manager = (UsbManager) getSystemService(Context.USB_SERVICE);
    // ------------------------------------------------------------------
    mPermissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(
            ACTION_USB_PERMISSION), 0);
    IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
    registerReceiver(mUsbReceiver, filter);
    // -------------------------------------------------------------------
    HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
    Iterator<UsbDevice> deviceIterator = deviceList.values().iterator();
    String i = "";
    while (deviceIterator.hasNext()) {
        device = deviceIterator.next();
        manager.requestPermission(device, mPermissionIntent);
        i += "n" + "DeviceID: " + device.getDeviceId() + "n"
                + "DeviceName: " + device.getDeviceName() + "n"
                + "DeviceClass: " + device.getDeviceClass() + " - "
                + "DeviceSubClass: " + device.getDeviceSubclass() + "n"
                + "VendorID: " + device.getVendorId() + "n"
                + "ProductID: " + device.getProductId() + "n"
                + "DeviceProtocol: " + device.getDeviceProtocol() + "n"
                + "Interface: " + device.getInterface(0) + "n";

        textInfo.setText(i);

UsbInterface usbInterface = device.getInterface(0);
        UsbEndpoint usbEndpoint = usbInterface.getEndpoint(0);

UsbDeviceConnection connection = manager.openDevice(device);
        connection.claimInterface(usbInterface, true);

String setData = "AT";
byte[] bytesVar = setData.getBytes();

        connection.bulkTransfer(endpoint, bytesVar, bytesVar.length, TIMEOUT);

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) {
                        // call method to set up device communication
                    }
                } else {
                    Log.d("ERROR", "permission denied for device " + device);
                }
            }
        }
    }
};