Android USB Host not able to read and write data for Cp2102SerialDriver

Question

I am working on Android host application where I need to read data from all attached device. Using usb to serial cable "Cp2102SerialDriver".

Here is the example link which I referring

http://code.google.com/p/usb-serial-for-android/

I am successfully able to display attached devices with vendor and product ID, here is the sample code

/** Simple container for a UsbDevice and its driver. */
private static class DeviceEntry {
    public UsbDevice device;
    public UsbSerialDriver driver;

    DeviceEntry(UsbDevice device, UsbSerialDriver driver) {
        this.device = device;
        this.driver = driver;
    }
}

final List<DeviceEntry> result = new ArrayList<DeviceEntry>();
            for (final UsbDevice device : mUsbManager.getDeviceList()
                    .values()) {

                final List<UsbSerialDriver> drivers = UsbSerialProber
                        .probeSingleDevice(mUsbManager, device);

                Log.d(TAG, "Found usb device: " + device);
                if (drivers.isEmpty()) {
                    Log.d(TAG, "  - No UsbSerialDriver available.");
                    result.add(new DeviceEntry(device, null));
                } else {
                    for (UsbSerialDriver driver : drivers) {
                        Log.d(TAG, "  + " + driver);
                        result.add(new DeviceEntry(device, driver));
                    }
                }

I refer to the android host tutorial

http://developer.android.com/guide/topics/connectivity/usb/host.html

to communicate with the devices

mListView.setOnItemClickListener(new ListView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            Log.d(TAG, "Pressed item " + position);
            if (position >= mEntries.size()) {
                Log.w(TAG, "Illegal position.");
                return;
            }

            final DeviceEntry entry = mEntries.get(position);


            if (entry.device != null) {

                IntentFilter intentfilter = new IntentFilter(
                        "com.android.example.USB_PERMISSION");
                DeviceListActivity.this.registerReceiver(
                        mUsbReceiverPermission, intentfilter);

                Toast.makeText(DeviceListActivity.this,
                        " Registered for broadcast reciever ",
                        Toast.LENGTH_SHORT).show();
                sendData();

            }


        }
    });


private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";
private final BroadcastReceiver mUsbReceiverPermission = new BroadcastReceiver() {

    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();

        Toast.makeText(getApplicationContext(), action, Toast.LENGTH_SHORT)
                .show();
        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 = mUsbManager.openDevice(device);
                    cp2102SerialDriver = new Cp2102SerialDriver(device,
                            usbDeviceConnection);
                    try {
                        cp2102SerialDriver.open();

                        Toast.makeText(getApplicationContext(),
                                "cp2102SerialDriver is open successfully",
                                Toast.LENGTH_SHORT).show();

                    } catch (IOException e) {
                        e.printStackTrace();
                    }

                }
                 } else {
                 Log.d(TAG, "permission denied for device " + device);

                 }
            }
        }
    }
};

To write data I am using this code

String data = etText.getText().toString() + "/n";

                bytes = data.getBytes(Charset.forName("UTF-8"));
                try {
                    cp2102SerialDriver.write(bytes, 3000);
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }

But while writing I am getting exception. Thanks in advance for any help here.

Answer 1

Now I have done it by myself that exception was occurring because I was not checking USB manager have permission or not. I have added two lines on click on selected device list on above mentioned code.

if (!mUsbManager.hasPermission(entry.device)) { mUsbManager.requestPermission(entry.device,pendingIntent); }