@Override
        public boolean getDTR() throws IOException {
            return mDtr;
        }
USB CDC/ACM serial driver implementation.

@author mike wakerly (opensource@hoho.com)
@see <a
     href="http://www.usb.org/developers/devclass_docs/usbcdc11.pdf">Universal
     Serial Bus Class Definitions for Communication Devices, v1.1</a>
usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/CdcAcmSerialDriver.java