668
2
16
30

1

The device is rooted. This is also true for all other Rikomagic III HDMI-sticks with up-to-date firmware. If this is the only reason not to use libusb, I would give it a try. But it would also be interesting to know how similar Android's USB stack and libusb are, if you know anything about it ... Also: How can I use it in C. – highsciguy Apr 26 '13 at 08:27

score 1 · Answer 4 · edited Apr 30 '13 at 16:33

You can also try to use android serial port api

Here is example of serial port init.

private FileDescriptor mFd;
private FileInputStream mFileInputStream;
private FileOutputStream mFileOutputStream;

public SerialPort(File device, int baudrate, int flags) throws SecurityException, IOException {

    /* Check access permission */
    if (!device.canRead() || !device.canWrite()) {
        try {
            /* Missing read/write permission, trying to chmod the file */
            Process su;
            su = Runtime.getRuntime().exec("/system/bin/su");
            String cmd = "chmod 666 " + device.getAbsolutePath() + "\n"
                    + "exit\n";
            su.getOutputStream().write(cmd.getBytes());
            if ((su.waitFor() != 0) || !device.canRead()
                    || !device.canWrite()) {
                throw new SecurityException();
            }
        } catch (Exception e) {
            e.printStackTrace();
            throw new SecurityException();
        }
    }

    mFd = open("/dev/ttyACM0", 9600, 0);
    if (mFd == null) {
        Log.e(TAG, "native open returns null");
        throw new IOException();
    }
    mFileInputStream = new FileInputStream(mFd);
    mFileOutputStream = new FileOutputStream(mFd);
}

So did it with use devices on USB host.