@Override
        public EnumSet<FlowControl> getSupportedFlowControl() {
            return EnumSet.of(FlowControl.NONE, FlowControl.RTS_CTS, FlowControl.DTR_DSR, FlowControl.XON_XOFF);
        }
emulate external XON/OFF
@throws IOException
usbSerialForAndroid/src/main/java/com/hoho/android/usbserial/driver/Cp21xxSerialDriver.java